xref: /frameworks/base/core/java/android/view/View.java

/*
 * Copyright (C) 2006 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package android.view;

import com.android.internal.R;
import com.android.internal.util.Predicate;
import com.android.internal.view.menu.MenuBuilder;

import android.content.ClipData;
import android.content.Context;
import android.content.res.Configuration;
import android.content.res.Resources;
import android.content.res.TypedArray;
import android.graphics.Bitmap;
import android.graphics.Camera;
import android.graphics.Canvas;
import android.graphics.Interpolator;
import android.graphics.LinearGradient;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.graphics.PixelFormat;
import android.graphics.Point;
import android.graphics.PorterDuff;
import android.graphics.PorterDuffXfermode;
import android.graphics.Rect;
import android.graphics.RectF;
import android.graphics.Region;
import android.graphics.Shader;
import android.graphics.drawable.ColorDrawable;
import android.graphics.drawable.Drawable;
import android.os.Handler;
import android.os.IBinder;
import android.os.Message;
import android.os.Parcel;
import android.os.Parcelable;
import android.os.RemoteException;
import android.os.SystemClock;
import android.os.SystemProperties;
import android.util.AttributeSet;
import android.util.Log;
import android.util.Pool;
import android.util.Poolable;
import android.util.PoolableManager;
import android.util.Pools;
import android.util.SparseArray;
import android.view.ContextMenu.ContextMenuInfo;
import android.view.accessibility.AccessibilityEvent;
import android.view.accessibility.AccessibilityEventSource;
import android.view.accessibility.AccessibilityManager;
import android.view.animation.Animation;
import android.view.animation.AnimationUtils;
import android.view.inputmethod.EditorInfo;
import android.view.inputmethod.InputConnection;
import android.view.inputmethod.InputMethodManager;
import android.widget.ScrollBarDrawable;

import java.lang.ref.WeakReference;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.WeakHashMap;

/**
 * <p>
 * This class represents the basic building block for user interface components. A View
 * occupies a rectangular area on the screen and is responsible for drawing and
 * event handling. View is the base class for <em>widgets</em>, which are
 * used to create interactive UI components (buttons, text fields, etc.). The
 * {@link android.view.ViewGroup} subclass is the base class for <em>layouts</em>, which
 * are invisible containers that hold other Views (or other ViewGroups) and define
 * their layout properties.
 * </p>
 *
 * <div class="special">
 * <p>For an introduction to using this class to develop your
 * application's user interface, read the Developer Guide documentation on
 * <strong><a href="{@docRoot}guide/topics/ui/index.html">User Interface</a></strong>. Special topics
 * include:
 * <br/><a href="{@docRoot}guide/topics/ui/declaring-layout.html">Declaring Layout</a>
 * <br/><a href="{@docRoot}guide/topics/ui/menus.html">Creating Menus</a>
 * <br/><a href="{@docRoot}guide/topics/ui/layout-objects.html">Common Layout Objects</a>
 * <br/><a href="{@docRoot}guide/topics/ui/binding.html">Binding to Data with AdapterView</a>
 * <br/><a href="{@docRoot}guide/topics/ui/ui-events.html">Handling UI Events</a>
 * <br/><a href="{@docRoot}guide/topics/ui/themes.html">Applying Styles and Themes</a>
 * <br/><a href="{@docRoot}guide/topics/ui/custom-components.html">Building Custom Components</a>
 * <br/><a href="{@docRoot}guide/topics/ui/how-android-draws.html">How Android Draws Views</a>.
 * </p>
 * </div>
 *
 * <a name="Using"></a>
 * <h3>Using Views</h3>
 * <p>
 * All of the views in a window are arranged in a single tree. You can add views
 * either from code or by specifying a tree of views in one or more XML layout
 * files. There are many specialized subclasses of views that act as controls or
 * are capable of displaying text, images, or other content.
 * </p>
 * <p>
 * Once you have created a tree of views, there are typically a few types of
 * common operations you may wish to perform:
 * <ul>
 * <li><strong>Set properties:</strong> for example setting the text of a
 * {@link android.widget.TextView}. The available properties and the methods
 * that set them will vary among the different subclasses of views. Note that
 * properties that are known at build time can be set in the XML layout
 * files.</li>
 * <li><strong>Set focus:</strong> The framework will handled moving focus in
 * response to user input. To force focus to a specific view, call
 * {@link #requestFocus}.</li>
 * <li><strong>Set up listeners:</strong> Views allow clients to set listeners
 * that will be notified when something interesting happens to the view. For
 * example, all views will let you set a listener to be notified when the view
 * gains or loses focus. You can register such a listener using
 * {@link #setOnFocusChangeListener}. Other view subclasses offer more
 * specialized listeners. For example, a Button exposes a listener to notify
 * clients when the button is clicked.</li>
 * <li><strong>Set visibility:</strong> You can hide or show views using
 * {@link #setVisibility}.</li>
 * </ul>
 * </p>
 * <p><em>
 * Note: The Android framework is responsible for measuring, laying out and
 * drawing views. You should not call methods that perform these actions on
 * views yourself unless you are actually implementing a
 * {@link android.view.ViewGroup}.
 * </em></p>
 *
 * <a name="Lifecycle"></a>
 * <h3>Implementing a Custom View</h3>
 *
 * <p>
 * To implement a custom view, you will usually begin by providing overrides for
 * some of the standard methods that the framework calls on all views. You do
 * not need to override all of these methods. In fact, you can start by just
 * overriding {@link #onDraw(android.graphics.Canvas)}.
 * <table border="2" width="85%" align="center" cellpadding="5">
 *     <thead>
 *         <tr><th>Category</th> <th>Methods</th> <th>Description</th></tr>
 *     </thead>
 *
 *     <tbody>
 *     <tr>
 *         <td rowspan="2">Creation</td>
 *         <td>Constructors</td>
 *         <td>There is a form of the constructor that are called when the view
 *         is created from code and a form that is called when the view is
 *         inflated from a layout file. The second form should parse and apply
 *         any attributes defined in the layout file.
 *         </td>
 *     </tr>
 *     <tr>
 *         <td><code>{@link #onFinishInflate()}</code></td>
 *         <td>Called after a view and all of its children has been inflated
 *         from XML.</td>
 *     </tr>
 *
 *     <tr>
 *         <td rowspan="3">Layout</td>
 *         <td><code>{@link #onMeasure}</code></td>
 *         <td>Called to determine the size requirements for this view and all
 *         of its children.
 *         </td>
 *     </tr>
 *     <tr>
 *         <td><code>{@link #onLayout}</code></td>
 *         <td>Called when this view should assign a size and position to all
 *         of its children.
 *         </td>
 *     </tr>
 *     <tr>
 *         <td><code>{@link #onSizeChanged}</code></td>
 *         <td>Called when the size of this view has changed.
 *         </td>
 *     </tr>
 *
 *     <tr>
 *         <td>Drawing</td>
 *         <td><code>{@link #onDraw}</code></td>
 *         <td>Called when the view should render its content.
 *         </td>
 *     </tr>
 *
 *     <tr>
 *         <td rowspan="4">Event processing</td>
 *         <td><code>{@link #onKeyDown}</code></td>
 *         <td>Called when a new key event occurs.
 *         </td>
 *     </tr>
 *     <tr>
 *         <td><code>{@link #onKeyUp}</code></td>
 *         <td>Called when a key up event occurs.
 *         </td>
 *     </tr>
 *     <tr>
 *         <td><code>{@link #onTrackballEvent}</code></td>
 *         <td>Called when a trackball motion event occurs.
 *         </td>
 *     </tr>
 *     <tr>
 *         <td><code>{@link #onTouchEvent}</code></td>
 *         <td>Called when a touch screen motion event occurs.
 *         </td>
 *     </tr>
 *
 *     <tr>
 *         <td rowspan="2">Focus</td>
 *         <td><code>{@link #onFocusChanged}</code></td>
 *         <td>Called when the view gains or loses focus.
 *         </td>
 *     </tr>
 *
 *     <tr>
 *         <td><code>{@link #onWindowFocusChanged}</code></td>
 *         <td>Called when the window containing the view gains or loses focus.
 *         </td>
 *     </tr>
 *
 *     <tr>
 *         <td rowspan="3">Attaching</td>
 *         <td><code>{@link #onAttachedToWindow()}</code></td>
 *         <td>Called when the view is attached to a window.
 *         </td>
 *     </tr>
 *
 *     <tr>
 *         <td><code>{@link #onDetachedFromWindow}</code></td>
 *         <td>Called when the view is detached from its window.
 *         </td>
 *     </tr>
 *
 *     <tr>
 *         <td><code>{@link #onWindowVisibilityChanged}</code></td>
 *         <td>Called when the visibility of the window containing the view
 *         has changed.
 *         </td>
 *     </tr>
 *     </tbody>
 *
 * </table>
 * </p>
 *
 * <a name="IDs"></a>
 * <h3>IDs</h3>
 * Views may have an integer id associated with them. These ids are typically
 * assigned in the layout XML files, and are used to find specific views within
 * the view tree. A common pattern is to:
 * <ul>
 * <li>Define a Button in the layout file and assign it a unique ID.
 * <pre>
 * &lt;Button
 *     android:id="@+id/my_button"
 *     android:layout_width="wrap_content"
 *     android:layout_height="wrap_content"
 *     android:text="@string/my_button_text"/&gt;
 * </pre></li>
 * <li>From the onCreate method of an Activity, find the Button
 * <pre class="prettyprint">
 *      Button myButton = (Button) findViewById(R.id.my_button);
 * </pre></li>
 * </ul>
 * <p>
 * View IDs need not be unique throughout the tree, but it is good practice to
 * ensure that they are at least unique within the part of the tree you are
 * searching.
 * </p>
 *
 * <a name="Position"></a>
 * <h3>Position</h3>
 * <p>
 * The geometry of a view is that of a rectangle. A view has a location,
 * expressed as a pair of <em>left</em> and <em>top</em> coordinates, and
 * two dimensions, expressed as a width and a height. The unit for location
 * and dimensions is the pixel.
 * </p>
 *
 * <p>
 * It is possible to retrieve the location of a view by invoking the methods
 * {@link #getLeft()} and {@link #getTop()}. The former returns the left, or X,
 * coordinate of the rectangle representing the view. The latter returns the
 * top, or Y, coordinate of the rectangle representing the view. These methods
 * both return the location of the view relative to its parent. For instance,
 * when getLeft() returns 20, that means the view is located 20 pixels to the
 * right of the left edge of its direct parent.
 * </p>
 *
 * <p>
 * In addition, several convenience methods are offered to avoid unnecessary
 * computations, namely {@link #getRight()} and {@link #getBottom()}.
 * These methods return the coordinates of the right and bottom edges of the
 * rectangle representing the view. For instance, calling {@link #getRight()}
 * is similar to the following computation: <code>getLeft() + getWidth()</code>
 * (see <a href="#SizePaddingMargins">Size</a> for more information about the width.)
 * </p>
 *
 * <a name="SizePaddingMargins"></a>
 * <h3>Size, padding and margins</h3>
 * <p>
 * The size of a view is expressed with a width and a height. A view actually
 * possess two pairs of width and height values.
 * </p>
 *
 * <p>
 * The first pair is known as <em>measured width</em> and
 * <em>measured height</em>. These dimensions define how big a view wants to be
 * within its parent (see <a href="#Layout">Layout</a> for more details.) The
 * measured dimensions can be obtained by calling {@link #getMeasuredWidth()}
 * and {@link #getMeasuredHeight()}.
 * </p>
 *
 * <p>
 * The second pair is simply known as <em>width</em> and <em>height</em>, or
 * sometimes <em>drawing width</em> and <em>drawing height</em>. These
 * dimensions define the actual size of the view on screen, at drawing time and
 * after layout. These values may, but do not have to, be different from the
 * measured width and height. The width and height can be obtained by calling
 * {@link #getWidth()} and {@link #getHeight()}.
 * </p>
 *
 * <p>
 * To measure its dimensions, a view takes into account its padding. The padding
 * is expressed in pixels for the left, top, right and bottom parts of the view.
 * Padding can be used to offset the content of the view by a specific amount of
 * pixels. For instance, a left padding of 2 will push the view's content by
 * 2 pixels to the right of the left edge. Padding can be set using the
 * {@link #setPadding(int, int, int, int)} method and queried by calling
 * {@link #getPaddingLeft()}, {@link #getPaddingTop()},
 * {@link #getPaddingRight()} and {@link #getPaddingBottom()}.
 * </p>
 *
 * <p>
 * Even though a view can define a padding, it does not provide any support for
 * margins. However, view groups provide such a support. Refer to
 * {@link android.view.ViewGroup} and
 * {@link android.view.ViewGroup.MarginLayoutParams} for further information.
 * </p>
 *
 * <a name="Layout"></a>
 * <h3>Layout</h3>
 * <p>
 * Layout is a two pass process: a measure pass and a layout pass. The measuring
 * pass is implemented in {@link #measure(int, int)} and is a top-down traversal
 * of the view tree. Each view pushes dimension specifications down the tree
 * during the recursion. At the end of the measure pass, every view has stored
 * its measurements. The second pass happens in
 * {@link #layout(int,int,int,int)} and is also top-down. During
 * this pass each parent is responsible for positioning all of its children
 * using the sizes computed in the measure pass.
 * </p>
 *
 * <p>
 * When a view's measure() method returns, its {@link #getMeasuredWidth()} and
 * {@link #getMeasuredHeight()} values must be set, along with those for all of
 * that view's descendants. A view's measured width and measured height values
 * must respect the constraints imposed by the view's parents. This guarantees
 * that at the end of the measure pass, all parents accept all of their
 * children's measurements. A parent view may call measure() more than once on
 * its children. For example, the parent may measure each child once with
 * unspecified dimensions to find out how big they want to be, then call
 * measure() on them again with actual numbers if the sum of all the children's
 * unconstrained sizes is too big or too small.
 * </p>
 *
 * <p>
 * The measure pass uses two classes to communicate dimensions. The
 * {@link MeasureSpec} class is used by views to tell their parents how they
 * want to be measured and positioned. The base LayoutParams class just
 * describes how big the view wants to be for both width and height. For each
 * dimension, it can specify one of:
 * <ul>
 * <li> an exact number
 * <li>MATCH_PARENT, which means the view wants to be as big as its parent
 * (minus padding)
 * <li> WRAP_CONTENT, which means that the view wants to be just big enough to
 * enclose its content (plus padding).
 * </ul>
 * There are subclasses of LayoutParams for different subclasses of ViewGroup.
 * For example, AbsoluteLayout has its own subclass of LayoutParams which adds
 * an X and Y value.
 * </p>
 *
 * <p>
 * MeasureSpecs are used to push requirements down the tree from parent to
 * child. A MeasureSpec can be in one of three modes:
 * <ul>
 * <li>UNSPECIFIED: This is used by a parent to determine the desired dimension
 * of a child view. For example, a LinearLayout may call measure() on its child
 * with the height set to UNSPECIFIED and a width of EXACTLY 240 to find out how
 * tall the child view wants to be given a width of 240 pixels.
 * <li>EXACTLY: This is used by the parent to impose an exact size on the
 * child. The child must use this size, and guarantee that all of its
 * descendants will fit within this size.
 * <li>AT_MOST: This is used by the parent to impose a maximum size on the
 * child. The child must gurantee that it and all of its descendants will fit
 * within this size.
 * </ul>
 * </p>
 *
 * <p>
 * To intiate a layout, call {@link #requestLayout}. This method is typically
 * called by a view on itself when it believes that is can no longer fit within
 * its current bounds.
 * </p>
 *
 * <a name="Drawing"></a>
 * <h3>Drawing</h3>
 * <p>
 * Drawing is handled by walking the tree and rendering each view that
 * intersects the the invalid region. Because the tree is traversed in-order,
 * this means that parents will draw before (i.e., behind) their children, with
 * siblings drawn in the order they appear in the tree.
 * If you set a background drawable for a View, then the View will draw it for you
 * before calling back to its <code>onDraw()</code> method.
 * </p>
 *
 * <p>
 * Note that the framework will not draw views that are not in the invalid region.
 * </p>
 *
 * <p>
 * To force a view to draw, call {@link #invalidate()}.
 * </p>
 *
 * <a name="EventHandlingThreading"></a>
 * <h3>Event Handling and Threading</h3>
 * <p>
 * The basic cycle of a view is as follows:
 * <ol>
 * <li>An event comes in and is dispatched to the appropriate view. The view
 * handles the event and notifies any listeners.</li>
 * <li>If in the course of processing the event, the view's bounds may need
 * to be changed, the view will call {@link #requestLayout()}.</li>
 * <li>Similarly, if in the course of processing the event the view's appearance
 * may need to be changed, the view will call {@link #invalidate()}.</li>
 * <li>If either {@link #requestLayout()} or {@link #invalidate()} were called,
 * the framework will take care of measuring, laying out, and drawing the tree
 * as appropriate.</li>
 * </ol>
 * </p>
 *
 * <p><em>Note: The entire view tree is single threaded. You must always be on
 * the UI thread when calling any method on any view.</em>
 * If you are doing work on other threads and want to update the state of a view
 * from that thread, you should use a {@link Handler}.
 * </p>
 *
 * <a name="FocusHandling"></a>
 * <h3>Focus Handling</h3>
 * <p>
 * The framework will handle routine focus movement in response to user input.
 * This includes changing the focus as views are removed or hidden, or as new
 * views become available. Views indicate their willingness to take focus
 * through the {@link #isFocusable} method. To change whether a view can take
 * focus, call {@link #setFocusable(boolean)}.  When in touch mode (see notes below)
 * views indicate whether they still would like focus via {@link #isFocusableInTouchMode}
 * and can change this via {@link #setFocusableInTouchMode(boolean)}.
 * </p>
 * <p>
 * Focus movement is based on an algorithm which finds the nearest neighbor in a
 * given direction. In rare cases, the default algorithm may not match the
 * intended behavior of the developer. In these situations, you can provide
 * explicit overrides by using these XML attributes in the layout file:
 * <pre>
 * nextFocusDown
 * nextFocusLeft
 * nextFocusRight
 * nextFocusUp
 * </pre>
 * </p>
 *
 *
 * <p>
 * To get a particular view to take focus, call {@link #requestFocus()}.
 * </p>
 *
 * <a name="TouchMode"></a>
 * <h3>Touch Mode</h3>
 * <p>
 * When a user is navigating a user interface via directional keys such as a D-pad, it is
 * necessary to give focus to actionable items such as buttons so the user can see
 * what will take input.  If the device has touch capabilities, however, and the user
 * begins interacting with the interface by touching it, it is no longer necessary to
 * always highlight, or give focus to, a particular view.  This motivates a mode
 * for interaction named 'touch mode'.
 * </p>
 * <p>
 * For a touch capable device, once the user touches the screen, the device
 * will enter touch mode.  From this point onward, only views for which
 * {@link #isFocusableInTouchMode} is true will be focusable, such as text editing widgets.
 * Other views that are touchable, like buttons, will not take focus when touched; they will
 * only fire the on click listeners.
 * </p>
 * <p>
 * Any time a user hits a directional key, such as a D-pad direction, the view device will
 * exit touch mode, and find a view to take focus, so that the user may resume interacting
 * with the user interface without touching the screen again.
 * </p>
 * <p>
 * The touch mode state is maintained across {@link android.app.Activity}s.  Call
 * {@link #isInTouchMode} to see whether the device is currently in touch mode.
 * </p>
 *
 * <a name="Scrolling"></a>
 * <h3>Scrolling</h3>
 * <p>
 * The framework provides basic support for views that wish to internally
 * scroll their content. This includes keeping track of the X and Y scroll
 * offset as well as mechanisms for drawing scrollbars. See
 * {@link #scrollBy(int, int)}, {@link #scrollTo(int, int)}, and
 * {@link #awakenScrollBars()} for more details.
 * </p>
 *
 * <a name="Tags"></a>
 * <h3>Tags</h3>
 * <p>
 * Unlike IDs, tags are not used to identify views. Tags are essentially an
 * extra piece of information that can be associated with a view. They are most
 * often used as a convenience to store data related to views in the views
 * themselves rather than by putting them in a separate structure.
 * </p>
 *
 * <a name="Animation"></a>
 * <h3>Animation</h3>
 * <p>
 * You can attach an {@link Animation} object to a view using
 * {@link #setAnimation(Animation)} or
 * {@link #startAnimation(Animation)}. The animation can alter the scale,
 * rotation, translation and alpha of a view over time. If the animation is
 * attached to a view that has children, the animation will affect the entire
 * subtree rooted by that node. When an animation is started, the framework will
 * take care of redrawing the appropriate views until the animation completes.
 * </p>
 * <p>
 * Starting with Android 3.0, the preferred way of animating views is to use the
 * {@link android.animation} package APIs.
 * </p>
 *
 * <a name="Security"></a>
 * <h3>Security</h3>
 * <p>
 * Sometimes it is essential that an application be able to verify that an action
 * is being performed with the full knowledge and consent of the user, such as
 * granting a permission request, making a purchase or clicking on an advertisement.
 * Unfortunately, a malicious application could try to spoof the user into
 * performing these actions, unaware, by concealing the intended purpose of the view.
 * As a remedy, the framework offers a touch filtering mechanism that can be used to
 * improve the security of views that provide access to sensitive functionality.
 * </p><p>
 * To enable touch filtering, call {@link #setFilterTouchesWhenObscured} or set the
 * android:filterTouchesWhenObscured layout attribute to true.  When enabled, the framework
 * will discard touches that are received whenever the view's window is obscured by
 * another visible window.  As a result, the view will not receive touches whenever a
 * toast, dialog or other window appears above the view's window.
 * </p><p>
 * For more fine-grained control over security, consider overriding the
 * {@link #onFilterTouchEventForSecurity} method to implement your own security policy.
 * See also {@link MotionEvent#FLAG_WINDOW_IS_OBSCURED}.
 * </p>
 *
 * @attr ref android.R.styleable#View_alpha
 * @attr ref android.R.styleable#View_background
 * @attr ref android.R.styleable#View_clickable
 * @attr ref android.R.styleable#View_contentDescription
 * @attr ref android.R.styleable#View_drawingCacheQuality
 * @attr ref android.R.styleable#View_duplicateParentState
 * @attr ref android.R.styleable#View_id
 * @attr ref android.R.styleable#View_fadingEdge
 * @attr ref android.R.styleable#View_fadingEdgeLength
 * @attr ref android.R.styleable#View_filterTouchesWhenObscured
 * @attr ref android.R.styleable#View_fitsSystemWindows
 * @attr ref android.R.styleable#View_isScrollContainer
 * @attr ref android.R.styleable#View_focusable
 * @attr ref android.R.styleable#View_focusableInTouchMode
 * @attr ref android.R.styleable#View_hapticFeedbackEnabled
 * @attr ref android.R.styleable#View_keepScreenOn
 * @attr ref android.R.styleable#View_layerType
 * @attr ref android.R.styleable#View_longClickable
 * @attr ref android.R.styleable#View_minHeight
 * @attr ref android.R.styleable#View_minWidth
 * @attr ref android.R.styleable#View_nextFocusDown
 * @attr ref android.R.styleable#View_nextFocusLeft
 * @attr ref android.R.styleable#View_nextFocusRight
 * @attr ref android.R.styleable#View_nextFocusUp
 * @attr ref android.R.styleable#View_onClick
 * @attr ref android.R.styleable#View_padding
 * @attr ref android.R.styleable#View_paddingBottom
 * @attr ref android.R.styleable#View_paddingLeft
 * @attr ref android.R.styleable#View_paddingRight
 * @attr ref android.R.styleable#View_paddingTop
 * @attr ref android.R.styleable#View_saveEnabled
 * @attr ref android.R.styleable#View_rotation
 * @attr ref android.R.styleable#View_rotationX
 * @attr ref android.R.styleable#View_rotationY
 * @attr ref android.R.styleable#View_scaleX
 * @attr ref android.R.styleable#View_scaleY
 * @attr ref android.R.styleable#View_scrollX
 * @attr ref android.R.styleable#View_scrollY
 * @attr ref android.R.styleable#View_scrollbarSize
 * @attr ref android.R.styleable#View_scrollbarStyle
 * @attr ref android.R.styleable#View_scrollbars
 * @attr ref android.R.styleable#View_scrollbarDefaultDelayBeforeFade
 * @attr ref android.R.styleable#View_scrollbarFadeDuration
 * @attr ref android.R.styleable#View_scrollbarTrackHorizontal
 * @attr ref android.R.styleable#View_scrollbarThumbHorizontal
 * @attr ref android.R.styleable#View_scrollbarThumbVertical
 * @attr ref android.R.styleable#View_scrollbarTrackVertical
 * @attr ref android.R.styleable#View_scrollbarAlwaysDrawHorizontalTrack
 * @attr ref android.R.styleable#View_scrollbarAlwaysDrawVerticalTrack
 * @attr ref android.R.styleable#View_soundEffectsEnabled
 * @attr ref android.R.styleable#View_tag
 * @attr ref android.R.styleable#View_transformPivotX
 * @attr ref android.R.styleable#View_transformPivotY
 * @attr ref android.R.styleable#View_translationX
 * @attr ref android.R.styleable#View_translationY
 * @attr ref android.R.styleable#View_visibility
 *
 * @see android.view.ViewGroup
 */
public class View implements Drawable.Callback, KeyEvent.Callback, AccessibilityEventSource {
    private static final boolean DBG = false;

    /**
     * The logging tag used by this class with android.util.Log.
     */
    protected static final String VIEW_LOG_TAG = "View";

    /**
     * Used to mark a View that has no ID.
     */
    public static final int NO_ID = -1;

    /**
     * This view does not want keystrokes. Use with TAKES_FOCUS_MASK when
     * calling setFlags.
     */
    private static final int NOT_FOCUSABLE = 0x00000000;

    /**
     * This view wants keystrokes. Use with TAKES_FOCUS_MASK when calling
     * setFlags.
     */
    private static final int FOCUSABLE = 0x00000001;

    /**
     * Mask for use with setFlags indicating bits used for focus.
     */
    private static final int FOCUSABLE_MASK = 0x00000001;

    /**
     * This view will adjust its padding to fit sytem windows (e.g. status bar)
     */
    private static final int FITS_SYSTEM_WINDOWS = 0x00000002;

    /**
     * This view is visible.  Use with {@link #setVisibility}.
     */
    public static final int VISIBLE = 0x00000000;

    /**
     * This view is invisible, but it still takes up space for layout purposes.
     * Use with {@link #setVisibility}.
     */
    public static final int INVISIBLE = 0x00000004;

    /**
     * This view is invisible, and it doesn't take any space for layout
     * purposes. Use with {@link #setVisibility}.
     */
    public static final int GONE = 0x00000008;

    /**
     * Mask for use with setFlags indicating bits used for visibility.
     * {@hide}
     */
    static final int VISIBILITY_MASK = 0x0000000C;

    private static final int[] VISIBILITY_FLAGS = {VISIBLE, INVISIBLE, GONE};

    /**
     * This view is enabled. Intrepretation varies by subclass.
     * Use with ENABLED_MASK when calling setFlags.
     * {@hide}
     */
    static final int ENABLED = 0x00000000;

    /**
     * This view is disabled. Intrepretation varies by subclass.
     * Use with ENABLED_MASK when calling setFlags.
     * {@hide}
     */
    static final int DISABLED = 0x00000020;

   /**
    * Mask for use with setFlags indicating bits used for indicating whether
    * this view is enabled
    * {@hide}
    */
    static final int ENABLED_MASK = 0x00000020;

    /**
     * This view won't draw. {@link #onDraw} won't be called and further
     * optimizations
     * will be performed. It is okay to have this flag set and a background.
     * Use with DRAW_MASK when calling setFlags.
     * {@hide}
     */
    static final int WILL_NOT_DRAW = 0x00000080;

    /**
     * Mask for use with setFlags indicating bits used for indicating whether
     * this view is will draw
     * {@hide}
     */
    static final int DRAW_MASK = 0x00000080;

    /**
     * <p>This view doesn't show scrollbars.</p>
     * {@hide}
     */
    static final int SCROLLBARS_NONE = 0x00000000;

    /**
     * <p>This view shows horizontal scrollbars.</p>
     * {@hide}
     */
    static final int SCROLLBARS_HORIZONTAL = 0x00000100;

    /**
     * <p>This view shows vertical scrollbars.</p>
     * {@hide}
     */
    static final int SCROLLBARS_VERTICAL = 0x00000200;

    /**
     * <p>Mask for use with setFlags indicating bits used for indicating which
     * scrollbars are enabled.</p>
     * {@hide}
     */
    static final int SCROLLBARS_MASK = 0x00000300;

    /**
     * Indicates that the view should filter touches when its window is obscured.
     * Refer to the class comments for more information about this security feature.
     * {@hide}
     */
    static final int FILTER_TOUCHES_WHEN_OBSCURED = 0x00000400;

    // note flag value 0x00000800 is now available for next flags...

    /**
     * <p>This view doesn't show fading edges.</p>
     * {@hide}
     */
    static final int FADING_EDGE_NONE = 0x00000000;

    /**
     * <p>This view shows horizontal fading edges.</p>
     * {@hide}
     */
    static final int FADING_EDGE_HORIZONTAL = 0x00001000;

    /**
     * <p>This view shows vertical fading edges.</p>
     * {@hide}
     */
    static final int FADING_EDGE_VERTICAL = 0x00002000;

    /**
     * <p>Mask for use with setFlags indicating bits used for indicating which
     * fading edges are enabled.</p>
     * {@hide}
     */
    static final int FADING_EDGE_MASK = 0x00003000;

    /**
     * <p>Indicates this view can be clicked. When clickable, a View reacts
     * to clicks by notifying the OnClickListener.<p>
     * {@hide}
     */
    static final int CLICKABLE = 0x00004000;

    /**
     * <p>Indicates this view is caching its drawing into a bitmap.</p>
     * {@hide}
     */
    static final int DRAWING_CACHE_ENABLED = 0x00008000;

    /**
     * <p>Indicates that no icicle should be saved for this view.<p>
     * {@hide}
     */
    static final int SAVE_DISABLED = 0x000010000;

    /**
     * <p>Mask for use with setFlags indicating bits used for the saveEnabled
     * property.</p>
     * {@hide}
     */
    static final int SAVE_DISABLED_MASK = 0x000010000;

    /**
     * <p>Indicates that no drawing cache should ever be created for this view.<p>
     * {@hide}
     */
    static final int WILL_NOT_CACHE_DRAWING = 0x000020000;

    /**
     * <p>Indicates this view can take / keep focus when int touch mode.</p>
     * {@hide}
     */
    static final int FOCUSABLE_IN_TOUCH_MODE = 0x00040000;

    /**
     * <p>Enables low quality mode for the drawing cache.</p>
     */
    public static final int DRAWING_CACHE_QUALITY_LOW = 0x00080000;

    /**
     * <p>Enables high quality mode for the drawing cache.</p>
     */
    public static final int DRAWING_CACHE_QUALITY_HIGH = 0x00100000;

    /**
     * <p>Enables automatic quality mode for the drawing cache.</p>
     */
    public static final int DRAWING_CACHE_QUALITY_AUTO = 0x00000000;

    private static final int[] DRAWING_CACHE_QUALITY_FLAGS = {
            DRAWING_CACHE_QUALITY_AUTO, DRAWING_CACHE_QUALITY_LOW, DRAWING_CACHE_QUALITY_HIGH
    };

    /**
     * <p>Mask for use with setFlags indicating bits used for the cache
     * quality property.</p>
     * {@hide}
     */
    static final int DRAWING_CACHE_QUALITY_MASK = 0x00180000;

    /**
     * <p>
     * Indicates this view can be long clicked. When long clickable, a View
     * reacts to long clicks by notifying the OnLongClickListener or showing a
     * context menu.
     * </p>
     * {@hide}
     */
    static final int LONG_CLICKABLE = 0x00200000;

    /**
     * <p>Indicates that this view gets its drawable states from its direct parent
     * and ignores its original internal states.</p>
     *
     * @hide
     */
    static final int DUPLICATE_PARENT_STATE = 0x00400000;

    /**
     * The scrollbar style to display the scrollbars inside the content area,
     * without increasing the padding. The scrollbars will be overlaid with
     * translucency on the view's content.
     */
    public static final int SCROLLBARS_INSIDE_OVERLAY = 0;

    /**
     * The scrollbar style to display the scrollbars inside the padded area,
     * increasing the padding of the view. The scrollbars will not overlap the
     * content area of the view.
     */
    public static final int SCROLLBARS_INSIDE_INSET = 0x01000000;

    /**
     * The scrollbar style to display the scrollbars at the edge of the view,
     * without increasing the padding. The scrollbars will be overlaid with
     * translucency.
     */
    public static final int SCROLLBARS_OUTSIDE_OVERLAY = 0x02000000;

    /**
     * The scrollbar style to display the scrollbars at the edge of the view,
     * increasing the padding of the view. The scrollbars will only overlap the
     * background, if any.
     */
    public static final int SCROLLBARS_OUTSIDE_INSET = 0x03000000;

    /**
     * Mask to check if the scrollbar style is overlay or inset.
     * {@hide}
     */
    static final int SCROLLBARS_INSET_MASK = 0x01000000;

    /**
     * Mask to check if the scrollbar style is inside or outside.
     * {@hide}
     */
    static final int SCROLLBARS_OUTSIDE_MASK = 0x02000000;

    /**
     * Mask for scrollbar style.
     * {@hide}
     */
    static final int SCROLLBARS_STYLE_MASK = 0x03000000;

    /**
     * View flag indicating that the screen should remain on while the
     * window containing this view is visible to the user.  This effectively
     * takes care of automatically setting the WindowManager's
     * {@link WindowManager.LayoutParams#FLAG_KEEP_SCREEN_ON}.
     */
    public static final int KEEP_SCREEN_ON = 0x04000000;

    /**
     * View flag indicating whether this view should have sound effects enabled
     * for events such as clicking and touching.
     */
    public static final int SOUND_EFFECTS_ENABLED = 0x08000000;

    /**
     * View flag indicating whether this view should have haptic feedback
     * enabled for events such as long presses.
     */
    public static final int HAPTIC_FEEDBACK_ENABLED = 0x10000000;

    /**
     * <p>Indicates that the view hierarchy should stop saving state when
     * it reaches this view.  If state saving is initiated immediately at
     * the view, it will be allowed.
     * {@hide}
     */
    static final int PARENT_SAVE_DISABLED = 0x20000000;

    /**
     * <p>Mask for use with setFlags indicating bits used for PARENT_SAVE_DISABLED.</p>
     * {@hide}
     */
    static final int PARENT_SAVE_DISABLED_MASK = 0x20000000;

    /**
     * View flag indicating whether {@link #addFocusables(ArrayList, int, int)}
     * should add all focusable Views regardless if they are focusable in touch mode.
     */
    public static final int FOCUSABLES_ALL = 0x00000000;

    /**
     * View flag indicating whether {@link #addFocusables(ArrayList, int, int)}
     * should add only Views focusable in touch mode.
     */
    public static final int FOCUSABLES_TOUCH_MODE = 0x00000001;

    /**
     * Use with {@link #focusSearch}. Move focus to the previous selectable
     * item.
     */
    public static final int FOCUS_BACKWARD = 0x00000001;

    /**
     * Use with {@link #focusSearch}. Move focus to the next selectable
     * item.
     */
    public static final int FOCUS_FORWARD = 0x00000002;

    /**
     * Use with {@link #focusSearch}. Move focus to the left.
     */
    public static final int FOCUS_LEFT = 0x00000011;

    /**
     * Use with {@link #focusSearch}. Move focus up.
     */
    public static final int FOCUS_UP = 0x00000021;

    /**
     * Use with {@link #focusSearch}. Move focus to the right.
     */
    public static final int FOCUS_RIGHT = 0x00000042;

    /**
     * Use with {@link #focusSearch}. Move focus down.
     */
    public static final int FOCUS_DOWN = 0x00000082;

    /**
     * Bits of {@link #getMeasuredWidthAndState()} and
     * {@link #getMeasuredWidthAndState()} that provide the actual measured size.
     */
    public static final int MEASURED_SIZE_MASK = 0x00ffffff;

    /**
     * Bits of {@link #getMeasuredWidthAndState()} and
     * {@link #getMeasuredWidthAndState()} that provide the additional state bits.
     */
    public static final int MEASURED_STATE_MASK = 0xff000000;

    /**
     * Bit shift of {@link #MEASURED_STATE_MASK} to get to the height bits
     * for functions that combine both width and height into a single int,
     * such as {@link #getMeasuredState()} and the childState argument of
     * {@link #resolveSizeAndState(int, int, int)}.
     */
    public static final int MEASURED_HEIGHT_STATE_SHIFT = 16;

    /**
     * Bit of {@link #getMeasuredWidthAndState()} and
     * {@link #getMeasuredWidthAndState()} that indicates the measured size
     * is smaller that the space the view would like to have.
     */
    public static final int MEASURED_STATE_TOO_SMALL = 0x01000000;

    /**
     * Base View state sets
     */
    // Singles
    /**
     * Indicates the view has no states set. States are used with
     * {@link android.graphics.drawable.Drawable} to change the drawing of the
     * view depending on its state.
     *
     * @see android.graphics.drawable.Drawable
     * @see #getDrawableState()
     */
    protected static final int[] EMPTY_STATE_SET;
    /**
     * Indicates the view is enabled. States are used with
     * {@link android.graphics.drawable.Drawable} to change the drawing of the
     * view depending on its state.
     *
     * @see android.graphics.drawable.Drawable
     * @see #getDrawableState()
     */
    protected static final int[] ENABLED_STATE_SET;
    /**
     * Indicates the view is focused. States are used with
     * {@link android.graphics.drawable.Drawable} to change the drawing of the
     * view depending on its state.
     *
     * @see android.graphics.drawable.Drawable
     * @see #getDrawableState()
     */
    protected static final int[] FOCUSED_STATE_SET;
    /**
     * Indicates the view is selected. States are used with
     * {@link android.graphics.drawable.Drawable} to change the drawing of the
     * view depending on its state.
     *
     * @see android.graphics.drawable.Drawable
     * @see #getDrawableState()
     */
    protected static final int[] SELECTED_STATE_SET;
    /**
     * Indicates the view is pressed. States are used with
     * {@link android.graphics.drawable.Drawable} to change the drawing of the
     * view depending on its state.
     *
     * @see android.graphics.drawable.Drawable
     * @see #getDrawableState()
     * @hide
     */
    protected static final int[] PRESSED_STATE_SET;
    /**
     * Indicates the view's window has focus. States are used with
     * {@link android.graphics.drawable.Drawable} to change the drawing of the
     * view depending on its state.
     *
     * @see android.graphics.drawable.Drawable
     * @see #getDrawableState()
     */
    protected static final int[] WINDOW_FOCUSED_STATE_SET;
    // Doubles
    /**
     * Indicates the view is enabled and has the focus.
     *
     * @see #ENABLED_STATE_SET
     * @see #FOCUSED_STATE_SET
     */
    protected static final int[] ENABLED_FOCUSED_STATE_SET;
    /**
     * Indicates the view is enabled and selected.
     *
     * @see #ENABLED_STATE_SET
     * @see #SELECTED_STATE_SET
     */
    protected static final int[] ENABLED_SELECTED_STATE_SET;
    /**
     * Indicates the view is enabled and that its window has focus.
     *
     * @see #ENABLED_STATE_SET
     * @see #WINDOW_FOCUSED_STATE_SET
     */
    protected static final int[] ENABLED_WINDOW_FOCUSED_STATE_SET;
    /**
     * Indicates the view is focused and selected.
     *
     * @see #FOCUSED_STATE_SET
     * @see #SELECTED_STATE_SET
     */
    protected static final int[] FOCUSED_SELECTED_STATE_SET;
    /**
     * Indicates the view has the focus and that its window has the focus.
     *
     * @see #FOCUSED_STATE_SET
     * @see #WINDOW_FOCUSED_STATE_SET
     */
    protected static final int[] FOCUSED_WINDOW_FOCUSED_STATE_SET;
    /**
     * Indicates the view is selected and that its window has the focus.
     *
     * @see #SELECTED_STATE_SET
     * @see #WINDOW_FOCUSED_STATE_SET
     */
    protected static final int[] SELECTED_WINDOW_FOCUSED_STATE_SET;
    // Triples
    /**
     * Indicates the view is enabled, focused and selected.
     *
     * @see #ENABLED_STATE_SET
     * @see #FOCUSED_STATE_SET
     * @see #SELECTED_STATE_SET
     */
    protected static final int[] ENABLED_FOCUSED_SELECTED_STATE_SET;
    /**
     * Indicates the view is enabled, focused and its window has the focus.
     *
     * @see #ENABLED_STATE_SET
     * @see #FOCUSED_STATE_SET
     * @see #WINDOW_FOCUSED_STATE_SET
     */
    protected static final int[] ENABLED_FOCUSED_WINDOW_FOCUSED_STATE_SET;
    /**
     * Indicates the view is enabled, selected and its window has the focus.
     *
     * @see #ENABLED_STATE_SET
     * @see #SELECTED_STATE_SET
     * @see #WINDOW_FOCUSED_STATE_SET
     */
    protected static final int[] ENABLED_SELECTED_WINDOW_FOCUSED_STATE_SET;
    /**
     * Indicates the view is focused, selected and its window has the focus.
     *
     * @see #FOCUSED_STATE_SET
     * @see #SELECTED_STATE_SET
     * @see #WINDOW_FOCUSED_STATE_SET
     */
    protected static final int[] FOCUSED_SELECTED_WINDOW_FOCUSED_STATE_SET;
    /**
     * Indicates the view is enabled, focused, selected and its window
     * has the focus.
     *
     * @see #ENABLED_STATE_SET
     * @see #FOCUSED_STATE_SET
     * @see #SELECTED_STATE_SET
     * @see #WINDOW_FOCUSED_STATE_SET
     */
    protected static final int[] ENABLED_FOCUSED_SELECTED_WINDOW_FOCUSED_STATE_SET;
    /**
     * Indicates the view is pressed and its window has the focus.
     *
     * @see #PRESSED_STATE_SET
     * @see #WINDOW_FOCUSED_STATE_SET
     */
    protected static final int[] PRESSED_WINDOW_FOCUSED_STATE_SET;
    /**
     * Indicates the view is pressed and selected.
     *
     * @see #PRESSED_STATE_SET
     * @see #SELECTED_STATE_SET
     */
    protected static final int[] PRESSED_SELECTED_STATE_SET;
    /**
     * Indicates the view is pressed, selected and its window has the focus.
     *
     * @see #PRESSED_STATE_SET
     * @see #SELECTED_STATE_SET
     * @see #WINDOW_FOCUSED_STATE_SET
     */
    protected static final int[] PRESSED_SELECTED_WINDOW_FOCUSED_STATE_SET;
    /**
     * Indicates the view is pressed and focused.
     *
     * @see #PRESSED_STATE_SET
     * @see #FOCUSED_STATE_SET
     */
    protected static final int[] PRESSED_FOCUSED_STATE_SET;
    /**
     * Indicates the view is pressed, focused and its window has the focus.
     *
     * @see #PRESSED_STATE_SET
     * @see #FOCUSED_STATE_SET
     * @see #WINDOW_FOCUSED_STATE_SET
     */
    protected static final int[] PRESSED_FOCUSED_WINDOW_FOCUSED_STATE_SET;
    /**
     * Indicates the view is pressed, focused and selected.
     *
     * @see #PRESSED_STATE_SET
     * @see #SELECTED_STATE_SET
     * @see #FOCUSED_STATE_SET
     */
    protected static final int[] PRESSED_FOCUSED_SELECTED_STATE_SET;
    /**
     * Indicates the view is pressed, focused, selected and its window has the focus.
     *
     * @see #PRESSED_STATE_SET
     * @see #FOCUSED_STATE_SET
     * @see #SELECTED_STATE_SET
     * @see #WINDOW_FOCUSED_STATE_SET
     */
    protected static final int[] PRESSED_FOCUSED_SELECTED_WINDOW_FOCUSED_STATE_SET;
    /**
     * Indicates the view is pressed and enabled.
     *
     * @see #PRESSED_STATE_SET
     * @see #ENABLED_STATE_SET
     */
    protected static final int[] PRESSED_ENABLED_STATE_SET;
    /**
     * Indicates the view is pressed, enabled and its window has the focus.
     *
     * @see #PRESSED_STATE_SET
     * @see #ENABLED_STATE_SET
     * @see #WINDOW_FOCUSED_STATE_SET
     */
    protected static final int[] PRESSED_ENABLED_WINDOW_FOCUSED_STATE_SET;
    /**
     * Indicates the view is pressed, enabled and selected.
     *
     * @see #PRESSED_STATE_SET
     * @see #ENABLED_STATE_SET
     * @see #SELECTED_STATE_SET
     */
    protected static final int[] PRESSED_ENABLED_SELECTED_STATE_SET;
    /**
     * Indicates the view is pressed, enabled, selected and its window has the
     * focus.
     *
     * @see #PRESSED_STATE_SET
     * @see #ENABLED_STATE_SET
     * @see #SELECTED_STATE_SET
     * @see #WINDOW_FOCUSED_STATE_SET
     */
    protected static final int[] PRESSED_ENABLED_SELECTED_WINDOW_FOCUSED_STATE_SET;
    /**
     * Indicates the view is pressed, enabled and focused.
     *
     * @see #PRESSED_STATE_SET
     * @see #ENABLED_STATE_SET
     * @see #FOCUSED_STATE_SET
     */
    protected static final int[] PRESSED_ENABLED_FOCUSED_STATE_SET;
    /**
     * Indicates the view is pressed, enabled, focused and its window has the
     * focus.
     *
     * @see #PRESSED_STATE_SET
     * @see #ENABLED_STATE_SET
     * @see #FOCUSED_STATE_SET
     * @see #WINDOW_FOCUSED_STATE_SET
     */
    protected static final int[] PRESSED_ENABLED_FOCUSED_WINDOW_FOCUSED_STATE_SET;
    /**
     * Indicates the view is pressed, enabled, focused and selected.
     *
     * @see #PRESSED_STATE_SET
     * @see #ENABLED_STATE_SET
     * @see #SELECTED_STATE_SET
     * @see #FOCUSED_STATE_SET
     */
    protected static final int[] PRESSED_ENABLED_FOCUSED_SELECTED_STATE_SET;
    /**
     * Indicates the view is pressed, enabled, focused, selected and its window
     * has the focus.
     *
     * @see #PRESSED_STATE_SET
     * @see #ENABLED_STATE_SET
     * @see #SELECTED_STATE_SET
     * @see #FOCUSED_STATE_SET
     * @see #WINDOW_FOCUSED_STATE_SET
     */
    protected static final int[] PRESSED_ENABLED_FOCUSED_SELECTED_WINDOW_FOCUSED_STATE_SET;

    /**
     * The order here is very important to {@link #getDrawableState()}
     */
    private static final int[][] VIEW_STATE_SETS;

    static final int VIEW_STATE_WINDOW_FOCUSED = 1;
    static final int VIEW_STATE_SELECTED = 1 << 1;
    static final int VIEW_STATE_FOCUSED = 1 << 2;
    static final int VIEW_STATE_ENABLED = 1 << 3;
    static final int VIEW_STATE_PRESSED = 1 << 4;
    static final int VIEW_STATE_ACTIVATED = 1 << 5;
    static final int VIEW_STATE_ACCELERATED = 1 << 6;

    static final int[] VIEW_STATE_IDS = new int[] {
        R.attr.state_window_focused,    VIEW_STATE_WINDOW_FOCUSED,
        R.attr.state_selected,          VIEW_STATE_SELECTED,
        R.attr.state_focused,           VIEW_STATE_FOCUSED,
        R.attr.state_enabled,           VIEW_STATE_ENABLED,
        R.attr.state_pressed,           VIEW_STATE_PRESSED,
        R.attr.state_activated,         VIEW_STATE_ACTIVATED,
        R.attr.state_accelerated,       VIEW_STATE_ACCELERATED,
    };

    static {
        if ((VIEW_STATE_IDS.length/2) != R.styleable.ViewDrawableStates.length) {
            throw new IllegalStateException(
                    "VIEW_STATE_IDs array length does not match ViewDrawableStates style array");
        }
        int[] orderedIds = new int[VIEW_STATE_IDS.length];
        for (int i = 0; i < R.styleable.ViewDrawableStates.length; i++) {
            int viewState = R.styleable.ViewDrawableStates[i];
            for (int j = 0; j<VIEW_STATE_IDS.length; j += 2) {
                if (VIEW_STATE_IDS[j] == viewState) {
                    orderedIds[i * 2] = viewState;
                    orderedIds[i * 2 + 1] = VIEW_STATE_IDS[j + 1];
                }
            }
        }
        final int NUM_BITS = VIEW_STATE_IDS.length / 2;
        VIEW_STATE_SETS = new int[1 << NUM_BITS][];
        for (int i = 0; i < VIEW_STATE_SETS.length; i++) {
            int numBits = Integer.bitCount(i);
            int[] set = new int[numBits];
            int pos = 0;
            for (int j = 0; j < orderedIds.length; j += 2) {
                if ((i & orderedIds[j+1]) != 0) {
                    set[pos++] = orderedIds[j];
                }
            }
            VIEW_STATE_SETS[i] = set;
        }

        EMPTY_STATE_SET = VIEW_STATE_SETS[0];
        WINDOW_FOCUSED_STATE_SET = VIEW_STATE_SETS[VIEW_STATE_WINDOW_FOCUSED];
        SELECTED_STATE_SET = VIEW_STATE_SETS[VIEW_STATE_SELECTED];
        SELECTED_WINDOW_FOCUSED_STATE_SET = VIEW_STATE_SETS[
                VIEW_STATE_WINDOW_FOCUSED | VIEW_STATE_SELECTED];
        FOCUSED_STATE_SET = VIEW_STATE_SETS[VIEW_STATE_FOCUSED];
        FOCUSED_WINDOW_FOCUSED_STATE_SET = VIEW_STATE_SETS[
                VIEW_STATE_WINDOW_FOCUSED | VIEW_STATE_FOCUSED];
        FOCUSED_SELECTED_STATE_SET = VIEW_STATE_SETS[
                VIEW_STATE_SELECTED | VIEW_STATE_FOCUSED];
        FOCUSED_SELECTED_WINDOW_FOCUSED_STATE_SET = VIEW_STATE_SETS[
                VIEW_STATE_WINDOW_FOCUSED | VIEW_STATE_SELECTED
                | VIEW_STATE_FOCUSED];
        ENABLED_STATE_SET = VIEW_STATE_SETS[VIEW_STATE_ENABLED];
        ENABLED_WINDOW_FOCUSED_STATE_SET = VIEW_STATE_SETS[
                VIEW_STATE_WINDOW_FOCUSED | VIEW_STATE_ENABLED];
        ENABLED_SELECTED_STATE_SET = VIEW_STATE_SETS[
                VIEW_STATE_SELECTED | VIEW_STATE_ENABLED];
        ENABLED_SELECTED_WINDOW_FOCUSED_STATE_SET = VIEW_STATE_SETS[
                VIEW_STATE_WINDOW_FOCUSED | VIEW_STATE_SELECTED
                | VIEW_STATE_ENABLED];
        ENABLED_FOCUSED_STATE_SET = VIEW_STATE_SETS[
                VIEW_STATE_FOCUSED | VIEW_STATE_ENABLED];
        ENABLED_FOCUSED_WINDOW_FOCUSED_STATE_SET = VIEW_STATE_SETS[
                VIEW_STATE_WINDOW_FOCUSED | VIEW_STATE_FOCUSED
                | VIEW_STATE_ENABLED];
        ENABLED_FOCUSED_SELECTED_STATE_SET = VIEW_STATE_SETS[
                VIEW_STATE_SELECTED | VIEW_STATE_FOCUSED
                | VIEW_STATE_ENABLED];
        ENABLED_FOCUSED_SELECTED_WINDOW_FOCUSED_STATE_SET = VIEW_STATE_SETS[
                VIEW_STATE_WINDOW_FOCUSED | VIEW_STATE_SELECTED
                | VIEW_STATE_FOCUSED| VIEW_STATE_ENABLED];

        PRESSED_STATE_SET = VIEW_STATE_SETS[VIEW_STATE_PRESSED];
        PRESSED_WINDOW_FOCUSED_STATE_SET = VIEW_STATE_SETS[
                VIEW_STATE_WINDOW_FOCUSED | VIEW_STATE_PRESSED];
        PRESSED_SELECTED_STATE_SET = VIEW_STATE_SETS[
                VIEW_STATE_SELECTED | VIEW_STATE_PRESSED];
        PRESSED_SELECTED_WINDOW_FOCUSED_STATE_SET = VIEW_STATE_SETS[
                VIEW_STATE_WINDOW_FOCUSED | VIEW_STATE_SELECTED
                | VIEW_STATE_PRESSED];
        PRESSED_FOCUSED_STATE_SET = VIEW_STATE_SETS[
                VIEW_STATE_FOCUSED | VIEW_STATE_PRESSED];
        PRESSED_FOCUSED_WINDOW_FOCUSED_STATE_SET = VIEW_STATE_SETS[
                VIEW_STATE_WINDOW_FOCUSED | VIEW_STATE_FOCUSED
                | VIEW_STATE_PRESSED];
        PRESSED_FOCUSED_SELECTED_STATE_SET = VIEW_STATE_SETS[
                VIEW_STATE_SELECTED | VIEW_STATE_FOCUSED
                | VIEW_STATE_PRESSED];
        PRESSED_FOCUSED_SELECTED_WINDOW_FOCUSED_STATE_SET = VIEW_STATE_SETS[
                VIEW_STATE_WINDOW_FOCUSED | VIEW_STATE_SELECTED
                | VIEW_STATE_FOCUSED | VIEW_STATE_PRESSED];
        PRESSED_ENABLED_STATE_SET = VIEW_STATE_SETS[
                VIEW_STATE_ENABLED | VIEW_STATE_PRESSED];
        PRESSED_ENABLED_WINDOW_FOCUSED_STATE_SET = VIEW_STATE_SETS[
                VIEW_STATE_WINDOW_FOCUSED | VIEW_STATE_ENABLED
                | VIEW_STATE_PRESSED];
        PRESSED_ENABLED_SELECTED_STATE_SET = VIEW_STATE_SETS[
                VIEW_STATE_SELECTED | VIEW_STATE_ENABLED
                | VIEW_STATE_PRESSED];
        PRESSED_ENABLED_SELECTED_WINDOW_FOCUSED_STATE_SET = VIEW_STATE_SETS[
                VIEW_STATE_WINDOW_FOCUSED | VIEW_STATE_SELECTED
                | VIEW_STATE_ENABLED | VIEW_STATE_PRESSED];
        PRESSED_ENABLED_FOCUSED_STATE_SET = VIEW_STATE_SETS[
                VIEW_STATE_FOCUSED | VIEW_STATE_ENABLED
                | VIEW_STATE_PRESSED];
        PRESSED_ENABLED_FOCUSED_WINDOW_FOCUSED_STATE_SET = VIEW_STATE_SETS[
                VIEW_STATE_WINDOW_FOCUSED | VIEW_STATE_FOCUSED
                | VIEW_STATE_ENABLED | VIEW_STATE_PRESSED];
        PRESSED_ENABLED_FOCUSED_SELECTED_STATE_SET = VIEW_STATE_SETS[
                VIEW_STATE_SELECTED | VIEW_STATE_FOCUSED
                | VIEW_STATE_ENABLED | VIEW_STATE_PRESSED];
        PRESSED_ENABLED_FOCUSED_SELECTED_WINDOW_FOCUSED_STATE_SET = VIEW_STATE_SETS[
                VIEW_STATE_WINDOW_FOCUSED | VIEW_STATE_SELECTED
                | VIEW_STATE_FOCUSED| VIEW_STATE_ENABLED
                | VIEW_STATE_PRESSED];
    }

    /**
     * Used by views that contain lists of items. This state indicates that
     * the view is showing the last item.
     * @hide
     */
    protected static final int[] LAST_STATE_SET = {R.attr.state_last};
    /**
     * Used by views that contain lists of items. This state indicates that
     * the view is showing the first item.
     * @hide
     */
    protected static final int[] FIRST_STATE_SET = {R.attr.state_first};
    /**
     * Used by views that contain lists of items. This state indicates that
     * the view is showing the middle item.
     * @hide
     */
    protected static final int[] MIDDLE_STATE_SET = {R.attr.state_middle};
    /**
     * Used by views that contain lists of items. This state indicates that
     * the view is showing only one item.
     * @hide
     */
    protected static final int[] SINGLE_STATE_SET = {R.attr.state_single};
    /**
     * Used by views that contain lists of items. This state indicates that
     * the view is pressed and showing the last item.
     * @hide
     */
    protected static final int[] PRESSED_LAST_STATE_SET = {R.attr.state_last, R.attr.state_pressed};
    /**
     * Used by views that contain lists of items. This state indicates that
     * the view is pressed and showing the first item.
     * @hide
     */
    protected static final int[] PRESSED_FIRST_STATE_SET = {R.attr.state_first, R.attr.state_pressed};
    /**
     * Used by views that contain lists of items. This state indicates that
     * the view is pressed and showing the middle item.
     * @hide
     */
    protected static final int[] PRESSED_MIDDLE_STATE_SET = {R.attr.state_middle, R.attr.state_pressed};
    /**
     * Used by views that contain lists of items. This state indicates that
     * the view is pressed and showing only one item.
     * @hide
     */
    protected static final int[] PRESSED_SINGLE_STATE_SET = {R.attr.state_single, R.attr.state_pressed};

    /**
     * Temporary Rect currently for use in setBackground().  This will probably
     * be extended in the future to hold our own class with more than just
     * a Rect. :)
     */
    static final ThreadLocal<Rect> sThreadLocal = new ThreadLocal<Rect>();

    /**
     * Map used to store views' tags.
     */
    private static WeakHashMap<View, SparseArray<Object>> sTags;

    /**
     * Lock used to access sTags.
     */
    private static final Object sTagsLock = new Object();

    /**
     * The animation currently associated with this view.
     * @hide
     */
    protected Animation mCurrentAnimation = null;

    /**
     * Width as measured during measure pass.
     * {@hide}
     */
    @ViewDebug.ExportedProperty(category = "measurement")
    /*package*/ int mMeasuredWidth;

    /**
     * Height as measured during measure pass.
     * {@hide}
     */
    @ViewDebug.ExportedProperty(category = "measurement")
    /*package*/ int mMeasuredHeight;

    /**
     * Flag to indicate that this view was marked INVALIDATED, or had its display list
     * invalidated, prior to the current drawing iteration. If true, the view must re-draw
     * its display list. This flag, used only when hw accelerated, allows us to clear the
     * flag while retaining this information until it's needed (at getDisplayList() time and
     * in drawChild(), when we decide to draw a view's children's display lists into our own).
     *
     * {@hide}
     */
    boolean mRecreateDisplayList = false;

    /**
     * The view's identifier.
     * {@hide}
     *
     * @see #setId(int)
     * @see #getId()
     */
    @ViewDebug.ExportedProperty(resolveId = true)
    int mID = NO_ID;

    /**
     * The view's tag.
     * {@hide}
     *
     * @see #setTag(Object)
     * @see #getTag()
     */
    protected Object mTag;

    // for mPrivateFlags:
    /** {@hide} */
    static final int WANTS_FOCUS                    = 0x00000001;
    /** {@hide} */
    static final int FOCUSED                        = 0x00000002;
    /** {@hide} */
    static final int SELECTED                       = 0x00000004;
    /** {@hide} */
    static final int IS_ROOT_NAMESPACE              = 0x00000008;
    /** {@hide} */
    static final int HAS_BOUNDS                     = 0x00000010;
    /** {@hide} */
    static final int DRAWN                          = 0x00000020;
    /**
     * When this flag is set, this view is running an animation on behalf of its
     * children and should therefore not cancel invalidate requests, even if they
     * lie outside of this view's bounds.
     *
     * {@hide}
     */
    static final int DRAW_ANIMATION                 = 0x00000040;
    /** {@hide} */
    static final int SKIP_DRAW                      = 0x00000080;
    /** {@hide} */
    static final int ONLY_DRAWS_BACKGROUND          = 0x00000100;
    /** {@hide} */
    static final int REQUEST_TRANSPARENT_REGIONS    = 0x00000200;
    /** {@hide} */
    static final int DRAWABLE_STATE_DIRTY           = 0x00000400;
    /** {@hide} */
    static final int MEASURED_DIMENSION_SET         = 0x00000800;
    /** {@hide} */
    static final int FORCE_LAYOUT                   = 0x00001000;
    /** {@hide} */
    static final int LAYOUT_REQUIRED                = 0x00002000;

    private static final int PRESSED                = 0x00004000;

    /** {@hide} */
    static final int DRAWING_CACHE_VALID            = 0x00008000;
    /**
     * Flag used to indicate that this view should be drawn once more (and only once
     * more) after its animation has completed.
     * {@hide}
     */
    static final int ANIMATION_STARTED              = 0x00010000;

    private static final int SAVE_STATE_CALLED      = 0x00020000;

    /**
     * Indicates that the View returned true when onSetAlpha() was called and that
     * the alpha must be restored.
     * {@hide}
     */
    static final int ALPHA_SET                      = 0x00040000;

    /**
     * Set by {@link #setScrollContainer(boolean)}.
     */
    static final int SCROLL_CONTAINER               = 0x00080000;

    /**
     * Set by {@link #setScrollContainer(boolean)}.
     */
    static final int SCROLL_CONTAINER_ADDED         = 0x00100000;

    /**
     * View flag indicating whether this view was invalidated (fully or partially.)
     *
     * @hide
     */
    static final int DIRTY                          = 0x00200000;

    /**
     * View flag indicating whether this view was invalidated by an opaque
     * invalidate request.
     *
     * @hide
     */
    static final int DIRTY_OPAQUE                   = 0x00400000;

    /**
     * Mask for {@link #DIRTY} and {@link #DIRTY_OPAQUE}.
     *
     * @hide
     */
    static final int DIRTY_MASK                     = 0x00600000;

    /**
     * Indicates whether the background is opaque.
     *
     * @hide
     */
    static final int OPAQUE_BACKGROUND              = 0x00800000;

    /**
     * Indicates whether the scrollbars are opaque.
     *
     * @hide
     */
    static final int OPAQUE_SCROLLBARS              = 0x01000000;

    /**
     * Indicates whether the view is opaque.
     *
     * @hide
     */
    static final int OPAQUE_MASK                    = 0x01800000;

    /**
     * Indicates a prepressed state;
     * the short time between ACTION_DOWN and recognizing
     * a 'real' press. Prepressed is used to recognize quick taps
     * even when they are shorter than ViewConfiguration.getTapTimeout().
     *
     * @hide
     */
    private static final int PREPRESSED             = 0x02000000;

    /**
     * Indicates whether the view is temporarily detached.
     *
     * @hide
     */
    static final int CANCEL_NEXT_UP_EVENT = 0x04000000;

    /**
     * Indicates that we should awaken scroll bars once attached
     *
     * @hide
     */
    private static final int AWAKEN_SCROLL_BARS_ON_ATTACH = 0x08000000;

    /**
     * Indicates that pivotX or pivotY were explicitly set and we should not assume the center
     * for transform operations
     *
     * @hide
     */
    private static final int PIVOT_EXPLICITLY_SET = 0x20000000;

    /** {@hide} */
    static final int ACTIVATED                    = 0x40000000;

    /**
     * Indicates that this view was specifically invalidated, not just dirtied because some
     * child view was invalidated. The flag is used to determine when we need to recreate
     * a view's display list (as opposed to just returning a reference to its existing
     * display list).
     *
     * @hide
     */
    static final int INVALIDATED                  = 0x80000000;

    /**
     * Always allow a user to over-scroll this view, provided it is a
     * view that can scroll.
     *
     * @see #getOverScrollMode()
     * @see #setOverScrollMode(int)
     */
    public static final int OVER_SCROLL_ALWAYS = 0;

    /**
     * Allow a user to over-scroll this view only if the content is large
     * enough to meaningfully scroll, provided it is a view that can scroll.
     *
     * @see #getOverScrollMode()
     * @see #setOverScrollMode(int)
     */
    public static final int OVER_SCROLL_IF_CONTENT_SCROLLS = 1;

    /**
     * Never allow a user to over-scroll this view.
     *
     * @see #getOverScrollMode()
     * @see #setOverScrollMode(int)
     */
    public static final int OVER_SCROLL_NEVER = 2;

    /**
     * View has requested the status bar to be visible (the default).
     *
     * @see #setSystemUiVisibility(int)
     */
    public static final int STATUS_BAR_VISIBLE = 0;

    /**
     * View has requested the status bar to be visible (the default).
     *
     * @see #setSystemUiVisibility(int)
     */
    public static final int STATUS_BAR_HIDDEN = 0x00000001;

    /**
     * Controls the over-scroll mode for this view.
     * See {@link #overScrollBy(int, int, int, int, int, int, int, int, boolean)},
     * {@link #OVER_SCROLL_ALWAYS}, {@link #OVER_SCROLL_IF_CONTENT_SCROLLS},
     * and {@link #OVER_SCROLL_NEVER}.
     */
    private int mOverScrollMode;

    /**
     * The parent this view is attached to.
     * {@hide}
     *
     * @see #getParent()
     */
    protected ViewParent mParent;

    /**
     * {@hide}
     */
    AttachInfo mAttachInfo;

    /**
     * {@hide}
     */
    @ViewDebug.ExportedProperty(flagMapping = {
        @ViewDebug.FlagToString(mask = FORCE_LAYOUT, equals = FORCE_LAYOUT,
                name = "FORCE_LAYOUT"),
        @ViewDebug.FlagToString(mask = LAYOUT_REQUIRED, equals = LAYOUT_REQUIRED,
                name = "LAYOUT_REQUIRED"),
        @ViewDebug.FlagToString(mask = DRAWING_CACHE_VALID, equals = DRAWING_CACHE_VALID,
            name = "DRAWING_CACHE_INVALID", outputIf = false),
        @ViewDebug.FlagToString(mask = DRAWN, equals = DRAWN, name = "DRAWN", outputIf = true),
        @ViewDebug.FlagToString(mask = DRAWN, equals = DRAWN, name = "NOT_DRAWN", outputIf = false),
        @ViewDebug.FlagToString(mask = DIRTY_MASK, equals = DIRTY_OPAQUE, name = "DIRTY_OPAQUE"),
        @ViewDebug.FlagToString(mask = DIRTY_MASK, equals = DIRTY, name = "DIRTY")
    })
    int mPrivateFlags;

    /**
     * This view's request for the visibility of the status bar.
     * @hide
     */
    int mSystemUiVisibility;

    /**
     * Count of how many windows this view has been attached to.
     */
    int mWindowAttachCount;

    /**
     * The layout parameters associated with this view and used by the parent
     * {@link android.view.ViewGroup} to determine how this view should be
     * laid out.
     * {@hide}
     */
    protected ViewGroup.LayoutParams mLayoutParams;

    /**
     * The view flags hold various views states.
     * {@hide}
     */
    @ViewDebug.ExportedProperty
    int mViewFlags;

    /**
     * The transform matrix for the View. This transform is calculated internally
     * based on the rotation, scaleX, and scaleY properties. The identity matrix
     * is used by default. Do *not* use this variable directly; instead call
     * getMatrix(), which will automatically recalculate the matrix if necessary
     * to get the correct matrix based on the latest rotation and scale properties.
     */
    private final Matrix mMatrix = new Matrix();

    /**
     * The transform matrix for the View. This transform is calculated internally
     * based on the rotation, scaleX, and scaleY properties. The identity matrix
     * is used by default. Do *not* use this variable directly; instead call
     * getInverseMatrix(), which will automatically recalculate the matrix if necessary
     * to get the correct matrix based on the latest rotation and scale properties.
     */
    private Matrix mInverseMatrix;

    /**
     * An internal variable that tracks whether we need to recalculate the
     * transform matrix, based on whether the rotation or scaleX/Y properties
     * have changed since the matrix was last calculated.
     */
    private boolean mMatrixDirty = false;

    /**
     * An internal variable that tracks whether we need to recalculate the
     * transform matrix, based on whether the rotation or scaleX/Y properties
     * have changed since the matrix was last calculated.
     */
    private boolean mInverseMatrixDirty = true;

    /**
     * A variable that tracks whether we need to recalculate the
     * transform matrix, based on whether the rotation or scaleX/Y properties
     * have changed since the matrix was last calculated. This variable
     * is only valid after a call to updateMatrix() or to a function that
     * calls it such as getMatrix(), hasIdentityMatrix() and getInverseMatrix().
     */
    private boolean mMatrixIsIdentity = true;

    /**
     * The Camera object is used to compute a 3D matrix when rotationX or rotationY are set.
     */
    private Camera mCamera = null;

    /**
     * This matrix is used when computing the matrix for 3D rotations.
     */
    private Matrix matrix3D = null;

    /**
     * These prev values are used to recalculate a centered pivot point when necessary. The
     * pivot point is only used in matrix operations (when rotation, scale, or translation are
     * set), so thes values are only used then as well.
     */
    private int mPrevWidth = -1;
    private int mPrevHeight = -1;

    private boolean mLastIsOpaque;

    /**
     * Convenience value to check for float values that are close enough to zero to be considered
     * zero.
     */
    private static final float NONZERO_EPSILON = .001f;

    /**
     * The degrees rotation around the vertical axis through the pivot point.
     */
    @ViewDebug.ExportedProperty
    private float mRotationY = 0f;

    /**
     * The degrees rotation around the horizontal axis through the pivot point.
     */
    @ViewDebug.ExportedProperty
    private float mRotationX = 0f;

    /**
     * The degrees rotation around the pivot point.
     */
    @ViewDebug.ExportedProperty
    private float mRotation = 0f;

    /**
     * The amount of translation of the object away from its left property (post-layout).
     */
    @ViewDebug.ExportedProperty
    private float mTranslationX = 0f;

    /**
     * The amount of translation of the object away from its top property (post-layout).
     */
    @ViewDebug.ExportedProperty
    private float mTranslationY = 0f;

    /**
     * The amount of scale in the x direction around the pivot point. A
     * value of 1 means no scaling is applied.
     */
    @ViewDebug.ExportedProperty
    private float mScaleX = 1f;

    /**
     * The amount of scale in the y direction around the pivot point. A
     * value of 1 means no scaling is applied.
     */
    @ViewDebug.ExportedProperty
    private float mScaleY = 1f;

    /**
     * The amount of scale in the x direction around the pivot point. A
     * value of 1 means no scaling is applied.
     */
    @ViewDebug.ExportedProperty
    private float mPivotX = 0f;

    /**
     * The amount of scale in the y direction around the pivot point. A
     * value of 1 means no scaling is applied.
     */
    @ViewDebug.ExportedProperty
    private float mPivotY = 0f;

    /**
     * The opacity of the View. This is a value from 0 to 1, where 0 means
     * completely transparent and 1 means completely opaque.
     */
    @ViewDebug.ExportedProperty
    private float mAlpha = 1f;

    /**
     * The distance in pixels from the left edge of this view's parent
     * to the left edge of this view.
     * {@hide}
     */
    @ViewDebug.ExportedProperty(category = "layout")
    protected int mLeft;
    /**
     * The distance in pixels from the left edge of this view's parent
     * to the right edge of this view.
     * {@hide}
     */
    @ViewDebug.ExportedProperty(category = "layout")
    protected int mRight;
    /**
     * The distance in pixels from the top edge of this view's parent
     * to the top edge of this view.
     * {@hide}
     */
    @ViewDebug.ExportedProperty(category = "layout")
    protected int mTop;
    /**
     * The distance in pixels from the top edge of this view's parent
     * to the bottom edge of this view.
     * {@hide}
     */
    @ViewDebug.ExportedProperty(category = "layout")
    protected int mBottom;

    /**
     * The offset, in pixels, by which the content of this view is scrolled
     * horizontally.
     * {@hide}
     */
    @ViewDebug.ExportedProperty(category = "scrolling")
    protected int mScrollX;
    /**
     * The offset, in pixels, by which the content of this view is scrolled
     * vertically.
     * {@hide}
     */
    @ViewDebug.ExportedProperty(category = "scrolling")
    protected int mScrollY;

    /**
     * The left padding in pixels, that is the distance in pixels between the
     * left edge of this view and the left edge of its content.
     * {@hide}
     */
    @ViewDebug.ExportedProperty(category = "padding")
    protected int mPaddingLeft;
    /**
     * The right padding in pixels, that is the distance in pixels between the
     * right edge of this view and the right edge of its content.
     * {@hide}
     */
    @ViewDebug.ExportedProperty(category = "padding")
    protected int mPaddingRight;
    /**
     * The top padding in pixels, that is the distance in pixels between the
     * top edge of this view and the top edge of its content.
     * {@hide}
     */
    @ViewDebug.ExportedProperty(category = "padding")
    protected int mPaddingTop;
    /**
     * The bottom padding in pixels, that is the distance in pixels between the
     * bottom edge of this view and the bottom edge of its content.
     * {@hide}
     */
    @ViewDebug.ExportedProperty(category = "padding")
    protected int mPaddingBottom;

    /**
     * Briefly describes the view and is primarily used for accessibility support.
     */
    private CharSequence mContentDescription;

    /**
     * Cache the paddingRight set by the user to append to the scrollbar's size.
     */
    @ViewDebug.ExportedProperty(category = "padding")
    int mUserPaddingRight;

    /**
     * Cache the paddingBottom set by the user to append to the scrollbar's size.
     */
    @ViewDebug.ExportedProperty(category = "padding")
    int mUserPaddingBottom;

    /**
     * Cache the paddingLeft set by the user to append to the scrollbar's size.
     */
    @ViewDebug.ExportedProperty(category = "padding")
    int mUserPaddingLeft;

    /**
     * @hide
     */
    int mOldWidthMeasureSpec = Integer.MIN_VALUE;
    /**
     * @hide
     */
    int mOldHeightMeasureSpec = Integer.MIN_VALUE;

    private Resources mResources = null;

    private Drawable mBGDrawable;

    private int mBackgroundResource;
    private boolean mBackgroundSizeChanged;

    /**
     * Listener used to dispatch focus change events.
     * This field should be made private, so it is hidden from the SDK.
     * {@hide}
     */
    protected OnFocusChangeListener mOnFocusChangeListener;

    /**
     * Listeners for layout change events.
     */
    private ArrayList<OnLayoutChangeListener> mOnLayoutChangeListeners;

    /**
     * Listener used to dispatch click events.
     * This field should be made private, so it is hidden from the SDK.
     * {@hide}
     */
    protected OnClickListener mOnClickListener;

    /**
     * Listener used to dispatch long click events.
     * This field should be made private, so it is hidden from the SDK.
     * {@hide}
     */
    protected OnLongClickListener mOnLongClickListener;

    /**
     * Listener used to build the context menu.
     * This field should be made private, so it is hidden from the SDK.
     * {@hide}
     */
    protected OnCreateContextMenuListener mOnCreateContextMenuListener;

    private OnKeyListener mOnKeyListener;

    private OnTouchListener mOnTouchListener;

    private OnDragListener mOnDragListener;

    private OnSystemUiVisibilityChangeListener mOnSystemUiVisibilityChangeListener;

    /**
     * The application environment this view lives in.
     * This field should be made private, so it is hidden from the SDK.
     * {@hide}
     */
    protected Context mContext;

    private ScrollabilityCache mScrollCache;

    private int[] mDrawableState = null;

    private Bitmap mDrawingCache;
    private Bitmap mUnscaledDrawingCache;
    private DisplayList mDisplayList;
    private HardwareLayer mHardwareLayer;

    /**
     * When this view has focus and the next focus is {@link #FOCUS_LEFT},
     * the user may specify which view to go to next.
     */
    private int mNextFocusLeftId = View.NO_ID;

    /**
     * When this view has focus and the next focus is {@link #FOCUS_RIGHT},
     * the user may specify which view to go to next.
     */
    private int mNextFocusRightId = View.NO_ID;

    /**
     * When this view has focus and the next focus is {@link #FOCUS_UP},
     * the user may specify which view to go to next.
     */
    private int mNextFocusUpId = View.NO_ID;

    /**
     * When this view has focus and the next focus is {@link #FOCUS_DOWN},
     * the user may specify which view to go to next.
     */
    private int mNextFocusDownId = View.NO_ID;

    /**
     * When this view has focus and the next focus is {@link #FOCUS_FORWARD},
     * the user may specify which view to go to next.
     */
    int mNextFocusForwardId = View.NO_ID;

    private CheckForLongPress mPendingCheckForLongPress;
    private CheckForTap mPendingCheckForTap = null;
    private PerformClick mPerformClick;

    private UnsetPressedState mUnsetPressedState;

    /**
     * Whether the long press's action has been invoked.  The tap's action is invoked on the
     * up event while a long press is invoked as soon as the long press duration is reached, so
     * a long press could be performed before the tap is checked, in which case the tap's action
     * should not be invoked.
     */
    private boolean mHasPerformedLongPress;

    /**
     * The minimum height of the view. We'll try our best to have the height
     * of this view to at least this amount.
     */
    @ViewDebug.ExportedProperty(category = "measurement")
    private int mMinHeight;

    /**
     * The minimum width of the view. We'll try our best to have the width
     * of this view to at least this amount.
     */
    @ViewDebug.ExportedProperty(category = "measurement")
    private int mMinWidth;

    /**
     * The delegate to handle touch events that are physically in this view
     * but should be handled by another view.
     */
    private TouchDelegate mTouchDelegate = null;

    /**
     * Solid color to use as a background when creating the drawing cache. Enables
     * the cache to use 16 bit bitmaps instead of 32 bit.
     */
    private int mDrawingCacheBackgroundColor = 0;

    /**
     * Special tree observer used when mAttachInfo is null.
     */
    private ViewTreeObserver mFloatingTreeObserver;

    /**
     * Cache the touch slop from the context that created the view.
     */
    private int mTouchSlop;

    /**
     * Cache drag/drop state
     *
     */
    boolean mCanAcceptDrop;

    /**
     * Flag indicating that a drag can cross window boundaries
     * @hide
     */
    public static final int DRAG_FLAG_GLOBAL = 1;

    /**
     * Position of the vertical scroll bar.
     */
    private int mVerticalScrollbarPosition;

    /**
     * Position the scroll bar at the default position as determined by the system.
     */
    public static final int SCROLLBAR_POSITION_DEFAULT = 0;

    /**
     * Position the scroll bar along the left edge.
     */
    public static final int SCROLLBAR_POSITION_LEFT = 1;

    /**
     * Position the scroll bar along the right edge.
     */
    public static final int SCROLLBAR_POSITION_RIGHT = 2;

    /**
     * Indicates that the view does not have a layer.
     *
     * @see #getLayerType()
     * @see #setLayerType(int, android.graphics.Paint)
     * @see #LAYER_TYPE_SOFTWARE
     * @see #LAYER_TYPE_HARDWARE
     */
    public static final int LAYER_TYPE_NONE = 0;

    /**
     * <p>Indicates that the view has a software layer. A software layer is backed
     * by a bitmap and causes the view to be rendered using Android's software
     * rendering pipeline, even if hardware acceleration is enabled.</p>
     *
     * <p>Software layers have various usages:</p>
     * <p>When the application is not using hardware acceleration, a software layer
     * is useful to apply a specific color filter and/or blending mode and/or
     * translucency to a view and all its children.</p>
     * <p>When the application is using hardware acceleration, a software layer
     * is useful to render drawing primitives not supported by the hardware
     * accelerated pipeline. It can also be used to cache a complex view tree
     * into a texture and reduce the complexity of drawing operations. For instance,
     * when animating a complex view tree with a translation, a software layer can
     * be used to render the view tree only once.</p>
     * <p>Software layers should be avoided when the affected view tree updates
     * often. Every update will require to re-render the software layer, which can
     * potentially be slow (particularly when hardware acceleration is turned on
     * since the layer will have to be uploaded into a hardware texture after every
     * update.)</p>
     *
     * @see #getLayerType()
     * @see #setLayerType(int, android.graphics.Paint)
     * @see #LAYER_TYPE_NONE
     * @see #LAYER_TYPE_HARDWARE
     */
    public static final int LAYER_TYPE_SOFTWARE = 1;

    /**
     * <p>Indicates that the view has a hardware layer. A hardware layer is backed
     * by a hardware specific texture (generally Frame Buffer Objects or FBO on
     * OpenGL hardware) and causes the view to be rendered using Android's hardware
     * rendering pipeline, but only if hardware acceleration is turned on for the
     * view hierarchy. When hardware acceleration is turned off, hardware layers
     * behave exactly as {@link #LAYER_TYPE_SOFTWARE software layers}.</p>
     *
     * <p>A hardware layer is useful to apply a specific color filter and/or
     * blending mode and/or translucency to a view and all its children.</p>
     * <p>A hardware layer can be used to cache a complex view tree into a
     * texture and reduce the complexity of drawing operations. For instance,
     * when animating a complex view tree with a translation, a hardware layer can
     * be used to render the view tree only once.</p>
     * <p>A hardware layer can also be used to increase the rendering quality when
     * rotation transformations are applied on a view. It can also be used to
     * prevent potential clipping issues when applying 3D transforms on a view.</p>
     *
     * @see #getLayerType()
     * @see #setLayerType(int, android.graphics.Paint)
     * @see #LAYER_TYPE_NONE
     * @see #LAYER_TYPE_SOFTWARE
     */
    public static final int LAYER_TYPE_HARDWARE = 2;

    @ViewDebug.ExportedProperty(category = "drawing", mapping = {
            @ViewDebug.IntToString(from = LAYER_TYPE_NONE, to = "NONE"),
            @ViewDebug.IntToString(from = LAYER_TYPE_SOFTWARE, to = "SOFTWARE"),
            @ViewDebug.IntToString(from = LAYER_TYPE_HARDWARE, to = "HARDWARE")
    })
    int mLayerType = LAYER_TYPE_NONE;
    Paint mLayerPaint;

    /**
     * Simple constructor to use when creating a view from code.
     *
     * @param context The Context the view is running in, through which it can
     *        access the current theme, resources, etc.
     */
    public View(Context context) {
        mContext = context;
        mResources = context != null ? context.getResources() : null;
        mViewFlags = SOUND_EFFECTS_ENABLED | HAPTIC_FEEDBACK_ENABLED;
        mTouchSlop = ViewConfiguration.get(context).getScaledTouchSlop();
        setOverScrollMode(OVER_SCROLL_IF_CONTENT_SCROLLS);
    }

    /**
     * Constructor that is called when inflating a view from XML. This is called
     * when a view is being constructed from an XML file, supplying attributes
     * that were specified in the XML file. This version uses a default style of
     * 0, so the only attribute values applied are those in the Context's Theme
     * and the given AttributeSet.
     *
     * <p>
     * The method onFinishInflate() will be called after all children have been
     * added.
     *
     * @param context The Context the view is running in, through which it can
     *        access the current theme, resources, etc.
     * @param attrs The attributes of the XML tag that is inflating the view.
     * @see #View(Context, AttributeSet, int)
     */
    public View(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }

    /**
     * Perform inflation from XML and apply a class-specific base style. This
     * constructor of View allows subclasses to use their own base style when
     * they are inflating. For example, a Button class's constructor would call
     * this version of the super class constructor and supply
     * <code>R.attr.buttonStyle</code> for <var>defStyle</var>; this allows
     * the theme's button style to modify all of the base view attributes (in
     * particular its background) as well as the Button class's attributes.
     *
     * @param context The Context the view is running in, through which it can
     *        access the current theme, resources, etc.
     * @param attrs The attributes of the XML tag that is inflating the view.
     * @param defStyle The default style to apply to this view. If 0, no style
     *        will be applied (beyond what is included in the theme). This may
     *        either be an attribute resource, whose value will be retrieved
     *        from the current theme, or an explicit style resource.
     * @see #View(Context, AttributeSet)
     */
    public View(Context context, AttributeSet attrs, int defStyle) {
        this(context);

        TypedArray a = context.obtainStyledAttributes(attrs, com.android.internal.R.styleable.View,
                defStyle, 0);

        Drawable background = null;

        int leftPadding = -1;
        int topPadding = -1;
        int rightPadding = -1;
        int bottomPadding = -1;

        int padding = -1;

        int viewFlagValues = 0;
        int viewFlagMasks = 0;

        boolean setScrollContainer = false;

        int x = 0;
        int y = 0;

        float tx = 0;
        float ty = 0;
        float rotation = 0;
        float rotationX = 0;
        float rotationY = 0;
        float sx = 1f;
        float sy = 1f;
        boolean transformSet = false;

        int scrollbarStyle = SCROLLBARS_INSIDE_OVERLAY;

        int overScrollMode = mOverScrollMode;
        final int N = a.getIndexCount();
        for (int i = 0; i < N; i++) {
            int attr = a.getIndex(i);
            switch (attr) {
                case com.android.internal.R.styleable.View_background:
                    background = a.getDrawable(attr);
                    break;
                case com.android.internal.R.styleable.View_padding:
                    padding = a.getDimensionPixelSize(attr, -1);
                    break;
                 case com.android.internal.R.styleable.View_paddingLeft:
                    leftPadding = a.getDimensionPixelSize(attr, -1);
                    break;
                case com.android.internal.R.styleable.View_paddingTop:
                    topPadding = a.getDimensionPixelSize(attr, -1);
                    break;
                case com.android.internal.R.styleable.View_paddingRight:
                    rightPadding = a.getDimensionPixelSize(attr, -1);
                    break;
                case com.android.internal.R.styleable.View_paddingBottom:
                    bottomPadding = a.getDimensionPixelSize(attr, -1);
                    break;
                case com.android.internal.R.styleable.View_scrollX:
                    x = a.getDimensionPixelOffset(attr, 0);
                    break;
                case com.android.internal.R.styleable.View_scrollY:
                    y = a.getDimensionPixelOffset(attr, 0);
                    break;
                case com.android.internal.R.styleable.View_alpha:
                    setAlpha(a.getFloat(attr, 1f));
                    break;
                case com.android.internal.R.styleable.View_transformPivotX:
                    setPivotX(a.getDimensionPixelOffset(attr, 0));
                    break;
                case com.android.internal.R.styleable.View_transformPivotY:
                    setPivotY(a.getDimensionPixelOffset(attr, 0));
                    break;
                case com.android.internal.R.styleable.View_translationX:
                    tx = a.getDimensionPixelOffset(attr, 0);
                    transformSet = true;
                    break;
                case com.android.internal.R.styleable.View_translationY:
                    ty = a.getDimensionPixelOffset(attr, 0);
                    transformSet = true;
                    break;
                case com.android.internal.R.styleable.View_rotation:
                    rotation = a.getFloat(attr, 0);
                    transformSet = true;
                    break;
                case com.android.internal.R.styleable.View_rotationX:
                    rotationX = a.getFloat(attr, 0);
                    transformSet = true;
                    break;
                case com.android.internal.R.styleable.View_rotationY:
                    rotationY = a.getFloat(attr, 0);
                    transformSet = true;
                    break;
                case com.android.internal.R.styleable.View_scaleX:
                    sx = a.getFloat(attr, 1f);
                    transformSet = true;
                    break;
                case com.android.internal.R.styleable.View_scaleY:
                    sy = a.getFloat(attr, 1f);
                    transformSet = true;
                    break;
                case com.android.internal.R.styleable.View_id:
                    mID = a.getResourceId(attr, NO_ID);
                    break;
                case com.android.internal.R.styleable.View_tag:
                    mTag = a.getText(attr);
                    break;
                case com.android.internal.R.styleable.View_fitsSystemWindows:
                    if (a.getBoolean(attr, false)) {
                        viewFlagValues |= FITS_SYSTEM_WINDOWS;
                        viewFlagMasks |= FITS_SYSTEM_WINDOWS;
                    }
                    break;
                case com.android.internal.R.styleable.View_focusable:
                    if (a.getBoolean(attr, false)) {
                        viewFlagValues |= FOCUSABLE;
                        viewFlagMasks |= FOCUSABLE_MASK;
                    }
                    break;
                case com.android.internal.R.styleable.View_focusableInTouchMode:
                    if (a.getBoolean(attr, false)) {
                        viewFlagValues |= FOCUSABLE_IN_TOUCH_MODE | FOCUSABLE;
                        viewFlagMasks |= FOCUSABLE_IN_TOUCH_MODE | FOCUSABLE_MASK;
                    }
                    break;
                case com.android.internal.R.styleable.View_clickable:
                    if (a.getBoolean(attr, false)) {
                        viewFlagValues |= CLICKABLE;
                        viewFlagMasks |= CLICKABLE;
                    }
                    break;
                case com.android.internal.R.styleable.View_longClickable:
                    if (a.getBoolean(attr, false)) {
                        viewFlagValues |= LONG_CLICKABLE;
                        viewFlagMasks |= LONG_CLICKABLE;
                    }
                    break;
                case com.android.internal.R.styleable.View_saveEnabled:
                    if (!a.getBoolean(attr, true)) {
                        viewFlagValues |= SAVE_DISABLED;
                        viewFlagMasks |= SAVE_DISABLED_MASK;
                    }
                    break;
                case com.android.internal.R.styleable.View_duplicateParentState:
                    if (a.getBoolean(attr, false)) {
                        viewFlagValues |= DUPLICATE_PARENT_STATE;
                        viewFlagMasks |= DUPLICATE_PARENT_STATE;
                    }
                    break;
                case com.android.internal.R.styleable.View_visibility:
                    final int visibility = a.getInt(attr, 0);
                    if (visibility != 0) {
                        viewFlagValues |= VISIBILITY_FLAGS[visibility];
                        viewFlagMasks |= VISIBILITY_MASK;
                    }
                    break;
                case com.android.internal.R.styleable.View_drawingCacheQuality:
                    final int cacheQuality = a.getInt(attr, 0);
                    if (cacheQuality != 0) {
                        viewFlagValues |= DRAWING_CACHE_QUALITY_FLAGS[cacheQuality];
                        viewFlagMasks |= DRAWING_CACHE_QUALITY_MASK;
                    }
                    break;
                case com.android.internal.R.styleable.View_contentDescription:
                    mContentDescription = a.getString(attr);
                    break;
                case com.android.internal.R.styleable.View_soundEffectsEnabled:
                    if (!a.getBoolean(attr, true)) {
                        viewFlagValues &= ~SOUND_EFFECTS_ENABLED;
                        viewFlagMasks |= SOUND_EFFECTS_ENABLED;
                    }
                    break;
                case com.android.internal.R.styleable.View_hapticFeedbackEnabled:
                    if (!a.getBoolean(attr, true)) {
                        viewFlagValues &= ~HAPTIC_FEEDBACK_ENABLED;
                        viewFlagMasks |= HAPTIC_FEEDBACK_ENABLED;
                    }
                    break;
                case R.styleable.View_scrollbars:
                    final int scrollbars = a.getInt(attr, SCROLLBARS_NONE);
                    if (scrollbars != SCROLLBARS_NONE) {
                        viewFlagValues |= scrollbars;
                        viewFlagMasks |= SCROLLBARS_MASK;
                        initializeScrollbars(a);
                    }
                    break;
                case R.styleable.View_fadingEdge:
                    final int fadingEdge = a.getInt(attr, FADING_EDGE_NONE);
                    if (fadingEdge != FADING_EDGE_NONE) {
                        viewFlagValues |= fadingEdge;
                        viewFlagMasks |= FADING_EDGE_MASK;
                        initializeFadingEdge(a);
                    }
                    break;
                case R.styleable.View_scrollbarStyle:
                    scrollbarStyle = a.getInt(attr, SCROLLBARS_INSIDE_OVERLAY);
                    if (scrollbarStyle != SCROLLBARS_INSIDE_OVERLAY) {
                        viewFlagValues |= scrollbarStyle & SCROLLBARS_STYLE_MASK;
                        viewFlagMasks |= SCROLLBARS_STYLE_MASK;
                    }
                    break;
                case R.styleable.View_isScrollContainer:
                    setScrollContainer = true;
                    if (a.getBoolean(attr, false)) {
                        setScrollContainer(true);
                    }
                    break;
                case com.android.internal.R.styleable.View_keepScreenOn:
                    if (a.getBoolean(attr, false)) {
                        viewFlagValues |= KEEP_SCREEN_ON;
                        viewFlagMasks |= KEEP_SCREEN_ON;
                    }
                    break;
                case R.styleable.View_filterTouchesWhenObscured:
                    if (a.getBoolean(attr, false)) {
                        viewFlagValues |= FILTER_TOUCHES_WHEN_OBSCURED;
                        viewFlagMasks |= FILTER_TOUCHES_WHEN_OBSCURED;
                    }
                    break;
                case R.styleable.View_nextFocusLeft:
                    mNextFocusLeftId = a.getResourceId(attr, View.NO_ID);
                    break;
                case R.styleable.View_nextFocusRight:
                    mNextFocusRightId = a.getResourceId(attr, View.NO_ID);
                    break;
                case R.styleable.View_nextFocusUp:
                    mNextFocusUpId = a.getResourceId(attr, View.NO_ID);
                    break;
                case R.styleable.View_nextFocusDown:
                    mNextFocusDownId = a.getResourceId(attr, View.NO_ID);
                    break;
                case R.styleable.View_nextFocusForward:
                    mNextFocusForwardId = a.getResourceId(attr, View.NO_ID);
                    break;
                case R.styleable.View_minWidth:
                    mMinWidth = a.getDimensionPixelSize(attr, 0);
                    break;
                case R.styleable.View_minHeight:
                    mMinHeight = a.getDimensionPixelSize(attr, 0);
                    break;
                case R.styleable.View_onClick:
                    if (context.isRestricted()) {
                        throw new IllegalStateException("The android:onClick attribute cannot "
                                + "be used within a restricted context");
                    }

                    final String handlerName = a.getString(attr);
                    if (handlerName != null) {
                        setOnClickListener(new OnClickListener() {
                            private Method mHandler;

                            public void onClick(View v) {
                                if (mHandler == null) {
                                    try {
                                        mHandler = getContext().getClass().getMethod(handlerName,
                                                View.class);
                                    } catch (NoSuchMethodException e) {
                                        int id = getId();
                                        String idText = id == NO_ID ? "" : " with id '"
                                                + getContext().getResources().getResourceEntryName(
                                                    id) + "'";
                                        throw new IllegalStateException("Could not find a method " +
                                                handlerName + "(View) in the activity "
                                                + getContext().getClass() + " for onClick handler"
                                                + " on view " + View.this.getClass() + idText, e);
                                    }
                                }

                                try {
                                    mHandler.invoke(getContext(), View.this);
                                } catch (IllegalAccessException e) {
                                    throw new IllegalStateException("Could not execute non "
                                            + "public method of the activity", e);
                                } catch (InvocationTargetException e) {
                                    throw new IllegalStateException("Could not execute "
                                            + "method of the activity", e);
                                }
                            }
                        });
                    }
                    break;
                case R.styleable.View_overScrollMode:
                    overScrollMode = a.getInt(attr, OVER_SCROLL_IF_CONTENT_SCROLLS);
                    break;
                case R.styleable.View_verticalScrollbarPosition:
                    mVerticalScrollbarPosition = a.getInt(attr, SCROLLBAR_POSITION_DEFAULT);
                    break;
                case R.styleable.View_layerType:
                    setLayerType(a.getInt(attr, LAYER_TYPE_NONE), null);
                    break;
            }
        }

        setOverScrollMode(overScrollMode);

        if (background != null) {
            setBackgroundDrawable(background);
        }

        if (padding >= 0) {
            leftPadding = padding;
            topPadding = padding;
            rightPadding = padding;
            bottomPadding = padding;
        }

        // If the user specified the padding (either with android:padding or
        // android:paddingLeft/Top/Right/Bottom), use this padding, otherwise
        // use the default padding or the padding from the background drawable
        // (stored at this point in mPadding*)
        setPadding(leftPadding >= 0 ? leftPadding : mPaddingLeft,
                topPadding >= 0 ? topPadding : mPaddingTop,
                rightPadding >= 0 ? rightPadding : mPaddingRight,
                bottomPadding >= 0 ? bottomPadding : mPaddingBottom);

        if (viewFlagMasks != 0) {
            setFlags(viewFlagValues, viewFlagMasks);
        }

        // Needs to be called after mViewFlags is set
        if (scrollbarStyle != SCROLLBARS_INSIDE_OVERLAY) {
            recomputePadding();
        }

        if (x != 0 || y != 0) {
            scrollTo(x, y);
        }

        if (transformSet) {
            setTranslationX(tx);
            setTranslationY(ty);
            setRotation(rotation);
            setRotationX(rotationX);
            setRotationY(rotationY);
            setScaleX(sx);
            setScaleY(sy);
        }

        if (!setScrollContainer && (viewFlagValues&SCROLLBARS_VERTICAL) != 0) {
            setScrollContainer(true);
        }

        computeOpaqueFlags();

        a.recycle();
    }

    /**
     * Non-public constructor for use in testing
     */
    View() {
    }

    /**
     * <p>
     * Initializes the fading edges from a given set of styled attributes. This
     * method should be called by subclasses that need fading edges and when an
     * instance of these subclasses is created programmatically rather than
     * being inflated from XML. This method is automatically called when the XML
     * is inflated.
     * </p>
     *
     * @param a the styled attributes set to initialize the fading edges from
     */
    protected void initializeFadingEdge(TypedArray a) {
        initScrollCache();

        mScrollCache.fadingEdgeLength = a.getDimensionPixelSize(
                R.styleable.View_fadingEdgeLength,
                ViewConfiguration.get(mContext).getScaledFadingEdgeLength());
    }

    /**
     * Returns the size of the vertical faded edges used to indicate that more
     * content in this view is visible.
     *
     * @return The size in pixels of the vertical faded edge or 0 if vertical
     *         faded edges are not enabled for this view.
     * @attr ref android.R.styleable#View_fadingEdgeLength
     */
    public int getVerticalFadingEdgeLength() {
        if (isVerticalFadingEdgeEnabled()) {
            ScrollabilityCache cache = mScrollCache;
            if (cache != null) {
                return cache.fadingEdgeLength;
            }
        }
        return 0;
    }

    /**
     * Set the size of the faded edge used to indicate that more content in this
     * view is available.  Will not change whether the fading edge is enabled; use
     * {@link #setVerticalFadingEdgeEnabled} or {@link #setHorizontalFadingEdgeEnabled}
     * to enable the fading edge for the vertical or horizontal fading edges.
     *
     * @param length The size in pixels of the faded edge used to indicate that more
     *        content in this view is visible.
     */
    public void setFadingEdgeLength(int length) {
        initScrollCache();
        mScrollCache.fadingEdgeLength = length;
    }

    /**
     * Returns the size of the horizontal faded edges used to indicate that more
     * content in this view is visible.
     *
     * @return The size in pixels of the horizontal faded edge or 0 if horizontal
     *         faded edges are not enabled for this view.
     * @attr ref android.R.styleable#View_fadingEdgeLength
     */
    public int getHorizontalFadingEdgeLength() {
        if (isHorizontalFadingEdgeEnabled()) {
            ScrollabilityCache cache = mScrollCache;
            if (cache != null) {
                return cache.fadingEdgeLength;
            }
        }
        return 0;
    }

    /**
     * Returns the width of the vertical scrollbar.
     *
     * @return The width in pixels of the vertical scrollbar or 0 if there
     *         is no vertical scrollbar.
     */
    public int getVerticalScrollbarWidth() {
        ScrollabilityCache cache = mScrollCache;
        if (cache != null) {
            ScrollBarDrawable scrollBar = cache.scrollBar;
            if (scrollBar != null) {
                int size = scrollBar.getSize(true);
                if (size <= 0) {
                    size = cache.scrollBarSize;
                }
                return size;
            }
            return 0;
        }
        return 0;
    }

    /**
     * Returns the height of the horizontal scrollbar.
     *
     * @return The height in pixels of the horizontal scrollbar or 0 if
     *         there is no horizontal scrollbar.
     */
    protected int getHorizontalScrollbarHeight() {
        ScrollabilityCache cache = mScrollCache;
        if (cache != null) {
            ScrollBarDrawable scrollBar = cache.scrollBar;
            if (scrollBar != null) {
                int size = scrollBar.getSize(false);
                if (size <= 0) {
                    size = cache.scrollBarSize;
                }
                return size;
            }
            return 0;
        }
        return 0;
    }

    /**
     * <p>
     * Initializes the scrollbars from a given set of styled attributes. This
     * method should be called by subclasses that need scrollbars and when an
     * instance of these subclasses is created programmatically rather than
     * being inflated from XML. This method is automatically called when the XML
     * is inflated.
     * </p>
     *
     * @param a the styled attributes set to initialize the scrollbars from
     */
    protected void initializeScrollbars(TypedArray a) {
        initScrollCache();

        final ScrollabilityCache scrollabilityCache = mScrollCache;

        if (scrollabilityCache.scrollBar == null) {
            scrollabilityCache.scrollBar = new ScrollBarDrawable();
        }

        final boolean fadeScrollbars = a.getBoolean(R.styleable.View_fadeScrollbars, true);

        if (!fadeScrollbars) {
            scrollabilityCache.state = ScrollabilityCache.ON;
        }
        scrollabilityCache.fadeScrollBars = fadeScrollbars;


        scrollabilityCache.scrollBarFadeDuration = a.getInt(
                R.styleable.View_scrollbarFadeDuration, ViewConfiguration
                        .getScrollBarFadeDuration());
        scrollabilityCache.scrollBarDefaultDelayBeforeFade = a.getInt(
                R.styleable.View_scrollbarDefaultDelayBeforeFade,
                ViewConfiguration.getScrollDefaultDelay());


        scrollabilityCache.scrollBarSize = a.getDimensionPixelSize(
                com.android.internal.R.styleable.View_scrollbarSize,
                ViewConfiguration.get(mContext).getScaledScrollBarSize());

        Drawable track = a.getDrawable(R.styleable.View_scrollbarTrackHorizontal);
        scrollabilityCache.scrollBar.setHorizontalTrackDrawable(track);

        Drawable thumb = a.getDrawable(R.styleable.View_scrollbarThumbHorizontal);
        if (thumb != null) {
            scrollabilityCache.scrollBar.setHorizontalThumbDrawable(thumb);
        }

        boolean alwaysDraw = a.getBoolean(R.styleable.View_scrollbarAlwaysDrawHorizontalTrack,
                false);
        if (alwaysDraw) {
            scrollabilityCache.scrollBar.setAlwaysDrawHorizontalTrack(true);
        }

        track = a.getDrawable(R.styleable.View_scrollbarTrackVertical);
        scrollabilityCache.scrollBar.setVerticalTrackDrawable(track);

        thumb = a.getDrawable(R.styleable.View_scrollbarThumbVertical);
        if (thumb != null) {
            scrollabilityCache.scrollBar.setVerticalThumbDrawable(thumb);
        }

        alwaysDraw = a.getBoolean(R.styleable.View_scrollbarAlwaysDrawVerticalTrack,
                false);
        if (alwaysDraw) {
            scrollabilityCache.scrollBar.setAlwaysDrawVerticalTrack(true);
        }

        // Re-apply user/background padding so that scrollbar(s) get added
        recomputePadding();
    }

    /**
     * <p>
     * Initalizes the scrollability cache if necessary.
     * </p>
     */
    private void initScrollCache() {
        if (mScrollCache == null) {
            mScrollCache = new ScrollabilityCache(ViewConfiguration.get(mContext), this);
        }
    }

    /**
     * Set the position of the vertical scroll bar. Should be one of
     * {@link #SCROLLBAR_POSITION_DEFAULT}, {@link #SCROLLBAR_POSITION_LEFT} or
     * {@link #SCROLLBAR_POSITION_RIGHT}.
     *
     * @param position Where the vertical scroll bar should be positioned.
     */
    public void setVerticalScrollbarPosition(int position) {
        if (mVerticalScrollbarPosition != position) {
            mVerticalScrollbarPosition = position;
            computeOpaqueFlags();
            recomputePadding();
        }
    }

    /**
     * @return The position where the vertical scroll bar will show, if applicable.
     * @see #setVerticalScrollbarPosition(int)
     */
    public int getVerticalScrollbarPosition() {
        return mVerticalScrollbarPosition;
    }

    /**
     * Register a callback to be invoked when focus of this view changed.
     *
     * @param l The callback that will run.
     */
    public void setOnFocusChangeListener(OnFocusChangeListener l) {
        mOnFocusChangeListener = l;
    }

    /**
     * Add a listener that will be called when the bounds of the view change due to
     * layout processing.
     *
     * @param listener The listener that will be called when layout bounds change.
     */
    public void addOnLayoutChangeListener(OnLayoutChangeListener listener) {
        if (mOnLayoutChangeListeners == null) {
            mOnLayoutChangeListeners = new ArrayList<OnLayoutChangeListener>();
        }
        mOnLayoutChangeListeners.add(listener);
    }

    /**
     * Remove a listener for layout changes.
     *
     * @param listener The listener for layout bounds change.
     */
    public void removeOnLayoutChangeListener(OnLayoutChangeListener listener) {
        if (mOnLayoutChangeListeners == null) {
            return;
        }
        mOnLayoutChangeListeners.remove(listener);
    }

    /**
     * Returns the focus-change callback registered for this view.
     *
     * @return The callback, or null if one is not registered.
     */
    public OnFocusChangeListener getOnFocusChangeListener() {
        return mOnFocusChangeListener;
    }

    /**
     * Register a callback to be invoked when this view is clicked. If this view is not
     * clickable, it becomes clickable.
     *
     * @param l The callback that will run
     *
     * @see #setClickable(boolean)
     */
    public void setOnClickListener(OnClickListener l) {
        if (!isClickable()) {
            setClickable(true);
        }
        mOnClickListener = l;
    }

    /**
     * Register a callback to be invoked when this view is clicked and held. If this view is not
     * long clickable, it becomes long clickable.
     *
     * @param l The callback that will run
     *
     * @see #setLongClickable(boolean)
     */
    public void setOnLongClickListener(OnLongClickListener l) {
        if (!isLongClickable()) {
            setLongClickable(true);
        }
        mOnLongClickListener = l;
    }

    /**
     * Register a callback to be invoked when the context menu for this view is
     * being built. If this view is not long clickable, it becomes long clickable.
     *
     * @param l The callback that will run
     *
     */
    public void setOnCreateContextMenuListener(OnCreateContextMenuListener l) {
        if (!isLongClickable()) {
            setLongClickable(true);
        }
        mOnCreateContextMenuListener = l;
    }

    /**
     * Call this view's OnClickListener, if it is defined.
     *
     * @return True there was an assigned OnClickListener that was called, false
     *         otherwise is returned.
     */
    public boolean performClick() {
        sendAccessibilityEvent(AccessibilityEvent.TYPE_VIEW_CLICKED);

        if (mOnClickListener != null) {
            playSoundEffect(SoundEffectConstants.CLICK);
            mOnClickListener.onClick(this);
            return true;
        }

        return false;
    }

    /**
     * Call this view's OnLongClickListener, if it is defined. Invokes the context menu if the
     * OnLongClickListener did not consume the event.
     *
     * @return True if one of the above receivers consumed the event, false otherwise.
     */
    public boolean performLongClick() {
        sendAccessibilityEvent(AccessibilityEvent.TYPE_VIEW_LONG_CLICKED);

        boolean handled = false;
        if (mOnLongClickListener != null) {
            handled = mOnLongClickListener.onLongClick(View.this);
        }
        if (!handled) {
            handled = showContextMenu();
        }
        if (handled) {
            performHapticFeedback(HapticFeedbackConstants.LONG_PRESS);
        }
        return handled;
    }

    /**
     * Bring up the context menu for this view.
     *
     * @return Whether a context menu was displayed.
     */
    public boolean showContextMenu() {
        return getParent().showContextMenuForChild(this);
    }

    /**
     * Start an action mode.
     *
     * @param callback Callback that will control the lifecycle of the action mode
     * @return The new action mode if it is started, null otherwise
     *
     * @see ActionMode
     */
    public ActionMode startActionMode(ActionMode.Callback callback) {
        return getParent().startActionModeForChild(this, callback);
    }

    /**
     * Register a callback to be invoked when a key is pressed in this view.
     * @param l the key listener to attach to this view
     */
    public void setOnKeyListener(OnKeyListener l) {
        mOnKeyListener = l;
    }

    /**
     * Register a callback to be invoked when a touch event is sent to this view.
     * @param l the touch listener to attach to this view
     */
    public void setOnTouchListener(OnTouchListener l) {
        mOnTouchListener = l;
    }

    /**
     * Register a callback to be invoked when a drag event is sent to this view.
     * @param l The drag listener to attach to this view
     */
    public void setOnDragListener(OnDragListener l) {
        mOnDragListener = l;
    }

    /**
     * Give this view focus. This will cause {@link #onFocusChanged} to be called.
     *
     * Note: this does not check whether this {@link View} should get focus, it just
     * gives it focus no matter what.  It should only be called internally by framework
     * code that knows what it is doing, namely {@link #requestFocus(int, Rect)}.
     *
     * @param direction values are View.FOCUS_UP, View.FOCUS_DOWN,
     *        View.FOCUS_LEFT or View.FOCUS_RIGHT. This is the direction which
     *        focus moved when requestFocus() is called. It may not always
     *        apply, in which case use the default View.FOCUS_DOWN.
     * @param previouslyFocusedRect The rectangle of the view that had focus
     *        prior in this View's coordinate system.
     */
    void handleFocusGainInternal(int direction, Rect previouslyFocusedRect) {
        if (DBG) {
            System.out.println(this + " requestFocus()");
        }

        if ((mPrivateFlags & FOCUSED) == 0) {
            mPrivateFlags |= FOCUSED;

            if (mParent != null) {
                mParent.requestChildFocus(this, this);
            }

            onFocusChanged(true, direction, previouslyFocusedRect);
            refreshDrawableState();
        }
    }

    /**
     * Request that a rectangle of this view be visible on the screen,
     * scrolling if necessary just enough.
     *
     * <p>A View should call this if it maintains some notion of which part
     * of its content is interesting.  For example, a text editing view
     * should call this when its cursor moves.
     *
     * @param rectangle The rectangle.
     * @return Whether any parent scrolled.
     */
    public boolean requestRectangleOnScreen(Rect rectangle) {
        return requestRectangleOnScreen(rectangle, false);
    }

    /**
     * Request that a rectangle of this view be visible on the screen,
     * scrolling if necessary just enough.
     *
     * <p>A View should call this if it maintains some notion of which part
     * of its content is interesting.  For example, a text editing view
     * should call this when its cursor moves.
     *
     * <p>When <code>immediate</code> is set to true, scrolling will not be
     * animated.
     *
     * @param rectangle The rectangle.
     * @param immediate True to forbid animated scrolling, false otherwise
     * @return Whether any parent scrolled.
     */
    public boolean requestRectangleOnScreen(Rect rectangle, boolean immediate) {
        View child = this;
        ViewParent parent = mParent;
        boolean scrolled = false;
        while (parent != null) {
            scrolled |= parent.requestChildRectangleOnScreen(child,
                    rectangle, immediate);

            // offset rect so next call has the rectangle in the
            // coordinate system of its direct child.
            rectangle.offset(child.getLeft(), child.getTop());
            rectangle.offset(-child.getScrollX(), -child.getScrollY());

            if (!(parent instanceof View)) {
                break;
            }

            child = (View) parent;
            parent = child.getParent();
        }
        return scrolled;
    }

    /**
     * Called when this view wants to give up focus. This will cause
     * {@link #onFocusChanged} to be called.
     */
    public void clearFocus() {
        if (DBG) {
            System.out.println(this + " clearFocus()");
        }

        if ((mPrivateFlags & FOCUSED) != 0) {
            mPrivateFlags &= ~FOCUSED;

            if (mParent != null) {
                mParent.clearChildFocus(this);
            }

            onFocusChanged(false, 0, null);
            refreshDrawableState();
        }
    }

    /**
     * Called to clear the focus of a view that is about to be removed.
     * Doesn't call clearChildFocus, which prevents this view from taking
     * focus again before it has been removed from the parent
     */
    void clearFocusForRemoval() {
        if ((mPrivateFlags & FOCUSED) != 0) {
            mPrivateFlags &= ~FOCUSED;

            onFocusChanged(false, 0, null);
            refreshDrawableState();
        }
    }

    /**
     * Called internally by the view system when a new view is getting focus.
     * This is what clears the old focus.
     */
    void unFocus() {
        if (DBG) {
            System.out.println(this + " unFocus()");
        }

        if ((mPrivateFlags & FOCUSED) != 0) {
            mPrivateFlags &= ~FOCUSED;

            onFocusChanged(false, 0, null);
            refreshDrawableState();
        }
    }

    /**
     * Returns true if this view has focus iteself, or is the ancestor of the
     * view that has focus.
     *
     * @return True if this view has or contains focus, false otherwise.
     */
    @ViewDebug.ExportedProperty(category = "focus")
    public boolean hasFocus() {
        return (mPrivateFlags & FOCUSED) != 0;
    }

    /**
     * Returns true if this view is focusable or if it contains a reachable View
     * for which {@link #hasFocusable()} returns true. A "reachable hasFocusable()"
     * is a View whose parents do not block descendants focus.
     *
     * Only {@link #VISIBLE} views are considered focusable.
     *
     * @return True if the view is focusable or if the view contains a focusable
     *         View, false otherwise.
     *
     * @see ViewGroup#FOCUS_BLOCK_DESCENDANTS
     */
    public boolean hasFocusable() {
        return (mViewFlags & VISIBILITY_MASK) == VISIBLE && isFocusable();
    }

    /**
     * Called by the view system when the focus state of this view changes.
     * When the focus change event is caused by directional navigation, direction
     * and previouslyFocusedRect provide insight into where the focus is coming from.
     * When overriding, be sure to call up through to the super class so that
     * the standard focus handling will occur.
     *
     * @param gainFocus True if the View has focus; false otherwise.
     * @param direction The direction focus has moved when requestFocus()
     *                  is called to give this view focus. Values are
     *                  {@link #FOCUS_UP}, {@link #FOCUS_DOWN}, {@link #FOCUS_LEFT},
     *                  {@link #FOCUS_RIGHT}, {@link #FOCUS_FORWARD}, or {@link #FOCUS_BACKWARD}.
     *                  It may not always apply, in which case use the default.
     * @param previouslyFocusedRect The rectangle, in this view's coordinate
     *        system, of the previously focused view.  If applicable, this will be
     *        passed in as finer grained information about where the focus is coming
     *        from (in addition to direction).  Will be <code>null</code> otherwise.
     */
    protected void onFocusChanged(boolean gainFocus, int direction, Rect previouslyFocusedRect) {
        if (gainFocus) {
            sendAccessibilityEvent(AccessibilityEvent.TYPE_VIEW_FOCUSED);
        }

        InputMethodManager imm = InputMethodManager.peekInstance();
        if (!gainFocus) {
            if (isPressed()) {
                setPressed(false);
            }
            if (imm != null && mAttachInfo != null
                    && mAttachInfo.mHasWindowFocus) {
                imm.focusOut(this);
            }
            onFocusLost();
        } else if (imm != null && mAttachInfo != null
                && mAttachInfo.mHasWindowFocus) {
            imm.focusIn(this);
        }

        invalidate(true);
        if (mOnFocusChangeListener != null) {
            mOnFocusChangeListener.onFocusChange(this, gainFocus);
        }

        if (mAttachInfo != null) {
            mAttachInfo.mKeyDispatchState.reset(this);
        }
    }

    /**
     * {@inheritDoc}
     */
    public void sendAccessibilityEvent(int eventType) {
        if (AccessibilityManager.getInstance(mContext).isEnabled()) {
            sendAccessibilityEventUnchecked(AccessibilityEvent.obtain(eventType));
        }
    }

    /**
     * {@inheritDoc}
     */
    public void sendAccessibilityEventUnchecked(AccessibilityEvent event) {
        if (!isShown()) {
            return;
        }
        event.setClassName(getClass().getName());
        event.setPackageName(getContext().getPackageName());
        event.setEnabled(isEnabled());
        event.setContentDescription(mContentDescription);

        if (event.getEventType() == AccessibilityEvent.TYPE_VIEW_FOCUSED && mAttachInfo != null) {
            ArrayList<View> focusablesTempList = mAttachInfo.mFocusablesTempList;
            getRootView().addFocusables(focusablesTempList, View.FOCUS_FORWARD, FOCUSABLES_ALL);
            event.setItemCount(focusablesTempList.size());
            event.setCurrentItemIndex(focusablesTempList.indexOf(this));
            focusablesTempList.clear();
        }

        dispatchPopulateAccessibilityEvent(event);

        AccessibilityManager.getInstance(mContext).sendAccessibilityEvent(event);
    }

    /**
     * Dispatches an {@link AccessibilityEvent} to the {@link View} children
     * to be populated.
     *
     * @param event The event.
     *
     * @return True if the event population was completed.
     */
    public boolean dispatchPopulateAccessibilityEvent(AccessibilityEvent event) {
        return false;
    }

    /**
     * Gets the {@link View} description. It briefly describes the view and is
     * primarily used for accessibility support. Set this property to enable
     * better accessibility support for your application. This is especially
     * true for views that do not have textual representation (For example,
     * ImageButton).
     *
     * @return The content descriptiopn.
     *
     * @attr ref android.R.styleable#View_contentDescription
     */
    public CharSequence getContentDescription() {
        return mContentDescription;
    }

    /**
     * Sets the {@link View} description. It briefly describes the view and is
     * primarily used for accessibility support. Set this property to enable
     * better accessibility support for your application. This is especially
     * true for views that do not have textual representation (For example,
     * ImageButton).
     *
     * @param contentDescription The content description.
     *
     * @attr ref android.R.styleable#View_contentDescription
     */
    public void setContentDescription(CharSequence contentDescription) {
        mContentDescription = contentDescription;
    }

    /**
     * Invoked whenever this view loses focus, either by losing window focus or by losing
     * focus within its window. This method can be used to clear any state tied to the
     * focus. For instance, if a button is held pressed with the trackball and the window
     * loses focus, this method can be used to cancel the press.
     *
     * Subclasses of View overriding this method should always call super.onFocusLost().
     *
     * @see #onFocusChanged(boolean, int, android.graphics.Rect)
     * @see #onWindowFocusChanged(boolean)
     *
     * @hide pending API council approval
     */
    protected void onFocusLost() {
        resetPressedState();
    }

    private void resetPressedState() {
        if ((mViewFlags & ENABLED_MASK) == DISABLED) {
            return;
        }

        if (isPressed()) {
            setPressed(false);

            if (!mHasPerformedLongPress) {
                removeLongPressCallback();
            }
        }
    }

    /**
     * Returns true if this view has focus
     *
     * @return True if this view has focus, false otherwise.
     */
    @ViewDebug.ExportedProperty(category = "focus")
    public boolean isFocused() {
        return (mPrivateFlags & FOCUSED) != 0;
    }

    /**
     * Find the view in the hierarchy rooted at this view that currently has
     * focus.
     *
     * @return The view that currently has focus, or null if no focused view can
     *         be found.
     */
    public View findFocus() {
        return (mPrivateFlags & FOCUSED) != 0 ? this : null;
    }

    /**
     * Change whether this view is one of the set of scrollable containers in
     * its window.  This will be used to determine whether the window can
     * resize or must pan when a soft input area is open -- scrollable
     * containers allow the window to use resize mode since the container
     * will appropriately shrink.
     */
    public void setScrollContainer(boolean isScrollContainer) {
        if (isScrollContainer) {
            if (mAttachInfo != null && (mPrivateFlags&SCROLL_CONTAINER_ADDED) == 0) {
                mAttachInfo.mScrollContainers.add(this);
                mPrivateFlags |= SCROLL_CONTAINER_ADDED;
            }
            mPrivateFlags |= SCROLL_CONTAINER;
        } else {
            if ((mPrivateFlags&SCROLL_CONTAINER_ADDED) != 0) {
                mAttachInfo.mScrollContainers.remove(this);
            }
            mPrivateFlags &= ~(SCROLL_CONTAINER|SCROLL_CONTAINER_ADDED);
        }
    }

    /**
     * Returns the quality of the drawing cache.
     *
     * @return One of {@link #DRAWING_CACHE_QUALITY_AUTO},
     *         {@link #DRAWING_CACHE_QUALITY_LOW}, or {@link #DRAWING_CACHE_QUALITY_HIGH}
     *
     * @see #setDrawingCacheQuality(int)
     * @see #setDrawingCacheEnabled(boolean)
     * @see #isDrawingCacheEnabled()
     *
     * @attr ref android.R.styleable#View_drawingCacheQuality
     */
    public int getDrawingCacheQuality() {
        return mViewFlags & DRAWING_CACHE_QUALITY_MASK;
    }

    /**
     * Set the drawing cache quality of this view. This value is used only when the
     * drawing cache is enabled
     *
     * @param quality One of {@link #DRAWING_CACHE_QUALITY_AUTO},
     *        {@link #DRAWING_CACHE_QUALITY_LOW}, or {@link #DRAWING_CACHE_QUALITY_HIGH}
     *
     * @see #getDrawingCacheQuality()
     * @see #setDrawingCacheEnabled(boolean)
     * @see #isDrawingCacheEnabled()
     *
     * @attr ref android.R.styleable#View_drawingCacheQuality
     */
    public void setDrawingCacheQuality(int quality) {
        setFlags(quality, DRAWING_CACHE_QUALITY_MASK);
    }

    /**
     * Returns whether the screen should remain on, corresponding to the current
     * value of {@link #KEEP_SCREEN_ON}.
     *
     * @return Returns true if {@link #KEEP_SCREEN_ON} is set.
     *
     * @see #setKeepScreenOn(boolean)
     *
     * @attr ref android.R.styleable#View_keepScreenOn
     */
    public boolean getKeepScreenOn() {
        return (mViewFlags & KEEP_SCREEN_ON) != 0;
    }

    /**
     * Controls whether the screen should remain on, modifying the
     * value of {@link #KEEP_SCREEN_ON}.
     *
     * @param keepScreenOn Supply true to set {@link #KEEP_SCREEN_ON}.
     *
     * @see #getKeepScreenOn()
     *
     * @attr ref android.R.styleable#View_keepScreenOn
     */
    public void setKeepScreenOn(boolean keepScreenOn) {
        setFlags(keepScreenOn ? KEEP_SCREEN_ON : 0, KEEP_SCREEN_ON);
    }

    /**
     * Gets the id of the view to use when the next focus is {@link #FOCUS_LEFT}.
     * @return The next focus ID, or {@link #NO_ID} if the framework should decide automatically.
     *
     * @attr ref android.R.styleable#View_nextFocusLeft
     */
    public int getNextFocusLeftId() {
        return mNextFocusLeftId;
    }

    /**
     * Sets the id of the view to use when the next focus is {@link #FOCUS_LEFT}.
     * @param nextFocusLeftId The next focus ID, or {@link #NO_ID} if the framework should
     * decide automatically.
     *
     * @attr ref android.R.styleable#View_nextFocusLeft
     */
    public void setNextFocusLeftId(int nextFocusLeftId) {
        mNextFocusLeftId = nextFocusLeftId;
    }

    /**
     * Gets the id of the view to use when the next focus is {@link #FOCUS_RIGHT}.
     * @return The next focus ID, or {@link #NO_ID} if the framework should decide automatically.
     *
     * @attr ref android.R.styleable#View_nextFocusRight
     */
    public int getNextFocusRightId() {
        return mNextFocusRightId;
    }

    /**
     * Sets the id of the view to use when the next focus is {@link #FOCUS_RIGHT}.
     * @param nextFocusRightId The next focus ID, or {@link #NO_ID} if the framework should
     * decide automatically.
     *
     * @attr ref android.R.styleable#View_nextFocusRight
     */
    public void setNextFocusRightId(int nextFocusRightId) {
        mNextFocusRightId = nextFocusRightId;
    }

    /**
     * Gets the id of the view to use when the next focus is {@link #FOCUS_UP}.
     * @return The next focus ID, or {@link #NO_ID} if the framework should decide automatically.
     *
     * @attr ref android.R.styleable#View_nextFocusUp
     */
    public int getNextFocusUpId() {
        return mNextFocusUpId;
    }

    /**
     * Sets the id of the view to use when the next focus is {@link #FOCUS_UP}.
     * @param nextFocusUpId The next focus ID, or {@link #NO_ID} if the framework should
     * decide automatically.
     *
     * @attr ref android.R.styleable#View_nextFocusUp
     */
    public void setNextFocusUpId(int nextFocusUpId) {
        mNextFocusUpId = nextFocusUpId;
    }

    /**
     * Gets the id of the view to use when the next focus is {@link #FOCUS_DOWN}.
     * @return The next focus ID, or {@link #NO_ID} if the framework should decide automatically.
     *
     * @attr ref android.R.styleable#View_nextFocusDown
     */
    public int getNextFocusDownId() {
        return mNextFocusDownId;
    }

    /**
     * Sets the id of the view to use when the next focus is {@link #FOCUS_DOWN}.
     * @param nextFocusDownId The next focus ID, or {@link #NO_ID} if the framework should
     * decide automatically.
     *
     * @attr ref android.R.styleable#View_nextFocusDown
     */
    public void setNextFocusDownId(int nextFocusDownId) {
        mNextFocusDownId = nextFocusDownId;
    }

    /**
     * Gets the id of the view to use when the next focus is {@link #FOCUS_FORWARD}.
     * @return The next focus ID, or {@link #NO_ID} if the framework should decide automatically.
     *
     * @attr ref android.R.styleable#View_nextFocusForward
     */
    public int getNextFocusForwardId() {
        return mNextFocusForwardId;
    }

    /**
     * Sets the id of the view to use when the next focus is {@link #FOCUS_FORWARD}.
     * @param nextFocusForwardId The next focus ID, or {@link #NO_ID} if the framework should
     * decide automatically.
     *
     * @attr ref android.R.styleable#View_nextFocusForward
     */
    public void setNextFocusForwardId(int nextFocusForwardId) {
        mNextFocusForwardId = nextFocusForwardId;
    }

    /**
     * Returns the visibility of this view and all of its ancestors
     *
     * @return True if this view and all of its ancestors are {@link #VISIBLE}
     */
    public boolean isShown() {
        View current = this;
        //noinspection ConstantConditions
        do {
            if ((current.mViewFlags & VISIBILITY_MASK) != VISIBLE) {
                return false;
            }
            ViewParent parent = current.mParent;
            if (parent == null) {
                return false; // We are not attached to the view root
            }
            if (!(parent instanceof View)) {
                return true;
            }
            current = (View) parent;
        } while (current != null);

        return false;
    }

    /**
     * Apply the insets for system windows to this view, if the FITS_SYSTEM_WINDOWS flag
     * is set
     *
     * @param insets Insets for system windows
     *
     * @return True if this view applied the insets, false otherwise
     */
    protected boolean fitSystemWindows(Rect insets) {
        if ((mViewFlags & FITS_SYSTEM_WINDOWS) == FITS_SYSTEM_WINDOWS) {
            mPaddingLeft = insets.left;
            mPaddingTop = insets.top;
            mPaddingRight = insets.right;
            mPaddingBottom = insets.bottom;
            requestLayout();
            return true;
        }
        return false;
    }

    /**
     * Determine if this view has the FITS_SYSTEM_WINDOWS flag set.
     * @return True if window has FITS_SYSTEM_WINDOWS set
     *
     * @hide
     */
    public boolean isFitsSystemWindowsFlagSet() {
        return (mViewFlags & FITS_SYSTEM_WINDOWS) == FITS_SYSTEM_WINDOWS;
    }

    /**
     * Returns the visibility status for this view.
     *
     * @return One of {@link #VISIBLE}, {@link #INVISIBLE}, or {@link #GONE}.
     * @attr ref android.R.styleable#View_visibility
     */
    @ViewDebug.ExportedProperty(mapping = {
        @ViewDebug.IntToString(from = VISIBLE,   to = "VISIBLE"),
        @ViewDebug.IntToString(from = INVISIBLE, to = "INVISIBLE"),
        @ViewDebug.IntToString(from = GONE,      to = "GONE")
    })
    public int getVisibility() {
        return mViewFlags & VISIBILITY_MASK;
    }

    /**
     * Set the enabled state of this view.
     *
     * @param visibility One of {@link #VISIBLE}, {@link #INVISIBLE}, or {@link #GONE}.
     * @attr ref android.R.styleable#View_visibility
     */
    @RemotableViewMethod
    public void setVisibility(int visibility) {
        setFlags(visibility, VISIBILITY_MASK);
        if (mBGDrawable != null) mBGDrawable.setVisible(visibility == VISIBLE, false);
    }

    /**
     * Returns the enabled status for this view. The interpretation of the
     * enabled state varies by subclass.
     *
     * @return True if this view is enabled, false otherwise.
     */
    @ViewDebug.ExportedProperty
    public boolean isEnabled() {
        return (mViewFlags & ENABLED_MASK) == ENABLED;
    }

    /**
     * Set the enabled state of this view. The interpretation of the enabled
     * state varies by subclass.
     *
     * @param enabled True if this view is enabled, false otherwise.
     */
    @RemotableViewMethod
    public void setEnabled(boolean enabled) {
        if (enabled == isEnabled()) return;

        setFlags(enabled ? ENABLED : DISABLED, ENABLED_MASK);

        /*
         * The View most likely has to change its appearance, so refresh
         * the drawable state.
         */
        refreshDrawableState();

        // Invalidate too, since the default behavior for views is to be
        // be drawn at 50% alpha rather than to change the drawable.
        invalidate(true);
    }

    /**
     * Set whether this view can receive the focus.
     *
     * Setting this to false will also ensure that this view is not focusable
     * in touch mode.
     *
     * @param focusable If true, this view can receive the focus.
     *
     * @see #setFocusableInTouchMode(boolean)
     * @attr ref android.R.styleable#View_focusable
     */
    public void setFocusable(boolean focusable) {
        if (!focusable) {
            setFlags(0, FOCUSABLE_IN_TOUCH_MODE);
        }
        setFlags(focusable ? FOCUSABLE : NOT_FOCUSABLE, FOCUSABLE_MASK);
    }

    /**
     * Set whether this view can receive focus while in touch mode.
     *
     * Setting this to true will also ensure that this view is focusable.
     *
     * @param focusableInTouchMode If true, this view can receive the focus while
     *   in touch mode.
     *
     * @see #setFocusable(boolean)
     * @attr ref android.R.styleable#View_focusableInTouchMode
     */
    public void setFocusableInTouchMode(boolean focusableInTouchMode) {
        // Focusable in touch mode should always be set before the focusable flag
        // otherwise, setting the focusable flag will trigger a focusableViewAvailable()
        // which, in touch mode, will not successfully request focus on this view
        // because the focusable in touch mode flag is not set
        setFlags(focusableInTouchMode ? FOCUSABLE_IN_TOUCH_MODE : 0, FOCUSABLE_IN_TOUCH_MODE);
        if (focusableInTouchMode) {
            setFlags(FOCUSABLE, FOCUSABLE_MASK);
        }
    }

    /**
     * Set whether this view should have sound effects enabled for events such as
     * clicking and touching.
     *
     * <p>You may wish to disable sound effects for a view if you already play sounds,
     * for instance, a dial key that plays dtmf tones.
     *
     * @param soundEffectsEnabled whether sound effects are enabled for this view.
     * @see #isSoundEffectsEnabled()
     * @see #playSoundEffect(int)
     * @attr ref android.R.styleable#View_soundEffectsEnabled
     */
    public void setSoundEffectsEnabled(boolean soundEffectsEnabled) {
        setFlags(soundEffectsEnabled ? SOUND_EFFECTS_ENABLED: 0, SOUND_EFFECTS_ENABLED);
    }

    /**
     * @return whether this view should have sound effects enabled for events such as
     *     clicking and touching.
     *
     * @see #setSoundEffectsEnabled(boolean)
     * @see #playSoundEffect(int)
     * @attr ref android.R.styleable#View_soundEffectsEnabled
     */
    @ViewDebug.ExportedProperty
    public boolean isSoundEffectsEnabled() {
        return SOUND_EFFECTS_ENABLED == (mViewFlags & SOUND_EFFECTS_ENABLED);
    }

    /**
     * Set whether this view should have haptic feedback for events such as
     * long presses.
     *
     * <p>You may wish to disable haptic feedback if your view already controls
     * its own haptic feedback.
     *
     * @param hapticFeedbackEnabled whether haptic feedback enabled for this view.
     * @see #isHapticFeedbackEnabled()
     * @see #performHapticFeedback(int)
     * @attr ref android.R.styleable#View_hapticFeedbackEnabled
     */
    public void setHapticFeedbackEnabled(boolean hapticFeedbackEnabled) {
        setFlags(hapticFeedbackEnabled ? HAPTIC_FEEDBACK_ENABLED: 0, HAPTIC_FEEDBACK_ENABLED);
    }

    /**
     * @return whether this view should have haptic feedback enabled for events
     * long presses.
     *
     * @see #setHapticFeedbackEnabled(boolean)
     * @see #performHapticFeedback(int)
     * @attr ref android.R.styleable#View_hapticFeedbackEnabled
     */
    @ViewDebug.ExportedProperty
    public boolean isHapticFeedbackEnabled() {
        return HAPTIC_FEEDBACK_ENABLED == (mViewFlags & HAPTIC_FEEDBACK_ENABLED);
    }

    /**
     * If this view doesn't do any drawing on its own, set this flag to
     * allow further optimizations. By default, this flag is not set on
     * View, but could be set on some View subclasses such as ViewGroup.
     *
     * Typically, if you override {@link #onDraw} you should clear this flag.
     *
     * @param willNotDraw whether or not this View draw on its own
     */
    public void setWillNotDraw(boolean willNotDraw) {
        setFlags(willNotDraw ? WILL_NOT_DRAW : 0, DRAW_MASK);
    }

    /**
     * Returns whether or not this View draws on its own.
     *
     * @return true if this view has nothing to draw, false otherwise
     */
    @ViewDebug.ExportedProperty(category = "drawing")
    public boolean willNotDraw() {
        return (mViewFlags & DRAW_MASK) == WILL_NOT_DRAW;
    }

    /**
     * When a View's drawing cache is enabled, drawing is redirected to an
     * offscreen bitmap. Some views, like an ImageView, must be able to
     * bypass this mechanism if they already draw a single bitmap, to avoid
     * unnecessary usage of the memory.
     *
     * @param willNotCacheDrawing true if this view does not cache its
     *        drawing, false otherwise
     */
    public void setWillNotCacheDrawing(boolean willNotCacheDrawing) {
        setFlags(willNotCacheDrawing ? WILL_NOT_CACHE_DRAWING : 0, WILL_NOT_CACHE_DRAWING);
    }

    /**
     * Returns whether or not this View can cache its drawing or not.
     *
     * @return true if this view does not cache its drawing, false otherwise
     */
    @ViewDebug.ExportedProperty(category = "drawing")
    public boolean willNotCacheDrawing() {
        return (mViewFlags & WILL_NOT_CACHE_DRAWING) == WILL_NOT_CACHE_DRAWING;
    }

    /**
     * Indicates whether this view reacts to click events or not.
     *
     * @return true if the view is clickable, false otherwise
     *
     * @see #setClickable(boolean)
     * @attr ref android.R.styleable#View_clickable
     */
    @ViewDebug.ExportedProperty
    public boolean isClickable() {
        return (mViewFlags & CLICKABLE) == CLICKABLE;
    }

    /**
     * Enables or disables click events for this view. When a view
     * is clickable it will change its state to "pressed" on every click.
     * Subclasses should set the view clickable to visually react to
     * user's clicks.
     *
     * @param clickable true to make the view clickable, false otherwise
     *
     * @see #isClickable()
     * @attr ref android.R.styleable#View_clickable
     */
    public void setClickable(boolean clickable) {
        setFlags(clickable ? CLICKABLE : 0, CLICKABLE);
    }

    /**
     * Indicates whether this view reacts to long click events or not.
     *
     * @return true if the view is long clickable, false otherwise
     *
     * @see #setLongClickable(boolean)
     * @attr ref android.R.styleable#View_longClickable
     */
    public boolean isLongClickable() {
        return (mViewFlags & LONG_CLICKABLE) == LONG_CLICKABLE;
    }

    /**
     * Enables or disables long click events for this view. When a view is long
     * clickable it reacts to the user holding down the button for a longer
     * duration than a tap. This event can either launch the listener or a
     * context menu.
     *
     * @param longClickable true to make the view long clickable, false otherwise
     * @see #isLongClickable()
     * @attr ref android.R.styleable#View_longClickable
     */
    public void setLongClickable(boolean longClickable) {
        setFlags(longClickable ? LONG_CLICKABLE : 0, LONG_CLICKABLE);
    }

    /**
     * Sets the pressed state for this view.
     *
     * @see #isClickable()
     * @see #setClickable(boolean)
     *
     * @param pressed Pass true to set the View's internal state to "pressed", or false to reverts
     *        the View's internal state from a previously set "pressed" state.
     */
    public void setPressed(boolean pressed) {
        if (pressed) {
            mPrivateFlags |= PRESSED;
        } else {
            mPrivateFlags &= ~PRESSED;
        }
        refreshDrawableState();
        dispatchSetPressed(pressed);
    }

    /**
     * Dispatch setPressed to all of this View's children.
     *
     * @see #setPressed(boolean)
     *
     * @param pressed The new pressed state
     */
    protected void dispatchSetPressed(boolean pressed) {
    }

    /**
     * Indicates whether the view is currently in pressed state. Unless
     * {@link #setPressed(boolean)} is explicitly called, only clickable views can enter
     * the pressed state.
     *
     * @see #setPressed
     * @see #isClickable()
     * @see #setClickable(boolean)
     *
     * @return true if the view is currently pressed, false otherwise
     */
    public boolean isPressed() {
        return (mPrivateFlags & PRESSED) == PRESSED;
    }

    /**
     * Indicates whether this view will save its state (that is,
     * whether its {@link #onSaveInstanceState} method will be called).
     *
     * @return Returns true if the view state saving is enabled, else false.
     *
     * @see #setSaveEnabled(boolean)
     * @attr ref android.R.styleable#View_saveEnabled
     */
    public boolean isSaveEnabled() {
        return (mViewFlags & SAVE_DISABLED_MASK) != SAVE_DISABLED;
    }

    /**
     * Controls whether the saving of this view's state is
     * enabled (that is, whether its {@link #onSaveInstanceState} method
     * will be called).  Note that even if freezing is enabled, the
     * view still must have an id assigned to it (via {@link #setId setId()})
     * for its state to be saved.  This flag can only disable the
     * saving of this view; any child views may still have their state saved.
     *
     * @param enabled Set to false to <em>disable</em> state saving, or true
     * (the default) to allow it.
     *
     * @see #isSaveEnabled()
     * @see #setId(int)
     * @see #onSaveInstanceState()
     * @attr ref android.R.styleable#View_saveEnabled
     */
    public void setSaveEnabled(boolean enabled) {
        setFlags(enabled ? 0 : SAVE_DISABLED, SAVE_DISABLED_MASK);
    }

    /**
     * Gets whether the framework should discard touches when the view's
     * window is obscured by another visible window.
     * Refer to the {@link View} security documentation for more details.
     *
     * @return True if touch filtering is enabled.
     *
     * @see #setFilterTouchesWhenObscured(boolean)
     * @attr ref android.R.styleable#View_filterTouchesWhenObscured
     */
    @ViewDebug.ExportedProperty
    public boolean getFilterTouchesWhenObscured() {
        return (mViewFlags & FILTER_TOUCHES_WHEN_OBSCURED) != 0;
    }

    /**
     * Sets whether the framework should discard touches when the view's
     * window is obscured by another visible window.
     * Refer to the {@link View} security documentation for more details.
     *
     * @param enabled True if touch filtering should be enabled.
     *
     * @see #getFilterTouchesWhenObscured
     * @attr ref android.R.styleable#View_filterTouchesWhenObscured
     */
    public void setFilterTouchesWhenObscured(boolean enabled) {
        setFlags(enabled ? 0 : FILTER_TOUCHES_WHEN_OBSCURED,
                FILTER_TOUCHES_WHEN_OBSCURED);
    }

    /**
     * Indicates whether the entire hierarchy under this view will save its
     * state when a state saving traversal occurs from its parent.  The default
     * is true; if false, these views will not be saved unless
     * {@link #saveHierarchyState(SparseArray)} is called directly on this view.
     *
     * @return Returns true if the view state saving from parent is enabled, else false.
     *
     * @see #setSaveFromParentEnabled(boolean)
     */
    public boolean isSaveFromParentEnabled() {
        return (mViewFlags & PARENT_SAVE_DISABLED_MASK) != PARENT_SAVE_DISABLED;
    }

    /**
     * Controls whether the entire hierarchy under this view will save its
     * state when a state saving traversal occurs from its parent.  The default
     * is true; if false, these views will not be saved unless
     * {@link #saveHierarchyState(SparseArray)} is called directly on this view.
     *
     * @param enabled Set to false to <em>disable</em> state saving, or true
     * (the default) to allow it.
     *
     * @see #isSaveFromParentEnabled()
     * @see #setId(int)
     * @see #onSaveInstanceState()
     */
    public void setSaveFromParentEnabled(boolean enabled) {
        setFlags(enabled ? 0 : PARENT_SAVE_DISABLED, PARENT_SAVE_DISABLED_MASK);
    }


    /**
     * Returns whether this View is able to take focus.
     *
     * @return True if this view can take focus, or false otherwise.
     * @attr ref android.R.styleable#View_focusable
     */
    @ViewDebug.ExportedProperty(category = "focus")
    public final boolean isFocusable() {
        return FOCUSABLE == (mViewFlags & FOCUSABLE_MASK);
    }

    /**
     * When a view is focusable, it may not want to take focus when in touch mode.
     * For example, a button would like focus when the user is navigating via a D-pad
     * so that the user can click on it, but once the user starts touching the screen,
     * the button shouldn't take focus
     * @return Whether the view is focusable in touch mode.
     * @attr ref android.R.styleable#View_focusableInTouchMode
     */
    @ViewDebug.ExportedProperty
    public final boolean isFocusableInTouchMode() {
        return FOCUSABLE_IN_TOUCH_MODE == (mViewFlags & FOCUSABLE_IN_TOUCH_MODE);
    }

    /**
     * Find the nearest view in the specified direction that can take focus.
     * This does not actually give focus to that view.
     *
     * @param direction One of FOCUS_UP, FOCUS_DOWN, FOCUS_LEFT, and FOCUS_RIGHT
     *
     * @return The nearest focusable in the specified direction, or null if none
     *         can be found.
     */
    public View focusSearch(int direction) {
        if (mParent != null) {
            return mParent.focusSearch(this, direction);
        } else {
            return null;
        }
    }

    /**
     * This method is the last chance for the focused view and its ancestors to
     * respond to an arrow key. This is called when the focused view did not
     * consume the key internally, nor could the view system find a new view in
     * the requested direction to give focus to.
     *
     * @param focused The currently focused view.
     * @param direction The direction focus wants to move. One of FOCUS_UP,
     *        FOCUS_DOWN, FOCUS_LEFT, and FOCUS_RIGHT.
     * @return True if the this view consumed this unhandled move.
     */
    public boolean dispatchUnhandledMove(View focused, int direction) {
        return false;
    }

    /**
     * If a user manually specified the next view id for a particular direction,
     * use the root to look up the view.
     * @param root The root view of the hierarchy containing this view.
     * @param direction One of FOCUS_UP, FOCUS_DOWN, FOCUS_LEFT, FOCUS_RIGHT, FOCUS_FORWARD,
     * or FOCUS_BACKWARD.
     * @return The user specified next view, or null if there is none.
     */
    View findUserSetNextFocus(View root, int direction) {
        switch (direction) {
            case FOCUS_LEFT:
                if (mNextFocusLeftId == View.NO_ID) return null;
                return findViewShouldExist(root, mNextFocusLeftId);
            case FOCUS_RIGHT:
                if (mNextFocusRightId == View.NO_ID) return null;
                return findViewShouldExist(root, mNextFocusRightId);
            case FOCUS_UP:
                if (mNextFocusUpId == View.NO_ID) return null;
                return findViewShouldExist(root, mNextFocusUpId);
            case FOCUS_DOWN:
                if (mNextFocusDownId == View.NO_ID) return null;
                return findViewShouldExist(root, mNextFocusDownId);
            case FOCUS_FORWARD:
                if (mNextFocusForwardId == View.NO_ID) return null;
                return findViewShouldExist(root, mNextFocusForwardId);
            case FOCUS_BACKWARD: {
                final int id = mID;
                return root.findViewByPredicate(new Predicate<View>() {
                    @Override
                    public boolean apply(View t) {
                        return t.mNextFocusForwardId == id;
                    }
                });
            }
        }
        return null;
    }

    private static View findViewShouldExist(View root, int childViewId) {
        View result = root.findViewById(childViewId);
        if (result == null) {
            Log.w(VIEW_LOG_TAG, "couldn't find next focus view specified "
                    + "by user for id " + childViewId);
        }
        return result;
    }

    /**
     * Find and return all focusable views that are descendants of this view,
     * possibly including this view if it is focusable itself.
     *
     * @param direction The direction of the focus
     * @return A list of focusable views
     */
    public ArrayList<View> getFocusables(int direction) {
        ArrayList<View> result = new ArrayList<View>(24);
        addFocusables(result, direction);
        return result;
    }

    /**
     * Add any focusable views that are descendants of this view (possibly
     * including this view if it is focusable itself) to views.  If we are in touch mode,
     * only add views that are also focusable in touch mode.
     *
     * @param views Focusable views found so far
     * @param direction The direction of the focus
     */
    public void addFocusables(ArrayList<View> views, int direction) {
        addFocusables(views, direction, FOCUSABLES_TOUCH_MODE);
    }

    /**
     * Adds any focusable views that are descendants of this view (possibly
     * including this view if it is focusable itself) to views. This method
     * adds all focusable views regardless if we are in touch mode or
     * only views focusable in touch mode if we are in touch mode depending on
     * the focusable mode paramater.
     *
     * @param views Focusable views found so far or null if all we are interested is
     *        the number of focusables.
     * @param direction The direction of the focus.
     * @param focusableMode The type of focusables to be added.
     *
     * @see #FOCUSABLES_ALL
     * @see #FOCUSABLES_TOUCH_MODE
     */
    public void addFocusables(ArrayList<View> views, int direction, int focusableMode) {
        if (!isFocusable()) {
            return;
        }

        if ((focusableMode & FOCUSABLES_TOUCH_MODE) == FOCUSABLES_TOUCH_MODE &&
                isInTouchMode() && !isFocusableInTouchMode()) {
            return;
        }

        if (views != null) {
            views.add(this);
        }
    }

    /**
     * Find and return all touchable views that are descendants of this view,
     * possibly including this view if it is touchable itself.
     *
     * @return A list of touchable views
     */
    public ArrayList<View> getTouchables() {
        ArrayList<View> result = new ArrayList<View>();
        addTouchables(result);
        return result;
    }

    /**
     * Add any touchable views that are descendants of this view (possibly
     * including this view if it is touchable itself) to views.
     *
     * @param views Touchable views found so far
     */
    public void addTouchables(ArrayList<View> views) {
        final int viewFlags = mViewFlags;

        if (((viewFlags & CLICKABLE) == CLICKABLE || (viewFlags & LONG_CLICKABLE) == LONG_CLICKABLE)
                && (viewFlags & ENABLED_MASK) == ENABLED) {
            views.add(this);
        }
    }

    /**
     * Call this to try to give focus to a specific view or to one of its
     * descendants.
     *
     * A view will not actually take focus if it is not focusable ({@link #isFocusable} returns false),
     * or if it is focusable and it is not focusable in touch mode ({@link #isFocusableInTouchMode})
     * while the device is in touch mode.
     *
     * See also {@link #focusSearch}, which is what you call to say that you
     * have focus, and you want your parent to look for the next one.
     *
     * This is equivalent to calling {@link #requestFocus(int, Rect)} with arguments
     * {@link #FOCUS_DOWN} and <code>null</code>.
     *
     * @return Whether this view or one of its descendants actually took focus.
     */
    public final boolean requestFocus() {
        return requestFocus(View.FOCUS_DOWN);
    }


    /**
     * Call this to try to give focus to a specific view or to one of its
     * descendants and give it a hint about what direction focus is heading.
     *
     * A view will not actually take focus if it is not focusable ({@link #isFocusable} returns false),
     * or if it is focusable and it is not focusable in touch mode ({@link #isFocusableInTouchMode})
     * while the device is in touch mode.
     *
     * See also {@link #focusSearch}, which is what you call to say that you
     * have focus, and you want your parent to look for the next one.
     *
     * This is equivalent to calling {@link #requestFocus(int, Rect)} with
     * <code>null</code> set for the previously focused rectangle.
     *
     * @param direction One of FOCUS_UP, FOCUS_DOWN, FOCUS_LEFT, and FOCUS_RIGHT
     * @return Whether this view or one of its descendants actually took focus.
     */
    public final boolean requestFocus(int direction) {
        return requestFocus(direction, null);
    }

    /**
     * Call this to try to give focus to a specific view or to one of its descendants
     * and give it hints about the direction and a specific rectangle that the focus
     * is coming from.  The rectangle can help give larger views a finer grained hint
     * about where focus is coming from, and therefore, where to show selection, or
     * forward focus change internally.
     *
     * A view will not actually take focus if it is not focusable ({@link #isFocusable} returns false),
     * or if it is focusable and it is not focusable in touch mode ({@link #isFocusableInTouchMode})
     * while the device is in touch mode.
     *
     * A View will not take focus if it is not visible.
     *
     * A View will not take focus if one of its parents has {@link android.view.ViewGroup#getDescendantFocusability()}
     * equal to {@link ViewGroup#FOCUS_BLOCK_DESCENDANTS}.
     *
     * See also {@link #focusSearch}, which is what you call to say that you
     * have focus, and you want your parent to look for the next one.
     *
     * You may wish to override this method if your custom {@link View} has an internal
     * {@link View} that it wishes to forward the request to.
     *
     * @param direction One of FOCUS_UP, FOCUS_DOWN, FOCUS_LEFT, and FOCUS_RIGHT
     * @param previouslyFocusedRect The rectangle (in this View's coordinate system)
     *        to give a finer grained hint about where focus is coming from.  May be null
     *        if there is no hint.
     * @return Whether this view or one of its descendants actually took focus.
     */
    public boolean requestFocus(int direction, Rect previouslyFocusedRect) {
        // need to be focusable
        if ((mViewFlags & FOCUSABLE_MASK) != FOCUSABLE ||
                (mViewFlags & VISIBILITY_MASK) != VISIBLE) {
            return false;
        }

        // need to be focusable in touch mode if in touch mode
        if (isInTouchMode() &&
                (FOCUSABLE_IN_TOUCH_MODE != (mViewFlags & FOCUSABLE_IN_TOUCH_MODE))) {
            return false;
        }

        // need to not have any parents blocking us
        if (hasAncestorThatBlocksDescendantFocus()) {
            return false;
        }

        handleFocusGainInternal(direction, previouslyFocusedRect);
        return true;
    }

    /** Gets the ViewRoot, or null if not attached. */
    /*package*/ ViewRoot getViewRoot() {
        View root = getRootView();
        return root != null ? (ViewRoot)root.getParent() : null;
    }

    /**
     * Call this to try to give focus to a specific view or to one of its descendants. This is a
     * special variant of {@link #requestFocus() } that will allow views that are not focuable in
     * touch mode to request focus when they are touched.
     *
     * @return Whether this view or one of its descendants actually took focus.
     *
     * @see #isInTouchMode()
     *
     */
    public final boolean requestFocusFromTouch() {
        // Leave touch mode if we need to
        if (isInTouchMode()) {
            ViewRoot viewRoot = getViewRoot();
            if (viewRoot != null) {
                viewRoot.ensureTouchMode(false);
            }
        }
        return requestFocus(View.FOCUS_DOWN);
    }

    /**
     * @return Whether any ancestor of this view blocks descendant focus.
     */
    private boolean hasAncestorThatBlocksDescendantFocus() {
        ViewParent ancestor = mParent;
        while (ancestor instanceof ViewGroup) {
            final ViewGroup vgAncestor = (ViewGroup) ancestor;
            if (vgAncestor.getDescendantFocusability() == ViewGroup.FOCUS_BLOCK_DESCENDANTS) {
                return true;
            } else {
                ancestor = vgAncestor.getParent();
            }
        }
        return false;
    }

    /**
     * @hide
     */
    public void dispatchStartTemporaryDetach() {
        onStartTemporaryDetach();
    }

    /**
     * This is called when a container is going to temporarily detach a child, with
     * {@link ViewGroup#detachViewFromParent(View) ViewGroup.detachViewFromParent}.
     * It will either be followed by {@link #onFinishTemporaryDetach()} or
     * {@link #onDetachedFromWindow()} when the container is done.
     */
    public void onStartTemporaryDetach() {
        removeUnsetPressCallback();
        mPrivateFlags |= CANCEL_NEXT_UP_EVENT;
    }

    /**
     * @hide
     */
    public void dispatchFinishTemporaryDetach() {
        onFinishTemporaryDetach();
    }

    /**
     * Called after {@link #onStartTemporaryDetach} when the container is done
     * changing the view.
     */
    public void onFinishTemporaryDetach() {
    }

    /**
     * capture information of this view for later analysis: developement only
     * check dynamic switch to make sure we only dump view
     * when ViewDebug.SYSTEM_PROPERTY_CAPTURE_VIEW) is set
     */
    private static void captureViewInfo(String subTag, View v) {
        if (v == null || SystemProperties.getInt(ViewDebug.SYSTEM_PROPERTY_CAPTURE_VIEW, 0) == 0) {
            return;
        }
        ViewDebug.dumpCapturedView(subTag, v);
    }

    /**
     * Return the global {@link KeyEvent.DispatcherState KeyEvent.DispatcherState}
     * for this view's window.  Returns null if the view is not currently attached
     * to the window.  Normally you will not need to use this directly, but
     * just use the standard high-level event callbacks like {@link #onKeyDown}.
     */
    public KeyEvent.DispatcherState getKeyDispatcherState() {
        return mAttachInfo != null ? mAttachInfo.mKeyDispatchState : null;
    }

    /**
     * Dispatch a key event before it is processed by any input method
     * associated with the view hierarchy.  This can be used to intercept
     * key events in special situations before the IME consumes them; a
     * typical example would be handling the BACK key to update the application's
     * UI instead of allowing the IME to see it and close itself.
     *
     * @param event The key event to be dispatched.
     * @return True if the event was handled, false otherwise.
     */
    public boolean dispatchKeyEventPreIme(KeyEvent event) {
        return onKeyPreIme(event.getKeyCode(), event);
    }

    /**
     * Dispatch a key event to the next view on the focus path. This path runs
     * from the top of the view tree down to the currently focused view. If this
     * view has focus, it will dispatch to itself. Otherwise it will dispatch
     * the next node down the focus path. This method also fires any key
     * listeners.
     *
     * @param event The key event to be dispatched.
     * @return True if the event was handled, false otherwise.
     */
    public boolean dispatchKeyEvent(KeyEvent event) {
        // If any attached key listener a first crack at the event.

        //noinspection SimplifiableIfStatement,deprecation
        if (android.util.Config.LOGV) {
            captureViewInfo("captureViewKeyEvent", this);
        }

        //noinspection SimplifiableIfStatement
        if (mOnKeyListener != null && (mViewFlags & ENABLED_MASK) == ENABLED
                && mOnKeyListener.onKey(this, event.getKeyCode(), event)) {
            return true;
        }

        return event.dispatch(this, mAttachInfo != null
                ? mAttachInfo.mKeyDispatchState : null, this);
    }

    /**
     * Dispatches a key shortcut event.
     *
     * @param event The key event to be dispatched.
     * @return True if the event was handled by the view, false otherwise.
     */
    public boolean dispatchKeyShortcutEvent(KeyEvent event) {
        return onKeyShortcut(event.getKeyCode(), event);
    }

    /**
     * Pass the touch screen motion event down to the target view, or this
     * view if it is the target.
     *
     * @param event The motion event to be dispatched.
     * @return True if the event was handled by the view, false otherwise.
     */
    public boolean dispatchTouchEvent(MotionEvent event) {
        if (!onFilterTouchEventForSecurity(event)) {
            return false;
        }

        //noinspection SimplifiableIfStatement
        if (mOnTouchListener != null && (mViewFlags & ENABLED_MASK) == ENABLED &&
                mOnTouchListener.onTouch(this, event)) {
            return true;
        }
        return onTouchEvent(event);
    }

    /**
     * Filter the touch event to apply security policies.
     *
     * @param event The motion event to be filtered.
     * @return True if the event should be dispatched, false if the event should be dropped.
     *
     * @see #getFilterTouchesWhenObscured
     */
    public boolean onFilterTouchEventForSecurity(MotionEvent event) {
        //noinspection RedundantIfStatement
        if ((mViewFlags & FILTER_TOUCHES_WHEN_OBSCURED) != 0
                && (event.getFlags() & MotionEvent.FLAG_WINDOW_IS_OBSCURED) != 0) {
            // Window is obscured, drop this touch.
            return false;
        }
        return true;
    }

    /**
     * Pass a trackball motion event down to the focused view.
     *
     * @param event The motion event to be dispatched.
     * @return True if the event was handled by the view, false otherwise.
     */
    public boolean dispatchTrackballEvent(MotionEvent event) {
        //Log.i("view", "view=" + this + ", " + event.toString());
        return onTrackballEvent(event);
    }

    /**
     * Called when the window containing this view gains or loses window focus.
     * ViewGroups should override to route to their children.
     *
     * @param hasFocus True if the window containing this view now has focus,
     *        false otherwise.
     */
    public void dispatchWindowFocusChanged(boolean hasFocus) {
        onWindowFocusChanged(hasFocus);
    }

    /**
     * Called when the window containing this view gains or loses focus.  Note
     * that this is separate from view focus: to receive key events, both
     * your view and its window must have focus.  If a window is displayed
     * on top of yours that takes input focus, then your own window will lose
     * focus but the view focus will remain unchanged.
     *
     * @param hasWindowFocus True if the window containing this view now has
     *        focus, false otherwise.
     */
    public void onWindowFocusChanged(boolean hasWindowFocus) {
        InputMethodManager imm = InputMethodManager.peekInstance();
        if (!hasWindowFocus) {
            if (isPressed()) {
                setPressed(false);
            }
            if (imm != null && (mPrivateFlags & FOCUSED) != 0) {
                imm.focusOut(this);
            }
            removeLongPressCallback();
            removeTapCallback();
            onFocusLost();
        } else if (imm != null && (mPrivateFlags & FOCUSED) != 0) {
            imm.focusIn(this);
        }
        refreshDrawableState();
    }

    /**
     * Returns true if this view is in a window that currently has window focus.
     * Note that this is not the same as the view itself having focus.
     *
     * @return True if this view is in a window that currently has window focus.
     */
    public boolean hasWindowFocus() {
        return mAttachInfo != null && mAttachInfo.mHasWindowFocus;
    }

    /**
     * Dispatch a view visibility change down the view hierarchy.
     * ViewGroups should override to route to their children.
     * @param changedView The view whose visibility changed. Could be 'this' or
     * an ancestor view.
     * @param visibility The new visibility of changedView: {@link #VISIBLE},
     * {@link #INVISIBLE} or {@link #GONE}.
     */
    protected void dispatchVisibilityChanged(View changedView, int visibility) {
        onVisibilityChanged(changedView, visibility);
    }

    /**
     * Called when the visibility of the view or an ancestor of the view is changed.
     * @param changedView The view whose visibility changed. Could be 'this' or
     * an ancestor view.
     * @param visibility The new visibility of changedView: {@link #VISIBLE},
     * {@link #INVISIBLE} or {@link #GONE}.
     */
    protected void onVisibilityChanged(View changedView, int visibility) {
        if (visibility == VISIBLE) {
            if (mAttachInfo != null) {
                initialAwakenScrollBars();
            } else {
                mPrivateFlags |= AWAKEN_SCROLL_BARS_ON_ATTACH;
            }
        }
    }

    /**
     * Dispatch a hint about whether this view is displayed. For instance, when
     * a View moves out of the screen, it might receives a display hint indicating
     * the view is not displayed. Applications should not <em>rely</em> on this hint
     * as there is no guarantee that they will receive one.
     *
     * @param hint A hint about whether or not this view is displayed:
     * {@link #VISIBLE} or {@link #INVISIBLE}.
     */
    public void dispatchDisplayHint(int hint) {
        onDisplayHint(hint);
    }

    /**
     * Gives this view a hint about whether is displayed or not. For instance, when
     * a View moves out of the screen, it might receives a display hint indicating
     * the view is not displayed. Applications should not <em>rely</em> on this hint
     * as there is no guarantee that they will receive one.
     *
     * @param hint A hint about whether or not this view is displayed:
     * {@link #VISIBLE} or {@link #INVISIBLE}.
     */
    protected void onDisplayHint(int hint) {
    }

    /**
     * Dispatch a window visibility change down the view hierarchy.
     * ViewGroups should override to route to their children.
     *
     * @param visibility The new visibility of the window.
     *
     * @see #onWindowVisibilityChanged
     */
    public void dispatchWindowVisibilityChanged(int visibility) {
        onWindowVisibilityChanged(visibility);
    }

    /**
     * Called when the window containing has change its visibility
     * (between {@link #GONE}, {@link #INVISIBLE}, and {@link #VISIBLE}).  Note
     * that this tells you whether or not your window is being made visible
     * to the window manager; this does <em>not</em> tell you whether or not
     * your window is obscured by other windows on the screen, even if it
     * is itself visible.
     *
     * @param visibility The new visibility of the window.
     */
    protected void onWindowVisibilityChanged(int visibility) {
        if (visibility == VISIBLE) {
            initialAwakenScrollBars();
        }
    }

    /**
     * Returns the current visibility of the window this view is attached to
     * (either {@link #GONE}, {@link #INVISIBLE}, or {@link #VISIBLE}).
     *
     * @return Returns the current visibility of the view's window.
     */
    public int getWindowVisibility() {
        return mAttachInfo != null ? mAttachInfo.mWindowVisibility : GONE;
    }

    /**
     * Retrieve the overall visible display size in which the window this view is
     * attached to has been positioned in.  This takes into account screen
     * decorations above the window, for both cases where the window itself
     * is being position inside of them or the window is being placed under
     * then and covered insets are used for the window to position its content
     * inside.  In effect, this tells you the available area where content can
     * be placed and remain visible to users.
     *
     * <p>This function requires an IPC back to the window manager to retrieve
     * the requested information, so should not be used in performance critical
     * code like drawing.
     *
     * @param outRect Filled in with the visible display frame.  If the view
     * is not attached to a window, this is simply the raw display size.
     */
    public void getWindowVisibleDisplayFrame(Rect outRect) {
        if (mAttachInfo != null) {
            try {
                mAttachInfo.mSession.getDisplayFrame(mAttachInfo.mWindow, outRect);
            } catch (RemoteException e) {
                return;
            }
            // XXX This is really broken, and probably all needs to be done
            // in the window manager, and we need to know more about whether
            // we want the area behind or in front of the IME.
            final Rect insets = mAttachInfo.mVisibleInsets;
            outRect.left += insets.left;
            outRect.top += insets.top;
            outRect.right -= insets.right;
            outRect.bottom -= insets.bottom;
            return;
        }
        Display d = WindowManagerImpl.getDefault().getDefaultDisplay();
        outRect.set(0, 0, d.getWidth(), d.getHeight());
    }

    /**
     * Dispatch a notification about a resource configuration change down
     * the view hierarchy.
     * ViewGroups should override to route to their children.
     *
     * @param newConfig The new resource configuration.
     *
     * @see #onConfigurationChanged
     */
    public void dispatchConfigurationChanged(Configuration newConfig) {
        onConfigurationChanged(newConfig);
    }

    /**
     * Called when the current configuration of the resources being used
     * by the application have changed.  You can use this to decide when
     * to reload resources that can changed based on orientation and other
     * configuration characterstics.  You only need to use this if you are
     * not relying on the normal {@link android.app.Activity} mechanism of
     * recreating the activity instance upon a configuration change.
     *
     * @param newConfig The new resource configuration.
     */
    protected void onConfigurationChanged(Configuration newConfig) {
    }

    /**
     * Private function to aggregate all per-view attributes in to the view
     * root.
     */
    void dispatchCollectViewAttributes(int visibility) {
        performCollectViewAttributes(visibility);
    }

    void performCollectViewAttributes(int visibility) {
        if ((visibility & VISIBILITY_MASK) == VISIBLE && mAttachInfo != null) {
            if ((mViewFlags & KEEP_SCREEN_ON) == KEEP_SCREEN_ON) {
                mAttachInfo.mKeepScreenOn = true;
            }
            mAttachInfo.mSystemUiVisibility |= mSystemUiVisibility;
            if (mOnSystemUiVisibilityChangeListener != null) {
                mAttachInfo.mHasSystemUiListeners = true;
            }
        }
    }

    void needGlobalAttributesUpdate(boolean force) {
        final AttachInfo ai = mAttachInfo;
        if (ai != null) {
            if (force || ai.mKeepScreenOn || (ai.mSystemUiVisibility != 0)
                    || ai.mHasSystemUiListeners) {
                ai.mRecomputeGlobalAttributes = true;
            }
        }
    }

    /**
     * Returns whether the device is currently in touch mode.  Touch mode is entered
     * once the user begins interacting with the device by touch, and affects various
     * things like whether focus is always visible to the user.
     *
     * @return Whether the device is in touch mode.
     */
    @ViewDebug.ExportedProperty
    public boolean isInTouchMode() {
        if (mAttachInfo != null) {
            return mAttachInfo.mInTouchMode;
        } else {
            return ViewRoot.isInTouchMode();
        }
    }

    /**
     * Returns the context the view is running in, through which it can
     * access the current theme, resources, etc.
     *
     * @return The view's Context.
     */
    @ViewDebug.CapturedViewProperty
    public final Context getContext() {
        return mContext;
    }

    /**
     * Handle a key event before it is processed by any input method
     * associated with the view hierarchy.  This can be used to intercept
     * key events in special situations before the IME consumes them; a
     * typical example would be handling the BACK key to update the application's
     * UI instead of allowing the IME to see it and close itself.
     *
     * @param keyCode The value in event.getKeyCode().
     * @param event Description of the key event.
     * @return If you handled the event, return true. If you want to allow the
     *         event to be handled by the next receiver, return false.
     */
    public boolean onKeyPreIme(int keyCode, KeyEvent event) {
        return false;
    }

    /**
     * Default implementation of {@link KeyEvent.Callback#onKeyDown(int, KeyEvent)
     * KeyEvent.Callback.onKeyDown()}: perform press of the view
     * when {@link KeyEvent#KEYCODE_DPAD_CENTER} or {@link KeyEvent#KEYCODE_ENTER}
     * is released, if the view is enabled and clickable.
     *
     * @param keyCode A key code that represents the button pressed, from
     *                {@link android.view.KeyEvent}.
     * @param event   The KeyEvent object that defines the button action.
     */
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        boolean result = false;

        switch (keyCode) {
            case KeyEvent.KEYCODE_DPAD_CENTER:
            case KeyEvent.KEYCODE_ENTER: {
                if ((mViewFlags & ENABLED_MASK) == DISABLED) {
                    return true;
                }
                // Long clickable items don't necessarily have to be clickable
                if (((mViewFlags & CLICKABLE) == CLICKABLE ||
                        (mViewFlags & LONG_CLICKABLE) == LONG_CLICKABLE) &&
                        (event.getRepeatCount() == 0)) {
                    setPressed(true);
                    if ((mViewFlags & LONG_CLICKABLE) == LONG_CLICKABLE) {
                        postCheckForLongClick(0);
                    }
                    return true;
                }
                break;
            }
        }
        return result;
    }

    /**
     * Default implementation of {@link KeyEvent.Callback#onKeyLongPress(int, KeyEvent)
     * KeyEvent.Callback.onKeyLongPress()}: always returns false (doesn't handle
     * the event).
     */
    public boolean onKeyLongPress(int keyCode, KeyEvent event) {
        return false;
    }

    /**
     * Default implementation of {@link KeyEvent.Callback#onKeyUp(int, KeyEvent)
     * KeyEvent.Callback.onKeyUp()}: perform clicking of the view
     * when {@link KeyEvent#KEYCODE_DPAD_CENTER} or
     * {@link KeyEvent#KEYCODE_ENTER} is released.
     *
     * @param keyCode A key code that represents the button pressed, from
     *                {@link android.view.KeyEvent}.
     * @param event   The KeyEvent object that defines the button action.
     */
    public boolean onKeyUp(int keyCode, KeyEvent event) {
        boolean result = false;

        switch (keyCode) {
            case KeyEvent.KEYCODE_DPAD_CENTER:
            case KeyEvent.KEYCODE_ENTER: {
                if ((mViewFlags & ENABLED_MASK) == DISABLED) {
                    return true;
                }
                if ((mViewFlags & CLICKABLE) == CLICKABLE && isPressed()) {
                    setPressed(false);

                    if (!mHasPerformedLongPress) {
                        // This is a tap, so remove the longpress check
                        removeLongPressCallback();

                        result = performClick();
                    }
                }
                break;
            }
        }
        return result;
    }

    /**
     * Default implementation of {@link KeyEvent.Callback#onKeyMultiple(int, int, KeyEvent)
     * KeyEvent.Callback.onKeyMultiple()}: always returns false (doesn't handle
     * the event).
     *
     * @param keyCode     A key code that represents the button pressed, from
     *                    {@link android.view.KeyEvent}.
     * @param repeatCount The number of times the action was made.
     * @param event       The KeyEvent object that defines the button action.
     */
    public boolean onKeyMultiple(int keyCode, int repeatCount, KeyEvent event) {
        return false;
    }

    /**
     * Called on the focused view when a key shortcut event is not handled.
     * Override this method to implement local key shortcuts for the View.
     * Key shortcuts can also be implemented by setting the
     * {@link MenuItem#setShortcut(char, char) shortcut} property of menu items.
     *
     * @param keyCode The value in event.getKeyCode().
     * @param event Description of the key event.
     * @return If you handled the event, return true. If you want to allow the
     *         event to be handled by the next receiver, return false.
     */
    public boolean onKeyShortcut(int keyCode, KeyEvent event) {
        return false;
    }

    /**
     * Check whether the called view is a text editor, in which case it
     * would make sense to automatically display a soft input window for
     * it.  Subclasses should override this if they implement
     * {@link #onCreateInputConnection(EditorInfo)} to return true if
     * a call on that method would return a non-null InputConnection, and
     * they are really a first-class editor that the user would normally
     * start typing on when the go into a window containing your view.
     *
     * <p>The default implementation always returns false.  This does
     * <em>not</em> mean that its {@link #onCreateInputConnection(EditorInfo)}
     * will not be called or the user can not otherwise perform edits on your
     * view; it is just a hint to the system that this is not the primary
     * purpose of this view.
     *
     * @return Returns true if this view is a text editor, else false.
     */
    public boolean onCheckIsTextEditor() {
        return false;
    }

    /**
     * Create a new InputConnection for an InputMethod to interact
     * with the view.  The default implementation returns null, since it doesn't
     * support input methods.  You can override this to implement such support.
     * This is only needed for views that take focus and text input.
     *
     * <p>When implementing this, you probably also want to implement
     * {@link #onCheckIsTextEditor()} to indicate you will return a
     * non-null InputConnection.
     *
     * @param outAttrs Fill in with attribute information about the connection.
     */
    public InputConnection onCreateInputConnection(EditorInfo outAttrs) {
        return null;
    }

    /**
     * Called by the {@link android.view.inputmethod.InputMethodManager}
     * when a view who is not the current
     * input connection target is trying to make a call on the manager.  The
     * default implementation returns false; you can override this to return
     * true for certain views if you are performing InputConnection proxying
     * to them.
     * @param view The View that is making the InputMethodManager call.
     * @return Return true to allow the call, false to reject.
     */
    public boolean checkInputConnectionProxy(View view) {
        return false;
    }

    /**
     * Show the context menu for this view. It is not safe to hold on to the
     * menu after returning from this method.
     *
     * You should normally not overload this method. Overload
     * {@link #onCreateContextMenu(ContextMenu)} or define an
     * {@link OnCreateContextMenuListener} to add items to the context menu.
     *
     * @param menu The context menu to populate
     */
    public void createContextMenu(ContextMenu menu) {
        ContextMenuInfo menuInfo = getContextMenuInfo();

        // Sets the current menu info so all items added to menu will have
        // my extra info set.
        ((MenuBuilder)menu).setCurrentMenuInfo(menuInfo);

        onCreateContextMenu(menu);
        if (mOnCreateContextMenuListener != null) {
            mOnCreateContextMenuListener.onCreateContextMenu(menu, this, menuInfo);
        }

        // Clear the extra information so subsequent items that aren't mine don't
        // have my extra info.
        ((MenuBuilder)menu).setCurrentMenuInfo(null);

        if (mParent != null) {
            mParent.createContextMenu(menu);
        }
    }

    /**
     * Views should implement this if they have extra information to associate
     * with the context menu. The return result is supplied as a parameter to
     * the {@link OnCreateContextMenuListener#onCreateContextMenu(ContextMenu, View, ContextMenuInfo)}
     * callback.
     *
     * @return Extra information about the item for which the context menu
     *         should be shown. This information will vary across different
     *         subclasses of View.
     */
    protected ContextMenuInfo getContextMenuInfo() {
        return null;
    }

    /**
     * Views should implement this if the view itself is going to add items to
     * the context menu.
     *
     * @param menu the context menu to populate
     */
    protected void onCreateContextMenu(ContextMenu menu) {
    }

    /**
     * Implement this method to handle trackball motion events.  The
     * <em>relative</em> movement of the trackball since the last event
     * can be retrieve with {@link MotionEvent#getX MotionEvent.getX()} and
     * {@link MotionEvent#getY MotionEvent.getY()}.  These are normalized so
     * that a movement of 1 corresponds to the user pressing one DPAD key (so
     * they will often be fractional values, representing the more fine-grained
     * movement information available from a trackball).
     *
     * @param event The motion event.
     * @return True if the event was handled, false otherwise.
     */
    public boolean onTrackballEvent(MotionEvent event) {
        return false;
    }

    /**
     * Implement this method to handle touch screen motion events.
     *
     * @param event The motion event.
     * @return True if the event was handled, false otherwise.
     */
    public boolean onTouchEvent(MotionEvent event) {
        final int viewFlags = mViewFlags;

        if ((viewFlags & ENABLED_MASK) == DISABLED) {
            // A disabled view that is clickable still consumes the touch
            // events, it just doesn't respond to them.
            return (((viewFlags & CLICKABLE) == CLICKABLE ||
                    (viewFlags & LONG_CLICKABLE) == LONG_CLICKABLE));
        }

        if (mTouchDelegate != null) {
            if (mTouchDelegate.onTouchEvent(event)) {
                return true;
            }
        }

        if (((viewFlags & CLICKABLE) == CLICKABLE ||
                (viewFlags & LONG_CLICKABLE) == LONG_CLICKABLE)) {
            switch (event.getAction()) {
                case MotionEvent.ACTION_UP:
                    boolean prepressed = (mPrivateFlags & PREPRESSED) != 0;
                    if ((mPrivateFlags & PRESSED) != 0 || prepressed) {
                        // take focus if we don't have it already and we should in
                        // touch mode.
                        boolean focusTaken = false;
                        if (isFocusable() && isFocusableInTouchMode() && !isFocused()) {
                            focusTaken = requestFocus();
                        }

                        if (prepressed) {
                            // The button is being released before we actually
                            // showed it as pressed.  Make it show the pressed
                            // state now (before scheduling the click) to ensure
                            // the user sees it.
                            mPrivateFlags |= PRESSED;
                            refreshDrawableState();
                       }

                        if (!mHasPerformedLongPress) {
                            // This is a tap, so remove the longpress check
                            removeLongPressCallback();

                            // Only perform take click actions if we were in the pressed state
                            if (!focusTaken) {
                                // Use a Runnable and post this rather than calling
                                // performClick directly. This lets other visual state
                                // of the view update before click actions start.
                                if (mPerformClick == null) {
                                    mPerformClick = new PerformClick();
                                }
                                if (!post(mPerformClick)) {
                                    performClick();
                                }
                            }
                        }

                        if (mUnsetPressedState == null) {
                            mUnsetPressedState = new UnsetPressedState();
                        }

                        if (prepressed) {
                            postDelayed(mUnsetPressedState,
                                    ViewConfiguration.getPressedStateDuration());
                        } else if (!post(mUnsetPressedState)) {
                            // If the post failed, unpress right now
                            mUnsetPressedState.run();
                        }
                        removeTapCallback();
                    }
                    break;

                case MotionEvent.ACTION_DOWN:
                    if (mPendingCheckForTap == null) {
                        mPendingCheckForTap = new CheckForTap();
                    }
                    mPrivateFlags |= PREPRESSED;
                    mHasPerformedLongPress = false;
                    postDelayed(mPendingCheckForTap, ViewConfiguration.getTapTimeout());
                    break;

                case MotionEvent.ACTION_CANCEL:
                    mPrivateFlags &= ~PRESSED;
                    refreshDrawableState();
                    removeTapCallback();
                    break;

                case MotionEvent.ACTION_MOVE:
                    final int x = (int) event.getX();
                    final int y = (int) event.getY();

                    // Be lenient about moving outside of buttons
                    if (!pointInView(x, y, mTouchSlop)) {
                        // Outside button
                        removeTapCallback();
                        if ((mPrivateFlags & PRESSED) != 0) {
                            // Remove any future long press/tap checks
                            removeLongPressCallback();

                            // Need to switch from pressed to not pressed
                            mPrivateFlags &= ~PRESSED;
                            refreshDrawableState();
                        }
                    }
                    break;
            }
            return true;
        }

        return false;
    }

    /**
     * Remove the longpress detection timer.
     */
    private void removeLongPressCallback() {
        if (mPendingCheckForLongPress != null) {
          removeCallbacks(mPendingCheckForLongPress);
        }
    }

    /**
     * Remove the pending click action
     */
    private void removePerformClickCallback() {
        if (mPerformClick != null) {
            removeCallbacks(mPerformClick);
        }
    }

    /**
     * Remove the prepress detection timer.
     */
    private void removeUnsetPressCallback() {
        if ((mPrivateFlags & PRESSED) != 0 && mUnsetPressedState != null) {
            setPressed(false);
            removeCallbacks(mUnsetPressedState);
        }
    }

    /**
     * Remove the tap detection timer.
     */
    private void removeTapCallback() {
        if (mPendingCheckForTap != null) {
            mPrivateFlags &= ~PREPRESSED;
            removeCallbacks(mPendingCheckForTap);
        }
    }

    /**
     * Cancels a pending long press.  Your subclass can use this if you
     * want the context menu to come up if the user presses and holds
     * at the same place, but you don't want it to come up if they press
     * and then move around enough to cause scrolling.
     */
    public void cancelLongPress() {
        removeLongPressCallback();

        /*
         * The prepressed state handled by the tap callback is a display
         * construct, but the tap callback will post a long press callback
         * less its own timeout. Remove it here.
         */
        removeTapCallback();
    }

    /**
     * Sets the TouchDelegate for this View.
     */
    public void setTouchDelegate(TouchDelegate delegate) {
        mTouchDelegate = delegate;
    }

    /**
     * Gets the TouchDelegate for this View.
     */
    public TouchDelegate getTouchDelegate() {
        return mTouchDelegate;
    }

    /**
     * Set flags controlling behavior of this view.
     *
     * @param flags Constant indicating the value which should be set
     * @param mask Constant indicating the bit range that should be changed
     */
    void setFlags(int flags, int mask) {
        int old = mViewFlags;
        mViewFlags = (mViewFlags & ~mask) | (flags & mask);

        int changed = mViewFlags ^ old;
        if (changed == 0) {
            return;
        }
        int privateFlags = mPrivateFlags;

        /* Check if the FOCUSABLE bit has changed */
        if (((changed & FOCUSABLE_MASK) != 0) &&
                ((privateFlags & HAS_BOUNDS) !=0)) {
            if (((old & FOCUSABLE_MASK) == FOCUSABLE)
                    && ((privateFlags & FOCUSED) != 0)) {
                /* Give up focus if we are no longer focusable */
                clearFocus();
            } else if (((old & FOCUSABLE_MASK) == NOT_FOCUSABLE)
                    && ((privateFlags & FOCUSED) == 0)) {
                /*
                 * Tell the view system that we are now available to take focus
                 * if no one else already has it.
                 */
                if (mParent != null) mParent.focusableViewAvailable(this);
            }
        }

        if ((flags & VISIBILITY_MASK) == VISIBLE) {
            if ((changed & VISIBILITY_MASK) != 0) {
                /*
                 * If this view is becoming visible, set the DRAWN flag so that
                 * the next invalidate() will not be skipped.
                 */
                mPrivateFlags |= DRAWN;

                needGlobalAttributesUpdate(true);

                // a view becoming visible is worth notifying the parent
                // about in case nothing has focus.  even if this specific view
                // isn't focusable, it may contain something that is, so let
                // the root view try to give this focus if nothing else does.
                if ((mParent != null) && (mBottom > mTop) && (mRight > mLeft)) {
                    mParent.focusableViewAvailable(this);
                }
            }
        }

        /* Check if the GONE bit has changed */
        if ((changed & GONE) != 0) {
            needGlobalAttributesUpdate(false);
            requestLayout();
            invalidate(true);

            if (((mViewFlags & VISIBILITY_MASK) == GONE)) {
                if (hasFocus()) clearFocus();
                destroyDrawingCache();
            }
            if (mAttachInfo != null) {
                mAttachInfo.mViewVisibilityChanged = true;
            }
        }

        /* Check if the VISIBLE bit has changed */
        if ((changed & INVISIBLE) != 0) {
            needGlobalAttributesUpdate(false);
            invalidate(true);

            if (((mViewFlags & VISIBILITY_MASK) == INVISIBLE) && hasFocus()) {
                // root view becoming invisible shouldn't clear focus
                if (getRootView() != this) {
                    clearFocus();
                }
            }
            if (mAttachInfo != null) {
                mAttachInfo.mViewVisibilityChanged = true;
            }
        }

        if ((changed & VISIBILITY_MASK) != 0) {
            if (mParent instanceof ViewGroup) {
                ((ViewGroup) mParent).onChildVisibilityChanged(this, (flags & VISIBILITY_MASK));
                ((View) mParent).invalidate(true);
            }
            dispatchVisibilityChanged(this, (flags & VISIBILITY_MASK));
        }

        if ((changed & WILL_NOT_CACHE_DRAWING) != 0) {
            destroyDrawingCache();
        }

        if ((changed & DRAWING_CACHE_ENABLED) != 0) {
            destroyDrawingCache();
            mPrivateFlags &= ~DRAWING_CACHE_VALID;
            invalidateParentCaches();
        }

        if ((changed & DRAWING_CACHE_QUALITY_MASK) != 0) {
            destroyDrawingCache();
            mPrivateFlags &= ~DRAWING_CACHE_VALID;
        }

        if ((changed & DRAW_MASK) != 0) {
            if ((mViewFlags & WILL_NOT_DRAW) != 0) {
                if (mBGDrawable != null) {
                    mPrivateFlags &= ~SKIP_DRAW;
                    mPrivateFlags |= ONLY_DRAWS_BACKGROUND;
                } else {
                    mPrivateFlags |= SKIP_DRAW;
                }
            } else {
                mPrivateFlags &= ~SKIP_DRAW;
            }
            requestLayout();
            invalidate(true);
        }

        if ((changed & KEEP_SCREEN_ON) != 0) {
            if (mParent != null && mAttachInfo != null && !mAttachInfo.mRecomputeGlobalAttributes) {
                mParent.recomputeViewAttributes(this);
            }
        }
    }

    /**
     * Change the view's z order in the tree, so it's on top of other sibling
     * views
     */
    public void bringToFront() {
        if (mParent != null) {
            mParent.bringChildToFront(this);
        }
    }

    /**
     * This is called in response to an internal scroll in this view (i.e., the
     * view scrolled its own contents). This is typically as a result of
     * {@link #scrollBy(int, int)} or {@link #scrollTo(int, int)} having been
     * called.
     *
     * @param l Current horizontal scroll origin.
     * @param t Current vertical scroll origin.
     * @param oldl Previous horizontal scroll origin.
     * @param oldt Previous vertical scroll origin.
     */
    protected void onScrollChanged(int l, int t, int oldl, int oldt) {
        mBackgroundSizeChanged = true;

        final AttachInfo ai = mAttachInfo;
        if (ai != null) {
            ai.mViewScrollChanged = true;
        }
    }

    /**
     * Interface definition for a callback to be invoked when the layout bounds of a view
     * changes due to layout processing.
     */
    public interface OnLayoutChangeListener {
        /**
         * Called when the focus state of a view has changed.
         *
         * @param v The view whose state has changed.
         * @param left The new value of the view's left property.
         * @param top The new value of the view's top property.
         * @param right The new value of the view's right property.
         * @param bottom The new value of the view's bottom property.
         * @param oldLeft The previous value of the view's left property.
         * @param oldTop The previous value of the view's top property.
         * @param oldRight The previous value of the view's right property.
         * @param oldBottom The previous value of the view's bottom property.
         */
        void onLayoutChange(View v, int left, int top, int right, int bottom,
            int oldLeft, int oldTop, int oldRight, int oldBottom);
    }

    /**
     * This is called during layout when the size of this view has changed. If
     * you were just added to the view hierarchy, you're called with the old
     * values of 0.
     *
     * @param w Current width of this view.
     * @param h Current height of this view.
     * @param oldw Old width of this view.
     * @param oldh Old height of this view.
     */
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
    }

    /**
     * Called by draw to draw the child views. This may be overridden
     * by derived classes to gain control just before its children are drawn
     * (but after its own view has been drawn).
     * @param canvas the canvas on which to draw the view
     */
    protected void dispatchDraw(Canvas canvas) {
    }

    /**
     * Gets the parent of this view. Note that the parent is a
     * ViewParent and not necessarily a View.
     *
     * @return Parent of this view.
     */
    public final ViewParent getParent() {
        return mParent;
    }

    /**
     * Return the scrolled left position of this view. This is the left edge of
     * the displayed part of your view. You do not need to draw any pixels
     * farther left, since those are outside of the frame of your view on
     * screen.
     *
     * @return The left edge of the displayed part of your view, in pixels.
     */
    public final int getScrollX() {
        return mScrollX;
    }

    /**
     * Return the scrolled top position of this view. This is the top edge of
     * the displayed part of your view. You do not need to draw any pixels above
     * it, since those are outside of the frame of your view on screen.
     *
     * @return The top edge of the displayed part of your view, in pixels.
     */
    public final int getScrollY() {
        return mScrollY;
    }

    /**
     * Return the width of the your view.
     *
     * @return The width of your view, in pixels.
     */
    @ViewDebug.ExportedProperty(category = "layout")
    public final int getWidth() {
        return mRight - mLeft;
    }

    /**
     * Return the height of your view.
     *
     * @return The height of your view, in pixels.
     */
    @ViewDebug.ExportedProperty(category = "layout")
    public final int getHeight() {
        return mBottom - mTop;
    }

    /**
     * Return the visible drawing bounds of your view. Fills in the output
     * rectangle with the values from getScrollX(), getScrollY(),
     * getWidth(), and getHeight().
     *
     * @param outRect The (scrolled) drawing bounds of the view.
     */
    public void getDrawingRect(Rect outRect) {
        outRect.left = mScrollX;
        outRect.top = mScrollY;
        outRect.right = mScrollX + (mRight - mLeft);
        outRect.bottom = mScrollY + (mBottom - mTop);
    }

    /**
     * Like {@link #getMeasuredWidthAndState()}, but only returns the
     * raw width component (that is the result is masked by
     * {@link #MEASURED_SIZE_MASK}).
     *
     * @return The raw measured width of this view.
     */
    public final int getMeasuredWidth() {
        return mMeasuredWidth & MEASURED_SIZE_MASK;
    }

    /**
     * Return the full width measurement information for this view as computed
     * by the most recent call to {@link #measure}.  This result is a bit mask
     * as defined by {@link #MEASURED_SIZE_MASK} and {@link #MEASURED_STATE_TOO_SMALL}.
     * This should be used during measurement and layout calculations only. Use
     * {@link #getWidth()} to see how wide a view is after layout.
     *
     * @return The measured width of this view as a bit mask.
     */
    public final int getMeasuredWidthAndState() {
        return mMeasuredWidth;
    }

    /**
     * Like {@link #getMeasuredHeightAndState()}, but only returns the
     * raw width component (that is the result is masked by
     * {@link #MEASURED_SIZE_MASK}).
     *
     * @return The raw measured height of this view.
     */
    public final int getMeasuredHeight() {
        return mMeasuredHeight & MEASURED_SIZE_MASK;
    }

    /**
     * Return the full height measurement information for this view as computed
     * by the most recent call to {@link #measure}.  This result is a bit mask
     * as defined by {@link #MEASURED_SIZE_MASK} and {@link #MEASURED_STATE_TOO_SMALL}.
     * This should be used during measurement and layout calculations only. Use
     * {@link #getHeight()} to see how wide a view is after layout.
     *
     * @return The measured width of this view as a bit mask.
     */
    public final int getMeasuredHeightAndState() {
        return mMeasuredHeight;
    }

    /**
     * Return only the state bits of {@link #getMeasuredWidthAndState()}
     * and {@link #getMeasuredHeightAndState()}, combined into one integer.
     * The width component is in the regular bits {@link #MEASURED_STATE_MASK}
     * and the height component is at the shifted bits
     * {@link #MEASURED_HEIGHT_STATE_SHIFT}>>{@link #MEASURED_STATE_MASK}.
     */
    public final int getMeasuredState() {
        return (mMeasuredWidth&MEASURED_STATE_MASK)
                | ((mMeasuredHeight>>MEASURED_HEIGHT_STATE_SHIFT)
                        & (MEASURED_STATE_MASK>>MEASURED_HEIGHT_STATE_SHIFT));
    }

    /**
     * The transform matrix of this view, which is calculated based on the current
     * roation, scale, and pivot properties.
     *
     * @see #getRotation()
     * @see #getScaleX()
     * @see #getScaleY()
     * @see #getPivotX()
     * @see #getPivotY()
     * @return The current transform matrix for the view
     */
    public Matrix getMatrix() {
        updateMatrix();
        return mMatrix;
    }

    /**
     * Utility function to determine if the value is far enough away from zero to be
     * considered non-zero.
     * @param value A floating point value to check for zero-ness
     * @return whether the passed-in value is far enough away from zero to be considered non-zero
     */
    private static boolean nonzero(float value) {
        return (value < -NONZERO_EPSILON || value > NONZERO_EPSILON);
    }

    /**
     * Returns true if the transform matrix is the identity matrix.
     * Recomputes the matrix if necessary.
     *
     * @return True if the transform matrix is the identity matrix, false otherwise.
     */
    final boolean hasIdentityMatrix() {
        updateMatrix();
        return mMatrixIsIdentity;
    }

    /**
     * Recomputes the transform matrix if necessary.
     */
    private void updateMatrix() {
        if (mMatrixDirty) {
            // transform-related properties have changed since the last time someone
            // asked for the matrix; recalculate it with the current values

            // Figure out if we need to update the pivot point
            if ((mPrivateFlags & PIVOT_EXPLICITLY_SET) == 0) {
                if ((mRight - mLeft) != mPrevWidth || (mBottom - mTop) != mPrevHeight) {
                    mPrevWidth = mRight - mLeft;
                    mPrevHeight = mBottom - mTop;
                    mPivotX = mPrevWidth / 2f;
                    mPivotY = mPrevHeight / 2f;
                }
            }
            mMatrix.reset();
            if (!nonzero(mRotationX) && !nonzero(mRotationY)) {
                mMatrix.setTranslate(mTranslationX, mTranslationY);
                mMatrix.preRotate(mRotation, mPivotX, mPivotY);
                mMatrix.preScale(mScaleX, mScaleY, mPivotX, mPivotY);
            } else {
                if (mCamera == null) {
                    mCamera = new Camera();
                    matrix3D = new Matrix();
                }
                mCamera.save();
                mMatrix.preScale(mScaleX, mScaleY, mPivotX, mPivotY);
                mCamera.rotateX(mRotationX);
                mCamera.rotateY(mRotationY);
                mCamera.rotateZ(-mRotation);
                mCamera.getMatrix(matrix3D);
                matrix3D.preTranslate(-mPivotX, -mPivotY);
                matrix3D.postTranslate(mPivotX + mTranslationX, mPivotY + mTranslationY);
                mMatrix.postConcat(matrix3D);
                mCamera.restore();
            }
            mMatrixDirty = false;
            mMatrixIsIdentity = mMatrix.isIdentity();
            mInverseMatrixDirty = true;
        }
    }

    /**
     * Utility method to retrieve the inverse of the current mMatrix property.
     * We cache the matrix to avoid recalculating it when transform properties
     * have not changed.
     *
     * @return The inverse of the current matrix of this view.
     */
    final Matrix getInverseMatrix() {
        updateMatrix();
        if (mInverseMatrixDirty) {
            if (mInverseMatrix == null) {
                mInverseMatrix = new Matrix();
            }
            mMatrix.invert(mInverseMatrix);
            mInverseMatrixDirty = false;
        }
        return mInverseMatrix;
    }

    /**
     * The degrees that the view is rotated around the pivot point.
     *
     * @see #getPivotX()
     * @see #getPivotY()
     * @return The degrees of rotation.
     */
    public float getRotation() {
        return mRotation;
    }

    /**
     * Sets the degrees that the view is rotated around the pivot point. Increasing values
     * result in clockwise rotation.
     *
     * @param rotation The degrees of rotation.
     * @see #getPivotX()
     * @see #getPivotY()
     *
     * @attr ref android.R.styleable#View_rotation
     */
    public void setRotation(float rotation) {
        if (mRotation != rotation) {
            invalidateParentCaches();
            // Double-invalidation is necessary to capture view's old and new areas
            invalidate(false);
            mRotation = rotation;
            mMatrixDirty = true;
            mPrivateFlags |= DRAWN; // force another invalidation with the new orientation
            invalidate(false);
        }
    }

    /**
     * The degrees that the view is rotated around the vertical axis through the pivot point.
     *
     * @see #getPivotX()
     * @see #getPivotY()
     * @return The degrees of Y rotation.
     */
    public float getRotationY() {
        return mRotationY;
    }

    /**
     * Sets the degrees that the view is rotated around the vertical axis through the pivot point.
     * Increasing values result in counter-clockwise rotation from the viewpoint of looking
     * down the y axis.
     *
     * @param rotationY The degrees of Y rotation.
     * @see #getPivotX()
     * @see #getPivotY()
     *
     * @attr ref android.R.styleable#View_rotationY
     */
    public void setRotationY(float rotationY) {
        if (mRotationY != rotationY) {
            invalidateParentCaches();
            // Double-invalidation is necessary to capture view's old and new areas
            invalidate(false);
            mRotationY = rotationY;
            mMatrixDirty = true;
            mPrivateFlags |= DRAWN; // force another invalidation with the new orientation
            invalidate(false);
        }
    }

    /**
     * The degrees that the view is rotated around the horizontal axis through the pivot point.
     *
     * @see #getPivotX()
     * @see #getPivotY()
     * @return The degrees of X rotation.
     */
    public float getRotationX() {
        return mRotationX;
    }

    /**
     * Sets the degrees that the view is rotated around the horizontal axis through the pivot point.
     * Increasing values result in clockwise rotation from the viewpoint of looking down the
     * x axis.
     *
     * @param rotationX The degrees of X rotation.
     * @see #getPivotX()
     * @see #getPivotY()
     *
     * @attr ref android.R.styleable#View_rotationX
     */
    public void setRotationX(float rotationX) {
        if (mRotationX != rotationX) {
            invalidateParentCaches();
            // Double-invalidation is necessary to capture view's old and new areas
            invalidate(false);
            mRotationX = rotationX;
            mMatrixDirty = true;
            mPrivateFlags |= DRAWN; // force another invalidation with the new orientation
            invalidate(false);
        }
    }

    /**
     * The amount that the view is scaled in x around the pivot point, as a proportion of
     * the view's unscaled width. A value of 1, the default, means that no scaling is applied.
     *
     * <p>By default, this is 1.0f.
     *
     * @see #getPivotX()
     * @see #getPivotY()
     * @return The scaling factor.
     */
    public float getScaleX() {
        return mScaleX;
    }

    /**
     * Sets the amount that the view is scaled in x around the pivot point, as a proportion of
     * the view's unscaled width. A value of 1 means that no scaling is applied.
     *
     * @param scaleX The scaling factor.
     * @see #getPivotX()
     * @see #getPivotY()
     *
     * @attr ref android.R.styleable#View_scaleX
     */
    public void setScaleX(float scaleX) {
        if (mScaleX != scaleX) {
            invalidateParentCaches();
            // Double-invalidation is necessary to capture view's old and new areas
            invalidate(false);
            mScaleX = scaleX;
            mMatrixDirty = true;
            mPrivateFlags |= DRAWN; // force another invalidation with the new orientation
            invalidate(false);
        }
    }

    /**
     * The amount that the view is scaled in y around the pivot point, as a proportion of
     * the view's unscaled height. A value of 1, the default, means that no scaling is applied.
     *
     * <p>By default, this is 1.0f.
     *
     * @see #getPivotX()
     * @see #getPivotY()
     * @return The scaling factor.
     */
    public float getScaleY() {
        return mScaleY;
    }

    /**
     * Sets the amount that the view is scaled in Y around the pivot point, as a proportion of
     * the view's unscaled width. A value of 1 means that no scaling is applied.
     *
     * @param scaleY The scaling factor.
     * @see #getPivotX()
     * @see #getPivotY()
     *
     * @attr ref android.R.styleable#View_scaleY
     */
    public void setScaleY(float scaleY) {
        if (mScaleY != scaleY) {
            invalidateParentCaches();
            // Double-invalidation is necessary to capture view's old and new areas
            invalidate(false);
            mScaleY = scaleY;
            mMatrixDirty = true;
            mPrivateFlags |= DRAWN; // force another invalidation with the new orientation
            invalidate(false);
        }
    }

    /**
     * The x location of the point around which the view is {@link #setRotation(float) rotated}
     * and {@link #setScaleX(float) scaled}.
     *
     * @see #getRotation()
     * @see #getScaleX()
     * @see #getScaleY()
     * @see #getPivotY()
     * @return The x location of the pivot point.
     */
    public float getPivotX() {
        return mPivotX;
    }

    /**
     * Sets the x location of the point around which the view is
     * {@link #setRotation(float) rotated} and {@link #setScaleX(float) scaled}.
     * By default, the pivot point is centered on the object.
     * Setting this property disables this behavior and causes the view to use only the
     * explicitly set pivotX and pivotY values.
     *
     * @param pivotX The x location of the pivot point.
     * @see #getRotation()
     * @see #getScaleX()
     * @see #getScaleY()
     * @see #getPivotY()
     *
     * @attr ref android.R.styleable#View_transformPivotX
     */
    public void setPivotX(float pivotX) {
        mPrivateFlags |= PIVOT_EXPLICITLY_SET;
        if (mPivotX != pivotX) {
            invalidateParentCaches();
            // Double-invalidation is necessary to capture view's old and new areas
            invalidate(false);
            mPivotX = pivotX;
            mMatrixDirty = true;
            mPrivateFlags |= DRAWN; // force another invalidation with the new orientation
            invalidate(false);
        }
    }

    /**
     * The y location of the point around which the view is {@link #setRotation(float) rotated}
     * and {@link #setScaleY(float) scaled}.
     *
     * @see #getRotation()
     * @see #getScaleX()
     * @see #getScaleY()
     * @see #getPivotY()
     * @return The y location of the pivot point.
     */
    public float getPivotY() {
        return mPivotY;
    }

    /**
     * Sets the y location of the point around which the view is {@link #setRotation(float) rotated}
     * and {@link #setScaleY(float) scaled}. By default, the pivot point is centered on the object.
     * Setting this property disables this behavior and causes the view to use only the
     * explicitly set pivotX and pivotY values.
     *
     * @param pivotY The y location of the pivot point.
     * @see #getRotation()
     * @see #getScaleX()
     * @see #getScaleY()
     * @see #getPivotY()
     *
     * @attr ref android.R.styleable#View_transformPivotY
     */
    public void setPivotY(float pivotY) {
        mPrivateFlags |= PIVOT_EXPLICITLY_SET;
        if (mPivotY != pivotY) {
            invalidateParentCaches();
            // Double-invalidation is necessary to capture view's old and new areas
            invalidate(false);
            mPivotY = pivotY;
            mMatrixDirty = true;
            mPrivateFlags |= DRAWN; // force another invalidation with the new orientation
            invalidate(false);
        }
    }

    /**
     * The opacity of the view. This is a value from 0 to 1, where 0 means the view is
     * completely transparent and 1 means the view is completely opaque.
     *
     * <p>By default this is 1.0f.
     * @return The opacity of the view.
     */
    public float getAlpha() {
        return mAlpha;
    }

    /**
     * <p>Sets the opacity of the view. This is a value from 0 to 1, where 0 means the view is
     * completely transparent and 1 means the view is completely opaque.</p>
     *
     * <p>If this view overrides {@link #onSetAlpha(int)} to return true, then this view is
     * responsible for applying the opacity itself. Otherwise, calling this method is
     * equivalent to calling {@link #setLayerType(int, android.graphics.Paint)} and
     * setting a hardware layer.</p>
     *
     * @param alpha The opacity of the view.
     *
     * @see #setLayerType(int, android.graphics.Paint)
     *
     * @attr ref android.R.styleable#View_alpha
     */
    public void setAlpha(float alpha) {
        mAlpha = alpha;
        invalidateParentCaches();
        if (onSetAlpha((int) (alpha * 255))) {
            mPrivateFlags |= ALPHA_SET;
            // subclass is handling alpha - don't optimize rendering cache invalidation
            invalidate(true);
        } else {
            mPrivateFlags &= ~ALPHA_SET;
            invalidate(false);
        }
    }

    /**
     * Top position of this view relative to its parent.
     *
     * @return The top of this view, in pixels.
     */
    @ViewDebug.CapturedViewProperty
    public final int getTop() {
        return mTop;
    }

    /**
     * Sets the top position of this view relative to its parent. This method is meant to be called
     * by the layout system and should not generally be called otherwise, because the property
     * may be changed at any time by the layout.
     *
     * @param top The top of this view, in pixels.
     */
    public final void setTop(int top) {
        if (top != mTop) {
            updateMatrix();
            if (mMatrixIsIdentity) {
                final ViewParent p = mParent;
                if (p != null && mAttachInfo != null) {
                    final Rect r = mAttachInfo.mTmpInvalRect;
                    int minTop;
                    int yLoc;
                    if (top < mTop) {
                        minTop = top;
                        yLoc = top - mTop;
                    } else {
                        minTop = mTop;
                        yLoc = 0;
                    }
                    r.set(0, yLoc, mRight - mLeft, mBottom - minTop);
                    p.invalidateChild(this, r);
                }
            } else {
                // Double-invalidation is necessary to capture view's old and new areas
                invalidate(true);
            }

            int width = mRight - mLeft;
            int oldHeight = mBottom - mTop;

            mTop = top;

            onSizeChanged(width, mBottom - mTop, width, oldHeight);

            if (!mMatrixIsIdentity) {
                if ((mPrivateFlags & PIVOT_EXPLICITLY_SET) == 0) {
                    // A change in dimension means an auto-centered pivot point changes, too
                    mMatrixDirty = true;
                }
                mPrivateFlags |= DRAWN; // force another invalidation with the new orientation
                invalidate(true);
            }
            mBackgroundSizeChanged = true;
            invalidateParentIfNeeded();
        }
    }

    /**
     * Bottom position of this view relative to its parent.
     *
     * @return The bottom of this view, in pixels.
     */
    @ViewDebug.CapturedViewProperty
    public final int getBottom() {
        return mBottom;
    }

    /**
     * True if this view has changed since the last time being drawn.
     *
     * @return The dirty state of this view.
     */
    public boolean isDirty() {
        return (mPrivateFlags & DIRTY_MASK) != 0;
    }

    /**
     * Sets the bottom position of this view relative to its parent. This method is meant to be
     * called by the layout system and should not generally be called otherwise, because the
     * property may be changed at any time by the layout.
     *
     * @param bottom The bottom of this view, in pixels.
     */
    public final void setBottom(int bottom) {
        if (bottom != mBottom) {
            updateMatrix();
            if (mMatrixIsIdentity) {
                final ViewParent p = mParent;
                if (p != null && mAttachInfo != null) {
                    final Rect r = mAttachInfo.mTmpInvalRect;
                    int maxBottom;
                    if (bottom < mBottom) {
                        maxBottom = mBottom;
                    } else {
                        maxBottom = bottom;
                    }
                    r.set(0, 0, mRight - mLeft, maxBottom - mTop);
                    p.invalidateChild(this, r);
                }
            } else {
                // Double-invalidation is necessary to capture view's old and new areas
                invalidate(true);
            }

            int width = mRight - mLeft;
            int oldHeight = mBottom - mTop;

            mBottom = bottom;

            onSizeChanged(width, mBottom - mTop, width, oldHeight);

            if (!mMatrixIsIdentity) {
                if ((mPrivateFlags & PIVOT_EXPLICITLY_SET) == 0) {
                    // A change in dimension means an auto-centered pivot point changes, too
                    mMatrixDirty = true;
                }
                mPrivateFlags |= DRAWN; // force another invalidation with the new orientation
                invalidate(true);
            }
            mBackgroundSizeChanged = true;
            invalidateParentIfNeeded();
        }
    }

    /**
     * Left position of this view relative to its parent.
     *
     * @return The left edge of this view, in pixels.
     */
    @ViewDebug.CapturedViewProperty
    public final int getLeft() {
        return mLeft;
    }

    /**
     * Sets the left position of this view relative to its parent. This method is meant to be called
     * by the layout system and should not generally be called otherwise, because the property
     * may be changed at any time by the layout.
     *
     * @param left The bottom of this view, in pixels.
     */
    public final void setLeft(int left) {
        if (left != mLeft) {
            updateMatrix();
            if (mMatrixIsIdentity) {
                final ViewParent p = mParent;
                if (p != null && mAttachInfo != null) {
                    final Rect r = mAttachInfo.mTmpInvalRect;
                    int minLeft;
                    int xLoc;
                    if (left < mLeft) {
                        minLeft = left;
                        xLoc = left - mLeft;
                    } else {
                        minLeft = mLeft;
                        xLoc = 0;
                    }
                    r.set(xLoc, 0, mRight - minLeft, mBottom - mTop);
                    p.invalidateChild(this, r);
                }
            } else {
                // Double-invalidation is necessary to capture view's old and new areas
                invalidate(true);
            }

            int oldWidth = mRight - mLeft;
            int height = mBottom - mTop;

            mLeft = left;

            onSizeChanged(mRight - mLeft, height, oldWidth, height);

            if (!mMatrixIsIdentity) {
                if ((mPrivateFlags & PIVOT_EXPLICITLY_SET) == 0) {
                    // A change in dimension means an auto-centered pivot point changes, too
                    mMatrixDirty = true;
                }
                mPrivateFlags |= DRAWN; // force another invalidation with the new orientation
                invalidate(true);
            }
            mBackgroundSizeChanged = true;
            invalidateParentIfNeeded();
        }
    }

    /**
     * Right position of this view relative to its parent.
     *
     * @return The right edge of this view, in pixels.
     */
    @ViewDebug.CapturedViewProperty
    public final int getRight() {
        return mRight;
    }

    /**
     * Sets the right position of this view relative to its parent. This method is meant to be called
     * by the layout system and should not generally be called otherwise, because the property
     * may be changed at any time by the layout.
     *
     * @param right The bottom of this view, in pixels.
     */
    public final void setRight(int right) {
        if (right != mRight) {
            updateMatrix();
            if (mMatrixIsIdentity) {
                final ViewParent p = mParent;
                if (p != null && mAttachInfo != null) {
                    final Rect r = mAttachInfo.mTmpInvalRect;
                    int maxRight;
                    if (right < mRight) {
                        maxRight = mRight;
                    } else {
                        maxRight = right;
                    }
                    r.set(0, 0, maxRight - mLeft, mBottom - mTop);
                    p.invalidateChild(this, r);
                }
            } else {
                // Double-invalidation is necessary to capture view's old and new areas
                invalidate(true);
            }

            int oldWidth = mRight - mLeft;
            int height = mBottom - mTop;

            mRight = right;

            onSizeChanged(mRight - mLeft, height, oldWidth, height);

            if (!mMatrixIsIdentity) {
                if ((mPrivateFlags & PIVOT_EXPLICITLY_SET) == 0) {
                    // A change in dimension means an auto-centered pivot point changes, too
                    mMatrixDirty = true;
                }
                mPrivateFlags |= DRAWN; // force another invalidation with the new orientation
                invalidate(true);
            }
            mBackgroundSizeChanged = true;
            invalidateParentIfNeeded();
        }
    }

    /**
     * The visual x position of this view, in pixels. This is equivalent to the
     * {@link #setTranslationX(float) translationX} property plus the current
     * {@link #getLeft() left} property.
     *
     * @return The visual x position of this view, in pixels.
     */
    public float getX() {
        return mLeft + mTranslationX;
    }

    /**
     * Sets the visual x position of this view, in pixels. This is equivalent to setting the
     * {@link #setTranslationX(float) translationX} property to be the difference between
     * the x value passed in and the current {@link #getLeft() left} property.
     *
     * @param x The visual x position of this view, in pixels.
     */
    public void setX(float x) {
        setTranslationX(x - mLeft);
    }

    /**
     * The visual y position of this view, in pixels. This is equivalent to the
     * {@link #setTranslationY(float) translationY} property plus the current
     * {@link #getTop() top} property.
     *
     * @return The visual y position of this view, in pixels.
     */
    public float getY() {
        return mTop + mTranslationY;
    }

    /**
     * Sets the visual y position of this view, in pixels. This is equivalent to setting the
     * {@link #setTranslationY(float) translationY} property to be the difference between
     * the y value passed in and the current {@link #getTop() top} property.
     *
     * @param y The visual y position of this view, in pixels.
     */
    public void setY(float y) {
        setTranslationY(y - mTop);
    }


    /**
     * The horizontal location of this view relative to its {@link #getLeft() left} position.
     * This position is post-layout, in addition to wherever the object's
     * layout placed it.
     *
     * @return The horizontal position of this view relative to its left position, in pixels.
     */
    public float getTranslationX() {
        return mTranslationX;
    }

    /**
     * Sets the horizontal location of this view relative to its {@link #getLeft() left} position.
     * This effectively positions the object post-layout, in addition to wherever the object's
     * layout placed it.
     *
     * @param translationX The horizontal position of this view relative to its left position,
     * in pixels.
     *
     * @attr ref android.R.styleable#View_translationX
     */
    public void setTranslationX(float translationX) {
        if (mTranslationX != translationX) {
            invalidateParentCaches();
            // Double-invalidation is necessary to capture view's old and new areas
            invalidate(false);
            mTranslationX = translationX;
            mMatrixDirty = true;
            mPrivateFlags |= DRAWN; // force another invalidation with the new orientation
            invalidate(false);
        }
    }

    /**
     * The horizontal location of this view relative to its {@link #getTop() top} position.
     * This position is post-layout, in addition to wherever the object's
     * layout placed it.
     *
     * @return The vertical position of this view relative to its top position,
     * in pixels.
     */
    public float getTranslationY() {
        return mTranslationY;
    }

    /**
     * Sets the vertical location of this view relative to its {@link #getTop() top} position.
     * This effectively positions the object post-layout, in addition to wherever the object's
     * layout placed it.
     *
     * @param translationY The vertical position of this view relative to its top position,
     * in pixels.
     *
     * @attr ref android.R.styleable#View_translationY
     */
    public void setTranslationY(float translationY) {
        if (mTranslationY != translationY) {
            invalidateParentCaches();
            // Double-invalidation is necessary to capture view's old and new areas
            invalidate(false);
            mTranslationY = translationY;
            mMatrixDirty = true;
            mPrivateFlags |= DRAWN; // force another invalidation with the new orientation
            invalidate(false);
        }
    }

    /**
     * Hit rectangle in parent's coordinates
     *
     * @param outRect The hit rectangle of the view.
     */
    public void getHitRect(Rect outRect) {
        updateMatrix();
        if (mMatrixIsIdentity || mAttachInfo == null) {
            outRect.set(mLeft, mTop, mRight, mBottom);
        } else {
            final RectF tmpRect = mAttachInfo.mTmpTransformRect;
            tmpRect.set(-mPivotX, -mPivotY, getWidth() - mPivotX, getHeight() - mPivotY);
            mMatrix.mapRect(tmpRect);
            outRect.set((int) tmpRect.left + mLeft, (int) tmpRect.top + mTop,
                    (int) tmpRect.right + mLeft, (int) tmpRect.bottom + mTop);
        }
    }

    /**
     * Determines whether the given point, in local coordinates is inside the view.
     */
    /*package*/ final boolean pointInView(float localX, float localY) {
        return localX >= 0 && localX < (mRight - mLeft)
                && localY >= 0 && localY < (mBottom - mTop);
    }

    /**
     * Utility method to determine whether the given point, in local coordinates,
     * is inside the view, where the area of the view is expanded by the slop factor.
     * This method is called while processing touch-move events to determine if the event
     * is still within the view.
     */
    private boolean pointInView(float localX, float localY, float slop) {
        return localX >= -slop && localY >= -slop && localX < ((mRight - mLeft) + slop) &&
                localY < ((mBottom - mTop) + slop);
    }

    /**
     * When a view has focus and the user navigates away from it, the next view is searched for
     * starting from the rectangle filled in by this method.
     *
     * By default, the rectange is the {@link #getDrawingRect})of the view.  However, if your
     * view maintains some idea of internal selection, such as a cursor, or a selected row
     * or column, you should override this method and fill in a more specific rectangle.
     *
     * @param r The rectangle to fill in, in this view's coordinates.
     */
    public void getFocusedRect(Rect r) {
        getDrawingRect(r);
    }

    /**
     * If some part of this view is not clipped by any of its parents, then
     * return that area in r in global (root) coordinates. To convert r to local
     * coordinates, offset it by -globalOffset (e.g. r.offset(-globalOffset.x,
     * -globalOffset.y)) If the view is completely clipped or translated out,
     * return false.
     *
     * @param r If true is returned, r holds the global coordinates of the
     *        visible portion of this view.
     * @param globalOffset If true is returned, globalOffset holds the dx,dy
     *        between this view and its root. globalOffet may be null.
     * @return true if r is non-empty (i.e. part of the view is visible at the
     *         root level.
     */
    public boolean getGlobalVisibleRect(Rect r, Point globalOffset) {
        int width = mRight - mLeft;
        int height = mBottom - mTop;
        if (width > 0 && height > 0) {
            r.set(0, 0, width, height);
            if (globalOffset != null) {
                globalOffset.set(-mScrollX, -mScrollY);
            }
            return mParent == null || mParent.getChildVisibleRect(this, r, globalOffset);
        }
        return false;
    }

    public final boolean getGlobalVisibleRect(Rect r) {
        return getGlobalVisibleRect(r, null);
    }

    public final boolean getLocalVisibleRect(Rect r) {
        Point offset = new Point();
        if (getGlobalVisibleRect(r, offset)) {
            r.offset(-offset.x, -offset.y); // make r local
            return true;
        }
        return false;
    }

    /**
     * Offset this view's vertical location by the specified number of pixels.
     *
     * @param offset the number of pixels to offset the view by
     */
    public void offsetTopAndBottom(int offset) {
        if (offset != 0) {
            updateMatrix();
            if (mMatrixIsIdentity) {
                final ViewParent p = mParent;
                if (p != null && mAttachInfo != null) {
                    final Rect r = mAttachInfo.mTmpInvalRect;
                    int minTop;
                    int maxBottom;
                    int yLoc;
                    if (offset < 0) {
                        minTop = mTop + offset;
                        maxBottom = mBottom;
                        yLoc = offset;
                    } else {
                        minTop = mTop;
                        maxBottom = mBottom + offset;
                        yLoc = 0;
                    }
                    r.set(0, yLoc, mRight - mLeft, maxBottom - minTop);
                    p.invalidateChild(this, r);
                }
            } else {
                invalidate(false);
            }

            mTop += offset;
            mBottom += offset;

            if (!mMatrixIsIdentity) {
                mPrivateFlags |= DRAWN; // force another invalidation with the new orientation
                invalidate(false);
            }
            invalidateParentIfNeeded();
        }
    }

    /**
     * Offset this view's horizontal location by the specified amount of pixels.
     *
     * @param offset the numer of pixels to offset the view by
     */
    public void offsetLeftAndRight(int offset) {
        if (offset != 0) {
            updateMatrix();
            if (mMatrixIsIdentity) {
                final ViewParent p = mParent;
                if (p != null && mAttachInfo != null) {
                    final Rect r = mAttachInfo.mTmpInvalRect;
                    int minLeft;
                    int maxRight;
                    if (offset < 0) {
                        minLeft = mLeft + offset;
                        maxRight = mRight;
                    } else {
                        minLeft = mLeft;
                        maxRight = mRight + offset;
                    }
                    r.set(0, 0, maxRight - minLeft, mBottom - mTop);
                    p.invalidateChild(this, r);
                }
            } else {
                invalidate(false);
            }

            mLeft += offset;
            mRight += offset;

            if (!mMatrixIsIdentity) {
                mPrivateFlags |= DRAWN; // force another invalidation with the new orientation
                invalidate(false);
            }
            invalidateParentIfNeeded();
        }
    }

    /**
     * Get the LayoutParams associated with this view. All views should have
     * layout parameters. These supply parameters to the <i>parent</i> of this
     * view specifying how it should be arranged. There are many subclasses of
     * ViewGroup.LayoutParams, and these correspond to the different subclasses
     * of ViewGroup that are responsible for arranging their children.
     * @return The LayoutParams associated with this view
     */
    @ViewDebug.ExportedProperty(deepExport = true, prefix = "layout_")
    public ViewGroup.LayoutParams getLayoutParams() {
        return mLayoutParams;
    }

    /**
     * Set the layout parameters associated with this view. These supply
     * parameters to the <i>parent</i> of this view specifying how it should be
     * arranged. There are many subclasses of ViewGroup.LayoutParams, and these
     * correspond to the different subclasses of ViewGroup that are responsible
     * for arranging their children.
     *
     * @param params the layout parameters for this view
     */
    public void setLayoutParams(ViewGroup.LayoutParams params) {
        if (params == null) {
            throw new NullPointerException("params == null");
        }
        mLayoutParams = params;
        requestLayout();
    }

    /**
     * Set the scrolled position of your view. This will cause a call to
     * {@link #onScrollChanged(int, int, int, int)} and the view will be
     * invalidated.
     * @param x the x position to scroll to
     * @param y the y position to scroll to
     */
    public void scrollTo(int x, int y) {
        if (mScrollX != x || mScrollY != y) {
            int oldX = mScrollX;
            int oldY = mScrollY;
            mScrollX = x;
            mScrollY = y;
            invalidateParentCaches();
            onScrollChanged(mScrollX, mScrollY, oldX, oldY);
            if (!awakenScrollBars()) {
                invalidate(true);
            }
        }
    }

    /**
     * Move the scrolled position of your view. This will cause a call to
     * {@link #onScrollChanged(int, int, int, int)} and the view will be
     * invalidated.
     * @param x the amount of pixels to scroll by horizontally
     * @param y the amount of pixels to scroll by vertically
     */
    public void scrollBy(int x, int y) {
        scrollTo(mScrollX + x, mScrollY + y);
    }

    /**
     * <p>Trigger the scrollbars to draw. When invoked this method starts an
     * animation to fade the scrollbars out after a default delay. If a subclass
     * provides animated scrolling, the start delay should equal the duration
     * of the scrolling animation.</p>
     *
     * <p>The animation starts only if at least one of the scrollbars is
     * enabled, as specified by {@link #isHorizontalScrollBarEnabled()} and
     * {@link #isVerticalScrollBarEnabled()}. When the animation is started,
     * this method returns true, and false otherwise. If the animation is
     * started, this method calls {@link #invalidate()}; in that case the
     * caller should not call {@link #invalidate()}.</p>
     *
     * <p>This method should be invoked every time a subclass directly updates
     * the scroll parameters.</p>
     *
     * <p>This method is automatically invoked by {@link #scrollBy(int, int)}
     * and {@link #scrollTo(int, int)}.</p>
     *
     * @return true if the animation is played, false otherwise
     *
     * @see #awakenScrollBars(int)
     * @see #scrollBy(int, int)
     * @see #scrollTo(int, int)
     * @see #isHorizontalScrollBarEnabled()
     * @see #isVerticalScrollBarEnabled()
     * @see #setHorizontalScrollBarEnabled(boolean)
     * @see #setVerticalScrollBarEnabled(boolean)
     */
    protected boolean awakenScrollBars() {
        return mScrollCache != null &&
                awakenScrollBars(mScrollCache.scrollBarDefaultDelayBeforeFade, true);
    }

    /**
     * Trigger the scrollbars to draw.
     * This method differs from awakenScrollBars() only in its default duration.
     * initialAwakenScrollBars() will show the scroll bars for longer than
     * usual to give the user more of a chance to notice them.
     *
     * @return true if the animation is played, false otherwise.
     */
    private boolean initialAwakenScrollBars() {
        return mScrollCache != null &&
                awakenScrollBars(mScrollCache.scrollBarDefaultDelayBeforeFade * 4, true);
    }

    /**
     * <p>
     * Trigger the scrollbars to draw. When invoked this method starts an
     * animation to fade the scrollbars out after a fixed delay. If a subclass
     * provides animated scrolling, the start delay should equal the duration of
     * the scrolling animation.
     * </p>
     *
     * <p>
     * The animation starts only if at least one of the scrollbars is enabled,
     * as specified by {@link #isHorizontalScrollBarEnabled()} and
     * {@link #isVerticalScrollBarEnabled()}. When the animation is started,
     * this method returns true, and false otherwise. If the animation is
     * started, this method calls {@link #invalidate()}; in that case the caller
     * should not call {@link #invalidate()}.
     * </p>
     *
     * <p>
     * This method should be invoked everytime a subclass directly updates the
     * scroll parameters.
     * </p>
     *
     * @param startDelay the delay, in milliseconds, after which the animation
     *        should start; when the delay is 0, the animation starts
     *        immediately
     * @return true if the animation is played, false otherwise
     *
     * @see #scrollBy(int, int)
     * @see #scrollTo(int, int)
     * @see #isHorizontalScrollBarEnabled()
     * @see #isVerticalScrollBarEnabled()
     * @see #setHorizontalScrollBarEnabled(boolean)
     * @see #setVerticalScrollBarEnabled(boolean)
     */
    protected boolean awakenScrollBars(int startDelay) {
        return awakenScrollBars(startDelay, true);
    }

    /**
     * <p>
     * Trigger the scrollbars to draw. When invoked this method starts an
     * animation to fade the scrollbars out after a fixed delay. If a subclass
     * provides animated scrolling, the start delay should equal the duration of
     * the scrolling animation.
     * </p>
     *
     * <p>
     * The animation starts only if at least one of the scrollbars is enabled,
     * as specified by {@link #isHorizontalScrollBarEnabled()} and
     * {@link #isVerticalScrollBarEnabled()}. When the animation is started,
     * this method returns true, and false otherwise. If the animation is
     * started, this method calls {@link #invalidate()} if the invalidate parameter
     * is set to true; in that case the caller
     * should not call {@link #invalidate()}.
     * </p>
     *
     * <p>
     * This method should be invoked everytime a subclass directly updates the
     * scroll parameters.
     * </p>
     *
     * @param startDelay the delay, in milliseconds, after which the animation
     *        should start; when the delay is 0, the animation starts
     *        immediately
     *
     * @param invalidate Wheter this method should call invalidate
     *
     * @return true if the animation is played, false otherwise
     *
     * @see #scrollBy(int, int)
     * @see #scrollTo(int, int)
     * @see #isHorizontalScrollBarEnabled()
     * @see #isVerticalScrollBarEnabled()
     * @see #setHorizontalScrollBarEnabled(boolean)
     * @see #setVerticalScrollBarEnabled(boolean)
     */
    protected boolean awakenScrollBars(int startDelay, boolean invalidate) {
        final ScrollabilityCache scrollCache = mScrollCache;

        if (scrollCache == null || !scrollCache.fadeScrollBars) {
            return false;
        }

        if (scrollCache.scrollBar == null) {
            scrollCache.scrollBar = new ScrollBarDrawable();
        }

        if (isHorizontalScrollBarEnabled() || isVerticalScrollBarEnabled()) {

            if (invalidate) {
                // Invalidate to show the scrollbars
                invalidate(true);
            }

            if (scrollCache.state == ScrollabilityCache.OFF) {
                // FIXME: this is copied from WindowManagerService.
                // We should get this value from the system when it
                // is possible to do so.
                final int KEY_REPEAT_FIRST_DELAY = 750;
                startDelay = Math.max(KEY_REPEAT_FIRST_DELAY, startDelay);
            }

            // Tell mScrollCache when we should start fading. This may
            // extend the fade start time if one was already scheduled
            long fadeStartTime = AnimationUtils.currentAnimationTimeMillis() + startDelay;
            scrollCache.fadeStartTime = fadeStartTime;
            scrollCache.state = ScrollabilityCache.ON;

            // Schedule our fader to run, unscheduling any old ones first
            if (mAttachInfo != null) {
                mAttachInfo.mHandler.removeCallbacks(scrollCache);
                mAttachInfo.mHandler.postAtTime(scrollCache, fadeStartTime);
            }

            return true;
        }

        return false;
    }

    /**
     * Mark the the area defined by dirty as needing to be drawn. If the view is
     * visible, {@link #onDraw} will be called at some point in the future.
     * This must be called from a UI thread. To call from a non-UI thread, call
     * {@link #postInvalidate()}.
     *
     * WARNING: This method is destructive to dirty.
     * @param dirty the rectangle representing the bounds of the dirty region
     */
    public void invalidate(Rect dirty) {
        if (ViewDebug.TRACE_HIERARCHY) {
            ViewDebug.trace(this, ViewDebug.HierarchyTraceType.INVALIDATE);
        }

        if ((mPrivateFlags & (DRAWN | HAS_BOUNDS)) == (DRAWN | HAS_BOUNDS) ||
                (mPrivateFlags & DRAWING_CACHE_VALID) == DRAWING_CACHE_VALID ||
                (mPrivateFlags & INVALIDATED) != INVALIDATED) {
            mPrivateFlags &= ~DRAWING_CACHE_VALID;
            mPrivateFlags |= INVALIDATED;
            final ViewParent p = mParent;
            final AttachInfo ai = mAttachInfo;
            //noinspection PointlessBooleanExpression,ConstantConditions
            if (!HardwareRenderer.RENDER_DIRTY_REGIONS) {
                if (p != null && ai != null && ai.mHardwareAccelerated) {
                    // fast-track for GL-enabled applications; just invalidate the whole hierarchy
                    // with a null dirty rect, which tells the ViewRoot to redraw everything
                    p.invalidateChild(this, null);
                    return;
                }
            }
            if (p != null && ai != null) {
                final int scrollX = mScrollX;
                final int scrollY = mScrollY;
                final Rect r = ai.mTmpInvalRect;
                r.set(dirty.left - scrollX, dirty.top - scrollY,
                        dirty.right - scrollX, dirty.bottom - scrollY);
                mParent.invalidateChild(this, r);
            }
        }
    }

    /**
     * Mark the the area defined by the rect (l,t,r,b) as needing to be drawn.
     * The coordinates of the dirty rect are relative to the view.
     * If the view is visible, {@link #onDraw} will be called at some point
     * in the future. This must be called from a UI thread. To call
     * from a non-UI thread, call {@link #postInvalidate()}.
     * @param l the left position of the dirty region
     * @param t the top position of the dirty region
     * @param r the right position of the dirty region
     * @param b the bottom position of the dirty region
     */
    public void invalidate(int l, int t, int r, int b) {
        if (ViewDebug.TRACE_HIERARCHY) {
            ViewDebug.trace(this, ViewDebug.HierarchyTraceType.INVALIDATE);
        }

        if ((mPrivateFlags & (DRAWN | HAS_BOUNDS)) == (DRAWN | HAS_BOUNDS) ||
                (mPrivateFlags & DRAWING_CACHE_VALID) == DRAWING_CACHE_VALID ||
                (mPrivateFlags & INVALIDATED) != INVALIDATED) {
            mPrivateFlags &= ~DRAWING_CACHE_VALID;
            mPrivateFlags |= INVALIDATED;
            final ViewParent p = mParent;
            final AttachInfo ai = mAttachInfo;
            //noinspection PointlessBooleanExpression,ConstantConditions
            if (!HardwareRenderer.RENDER_DIRTY_REGIONS) {
                if (p != null && ai != null && ai.mHardwareAccelerated) {
                    // fast-track for GL-enabled applications; just invalidate the whole hierarchy
                    // with a null dirty rect, which tells the ViewRoot to redraw everything
                    p.invalidateChild(this, null);
                    return;
                }
            }
            if (p != null && ai != null && l < r && t < b) {
                final int scrollX = mScrollX;
                final int scrollY = mScrollY;
                final Rect tmpr = ai.mTmpInvalRect;
                tmpr.set(l - scrollX, t - scrollY, r - scrollX, b - scrollY);
                p.invalidateChild(this, tmpr);
            }
        }
    }

    /**
     * Invalidate the whole view. If the view is visible, {@link #onDraw} will
     * be called at some point in the future. This must be called from a
     * UI thread. To call from a non-UI thread, call {@link #postInvalidate()}.
     */
    public void invalidate() {
        invalidate(true);
    }

    /**
     * This is where the invalidate() work actually happens. A full invalidate()
     * causes the drawing cache to be invalidated, but this function can be called with
     * invalidateCache set to false to skip that invalidation step for cases that do not
     * need it (for example, a component that remains at the same dimensions with the same
     * content).
     *
     * @param invalidateCache Whether the drawing cache for this view should be invalidated as
     * well. This is usually true for a full invalidate, but may be set to false if the
     * View's contents or dimensions have not changed.
     */
    private void invalidate(boolean invalidateCache) {
        if (ViewDebug.TRACE_HIERARCHY) {
            ViewDebug.trace(this, ViewDebug.HierarchyTraceType.INVALIDATE);
        }

        if ((mPrivateFlags & (DRAWN | HAS_BOUNDS)) == (DRAWN | HAS_BOUNDS) ||
                (invalidateCache && (mPrivateFlags & DRAWING_CACHE_VALID) == DRAWING_CACHE_VALID) ||
                (mPrivateFlags & INVALIDATED) != INVALIDATED || isOpaque() != mLastIsOpaque) {
            mLastIsOpaque = isOpaque();
            mPrivateFlags &= ~DRAWN;
            if (invalidateCache) {
                mPrivateFlags |= INVALIDATED;
                mPrivateFlags &= ~DRAWING_CACHE_VALID;
            }
            final AttachInfo ai = mAttachInfo;
            final ViewParent p = mParent;
            //noinspection PointlessBooleanExpression,ConstantConditions
            if (!HardwareRenderer.RENDER_DIRTY_REGIONS) {
                if (p != null && ai != null && ai.mHardwareAccelerated) {
                    // fast-track for GL-enabled applications; just invalidate the whole hierarchy
                    // with a null dirty rect, which tells the ViewRoot to redraw everything
                    p.invalidateChild(this, null);
                    return;
                }
            }

            if (p != null && ai != null) {
                final Rect r = ai.mTmpInvalRect;
                r.set(0, 0, mRight - mLeft, mBottom - mTop);
                // Don't call invalidate -- we don't want to internally scroll
                // our own bounds
                p.invalidateChild(this, r);
            }
        }
    }

    /**
     * Used to indicate that the parent of this view should clear its caches. This functionality
     * is used to force the parent to rebuild its display list (when hardware-accelerated),
     * which is necessary when various parent-managed properties of the view change, such as
     * alpha, translationX/Y, scrollX/Y, scaleX/Y, and rotation/X/Y. This method only
     * clears the parent caches and does not causes an invalidate event.
     *
     * @hide
     */
    protected void invalidateParentCaches() {
        if (mParent instanceof View) {
            ((View) mParent).mPrivateFlags |= INVALIDATED;
        }
    }

    /**
     * Used to indicate that the parent of this view should be invalidated. This functionality
     * is used to force the parent to rebuild its display list (when hardware-accelerated),
     * which is necessary when various parent-managed properties of the view change, such as
     * alpha, translationX/Y, scrollX/Y, scaleX/Y, and rotation/X/Y. This method will propagate
     * an invalidation event to the parent.
     *
     * @hide
     */
    protected void invalidateParentIfNeeded() {
        if (isHardwareAccelerated() && mParent instanceof View) {
            ((View) mParent).invalidate(true);
        }
    }

    /**
     * Indicates whether this View is opaque. An opaque View guarantees that it will
     * draw all the pixels overlapping its bounds using a fully opaque color.
     *
     * Subclasses of View should override this method whenever possible to indicate
     * whether an instance is opaque. Opaque Views are treated in a special way by
     * the View hierarchy, possibly allowing it to perform optimizations during
     * invalidate/draw passes.
     *
     * @return True if this View is guaranteed to be fully opaque, false otherwise.
     */
    @ViewDebug.ExportedProperty(category = "drawing")
    public boolean isOpaque() {
        return (mPrivateFlags & OPAQUE_MASK) == OPAQUE_MASK &&
                (mAlpha >= 1.0f - ViewConfiguration.ALPHA_THRESHOLD);
    }

    /**
     * @hide
     */
    protected void computeOpaqueFlags() {
        // Opaque if:
        //   - Has a background
        //   - Background is opaque
        //   - Doesn't have scrollbars or scrollbars are inside overlay

        if (mBGDrawable != null && mBGDrawable.getOpacity() == PixelFormat.OPAQUE) {
            mPrivateFlags |= OPAQUE_BACKGROUND;
        } else {
            mPrivateFlags &= ~OPAQUE_BACKGROUND;
        }

        final int flags = mViewFlags;
        if (((flags & SCROLLBARS_VERTICAL) == 0 && (flags & SCROLLBARS_HORIZONTAL) == 0) ||
                (flags & SCROLLBARS_STYLE_MASK) == SCROLLBARS_INSIDE_OVERLAY) {
            mPrivateFlags |= OPAQUE_SCROLLBARS;
        } else {
            mPrivateFlags &= ~OPAQUE_SCROLLBARS;
        }
    }

    /**
     * @hide
     */
    protected boolean hasOpaqueScrollbars() {
        return (mPrivateFlags & OPAQUE_SCROLLBARS) == OPAQUE_SCROLLBARS;
    }

    /**
     * @return A handler associated with the thread running the View. This
     * handler can be used to pump events in the UI events queue.
     */
    public Handler getHandler() {
        if (mAttachInfo != null) {
            return mAttachInfo.mHandler;
        }
        return null;
    }

    /**
     * Causes the Runnable to be added to the message queue.
     * The runnable will be run on the user interface thread.
     *
     * @param action The Runnable that will be executed.
     *
     * @return Returns true if the Runnable was successfully placed in to the
     *         message queue.  Returns false on failure, usually because the
     *         looper processing the message queue is exiting.
     */
    public boolean post(Runnable action) {
        Handler handler;
        if (mAttachInfo != null) {
            handler = mAttachInfo.mHandler;
        } else {
            // Assume that post will succeed later
            ViewRoot.getRunQueue().post(action);
            return true;
        }

        return handler.post(action);
    }

    /**
     * Causes the Runnable to be added to the message queue, to be run
     * after the specified amount of time elapses.
     * The runnable will be run on the user interface thread.
     *
     * @param action The Runnable that will be executed.
     * @param delayMillis The delay (in milliseconds) until the Runnable
     *        will be executed.
     *
     * @return true if the Runnable was successfully placed in to the
     *         message queue.  Returns false on failure, usually because the
     *         looper processing the message queue is exiting.  Note that a
     *         result of true does not mean the Runnable will be processed --
     *         if the looper is quit before the delivery time of the message
     *         occurs then the message will be dropped.
     */
    public boolean postDelayed(Runnable action, long delayMillis) {
        Handler handler;
        if (mAttachInfo != null) {
            handler = mAttachInfo.mHandler;
        } else {
            // Assume that post will succeed later
            ViewRoot.getRunQueue().postDelayed(action, delayMillis);
            return true;
        }

        return handler.postDelayed(action, delayMillis);
    }

    /**
     * Removes the specified Runnable from the message queue.
     *
     * @param action The Runnable to remove from the message handling queue
     *
     * @return true if this view could ask the Handler to remove the Runnable,
     *         false otherwise. When the returned value is true, the Runnable
     *         may or may not have been actually removed from the message queue
     *         (for instance, if the Runnable was not in the queue already.)
     */
    public boolean removeCallbacks(Runnable action) {
        Handler handler;
        if (mAttachInfo != null) {
            handler = mAttachInfo.mHandler;
        } else {
            // Assume that post will succeed later
            ViewRoot.getRunQueue().removeCallbacks(action);
            return true;
        }

        handler.removeCallbacks(action);
        return true;
    }

    /**
     * Cause an invalidate to happen on a subsequent cycle through the event loop.
     * Use this to invalidate the View from a non-UI thread.
     *
     * @see #invalidate()
     */
    public void postInvalidate() {
        postInvalidateDelayed(0);
    }

    /**
     * Cause an invalidate of the specified area to happen on a subsequent cycle
     * through the event loop. Use this to invalidate the View from a non-UI thread.
     *
     * @param left The left coordinate of the rectangle to invalidate.
     * @param top The top coordinate of the rectangle to invalidate.
     * @param right The right coordinate of the rectangle to invalidate.
     * @param bottom The bottom coordinate of the rectangle to invalidate.
     *
     * @see #invalidate(int, int, int, int)
     * @see #invalidate(Rect)
     */
    public void postInvalidate(int left, int top, int right, int bottom) {
        postInvalidateDelayed(0, left, top, right, bottom);
    }

    /**
     * Cause an invalidate to happen on a subsequent cycle through the event
     * loop. Waits for the specified amount of time.
     *
     * @param delayMilliseconds the duration in milliseconds to delay the
     *         invalidation by
     */
    public void postInvalidateDelayed(long delayMilliseconds) {
        // We try only with the AttachInfo because there's no point in invalidating
        // if we are not attached to our window
        if (mAttachInfo != null) {
            Message msg = Message.obtain();
            msg.what = AttachInfo.INVALIDATE_MSG;
            msg.obj = this;
            mAttachInfo.mHandler.sendMessageDelayed(msg, delayMilliseconds);
        }
    }

    /**
     * Cause an invalidate of the specified area to happen on a subsequent cycle
     * through the event loop. Waits for the specified amount of time.
     *
     * @param delayMilliseconds the duration in milliseconds to delay the
     *         invalidation by
     * @param left The left coordinate of the rectangle to invalidate.
     * @param top The top coordinate of the rectangle to invalidate.
     * @param right The right coordinate of the rectangle to invalidate.
     * @param bottom The bottom coordinate of the rectangle to invalidate.
     */
    public void postInvalidateDelayed(long delayMilliseconds, int left, int top,
            int right, int bottom) {

        // We try only with the AttachInfo because there's no point in invalidating
        // if we are not attached to our window
        if (mAttachInfo != null) {
            final AttachInfo.InvalidateInfo info = AttachInfo.InvalidateInfo.acquire();
            info.target = this;
            info.left = left;
            info.top = top;
            info.right = right;
            info.bottom = bottom;

            final Message msg = Message.obtain();
            msg.what = AttachInfo.INVALIDATE_RECT_MSG;
            msg.obj = info;
            mAttachInfo.mHandler.sendMessageDelayed(msg, delayMilliseconds);
        }
    }

    /**
     * Called by a parent to request that a child update its values for mScrollX
     * and mScrollY if necessary. This will typically be done if the child is
     * animating a scroll using a {@link android.widget.Scroller Scroller}
     * object.
     */
    public void computeScroll() {
    }

    /**
     * <p>Indicate whether the horizontal edges are faded when the view is
     * scrolled horizontally.</p>
     *
     * @return true if the horizontal edges should are faded on scroll, false
     *         otherwise
     *
     * @see #setHorizontalFadingEdgeEnabled(boolean)
     * @attr ref android.R.styleable#View_fadingEdge
     */
    public boolean isHorizontalFadingEdgeEnabled() {
        return (mViewFlags & FADING_EDGE_HORIZONTAL) == FADING_EDGE_HORIZONTAL;
    }

    /**
     * <p>Define whether the horizontal edges should be faded when this view
     * is scrolled horizontally.</p>
     *
     * @param horizontalFadingEdgeEnabled true if the horizontal edges should
     *                                    be faded when the view is scrolled
     *                                    horizontally
     *
     * @see #isHorizontalFadingEdgeEnabled()
     * @attr ref android.R.styleable#View_fadingEdge
     */
    public void setHorizontalFadingEdgeEnabled(boolean horizontalFadingEdgeEnabled) {
        if (isHorizontalFadingEdgeEnabled() != horizontalFadingEdgeEnabled) {
            if (horizontalFadingEdgeEnabled) {
                initScrollCache();
            }

            mViewFlags ^= FADING_EDGE_HORIZONTAL;
        }
    }

    /**
     * <p>Indicate whether the vertical edges are faded when the view is
     * scrolled horizontally.</p>
     *
     * @return true if the vertical edges should are faded on scroll, false
     *         otherwise
     *
     * @see #setVerticalFadingEdgeEnabled(boolean)
     * @attr ref android.R.styleable#View_fadingEdge
     */
    public boolean isVerticalFadingEdgeEnabled() {
        return (mViewFlags & FADING_EDGE_VERTICAL) == FADING_EDGE_VERTICAL;
    }

    /**
     * <p>Define whether the vertical edges should be faded when this view
     * is scrolled vertically.</p>
     *
     * @param verticalFadingEdgeEnabled true if the vertical edges should
     *                                  be faded when the view is scrolled
     *                                  vertically
     *
     * @see #isVerticalFadingEdgeEnabled()
     * @attr ref android.R.styleable#View_fadingEdge
     */
    public void setVerticalFadingEdgeEnabled(boolean verticalFadingEdgeEnabled) {
        if (isVerticalFadingEdgeEnabled() != verticalFadingEdgeEnabled) {
            if (verticalFadingEdgeEnabled) {
                initScrollCache();
            }

            mViewFlags ^= FADING_EDGE_VERTICAL;
        }
    }

    /**
     * Returns the strength, or intensity, of the top faded edge. The strength is
     * a value between 0.0 (no fade) and 1.0 (full fade). The default implementation
     * returns 0.0 or 1.0 but no value in between.
     *
     * Subclasses should override this method to provide a smoother fade transition
     * when scrolling occurs.
     *
     * @return the intensity of the top fade as a float between 0.0f and 1.0f
     */
    protected float getTopFadingEdgeStrength() {
        return computeVerticalScrollOffset() > 0 ? 1.0f : 0.0f;
    }

    /**
     * Returns the strength, or intensity, of the bottom faded edge. The strength is
     * a value between 0.0 (no fade) and 1.0 (full fade). The default implementation
     * returns 0.0 or 1.0 but no value in between.
     *
     * Subclasses should override this method to provide a smoother fade transition
     * when scrolling occurs.
     *
     * @return the intensity of the bottom fade as a float between 0.0f and 1.0f
     */
    protected float getBottomFadingEdgeStrength() {
        return computeVerticalScrollOffset() + computeVerticalScrollExtent() <
                computeVerticalScrollRange() ? 1.0f : 0.0f;
    }

    /**
     * Returns the strength, or intensity, of the left faded edge. The strength is
     * a value between 0.0 (no fade) and 1.0 (full fade). The default implementation
     * returns 0.0 or 1.0 but no value in between.
     *
     * Subclasses should override this method to provide a smoother fade transition
     * when scrolling occurs.
     *
     * @return the intensity of the left fade as a float between 0.0f and 1.0f
     */
    protected float getLeftFadingEdgeStrength() {
        return computeHorizontalScrollOffset() > 0 ? 1.0f : 0.0f;
    }

    /**
     * Returns the strength, or intensity, of the right faded edge. The strength is
     * a value between 0.0 (no fade) and 1.0 (full fade). The default implementation
     * returns 0.0 or 1.0 but no value in between.
     *
     * Subclasses should override this method to provide a smoother fade transition
     * when scrolling occurs.
     *
     * @return the intensity of the right fade as a float between 0.0f and 1.0f
     */
    protected float getRightFadingEdgeStrength() {
        return computeHorizontalScrollOffset() + computeHorizontalScrollExtent() <
                computeHorizontalScrollRange() ? 1.0f : 0.0f;
    }

    /**
     * <p>Indicate whether the horizontal scrollbar should be drawn or not. The
     * scrollbar is not drawn by default.</p>
     *
     * @return true if the horizontal scrollbar should be painted, false
     *         otherwise
     *
     * @see #setHorizontalScrollBarEnabled(boolean)
     */
    public boolean isHorizontalScrollBarEnabled() {
        return (mViewFlags & SCROLLBARS_HORIZONTAL) == SCROLLBARS_HORIZONTAL;
    }

    /**
     * <p>Define whether the horizontal scrollbar should be drawn or not. The
     * scrollbar is not drawn by default.</p>
     *
     * @param horizontalScrollBarEnabled true if the horizontal scrollbar should
     *                                   be painted
     *
     * @see #isHorizontalScrollBarEnabled()
     */
    public void setHorizontalScrollBarEnabled(boolean horizontalScrollBarEnabled) {
        if (isHorizontalScrollBarEnabled() != horizontalScrollBarEnabled) {
            mViewFlags ^= SCROLLBARS_HORIZONTAL;
            computeOpaqueFlags();
            recomputePadding();
        }
    }

    /**
     * <p>Indicate whether the vertical scrollbar should be drawn or not. The
     * scrollbar is not drawn by default.</p>
     *
     * @return true if the vertical scrollbar should be painted, false
     *         otherwise
     *
     * @see #setVerticalScrollBarEnabled(boolean)
     */
    public boolean isVerticalScrollBarEnabled() {
        return (mViewFlags & SCROLLBARS_VERTICAL) == SCROLLBARS_VERTICAL;
    }

    /**
     * <p>Define whether the vertical scrollbar should be drawn or not. The
     * scrollbar is not drawn by default.</p>
     *
     * @param verticalScrollBarEnabled true if the vertical scrollbar should
     *                                 be painted
     *
     * @see #isVerticalScrollBarEnabled()
     */
    public void setVerticalScrollBarEnabled(boolean verticalScrollBarEnabled) {
        if (isVerticalScrollBarEnabled() != verticalScrollBarEnabled) {
            mViewFlags ^= SCROLLBARS_VERTICAL;
            computeOpaqueFlags();
            recomputePadding();
        }
    }

    /**
     * @hide
     */
    protected void recomputePadding() {
        setPadding(mUserPaddingLeft, mPaddingTop, mUserPaddingRight, mUserPaddingBottom);
    }

    /**
     * Define whether scrollbars will fade when the view is not scrolling.
     *
     * @param fadeScrollbars wheter to enable fading
     *
     */
    public void setScrollbarFadingEnabled(boolean fadeScrollbars) {
        initScrollCache();
        final ScrollabilityCache scrollabilityCache = mScrollCache;
        scrollabilityCache.fadeScrollBars = fadeScrollbars;
        if (fadeScrollbars) {
            scrollabilityCache.state = ScrollabilityCache.OFF;
        } else {
            scrollabilityCache.state = ScrollabilityCache.ON;
        }
    }

    /**
     *
     * Returns true if scrollbars will fade when this view is not scrolling
     *
     * @return true if scrollbar fading is enabled
     */
    public boolean isScrollbarFadingEnabled() {
        return mScrollCache != null && mScrollCache.fadeScrollBars;
    }

    /**
     * <p>Specify the style of the scrollbars. The scrollbars can be overlaid or
     * inset. When inset, they add to the padding of the view. And the scrollbars
     * can be drawn inside the padding area or on the edge of the view. For example,
     * if a view has a background drawable and you want to draw the scrollbars
     * inside the padding specified by the drawable, you can use
     * SCROLLBARS_INSIDE_OVERLAY or SCROLLBARS_INSIDE_INSET. If you want them to
     * appear at the edge of the view, ignoring the padding, then you can use
     * SCROLLBARS_OUTSIDE_OVERLAY or SCROLLBARS_OUTSIDE_INSET.</p>
     * @param style the style of the scrollbars. Should be one of
     * SCROLLBARS_INSIDE_OVERLAY, SCROLLBARS_INSIDE_INSET,
     * SCROLLBARS_OUTSIDE_OVERLAY or SCROLLBARS_OUTSIDE_INSET.
     * @see #SCROLLBARS_INSIDE_OVERLAY
     * @see #SCROLLBARS_INSIDE_INSET
     * @see #SCROLLBARS_OUTSIDE_OVERLAY
     * @see #SCROLLBARS_OUTSIDE_INSET
     */
    public void setScrollBarStyle(int style) {
        if (style != (mViewFlags & SCROLLBARS_STYLE_MASK)) {
            mViewFlags = (mViewFlags & ~SCROLLBARS_STYLE_MASK) | (style & SCROLLBARS_STYLE_MASK);
            computeOpaqueFlags();
            recomputePadding();
        }
    }

    /**
     * <p>Returns the current scrollbar style.</p>
     * @return the current scrollbar style
     * @see #SCROLLBARS_INSIDE_OVERLAY
     * @see #SCROLLBARS_INSIDE_INSET
     * @see #SCROLLBARS_OUTSIDE_OVERLAY
     * @see #SCROLLBARS_OUTSIDE_INSET
     */
    public int getScrollBarStyle() {
        return mViewFlags & SCROLLBARS_STYLE_MASK;
    }

    /**
     * <p>Compute the horizontal range that the horizontal scrollbar
     * represents.</p>
     *
     * <p>The range is expressed in arbitrary units that must be the same as the
     * units used by {@link #computeHorizontalScrollExtent()} and
     * {@link #computeHorizontalScrollOffset()}.</p>
     *
     * <p>The default range is the drawing width of this view.</p>
     *
     * @return the total horizontal range represented by the horizontal
     *         scrollbar
     *
     * @see #computeHorizontalScrollExtent()
     * @see #computeHorizontalScrollOffset()
     * @see android.widget.ScrollBarDrawable
     */
    protected int computeHorizontalScrollRange() {
        return getWidth();
    }

    /**
     * <p>Compute the horizontal offset of the horizontal scrollbar's thumb
     * within the horizontal range. This value is used to compute the position
     * of the thumb within the scrollbar's track.</p>
     *
     * <p>The range is expressed in arbitrary units that must be the same as the
     * units used by {@link #computeHorizontalScrollRange()} and
     * {@link #computeHorizontalScrollExtent()}.</p>
     *
     * <p>The default offset is the scroll offset of this view.</p>
     *
     * @return the horizontal offset of the scrollbar's thumb
     *
     * @see #computeHorizontalScrollRange()
     * @see #computeHorizontalScrollExtent()
     * @see android.widget.ScrollBarDrawable
     */
    protected int computeHorizontalScrollOffset() {
        return mScrollX;
    }

    /**
     * <p>Compute the horizontal extent of the horizontal scrollbar's thumb
     * within the horizontal range. This value is used to compute the length
     * of the thumb within the scrollbar's track.</p>
     *
     * <p>The range is expressed in arbitrary units that must be the same as the
     * units used by {@link #computeHorizontalScrollRange()} and
     * {@link #computeHorizontalScrollOffset()}.</p>
     *
     * <p>The default extent is the drawing width of this view.</p>
     *
     * @return the horizontal extent of the scrollbar's thumb
     *
     * @see #computeHorizontalScrollRange()
     * @see #computeHorizontalScrollOffset()
     * @see android.widget.ScrollBarDrawable
     */
    protected int computeHorizontalScrollExtent() {
        return getWidth();
    }

    /**
     * <p>Compute the vertical range that the vertical scrollbar represents.</p>
     *
     * <p>The range is expressed in arbitrary units that must be the same as the
     * units used by {@link #computeVerticalScrollExtent()} and
     * {@link #computeVerticalScrollOffset()}.</p>
     *
     * @return the total vertical range represented by the vertical scrollbar
     *
     * <p>The default range is the drawing height of this view.</p>
     *
     * @see #computeVerticalScrollExtent()
     * @see #computeVerticalScrollOffset()
     * @see android.widget.ScrollBarDrawable
     */
    protected int computeVerticalScrollRange() {
        return getHeight();
    }

    /**
     * <p>Compute the vertical offset of the vertical scrollbar's thumb
     * within the horizontal range. This value is used to compute the position
     * of the thumb within the scrollbar's track.</p>
     *
     * <p>The range is expressed in arbitrary units that must be the same as the
     * units used by {@link #computeVerticalScrollRange()} and
     * {@link #computeVerticalScrollExtent()}.</p>
     *
     * <p>The default offset is the scroll offset of this view.</p>
     *
     * @return the vertical offset of the scrollbar's thumb
     *
     * @see #computeVerticalScrollRange()
     * @see #computeVerticalScrollExtent()
     * @see android.widget.ScrollBarDrawable
     */
    protected int computeVerticalScrollOffset() {
        return mScrollY;
    }

    /**
     * <p>Compute the vertical extent of the horizontal scrollbar's thumb
     * within the vertical range. This value is used to compute the length
     * of the thumb within the scrollbar's track.</p>
     *
     * <p>The range is expressed in arbitrary units that must be the same as the
     * units used by {@link #computeVerticalScrollRange()} and
     * {@link #computeVerticalScrollOffset()}.</p>
     *
     * <p>The default extent is the drawing height of this view.</p>
     *
     * @return the vertical extent of the scrollbar's thumb
     *
     * @see #computeVerticalScrollRange()
     * @see #computeVerticalScrollOffset()
     * @see android.widget.ScrollBarDrawable
     */
    protected int computeVerticalScrollExtent() {
        return getHeight();
    }

    /**
     * <p>Request the drawing of the horizontal and the vertical scrollbar. The
     * scrollbars are painted only if they have been awakened first.</p>
     *
     * @param canvas the canvas on which to draw the scrollbars
     *
     * @see #awakenScrollBars(int)
     */
    protected final void onDrawScrollBars(Canvas canvas) {
        // scrollbars are drawn only when the animation is running
        final ScrollabilityCache cache = mScrollCache;
        if (cache != null) {

            int state = cache.state;

            if (state == ScrollabilityCache.OFF) {
                return;
            }

            boolean invalidate = false;

            if (state == ScrollabilityCache.FADING) {
                // We're fading -- get our fade interpolation
                if (cache.interpolatorValues == null) {
                    cache.interpolatorValues = new float[1];
                }

                float[] values = cache.interpolatorValues;

                // Stops the animation if we're done
                if (cache.scrollBarInterpolator.timeToValues(values) ==
                        Interpolator.Result.FREEZE_END) {
                    cache.state = ScrollabilityCache.OFF;
                } else {
                    cache.scrollBar.setAlpha(Math.round(values[0]));
                }

                // This will make the scroll bars inval themselves after
                // drawing. We only want this when we're fading so that
                // we prevent excessive redraws
                invalidate = true;
            } else {
                // We're just on -- but we may have been fading before so
                // reset alpha
                cache.scrollBar.setAlpha(255);
            }


            final int viewFlags = mViewFlags;

            final boolean drawHorizontalScrollBar =
                (viewFlags & SCROLLBARS_HORIZONTAL) == SCROLLBARS_HORIZONTAL;
            final boolean drawVerticalScrollBar =
                (viewFlags & SCROLLBARS_VERTICAL) == SCROLLBARS_VERTICAL
                && !isVerticalScrollBarHidden();

            if (drawVerticalScrollBar || drawHorizontalScrollBar) {
                final int width = mRight - mLeft;
                final int height = mBottom - mTop;

                final ScrollBarDrawable scrollBar = cache.scrollBar;
                int size = scrollBar.getSize(false);
                if (size <= 0) {
                    size = cache.scrollBarSize;
                }

                final int scrollX = mScrollX;
                final int scrollY = mScrollY;
                final int inside = (viewFlags & SCROLLBARS_OUTSIDE_MASK) == 0 ? ~0 : 0;

                int left, top, right, bottom;

                if (drawHorizontalScrollBar) {
                    scrollBar.setParameters(computeHorizontalScrollRange(),
                                            computeHorizontalScrollOffset(),
                                            computeHorizontalScrollExtent(), false);
                    final int verticalScrollBarGap = drawVerticalScrollBar ?
                            getVerticalScrollbarWidth() : 0;
                    top = scrollY + height - size - (mUserPaddingBottom & inside);
                    left = scrollX + (mPaddingLeft & inside);
                    right = scrollX + width - (mUserPaddingRight & inside) - verticalScrollBarGap;
                    bottom = top + size;
                    onDrawHorizontalScrollBar(canvas, scrollBar, left, top, right, bottom);
                    if (invalidate) {
                        invalidate(left, top, right, bottom);
                    }
                }

                if (drawVerticalScrollBar) {
                    scrollBar.setParameters(computeVerticalScrollRange(),
                                            computeVerticalScrollOffset(),
                                            computeVerticalScrollExtent(), true);
                    switch (mVerticalScrollbarPosition) {
                        default:
                        case SCROLLBAR_POSITION_DEFAULT:
                        case SCROLLBAR_POSITION_RIGHT:
                            left = scrollX + width - size - (mUserPaddingRight & inside);
                            break;
                        case SCROLLBAR_POSITION_LEFT:
                            left = scrollX + (mUserPaddingLeft & inside);
                            break;
                    }
                    top = scrollY + (mPaddingTop & inside);
                    right = left + size;
                    bottom = scrollY + height - (mUserPaddingBottom & inside);
                    onDrawVerticalScrollBar(canvas, scrollBar, left, top, right, bottom);
                    if (invalidate) {
                        invalidate(left, top, right, bottom);
                    }
                }
            }
        }
    }

    /**
     * Override this if the vertical scrollbar needs to be hidden in a subclass, like when
     * FastScroller is visible.
     * @return whether to temporarily hide the vertical scrollbar
     * @hide
     */
    protected boolean isVerticalScrollBarHidden() {
        return false;
    }

    /**
     * <p>Draw the horizontal scrollbar if
     * {@link #isHorizontalScrollBarEnabled()} returns true.</p>
     *
     * @param canvas the canvas on which to draw the scrollbar
     * @param scrollBar the scrollbar's drawable
     *
     * @see #isHorizontalScrollBarEnabled()
     * @see #computeHorizontalScrollRange()
     * @see #computeHorizontalScrollExtent()
     * @see #computeHorizontalScrollOffset()
     * @see android.widget.ScrollBarDrawable
     * @hide
     */
    protected void onDrawHorizontalScrollBar(Canvas canvas, Drawable scrollBar,
            int l, int t, int r, int b) {
        scrollBar.setBounds(l, t, r, b);
        scrollBar.draw(canvas);
    }

    /**
     * <p>Draw the vertical scrollbar if {@link #isVerticalScrollBarEnabled()}
     * returns true.</p>
     *
     * @param canvas the canvas on which to draw the scrollbar
     * @param scrollBar the scrollbar's drawable
     *
     * @see #isVerticalScrollBarEnabled()
     * @see #computeVerticalScrollRange()
     * @see #computeVerticalScrollExtent()
     * @see #computeVerticalScrollOffset()
     * @see android.widget.ScrollBarDrawable
     * @hide
     */
    protected void onDrawVerticalScrollBar(Canvas canvas, Drawable scrollBar,
            int l, int t, int r, int b) {
        scrollBar.setBounds(l, t, r, b);
        scrollBar.draw(canvas);
    }

    /**
     * Implement this to do your drawing.
     *
     * @param canvas the canvas on which the background will be drawn
     */
    protected void onDraw(Canvas canvas) {
    }

    /*
     * Caller is responsible for calling requestLayout if necessary.
     * (This allows addViewInLayout to not request a new layout.)
     */
    void assignParent(ViewParent parent) {
        if (mParent == null) {
            mParent = parent;
        } else if (parent == null) {
            mParent = null;
        } else {
            throw new RuntimeException("view " + this + " being added, but"
                    + " it already has a parent");
        }
    }

    /**
     * This is called when the view is attached to a window.  At this point it
     * has a Surface and will start drawing.  Note that this function is
     * guaranteed to be called before {@link #onDraw}, however it may be called
     * any time before the first onDraw -- including before or after
     * {@link #onMeasure}.
     *
     * @see #onDetachedFromWindow()
     */
    protected void onAttachedToWindow() {
        if ((mPrivateFlags & REQUEST_TRANSPARENT_REGIONS) != 0) {
            mParent.requestTransparentRegion(this);
        }
        if ((mPrivateFlags & AWAKEN_SCROLL_BARS_ON_ATTACH) != 0) {
            initialAwakenScrollBars();
            mPrivateFlags &= ~AWAKEN_SCROLL_BARS_ON_ATTACH;
        }
        jumpDrawablesToCurrentState();
    }

    /**
     * This is called when the view is detached from a window.  At this point it
     * no longer has a surface for drawing.
     *
     * @see #onAttachedToWindow()
     */
    protected void onDetachedFromWindow() {
        mPrivateFlags &= ~CANCEL_NEXT_UP_EVENT;

        removeUnsetPressCallback();
        removeLongPressCallback();
        removePerformClickCallback();

        destroyDrawingCache();

        if (mHardwareLayer != null) {
            mHardwareLayer.destroy();
            mHardwareLayer = null;
        }

        if (mDisplayList != null) {
            mDisplayList.invalidate();
        }

        if (mAttachInfo != null) {
            mAttachInfo.mHandler.removeMessages(AttachInfo.INVALIDATE_MSG, this);
            mAttachInfo.mHandler.removeMessages(AttachInfo.INVALIDATE_RECT_MSG, this);
        }

        mCurrentAnimation = null;
    }

    /**
     * @return The number of times this view has been attached to a window
     */
    protected int getWindowAttachCount() {
        return mWindowAttachCount;
    }

    /**
     * Retrieve a unique token identifying the window this view is attached to.
     * @return Return the window's token for use in
     * {@link WindowManager.LayoutParams#token WindowManager.LayoutParams.token}.
     */
    public IBinder getWindowToken() {
        return mAttachInfo != null ? mAttachInfo.mWindowToken : null;
    }

    /**
     * Retrieve a unique token identifying the top-level "real" window of
     * the window that this view is attached to.  That is, this is like
     * {@link #getWindowToken}, except if the window this view in is a panel
     * window (attached to another containing window), then the token of
     * the containing window is returned instead.
     *
     * @return Returns the associated window token, either
     * {@link #getWindowToken()} or the containing window's token.
     */
    public IBinder getApplicationWindowToken() {
        AttachInfo ai = mAttachInfo;
        if (ai != null) {
            IBinder appWindowToken = ai.mPanelParentWindowToken;
            if (appWindowToken == null) {
                appWindowToken = ai.mWindowToken;
            }
            return appWindowToken;
        }
        return null;
    }

    /**
     * Retrieve private session object this view hierarchy is using to
     * communicate with the window manager.
     * @return the session object to communicate with the window manager
     */
    /*package*/ IWindowSession getWindowSession() {
        return mAttachInfo != null ? mAttachInfo.mSession : null;
    }

    /**
     * @param info the {@link android.view.View.AttachInfo} to associated with
     *        this view
     */
    void dispatchAttachedToWindow(AttachInfo info, int visibility) {
        //System.out.println("Attached! " + this);
        mAttachInfo = info;
        mWindowAttachCount++;
        // We will need to evaluate the drawable state at least once.
        mPrivateFlags |= DRAWABLE_STATE_DIRTY;
        if (mFloatingTreeObserver != null) {
            info.mTreeObserver.merge(mFloatingTreeObserver);
            mFloatingTreeObserver = null;
        }
        if ((mPrivateFlags&SCROLL_CONTAINER) != 0) {
            mAttachInfo.mScrollContainers.add(this);
            mPrivateFlags |= SCROLL_CONTAINER_ADDED;
        }
        performCollectViewAttributes(visibility);
        onAttachedToWindow();
        int vis = info.mWindowVisibility;
        if (vis != GONE) {
            onWindowVisibilityChanged(vis);
        }
        if ((mPrivateFlags&DRAWABLE_STATE_DIRTY) != 0) {
            // If nobody has evaluated the drawable state yet, then do it now.
            refreshDrawableState();
        }
    }

    void dispatchDetachedFromWindow() {
        //System.out.println("Detached! " + this);
        AttachInfo info = mAttachInfo;
        if (info != null) {
            int vis = info.mWindowVisibility;
            if (vis != GONE) {
                onWindowVisibilityChanged(GONE);
            }
        }

        onDetachedFromWindow();
        if ((mPrivateFlags&SCROLL_CONTAINER_ADDED) != 0) {
            mAttachInfo.mScrollContainers.remove(this);
            mPrivateFlags &= ~SCROLL_CONTAINER_ADDED;
        }
        mAttachInfo = null;
    }

    /**
     * Store this view hierarchy's frozen state into the given container.
     *
     * @param container The SparseArray in which to save the view's state.
     *
     * @see #restoreHierarchyState
     * @see #dispatchSaveInstanceState
     * @see #onSaveInstanceState
     */
    public void saveHierarchyState(SparseArray<Parcelable> container) {
        dispatchSaveInstanceState(container);
    }

    /**
     * Called by {@link #saveHierarchyState} to store the state for this view and its children.
     * May be overridden to modify how freezing happens to a view's children; for example, some
     * views may want to not store state for their children.
     *
     * @param container The SparseArray in which to save the view's state.
     *
     * @see #dispatchRestoreInstanceState
     * @see #saveHierarchyState
     * @see #onSaveInstanceState
     */
    protected void dispatchSaveInstanceState(SparseArray<Parcelable> container) {
        if (mID != NO_ID && (mViewFlags & SAVE_DISABLED_MASK) == 0) {
            mPrivateFlags &= ~SAVE_STATE_CALLED;
            Parcelable state = onSaveInstanceState();
            if ((mPrivateFlags & SAVE_STATE_CALLED) == 0) {
                throw new IllegalStateException(
                        "Derived class did not call super.onSaveInstanceState()");
            }
            if (state != null) {
                // Log.i("View", "Freezing #" + Integer.toHexString(mID)
                // + ": " + state);
                container.put(mID, state);
            }
        }
    }

    /**
     * Hook allowing a view to generate a representation of its internal state
     * that can later be used to create a new instance with that same state.
     * This state should only contain information that is not persistent or can
     * not be reconstructed later. For example, you will never store your
     * current position on screen because that will be computed again when a
     * new instance of the view is placed in its view hierarchy.
     * <p>
     * Some examples of things you may store here: the current cursor position
     * in a text view (but usually not the text itself since that is stored in a
     * content provider or other persistent storage), the currently selected
     * item in a list view.
     *
     * @return Returns a Parcelable object containing the view's current dynamic
     *         state, or null if there is nothing interesting to save. The
     *         default implementation returns null.
     * @see #onRestoreInstanceState
     * @see #saveHierarchyState
     * @see #dispatchSaveInstanceState
     * @see #setSaveEnabled(boolean)
     */
    protected Parcelable onSaveInstanceState() {
        mPrivateFlags |= SAVE_STATE_CALLED;
        return BaseSavedState.EMPTY_STATE;
    }

    /**
     * Restore this view hierarchy's frozen state from the given container.
     *
     * @param container The SparseArray which holds previously frozen states.
     *
     * @see #saveHierarchyState
     * @see #dispatchRestoreInstanceState
     * @see #onRestoreInstanceState
     */
    public void restoreHierarchyState(SparseArray<Parcelable> container) {
        dispatchRestoreInstanceState(container);
    }

    /**
     * Called by {@link #restoreHierarchyState} to retrieve the state for this view and its
     * children. May be overridden to modify how restoreing happens to a view's children; for
     * example, some views may want to not store state for their children.
     *
     * @param container The SparseArray which holds previously saved state.
     *
     * @see #dispatchSaveInstanceState
     * @see #restoreHierarchyState
     * @see #onRestoreInstanceState
     */
    protected void dispatchRestoreInstanceState(SparseArray<Parcelable> container) {
        if (mID != NO_ID) {
            Parcelable state = container.get(mID);
            if (state != null) {
                // Log.i("View", "Restoreing #" + Integer.toHexString(mID)
                // + ": " + state);
                mPrivateFlags &= ~SAVE_STATE_CALLED;
                onRestoreInstanceState(state);
                if ((mPrivateFlags & SAVE_STATE_CALLED) == 0) {
                    throw new IllegalStateException(
                            "Derived class did not call super.onRestoreInstanceState()");
                }
            }
        }
    }

    /**
     * Hook allowing a view to re-apply a representation of its internal state that had previously
     * been generated by {@link #onSaveInstanceState}. This function will never be called with a
     * null state.
     *
     * @param state The frozen state that had previously been returned by
     *        {@link #onSaveInstanceState}.
     *
     * @see #onSaveInstanceState
     * @see #restoreHierarchyState
     * @see #dispatchRestoreInstanceState
     */
    protected void onRestoreInstanceState(Parcelable state) {
        mPrivateFlags |= SAVE_STATE_CALLED;
        if (state != BaseSavedState.EMPTY_STATE && state != null) {
            throw new IllegalArgumentException("Wrong state class, expecting View State but "
                    + "received " + state.getClass().toString() + " instead. This usually happens "
                    + "when two views of different type have the same id in the same hierarchy. "
                    + "This view's id is " + ViewDebug.resolveId(mContext, getId()) + ". Make sure "
                    + "other views do not use the same id.");
        }
    }

    /**
     * <p>Return the time at which the drawing of the view hierarchy started.</p>
     *
     * @return the drawing start time in milliseconds
     */
    public long getDrawingTime() {
        return mAttachInfo != null ? mAttachInfo.mDrawingTime : 0;
    }

    /**
     * <p>Enables or disables the duplication of the parent's state into this view. When
     * duplication is enabled, this view gets its drawable state from its parent rather
     * than from its own internal properties.</p>
     *
     * <p>Note: in the current implementation, setting this property to true after the
     * view was added to a ViewGroup might have no effect at all. This property should
     * always be used from XML or set to true before adding this view to a ViewGroup.</p>
     *
     * <p>Note: if this view's parent addStateFromChildren property is enabled and this
     * property is enabled, an exception will be thrown.</p>
     *
     * <p>Note: if the child view uses and updates additionnal states which are unknown to the
     * parent, these states should not be affected by this method.</p>
     *
     * @param enabled True to enable duplication of the parent's drawable state, false
     *                to disable it.
     *
     * @see #getDrawableState()
     * @see #isDuplicateParentStateEnabled()
     */
    public void setDuplicateParentStateEnabled(boolean enabled) {
        setFlags(enabled ? DUPLICATE_PARENT_STATE : 0, DUPLICATE_PARENT_STATE);
    }

    /**
     * <p>Indicates whether this duplicates its drawable state from its parent.</p>
     *
     * @return True if this view's drawable state is duplicated from the parent,
     *         false otherwise
     *
     * @see #getDrawableState()
     * @see #setDuplicateParentStateEnabled(boolean)
     */
    public boolean isDuplicateParentStateEnabled() {
        return (mViewFlags & DUPLICATE_PARENT_STATE) == DUPLICATE_PARENT_STATE;
    }

    /**
     * <p>Specifies the type of layer backing this view. The layer can be
     * {@link #LAYER_TYPE_NONE disabled}, {@link #LAYER_TYPE_SOFTWARE software} or
     * {@link #LAYER_TYPE_HARDWARE hardware}.</p>
     *
     * <p>A layer is associated with an optional {@link android.graphics.Paint}
     * instance that controls how the layer is composed on screen. The following
     * properties of the paint are taken into account when composing the layer:</p>
     * <ul>
     * <li>{@link android.graphics.Paint#getAlpha() Translucency (alpha)}</li>
     * <li>{@link android.graphics.Paint#getXfermode() Blending mode}</li>
     * <li>{@link android.graphics.Paint#getColorFilter() Color filter}</li>
     * </ul>
     *
     * <p>If this view has an alpha value set to < 1.0 by calling
     * {@link #setAlpha(float)}, the alpha value of the layer's paint is replaced by
     * this view's alpha value. Calling {@link #setAlpha(float)} is therefore
     * equivalent to setting a hardware layer on this view and providing a paint with
     * the desired alpha value.<p>
     *
     * <p>Refer to the documentation of {@link #LAYER_TYPE_NONE disabled},
     * {@link #LAYER_TYPE_SOFTWARE software} and {@link #LAYER_TYPE_HARDWARE hardware}
     * for more information on when and how to use layers.</p>
     *
     * @param layerType The ype of layer to use with this view, must be one of
     *        {@link #LAYER_TYPE_NONE}, {@link #LAYER_TYPE_SOFTWARE} or
     *        {@link #LAYER_TYPE_HARDWARE}
     * @param paint The paint used to compose the layer. This argument is optional
     *        and can be null. It is ignored when the layer type is
     *        {@link #LAYER_TYPE_NONE}
     *
     * @see #getLayerType()
     * @see #LAYER_TYPE_NONE
     * @see #LAYER_TYPE_SOFTWARE
     * @see #LAYER_TYPE_HARDWARE
     * @see #setAlpha(float)
     *
     * @attr ref android.R.styleable#View_layerType
     */
    public void setLayerType(int layerType, Paint paint) {
        if (layerType < LAYER_TYPE_NONE || layerType > LAYER_TYPE_HARDWARE) {
            throw new IllegalArgumentException("Layer type can only be one of: LAYER_TYPE_NONE, "
                    + "LAYER_TYPE_SOFTWARE or LAYER_TYPE_HARDWARE");
        }

        if (layerType == mLayerType) {
            if (layerType != LAYER_TYPE_NONE && paint != mLayerPaint) {
                mLayerPaint = paint == null ? new Paint() : paint;
                invalidateParentCaches();
                invalidate(true);
            }
            return;
        }

        // Destroy any previous software drawing cache if needed
        switch (mLayerType) {
            case LAYER_TYPE_SOFTWARE:
                if (mDrawingCache != null) {
                    mDrawingCache.recycle();
                    mDrawingCache = null;
                }

                if (mUnscaledDrawingCache != null) {
                    mUnscaledDrawingCache.recycle();
                    mUnscaledDrawingCache = null;
                }
                break;
            case LAYER_TYPE_HARDWARE:
                if (mHardwareLayer != null) {
                    mHardwareLayer.destroy();
                    mHardwareLayer = null;
                }
                break;
            default:
                break;
        }

        mLayerType = layerType;
        mLayerPaint = mLayerType == LAYER_TYPE_NONE ? null : (paint == null ? new Paint() : paint);

        invalidateParentCaches();
        invalidate(true);
    }

    /**
     * Indicates what type of layer is currently associated with this view. By default
     * a view does not have a layer, and the layer type is {@link #LAYER_TYPE_NONE}.
     * Refer to the documentation of {@link #setLayerType(int, android.graphics.Paint)}
     * for more information on the different types of layers.
     *
     * @return {@link #LAYER_TYPE_NONE}, {@link #LAYER_TYPE_SOFTWARE} or
     *         {@link #LAYER_TYPE_HARDWARE}
     *
     * @see #setLayerType(int, android.graphics.Paint)
     * @see #LAYER_TYPE_NONE
     * @see #LAYER_TYPE_SOFTWARE
     * @see #LAYER_TYPE_HARDWARE
     */
    public int getLayerType() {
        return mLayerType;
    }

    /**
     * <p>Returns a hardware layer that can be used to draw this view again
     * without executing its draw method.</p>
     *
     * @return A HardwareLayer ready to render, or null if an error occurred.
     */
    HardwareLayer getHardwareLayer() {
        if (mAttachInfo == null || mAttachInfo.mHardwareRenderer == null) {
            return null;
        }

        final int width = mRight - mLeft;
        final int height = mBottom - mTop;

        if (width == 0 || height == 0) {
            return null;
        }

        if ((mPrivateFlags & DRAWING_CACHE_VALID) == 0 || mHardwareLayer == null) {
            if (mHardwareLayer == null) {
                mHardwareLayer = mAttachInfo.mHardwareRenderer.createHardwareLayer(
                        width, height, isOpaque());
            } else if (mHardwareLayer.getWidth() != width || mHardwareLayer.getHeight() != height) {
                mHardwareLayer.resize(width, height);
            }

            Canvas currentCanvas = mAttachInfo.mHardwareCanvas;
            final HardwareCanvas canvas = mHardwareLayer.start(currentCanvas);
            mAttachInfo.mHardwareCanvas = canvas;
            try {
                canvas.setViewport(width, height);
                // TODO: We should pass the dirty rect
                canvas.onPreDraw(null);

                computeScroll();
                canvas.translate(-mScrollX, -mScrollY);

                final int restoreCount = canvas.save();

                mPrivateFlags |= DRAWN | DRAWING_CACHE_VALID;

                // Fast path for layouts with no backgrounds
                if ((mPrivateFlags & SKIP_DRAW) == SKIP_DRAW) {
                    mPrivateFlags &= ~DIRTY_MASK;
                    dispatchDraw(canvas);
                } else {
                    draw(canvas);
                }

                canvas.restoreToCount(restoreCount);
            } finally {
                canvas.onPostDraw();
                mHardwareLayer.end(currentCanvas);
                mAttachInfo.mHardwareCanvas = currentCanvas;
            }
        }

        return mHardwareLayer;
    }

    /**
     * <p>Enables or disables the drawing cache. When the drawing cache is enabled, the next call
     * to {@link #getDrawingCache()} or {@link #buildDrawingCache()} will draw the view in a
     * bitmap. Calling {@link #draw(android.graphics.Canvas)} will not draw from the cache when
     * the cache is enabled. To benefit from the cache, you must request the drawing cache by
     * calling {@link #getDrawingCache()} and draw it on screen if the returned bitmap is not
     * null.</p>
     *
     * <p>Enabling the drawing cache is similar to
     * {@link #setLayerType(int, android.graphics.Paint) setting a layer} when hardware
     * acceleration is turned off. When hardware acceleration is turned on, enabling the
     * drawing cache has no effect on rendering because the system uses a different mechanism
     * for acceleration which ignores the flag. If you want to use a Bitmap for the view, even
     * when hardware acceleration is enabled, see {@link #setLayerType(int, android.graphics.Paint)}
     * for information on how to enable software and hardware layers.</p>
     *
     * <p>This API can be used to manually generate
     * a bitmap copy of this view, by setting the flag to <code>true</code> and calling
     * {@link #getDrawingCache()}.</p>
     *
     * @param enabled true to enable the drawing cache, false otherwise
     *
     * @see #isDrawingCacheEnabled()
     * @see #getDrawingCache()
     * @see #buildDrawingCache()
     * @see #setLayerType(int, android.graphics.Paint)
     */
    public void setDrawingCacheEnabled(boolean enabled) {
        setFlags(enabled ? DRAWING_CACHE_ENABLED : 0, DRAWING_CACHE_ENABLED);
    }

    /**
     * <p>Indicates whether the drawing cache is enabled for this view.</p>
     *
     * @return true if the drawing cache is enabled
     *
     * @see #setDrawingCacheEnabled(boolean)
     * @see #getDrawingCache()
     */
    @ViewDebug.ExportedProperty(category = "drawing")
    public boolean isDrawingCacheEnabled() {
        return (mViewFlags & DRAWING_CACHE_ENABLED) == DRAWING_CACHE_ENABLED;
    }

    /**
     * Debugging utility which recursively outputs the dirty state of a view and its
     * descendants.
     *
     * @hide
     */
    public void outputDirtyFlags(String indent, boolean clear, int clearMask) {
        Log.d("View", indent + this + "             DIRTY(" + (mPrivateFlags & View.DIRTY_MASK) +
                ") DRAWN(" + (mPrivateFlags & DRAWN) + ")" + " CACHE_VALID(" +
                (mPrivateFlags & View.DRAWING_CACHE_VALID) +
                ") INVALIDATED(" + (mPrivateFlags & INVALIDATED) + ")");
        if (clear) {
            mPrivateFlags &= clearMask;
        }
        if (this instanceof ViewGroup) {
            ViewGroup parent = (ViewGroup) this;
            final int count = parent.getChildCount();
            for (int i = 0; i < count; i++) {
                final View child = parent.getChildAt(i);
                child.outputDirtyFlags(indent + "  ", clear, clearMask);
            }
        }
    }

    /**
     * This method is used by ViewGroup to cause its children to restore or recreate their
     * display lists. It is called by getDisplayList() when the parent ViewGroup does not need
     * to recreate its own display list, which would happen if it went through the normal
     * draw/dispatchDraw mechanisms.
     *
     * @hide
     */
    protected void dispatchGetDisplayList() {}

    /**
     * <p>Returns a display list that can be used to draw this view again
     * without executing its draw method.</p>
     *
     * @return A DisplayList ready to replay, or null if caching is not enabled.
     *
     * @hide
     */
    public DisplayList getDisplayList() {
        if (mAttachInfo == null || mAttachInfo.mHardwareRenderer == null) {
            return null;
        }

        if (((mPrivateFlags & DRAWING_CACHE_VALID) == 0 ||
                mDisplayList == null || !mDisplayList.isValid() ||
                mRecreateDisplayList)) {
            // Don't need to recreate the display list, just need to tell our
            // children to restore/recreate theirs
            if (mDisplayList != null && mDisplayList.isValid() &&
                    !mRecreateDisplayList) {
                mPrivateFlags |= DRAWN | DRAWING_CACHE_VALID;
                mPrivateFlags &= ~DIRTY_MASK;
                dispatchGetDisplayList();

                return mDisplayList;
            }

            // If we got here, we're recreating it. Mark it as such to ensure that
            // we copy in child display lists into ours in drawChild()
            mRecreateDisplayList = true;
            if (mDisplayList == null) {
                mDisplayList = mAttachInfo.mHardwareRenderer.createDisplayList(this);
                // If we're creating a new display list, make sure our parent gets invalidated
                // since they will need to recreate their display list to account for this
                // new child display list.
                invalidateParentCaches();
            }

            final HardwareCanvas canvas = mDisplayList.start();
            try {
                int width = mRight - mLeft;
                int height = mBottom - mTop;

                canvas.setViewport(width, height);
                // The dirty rect should always be null for a display list
                canvas.onPreDraw(null);

                final int restoreCount = canvas.save();

                computeScroll();
                canvas.translate(-mScrollX, -mScrollY);
                mPrivateFlags |= DRAWN | DRAWING_CACHE_VALID;

                // Fast path for layouts with no backgrounds
                if ((mPrivateFlags & SKIP_DRAW) == SKIP_DRAW) {
                    mPrivateFlags &= ~DIRTY_MASK;
                    dispatchDraw(canvas);
                } else {
                    draw(canvas);
                }

                canvas.restoreToCount(restoreCount);
            } finally {
                canvas.onPostDraw();

                mDisplayList.end();
            }
        } else {
            mPrivateFlags |= DRAWN | DRAWING_CACHE_VALID;
            mPrivateFlags &= ~DIRTY_MASK;
        }

        return mDisplayList;
    }

    /**
     * <p>Calling this method is equivalent to calling <code>getDrawingCache(false)</code>.</p>
     *
     * @return A non-scaled bitmap representing this view or null if cache is disabled.
     *
     * @see #getDrawingCache(boolean)
     */
    public Bitmap getDrawingCache() {
        return getDrawingCache(false);
    }

    /**
     * <p>Returns the bitmap in which this view drawing is cached. The returned bitmap
     * is null when caching is disabled. If caching is enabled and the cache is not ready,
     * this method will create it. Calling {@link #draw(android.graphics.Canvas)} will not
     * draw from the cache when the cache is enabled. To benefit from the cache, you must
     * request the drawing cache by calling this method and draw it on screen if the
     * returned bitmap is not null.</p>
     *
     * <p>Note about auto scaling in compatibility mode: When auto scaling is not enabled,
     * this method will create a bitmap of the same size as this view. Because this bitmap
     * will be drawn scaled by the parent ViewGroup, the result on screen might show
     * scaling artifacts. To avoid such artifacts, you should call this method by setting
     * the auto scaling to true. Doing so, however, will generate a bitmap of a different
     * size than the view. This implies that your application must be able to handle this
     * size.</p>
     *
     * @param autoScale Indicates whether the generated bitmap should be scaled based on
     *        the current density of the screen when the application is in compatibility
     *        mode.
     *
     * @return A bitmap representing this view or null if cache is disabled.
     *
     * @see #setDrawingCacheEnabled(boolean)
     * @see #isDrawingCacheEnabled()
     * @see #buildDrawingCache(boolean)
     * @see #destroyDrawingCache()
     */
    public Bitmap getDrawingCache(boolean autoScale) {
        if ((mViewFlags & WILL_NOT_CACHE_DRAWING) == WILL_NOT_CACHE_DRAWING) {
            return null;
        }
        if ((mViewFlags & DRAWING_CACHE_ENABLED) == DRAWING_CACHE_ENABLED) {
            buildDrawingCache(autoScale);
        }
        return autoScale ? mDrawingCache : mUnscaledDrawingCache;
    }

    /**
     * <p>Frees the resources used by the drawing cache. If you call
     * {@link #buildDrawingCache()} manually without calling
     * {@link #setDrawingCacheEnabled(boolean) setDrawingCacheEnabled(true)}, you
     * should cleanup the cache with this method afterwards.</p>
     *
     * @see #setDrawingCacheEnabled(boolean)
     * @see #buildDrawingCache()
     * @see #getDrawingCache()
     */
    public void destroyDrawingCache() {
        if (mDrawingCache != null) {
            mDrawingCache.recycle();
            mDrawingCache = null;
        }
        if (mUnscaledDrawingCache != null) {
            mUnscaledDrawingCache.recycle();
            mUnscaledDrawingCache = null;
        }
    }

    /**
     * Setting a solid background color for the drawing cache's bitmaps will improve
     * perfromance and memory usage. Note, though that this should only be used if this
     * view will always be drawn on top of a solid color.
     *
     * @param color The background color to use for the drawing cache's bitmap
     *
     * @see #setDrawingCacheEnabled(boolean)
     * @see #buildDrawingCache()
     * @see #getDrawingCache()
     */
    public void setDrawingCacheBackgroundColor(int color) {
        if (color != mDrawingCacheBackgroundColor) {
            mDrawingCacheBackgroundColor = color;
            mPrivateFlags &= ~DRAWING_CACHE_VALID;
        }
    }

    /**
     * @see #setDrawingCacheBackgroundColor(int)
     *
     * @return The background color to used for the drawing cache's bitmap
     */
    public int getDrawingCacheBackgroundColor() {
        return mDrawingCacheBackgroundColor;
    }

    /**
     * <p>Calling this method is equivalent to calling <code>buildDrawingCache(false)</code>.</p>
     *
     * @see #buildDrawingCache(boolean)
     */
    public void buildDrawingCache() {
        buildDrawingCache(false);
    }

    /**
     * <p>Forces the drawing cache to be built if the drawing cache is invalid.</p>
     *
     * <p>If you call {@link #buildDrawingCache()} manually without calling
     * {@link #setDrawingCacheEnabled(boolean) setDrawingCacheEnabled(true)}, you
     * should cleanup the cache by calling {@link #destroyDrawingCache()} afterwards.</p>
     *
     * <p>Note about auto scaling in compatibility mode: When auto scaling is not enabled,
     * this method will create a bitmap of the same size as this view. Because this bitmap
     * will be drawn scaled by the parent ViewGroup, the result on screen might show
     * scaling artifacts. To avoid such artifacts, you should call this method by setting
     * the auto scaling to true. Doing so, however, will generate a bitmap of a different
     * size than the view. This implies that your application must be able to handle this
     * size.</p>
     *
     * <p>You should avoid calling this method when hardware acceleration is enabled. If
     * you do not need the drawing cache bitmap, calling this method will increase memory
     * usage and cause the view to be rendered in software once, thus negatively impacting
     * performance.</p>
     *
     * @see #getDrawingCache()
     * @see #destroyDrawingCache()
     */
    public void buildDrawingCache(boolean autoScale) {
        if ((mPrivateFlags & DRAWING_CACHE_VALID) == 0 || (autoScale ?
                mDrawingCache == null : mUnscaledDrawingCache == null)) {

            if (ViewDebug.TRACE_HIERARCHY) {
                ViewDebug.trace(this, ViewDebug.HierarchyTraceType.BUILD_CACHE);
            }

            int width = mRight - mLeft;
            int height = mBottom - mTop;

            final AttachInfo attachInfo = mAttachInfo;
            final boolean scalingRequired = attachInfo != null && attachInfo.mScalingRequired;

            if (autoScale && scalingRequired) {
                width = (int) ((width * attachInfo.mApplicationScale) + 0.5f);
                height = (int) ((height * attachInfo.mApplicationScale) + 0.5f);
            }

            final int drawingCacheBackgroundColor = mDrawingCacheBackgroundColor;
            final boolean opaque = drawingCacheBackgroundColor != 0 || isOpaque();
            final boolean use32BitCache = attachInfo != null && attachInfo.mUse32BitDrawingCache;

            if (width <= 0 || height <= 0 ||
                     // Projected bitmap size in bytes
                    (width * height * (opaque && !use32BitCache ? 2 : 4) >
                            ViewConfiguration.get(mContext).getScaledMaximumDrawingCacheSize())) {
                destroyDrawingCache();
                return;
            }

            boolean clear = true;
            Bitmap bitmap = autoScale ? mDrawingCache : mUnscaledDrawingCache;

            if (bitmap == null || bitmap.getWidth() != width || bitmap.getHeight() != height) {
                Bitmap.Config quality;
                if (!opaque) {
                    switch (mViewFlags & DRAWING_CACHE_QUALITY_MASK) {
                        case DRAWING_CACHE_QUALITY_AUTO:
                            quality = Bitmap.Config.ARGB_8888;
                            break;
                        case DRAWING_CACHE_QUALITY_LOW:
                            quality = Bitmap.Config.ARGB_4444;
                            break;
                        case DRAWING_CACHE_QUALITY_HIGH:
                            quality = Bitmap.Config.ARGB_8888;
                            break;
                        default:
                            quality = Bitmap.Config.ARGB_8888;
                            break;
                    }
                } else {
                    // Optimization for translucent windows
                    // If the window is translucent, use a 32 bits bitmap to benefit from memcpy()
                    quality = use32BitCache ? Bitmap.Config.ARGB_8888 : Bitmap.Config.RGB_565;
                }

                // Try to cleanup memory
                if (bitmap != null) bitmap.recycle();

                try {
                    bitmap = Bitmap.createBitmap(width, height, quality);
                    bitmap.setDensity(getResources().getDisplayMetrics().densityDpi);
                    if (autoScale) {
                        mDrawingCache = bitmap;
                    } else {
                        mUnscaledDrawingCache = bitmap;
                    }
                    if (opaque && use32BitCache) bitmap.setHasAlpha(false);
                } catch (OutOfMemoryError e) {
                    // If there is not enough memory to create the bitmap cache, just
                    // ignore the issue as bitmap caches are not required to draw the
                    // view hierarchy
                    if (autoScale) {
                        mDrawingCache = null;
                    } else {
                        mUnscaledDrawingCache = null;
                    }
                    return;
                }

                clear = drawingCacheBackgroundColor != 0;
            }

            Canvas canvas;
            if (attachInfo != null) {
                canvas = attachInfo.mCanvas;
                if (canvas == null) {
                    canvas = new Canvas();
                }
                canvas.setBitmap(bitmap);
                // Temporarily clobber the cached Canvas in case one of our children
                // is also using a drawing cache. Without this, the children would
                // steal the canvas by attaching their own bitmap to it and bad, bad
                // thing would happen (invisible views, corrupted drawings, etc.)
                attachInfo.mCanvas = null;
            } else {
                // This case should hopefully never or seldom happen
                canvas = new Canvas(bitmap);
            }

            if (clear) {
                bitmap.eraseColor(drawingCacheBackgroundColor);
            }

            computeScroll();
            final int restoreCount = canvas.save();

            if (autoScale && scalingRequired) {
                final float scale = attachInfo.mApplicationScale;
                canvas.scale(scale, scale);
            }

            canvas.translate(-mScrollX, -mScrollY);

            mPrivateFlags |= DRAWN;
            if (mAttachInfo == null || !mAttachInfo.mHardwareAccelerated ||
                    mLayerType != LAYER_TYPE_NONE) {
                mPrivateFlags |= DRAWING_CACHE_VALID;
            }

            // Fast path for layouts with no backgrounds
            if ((mPrivateFlags & SKIP_DRAW) == SKIP_DRAW) {
                if (ViewDebug.TRACE_HIERARCHY) {
                    ViewDebug.trace(this, ViewDebug.HierarchyTraceType.DRAW);
                }
                mPrivateFlags &= ~DIRTY_MASK;
                dispatchDraw(canvas);
            } else {
                draw(canvas);
            }

            canvas.restoreToCount(restoreCount);

            if (attachInfo != null) {
                // Restore the cached Canvas for our siblings
                attachInfo.mCanvas = canvas;
            }
        }
    }

    /**
     * Create a snapshot of the view into a bitmap.  We should probably make
     * some form of this public, but should think about the API.
     */
    Bitmap createSnapshot(Bitmap.Config quality, int backgroundColor, boolean skipChildren) {
        int width = mRight - mLeft;
        int height = mBottom - mTop;

        final AttachInfo attachInfo = mAttachInfo;
        final float scale = attachInfo != null ? attachInfo.mApplicationScale : 1.0f;
        width = (int) ((width * scale) + 0.5f);
        height = (int) ((height * scale) + 0.5f);

        Bitmap bitmap = Bitmap.createBitmap(width > 0 ? width : 1, height > 0 ? height : 1, quality);
        if (bitmap == null) {
            throw new OutOfMemoryError();
        }

        bitmap.setDensity(getResources().getDisplayMetrics().densityDpi);

        Canvas canvas;
        if (attachInfo != null) {
            canvas = attachInfo.mCanvas;
            if (canvas == null) {
                canvas = new Canvas();
            }
            canvas.setBitmap(bitmap);
            // Temporarily clobber the cached Canvas in case one of our children
            // is also using a drawing cache. Without this, the children would
            // steal the canvas by attaching their own bitmap to it and bad, bad
            // things would happen (invisible views, corrupted drawings, etc.)
            attachInfo.mCanvas = null;
        } else {
            // This case should hopefully never or seldom happen
            canvas = new Canvas(bitmap);
        }

        if ((backgroundColor & 0xff000000) != 0) {
            bitmap.eraseColor(backgroundColor);
        }

        computeScroll();
        final int restoreCount = canvas.save();
        canvas.scale(scale, scale);
        canvas.translate(-mScrollX, -mScrollY);

        // Temporarily remove the dirty mask
        int flags = mPrivateFlags;
        mPrivateFlags &= ~DIRTY_MASK;

        // Fast path for layouts with no backgrounds
        if ((mPrivateFlags & SKIP_DRAW) == SKIP_DRAW) {
            dispatchDraw(canvas);
        } else {
            draw(canvas);
        }

        mPrivateFlags = flags;

        canvas.restoreToCount(restoreCount);

        if (attachInfo != null) {
            // Restore the cached Canvas for our siblings
            attachInfo.mCanvas = canvas;
        }

        return bitmap;
    }

    /**
     * Indicates whether this View is currently in edit mode. A View is usually
     * in edit mode when displayed within a developer tool. For instance, if
     * this View is being drawn by a visual user interface builder, this method
     * should return true.
     *
     * Subclasses should check the return value of this method to provide
     * different behaviors if their normal behavior might interfere with the
     * host environment. For instance: the class spawns a thread in its
     * constructor, the drawing code relies on device-specific features, etc.
     *
     * This method is usually checked in the drawing code of custom widgets.
     *
     * @return True if this View is in edit mode, false otherwise.
     */
    public boolean isInEditMode() {
        return false;
    }

    /**
     * If the View draws content inside its padding and enables fading edges,
     * it needs to support padding offsets. Padding offsets are added to the
     * fading edges to extend the length of the fade so that it covers pixels
     * drawn inside the padding.
     *
     * Subclasses of this class should override this method if they need
     * to draw content inside the padding.
     *
     * @return True if padding offset must be applied, false otherwise.
     *
     * @see #getLeftPaddingOffset()
     * @see #getRightPaddingOffset()
     * @see #getTopPaddingOffset()
     * @see #getBottomPaddingOffset()
     *
     * @since CURRENT
     */
    protected boolean isPaddingOffsetRequired() {
        return false;
    }

    /**
     * Amount by which to extend the left fading region. Called only when
     * {@link #isPaddingOffsetRequired()} returns true.
     *
     * @return The left padding offset in pixels.
     *
     * @see #isPaddingOffsetRequired()
     *
     * @since CURRENT
     */
    protected int getLeftPaddingOffset() {
        return 0;
    }

    /**
     * Amount by which to extend the right fading region. Called only when
     * {@link #isPaddingOffsetRequired()} returns true.
     *
     * @return The right padding offset in pixels.
     *
     * @see #isPaddingOffsetRequired()
     *
     * @since CURRENT
     */
    protected int getRightPaddingOffset() {
        return 0;
    }

    /**
     * Amount by which to extend the top fading region. Called only when
     * {@link #isPaddingOffsetRequired()} returns true.
     *
     * @return The top padding offset in pixels.
     *
     * @see #isPaddingOffsetRequired()
     *
     * @since CURRENT
     */
    protected int getTopPaddingOffset() {
        return 0;
    }

    /**
     * Amount by which to extend the bottom fading region. Called only when
     * {@link #isPaddingOffsetRequired()} returns true.
     *
     * @return The bottom padding offset in pixels.
     *
     * @see #isPaddingOffsetRequired()
     *
     * @since CURRENT
     */
    protected int getBottomPaddingOffset() {
        return 0;
    }

    /**
     * <p>Indicates whether this view is attached to an hardware accelerated
     * window or not.</p>
     *
     * <p>Even if this method returns true, it does not mean that every call
     * to {@link #draw(android.graphics.Canvas)} will be made with an hardware
     * accelerated {@link android.graphics.Canvas}. For instance, if this view
     * is drawn onto an offscren {@link android.graphics.Bitmap} and its
     * window is hardware accelerated,
     * {@link android.graphics.Canvas#isHardwareAccelerated()} will likely
     * return false, and this method will return true.</p>
     *
     * @return True if the view is attached to a window and the window is
     *         hardware accelerated; false in any other case.
     */
    public boolean isHardwareAccelerated() {
        return mAttachInfo != null && mAttachInfo.mHardwareAccelerated;
    }

    /**
     * Manually render this view (and all of its children) to the given Canvas.
     * The view must have already done a full layout before this function is
     * called.  When implementing a view, implement {@link #onDraw} instead of
     * overriding this method. If you do need to override this method, call
     * the superclass version.
     *
     * @param canvas The Canvas to which the View is rendered.
     */
    public void draw(Canvas canvas) {
        if (ViewDebug.TRACE_HIERARCHY) {
            ViewDebug.trace(this, ViewDebug.HierarchyTraceType.DRAW);
        }

        final int privateFlags = mPrivateFlags;
        final boolean dirtyOpaque = (privateFlags & DIRTY_MASK) == DIRTY_OPAQUE &&
                (mAttachInfo == null || !mAttachInfo.mIgnoreDirtyState);
        mPrivateFlags = (privateFlags & ~DIRTY_MASK) | DRAWN;

        /*
         * Draw traversal performs several drawing steps which must be executed
         * in the appropriate order:
         *
         *      1. Draw the background
         *      2. If necessary, save the canvas' layers to prepare for fading
         *      3. Draw view's content
         *      4. Draw children
         *      5. If necessary, draw the fading edges and restore layers
         *      6. Draw decorations (scrollbars for instance)
         */

        // Step 1, draw the background, if needed
        int saveCount;

        if (!dirtyOpaque) {
            final Drawable background = mBGDrawable;
            if (background != null) {
                final int scrollX = mScrollX;
                final int scrollY = mScrollY;

                if (mBackgroundSizeChanged) {
                    background.setBounds(0, 0,  mRight - mLeft, mBottom - mTop);
                    mBackgroundSizeChanged = false;
                }

                if ((scrollX | scrollY) == 0) {
                    background.draw(canvas);
                } else {
                    canvas.translate(scrollX, scrollY);
                    background.draw(canvas);
                    canvas.translate(-scrollX, -scrollY);
                }
            }
        }

        // skip step 2 & 5 if possible (common case)
        final int viewFlags = mViewFlags;
        boolean horizontalEdges = (viewFlags & FADING_EDGE_HORIZONTAL) != 0;
        boolean verticalEdges = (viewFlags & FADING_EDGE_VERTICAL) != 0;
        if (!verticalEdges && !horizontalEdges) {
            // Step 3, draw the content
            if (!dirtyOpaque) onDraw(canvas);

            // Step 4, draw the children
            dispatchDraw(canvas);

            // Step 6, draw decorations (scrollbars)
            onDrawScrollBars(canvas);

            // we're done...
            return;
        }

        /*
         * Here we do the full fledged routine...
         * (this is an uncommon case where speed matters less,
         * this is why we repeat some of the tests that have been
         * done above)
         */

        boolean drawTop = false;
        boolean drawBottom = false;
        boolean drawLeft = false;
        boolean drawRight = false;

        float topFadeStrength = 0.0f;
        float bottomFadeStrength = 0.0f;
        float leftFadeStrength = 0.0f;
        float rightFadeStrength = 0.0f;

        // Step 2, save the canvas' layers
        int paddingLeft = mPaddingLeft;
        int paddingTop = mPaddingTop;

        final boolean offsetRequired = isPaddingOffsetRequired();
        if (offsetRequired) {
            paddingLeft += getLeftPaddingOffset();
            paddingTop += getTopPaddingOffset();
        }

        int left = mScrollX + paddingLeft;
        int right = left + mRight - mLeft - mPaddingRight - paddingLeft;
        int top = mScrollY + paddingTop;
        int bottom = top + mBottom - mTop - mPaddingBottom - paddingTop;

        if (offsetRequired) {
            right += getRightPaddingOffset();
            bottom += getBottomPaddingOffset();
        }

        final ScrollabilityCache scrollabilityCache = mScrollCache;
        int length = scrollabilityCache.fadingEdgeLength;

        // clip the fade length if top and bottom fades overlap
        // overlapping fades produce odd-looking artifacts
        if (verticalEdges && (top + length > bottom - length)) {
            length = (bottom - top) / 2;
        }

        // also clip horizontal fades if necessary
        if (horizontalEdges && (left + length > right - length)) {
            length = (right - left) / 2;
        }

        if (verticalEdges) {
            topFadeStrength = Math.max(0.0f, Math.min(1.0f, getTopFadingEdgeStrength()));
            drawTop = topFadeStrength > 0.0f;
            bottomFadeStrength = Math.max(0.0f, Math.min(1.0f, getBottomFadingEdgeStrength()));
            drawBottom = bottomFadeStrength > 0.0f;
        }

        if (horizontalEdges) {
            leftFadeStrength = Math.max(0.0f, Math.min(1.0f, getLeftFadingEdgeStrength()));
            drawLeft = leftFadeStrength > 0.0f;
            rightFadeStrength = Math.max(0.0f, Math.min(1.0f, getRightFadingEdgeStrength()));
            drawRight = rightFadeStrength > 0.0f;
        }

        saveCount = canvas.getSaveCount();

        int solidColor = getSolidColor();
        if (solidColor == 0) {
            final int flags = Canvas.HAS_ALPHA_LAYER_SAVE_FLAG;

            if (drawTop) {
                canvas.saveLayer(left, top, right, top + length, null, flags);
            }

            if (drawBottom) {
                canvas.saveLayer(left, bottom - length, right, bottom, null, flags);
            }

            if (drawLeft) {
                canvas.saveLayer(left, top, left + length, bottom, null, flags);
            }

            if (drawRight) {
                canvas.saveLayer(right - length, top, right, bottom, null, flags);
            }
        } else {
            scrollabilityCache.setFadeColor(solidColor);
        }

        // Step 3, draw the content
        if (!dirtyOpaque) onDraw(canvas);

        // Step 4, draw the children
        dispatchDraw(canvas);

        // Step 5, draw the fade effect and restore layers
        final Paint p = scrollabilityCache.paint;
        final Matrix matrix = scrollabilityCache.matrix;
        final Shader fade = scrollabilityCache.shader;
        final float fadeHeight = scrollabilityCache.fadingEdgeLength;

        if (drawTop) {
            matrix.setScale(1, fadeHeight * topFadeStrength);
            matrix.postTranslate(left, top);
            fade.setLocalMatrix(matrix);
            canvas.drawRect(left, top, right, top + length, p);
        }

        if (drawBottom) {
            matrix.setScale(1, fadeHeight * bottomFadeStrength);
            matrix.postRotate(180);
            matrix.postTranslate(left, bottom);
            fade.setLocalMatrix(matrix);
            canvas.drawRect(left, bottom - length, right, bottom, p);
        }

        if (drawLeft) {
            matrix.setScale(1, fadeHeight * leftFadeStrength);
            matrix.postRotate(-90);
            matrix.postTranslate(left, top);
            fade.setLocalMatrix(matrix);
            canvas.drawRect(left, top, left + length, bottom, p);
        }

        if (drawRight) {
            matrix.setScale(1, fadeHeight * rightFadeStrength);
            matrix.postRotate(90);
            matrix.postTranslate(right, top);
            fade.setLocalMatrix(matrix);
            canvas.drawRect(right - length, top, right, bottom, p);
        }

        canvas.restoreToCount(saveCount);

        // Step 6, draw decorations (scrollbars)
        onDrawScrollBars(canvas);
    }

    /**
     * Override this if your view is known to always be drawn on top of a solid color background,
     * and needs to draw fading edges. Returning a non-zero color enables the view system to
     * optimize the drawing of the fading edges. If you do return a non-zero color, the alpha
     * should be set to 0xFF.
     *
     * @see #setVerticalFadingEdgeEnabled
     * @see #setHorizontalFadingEdgeEnabled
     *
     * @return The known solid color background for this view, or 0 if the color may vary
     */
    public int getSolidColor() {
        return 0;
    }

    /**
     * Build a human readable string representation of the specified view flags.
     *
     * @param flags the view flags to convert to a string
     * @return a String representing the supplied flags
     */
    private static String printFlags(int flags) {
        String output = "";
        int numFlags = 0;
        if ((flags & FOCUSABLE_MASK) == FOCUSABLE) {
            output += "TAKES_FOCUS";
            numFlags++;
        }

        switch (flags & VISIBILITY_MASK) {
        case INVISIBLE:
            if (numFlags > 0) {
                output += " ";
            }
            output += "INVISIBLE";
            // USELESS HERE numFlags++;
            break;
        case GONE:
            if (numFlags > 0) {
                output += " ";
            }
            output += "GONE";
            // USELESS HERE numFlags++;
            break;
        default:
            break;
        }
        return output;
    }

    /**
     * Build a human readable string representation of the specified private
     * view flags.
     *
     * @param privateFlags the private view flags to convert to a string
     * @return a String representing the supplied flags
     */
    private static String printPrivateFlags(int privateFlags) {
        String output = "";
        int numFlags = 0;

        if ((privateFlags & WANTS_FOCUS) == WANTS_FOCUS) {
            output += "WANTS_FOCUS";
            numFlags++;
        }

        if ((privateFlags & FOCUSED) == FOCUSED) {
            if (numFlags > 0) {
                output += " ";
            }
            output += "FOCUSED";
            numFlags++;
        }

        if ((privateFlags & SELECTED) == SELECTED) {
            if (numFlags > 0) {
                output += " ";
            }
            output += "SELECTED";
            numFlags++;
        }

        if ((privateFlags & IS_ROOT_NAMESPACE) == IS_ROOT_NAMESPACE) {
            if (numFlags > 0) {
                output += " ";
            }
            output += "IS_ROOT_NAMESPACE";
            numFlags++;
        }

        if ((privateFlags & HAS_BOUNDS) == HAS_BOUNDS) {
            if (numFlags > 0) {
                output += " ";
            }
            output += "HAS_BOUNDS";
            numFlags++;
        }

        if ((privateFlags & DRAWN) == DRAWN) {
            if (numFlags > 0) {
                output += " ";
            }
            output += "DRAWN";
            // USELESS HERE numFlags++;
        }
        return output;
    }

    /**
     * <p>Indicates whether or not this view's layout will be requested during
     * the next hierarchy layout pass.</p>
     *
     * @return true if the layout will be forced during next layout pass
     */
    public boolean isLayoutRequested() {
        return (mPrivateFlags & FORCE_LAYOUT) == FORCE_LAYOUT;
    }

    /**
     * Assign a size and position to a view and all of its
     * descendants
     *
     * <p>This is the second phase of the layout mechanism.
     * (The first is measuring). In this phase, each parent calls
     * layout on all of its children to position them.
     * This is typically done using the child measurements
     * that were stored in the measure pass().</p>
     *
     * <p>Derived classes should not override this method.
     * Derived classes with children should override
     * onLayout. In that method, they should
     * call layout on each of their children.</p>
     *
     * @param l Left position, relative to parent
     * @param t Top position, relative to parent
     * @param r Right position, relative to parent
     * @param b Bottom position, relative to parent
     */
    @SuppressWarnings({"unchecked"})
    public void layout(int l, int t, int r, int b) {
        int oldL = mLeft;
        int oldT = mTop;
        int oldB = mBottom;
        int oldR = mRight;
        boolean changed = setFrame(l, t, r, b);
        if (changed || (mPrivateFlags & LAYOUT_REQUIRED) == LAYOUT_REQUIRED) {
            if (ViewDebug.TRACE_HIERARCHY) {
                ViewDebug.trace(this, ViewDebug.HierarchyTraceType.ON_LAYOUT);
            }

            onLayout(changed, l, t, r, b);
            mPrivateFlags &= ~LAYOUT_REQUIRED;

            if (mOnLayoutChangeListeners != null) {
                ArrayList<OnLayoutChangeListener> listenersCopy =
                        (ArrayList<OnLayoutChangeListener>) mOnLayoutChangeListeners.clone();
                int numListeners = listenersCopy.size();
                for (int i = 0; i < numListeners; ++i) {
                    listenersCopy.get(i).onLayoutChange(this, l, t, r, b, oldL, oldT, oldR, oldB);
                }
            }
        }
        mPrivateFlags &= ~FORCE_LAYOUT;
    }

    /**
     * Called from layout when this view should
     * assign a size and position to each of its children.
     *
     * Derived classes with children should override
     * this method and call layout on each of
     * their children.
     * @param changed This is a new size or position for this view
     * @param left Left position, relative to parent
     * @param top Top position, relative to parent
     * @param right Right position, relative to parent
     * @param bottom Bottom position, relative to parent
     */
    protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
    }

    /**
     * Assign a size and position to this view.
     *
     * This is called from layout.
     *
     * @param left Left position, relative to parent
     * @param top Top position, relative to parent
     * @param right Right position, relative to parent
     * @param bottom Bottom position, relative to parent
     * @return true if the new size and position are different than the
     *         previous ones
     * {@hide}
     */
    protected boolean setFrame(int left, int top, int right, int bottom) {
        boolean changed = false;

        if (DBG) {
            Log.d("View", this + " View.setFrame(" + left + "," + top + ","
                    + right + "," + bottom + ")");
        }

        if (mLeft != left || mRight != right || mTop != top || mBottom != bottom) {
            changed = true;

            // Remember our drawn bit
            int drawn = mPrivateFlags & DRAWN;

            // Invalidate our old position
            invalidate(true);


            int oldWidth = mRight - mLeft;
            int oldHeight = mBottom - mTop;

            mLeft = left;
            mTop = top;
            mRight = right;
            mBottom = bottom;

            mPrivateFlags |= HAS_BOUNDS;

            int newWidth = right - left;
            int newHeight = bottom - top;

            if (newWidth != oldWidth || newHeight != oldHeight) {
                if ((mPrivateFlags & PIVOT_EXPLICITLY_SET) == 0) {
                    // A change in dimension means an auto-centered pivot point changes, too
                    mMatrixDirty = true;
                }
                onSizeChanged(newWidth, newHeight, oldWidth, oldHeight);
            }

            if ((mViewFlags & VISIBILITY_MASK) == VISIBLE) {
                // If we are visible, force the DRAWN bit to on so that
                // this invalidate will go through (at least to our parent).
                // This is because someone may have invalidated this view
                // before this call to setFrame came in, thereby clearing
                // the DRAWN bit.
                mPrivateFlags |= DRAWN;
                invalidate(true);
            }

            // Reset drawn bit to original value (invalidate turns it off)
            mPrivateFlags |= drawn;

            mBackgroundSizeChanged = true;
        }
        return changed;
    }

    /**
     * Finalize inflating a view from XML.  This is called as the last phase
     * of inflation, after all child views have been added.
     *
     * <p>Even if the subclass overrides onFinishInflate, they should always be
     * sure to call the super method, so that we get called.
     */
    protected void onFinishInflate() {
    }

    /**
     * Returns the resources associated with this view.
     *
     * @return Resources object.
     */
    public Resources getResources() {
        return mResources;
    }

    /**
     * Invalidates the specified Drawable.
     *
     * @param drawable the drawable to invalidate
     */
    public void invalidateDrawable(Drawable drawable) {
        if (verifyDrawable(drawable)) {
            final Rect dirty = drawable.getBounds();
            final int scrollX = mScrollX;
            final int scrollY = mScrollY;

            invalidate(dirty.left + scrollX, dirty.top + scrollY,
                    dirty.right + scrollX, dirty.bottom + scrollY);
        }
    }

    /**
     * Schedules an action on a drawable to occur at a specified time.
     *
     * @param who the recipient of the action
     * @param what the action to run on the drawable
     * @param when the time at which the action must occur. Uses the
     *        {@link SystemClock#uptimeMillis} timebase.
     */
    public void scheduleDrawable(Drawable who, Runnable what, long when) {
        if (verifyDrawable(who) && what != null && mAttachInfo != null) {
            mAttachInfo.mHandler.postAtTime(what, who, when);
        }
    }

    /**
     * Cancels a scheduled action on a drawable.
     *
     * @param who the recipient of the action
     * @param what the action to cancel
     */
    public void unscheduleDrawable(Drawable who, Runnable what) {
        if (verifyDrawable(who) && what != null && mAttachInfo != null) {
            mAttachInfo.mHandler.removeCallbacks(what, who);
        }
    }

    /**
     * Unschedule any events associated with the given Drawable.  This can be
     * used when selecting a new Drawable into a view, so that the previous
     * one is completely unscheduled.
     *
     * @param who The Drawable to unschedule.
     *
     * @see #drawableStateChanged
     */
    public void unscheduleDrawable(Drawable who) {
        if (mAttachInfo != null) {
            mAttachInfo.mHandler.removeCallbacksAndMessages(who);
        }
    }

    /**
     * If your view subclass is displaying its own Drawable objects, it should
     * override this function and return true for any Drawable it is
     * displaying.  This allows animations for those drawables to be
     * scheduled.
     *
     * <p>Be sure to call through to the super class when overriding this
     * function.
     *
     * @param who The Drawable to verify.  Return true if it is one you are
     *            displaying, else return the result of calling through to the
     *            super class.
     *
     * @return boolean If true than the Drawable is being displayed in the
     *         view; else false and it is not allowed to animate.
     *
     * @see #unscheduleDrawable
     * @see #drawableStateChanged
     */
    protected boolean verifyDrawable(Drawable who) {
        return who == mBGDrawable;
    }

    /**
     * This function is called whenever the state of the view changes in such
     * a way that it impacts the state of drawables being shown.
     *
     * <p>Be sure to call through to the superclass when overriding this
     * function.
     *
     * @see Drawable#setState
     */
    protected void drawableStateChanged() {
        Drawable d = mBGDrawable;
        if (d != null && d.isStateful()) {
            d.setState(getDrawableState());
        }
    }

    /**
     * Call this to force a view to update its drawable state. This will cause
     * drawableStateChanged to be called on this view. Views that are interested
     * in the new state should call getDrawableState.
     *
     * @see #drawableStateChanged
     * @see #getDrawableState
     */
    public void refreshDrawableState() {
        mPrivateFlags |= DRAWABLE_STATE_DIRTY;
        drawableStateChanged();

        ViewParent parent = mParent;
        if (parent != null) {
            parent.childDrawableStateChanged(this);
        }
    }

    /**
     * Return an array of resource IDs of the drawable states representing the
     * current state of the view.
     *
     * @return The current drawable state
     *
     * @see Drawable#setState
     * @see #drawableStateChanged
     * @see #onCreateDrawableState
     */
    public final int[] getDrawableState() {
        if ((mDrawableState != null) && ((mPrivateFlags & DRAWABLE_STATE_DIRTY) == 0)) {
            return mDrawableState;
        } else {
            mDrawableState = onCreateDrawableState(0);
            mPrivateFlags &= ~DRAWABLE_STATE_DIRTY;
            return mDrawableState;
        }
    }

    /**
     * Generate the new {@link android.graphics.drawable.Drawable} state for
     * this view. This is called by the view
     * system when the cached Drawable state is determined to be invalid.  To
     * retrieve the current state, you should use {@link #getDrawableState}.
     *
     * @param extraSpace if non-zero, this is the number of extra entries you
     * would like in the returned array in which you can place your own
     * states.
     *
     * @return Returns an array holding the current {@link Drawable} state of
     * the view.
     *
     * @see #mergeDrawableStates
     */
    protected int[] onCreateDrawableState(int extraSpace) {
        if ((mViewFlags & DUPLICATE_PARENT_STATE) == DUPLICATE_PARENT_STATE &&
                mParent instanceof View) {
            return ((View) mParent).onCreateDrawableState(extraSpace);
        }

        int[] drawableState;

        int privateFlags = mPrivateFlags;

        int viewStateIndex = 0;
        if ((privateFlags & PRESSED) != 0) viewStateIndex |= VIEW_STATE_PRESSED;
        if ((mViewFlags & ENABLED_MASK) == ENABLED) viewStateIndex |= VIEW_STATE_ENABLED;
        if (isFocused()) viewStateIndex |= VIEW_STATE_FOCUSED;
        if ((privateFlags & SELECTED) != 0) viewStateIndex |= VIEW_STATE_SELECTED;
        if (hasWindowFocus()) viewStateIndex |= VIEW_STATE_WINDOW_FOCUSED;
        if ((privateFlags & ACTIVATED) != 0) viewStateIndex |= VIEW_STATE_ACTIVATED;
        if (mAttachInfo != null && mAttachInfo.mHardwareAccelerationRequested) {
            // This is set if HW acceleration is requested, even if the current
            // process doesn't allow it.  This is just to allow app preview
            // windows to better match their app.
            viewStateIndex |= VIEW_STATE_ACCELERATED;
        }

        drawableState = VIEW_STATE_SETS[viewStateIndex];

        //noinspection ConstantIfStatement
        if (false) {
            Log.i("View", "drawableStateIndex=" + viewStateIndex);
            Log.i("View", toString()
                    + " pressed=" + ((privateFlags & PRESSED) != 0)
                    + " en=" + ((mViewFlags & ENABLED_MASK) == ENABLED)
                    + " fo=" + hasFocus()
                    + " sl=" + ((privateFlags & SELECTED) != 0)
                    + " wf=" + hasWindowFocus()
                    + ": " + Arrays.toString(drawableState));
        }

        if (extraSpace == 0) {
            return drawableState;
        }

        final int[] fullState;
        if (drawableState != null) {
            fullState = new int[drawableState.length + extraSpace];
            System.arraycopy(drawableState, 0, fullState, 0, drawableState.length);
        } else {
            fullState = new int[extraSpace];
        }

        return fullState;
    }

    /**
     * Merge your own state values in <var>additionalState</var> into the base
     * state values <var>baseState</var> that were returned by
     * {@link #onCreateDrawableState}.
     *
     * @param baseState The base state values returned by
     * {@link #onCreateDrawableState}, which will be modified to also hold your
     * own additional state values.
     *
     * @param additionalState The additional state values you would like
     * added to <var>baseState</var>; this array is not modified.
     *
     * @return As a convenience, the <var>baseState</var> array you originally
     * passed into the function is returned.
     *
     * @see #onCreateDrawableState
     */
    protected static int[] mergeDrawableStates(int[] baseState, int[] additionalState) {
        final int N = baseState.length;
        int i = N - 1;
        while (i >= 0 && baseState[i] == 0) {
            i--;
        }
        System.arraycopy(additionalState, 0, baseState, i + 1, additionalState.length);
        return baseState;
    }

    /**
     * Call {@link Drawable#jumpToCurrentState() Drawable.jumpToCurrentState()}
     * on all Drawable objects associated with this view.
     */
    public void jumpDrawablesToCurrentState() {
        if (mBGDrawable != null) {
            mBGDrawable.jumpToCurrentState();
        }
    }

    /**
     * Sets the background color for this view.
     * @param color the color of the background
     */
    @RemotableViewMethod
    public void setBackgroundColor(int color) {
        if (mBGDrawable instanceof ColorDrawable) {
            ((ColorDrawable) mBGDrawable).setColor(color);
        } else {
            setBackgroundDrawable(new ColorDrawable(color));
        }
    }

    /**
     * Set the background to a given resource. The resource should refer to
     * a Drawable object or 0 to remove the background.
     * @param resid The identifier of the resource.
     * @attr ref android.R.styleable#View_background
     */
    @RemotableViewMethod
    public void setBackgroundResource(int resid) {
        if (resid != 0 && resid == mBackgroundResource) {
            return;
        }

        Drawable d= null;
        if (resid != 0) {
            d = mResources.getDrawable(resid);
        }
        setBackgroundDrawable(d);

        mBackgroundResource = resid;
    }

    /**
     * Set the background to a given Drawable, or remove the background. If the
     * background has padding, this View's padding is set to the background's
     * padding. However, when a background is removed, this View's padding isn't
     * touched. If setting the padding is desired, please use
     * {@link #setPadding(int, int, int, int)}.
     *
     * @param d The Drawable to use as the background, or null to remove the
     *        background
     */
    public void setBackgroundDrawable(Drawable d) {
        boolean requestLayout = false;

        mBackgroundResource = 0;

        /*
         * Regardless of whether we're setting a new background or not, we want
         * to clear the previous drawable.
         */
        if (mBGDrawable != null) {
            mBGDrawable.setCallback(null);
            unscheduleDrawable(mBGDrawable);
        }

        if (d != null) {
            Rect padding = sThreadLocal.get();
            if (padding == null) {
                padding = new Rect();
                sThreadLocal.set(padding);
            }
            if (d.getPadding(padding)) {
                setPadding(padding.left, padding.top, padding.right, padding.bottom);
            }

            // Compare the minimum sizes of the old Drawable and the new.  If there isn't an old or
            // if it has a different minimum size, we should layout again
            if (mBGDrawable == null || mBGDrawable.getMinimumHeight() != d.getMinimumHeight() ||
                    mBGDrawable.getMinimumWidth() != d.getMinimumWidth()) {
                requestLayout = true;
            }

            d.setCallback(this);
            if (d.isStateful()) {
                d.setState(getDrawableState());
            }
            d.setVisible(getVisibility() == VISIBLE, false);
            mBGDrawable = d;

            if ((mPrivateFlags & SKIP_DRAW) != 0) {
                mPrivateFlags &= ~SKIP_DRAW;
                mPrivateFlags |= ONLY_DRAWS_BACKGROUND;
                requestLayout = true;
            }
        } else {
            /* Remove the background */
            mBGDrawable = null;

            if ((mPrivateFlags & ONLY_DRAWS_BACKGROUND) != 0) {
                /*
                 * This view ONLY drew the background before and we're removing
                 * the background, so now it won't draw anything
                 * (hence we SKIP_DRAW)
                 */
                mPrivateFlags &= ~ONLY_DRAWS_BACKGROUND;
                mPrivateFlags |= SKIP_DRAW;
            }

            /*
             * When the background is set, we try to apply its padding to this
             * View. When the background is removed, we don't touch this View's
             * padding. This is noted in the Javadocs. Hence, we don't need to
             * requestLayout(), the invalidate() below is sufficient.
             */

            // The old background's minimum size could have affected this
            // View's layout, so let's requestLayout
            requestLayout = true;
        }

        computeOpaqueFlags();

        if (requestLayout) {
            requestLayout();
        }

        mBackgroundSizeChanged = true;
        invalidate(true);
    }

    /**
     * Gets the background drawable
     * @return The drawable used as the background for this view, if any.
     */
    public Drawable getBackground() {
        return mBGDrawable;
    }

    /**
     * Sets the padding. The view may add on the space required to display
     * the scrollbars, depending on the style and visibility of the scrollbars.
     * So the values returned from {@link #getPaddingLeft}, {@link #getPaddingTop},
     * {@link #getPaddingRight} and {@link #getPaddingBottom} may be different
     * from the values set in this call.
     *
     * @attr ref android.R.styleable#View_padding
     * @attr ref android.R.styleable#View_paddingBottom
     * @attr ref android.R.styleable#View_paddingLeft
     * @attr ref android.R.styleable#View_paddingRight
     * @attr ref android.R.styleable#View_paddingTop
     * @param left the left padding in pixels
     * @param top the top padding in pixels
     * @param right the right padding in pixels
     * @param bottom the bottom padding in pixels
     */
    public void setPadding(int left, int top, int right, int bottom) {
        boolean changed = false;

        mUserPaddingLeft = left;
        mUserPaddingRight = right;
        mUserPaddingBottom = bottom;

        final int viewFlags = mViewFlags;

        // Common case is there are no scroll bars.
        if ((viewFlags & (SCROLLBARS_VERTICAL|SCROLLBARS_HORIZONTAL)) != 0) {
            if ((viewFlags & SCROLLBARS_VERTICAL) != 0) {
                // TODO Determine what to do with SCROLLBAR_POSITION_DEFAULT based on RTL settings.
                final int offset = (viewFlags & SCROLLBARS_INSET_MASK) == 0
                        ? 0 : getVerticalScrollbarWidth();
                switch (mVerticalScrollbarPosition) {
                    case SCROLLBAR_POSITION_DEFAULT:
                    case SCROLLBAR_POSITION_RIGHT:
                        right += offset;
                        break;
                    case SCROLLBAR_POSITION_LEFT:
                        left += offset;
                        break;
                }
            }
            if ((viewFlags & SCROLLBARS_HORIZONTAL) != 0) {
                bottom += (viewFlags & SCROLLBARS_INSET_MASK) == 0
                        ? 0 : getHorizontalScrollbarHeight();
            }
        }

        if (mPaddingLeft != left) {
            changed = true;
            mPaddingLeft = left;
        }
        if (mPaddingTop != top) {
            changed = true;
            mPaddingTop = top;
        }
        if (mPaddingRight != right) {
            changed = true;
            mPaddingRight = right;
        }
        if (mPaddingBottom != bottom) {
            changed = true;
            mPaddingBottom = bottom;
        }

        if (changed) {
            requestLayout();
        }
    }

    /**
     * Returns the top padding of this view.
     *
     * @return the top padding in pixels
     */
    public int getPaddingTop() {
        return mPaddingTop;
    }

    /**
     * Returns the bottom padding of this view. If there are inset and enabled
     * scrollbars, this value may include the space required to display the
     * scrollbars as well.
     *
     * @return the bottom padding in pixels
     */
    public int getPaddingBottom() {
        return mPaddingBottom;
    }

    /**
     * Returns the left padding of this view. If there are inset and enabled
     * scrollbars, this value may include the space required to display the
     * scrollbars as well.
     *
     * @return the left padding in pixels
     */
    public int getPaddingLeft() {
        return mPaddingLeft;
    }

    /**
     * Returns the right padding of this view. If there are inset and enabled
     * scrollbars, this value may include the space required to display the
     * scrollbars as well.
     *
     * @return the right padding in pixels
     */
    public int getPaddingRight() {
        return mPaddingRight;
    }

    /**
     * Changes the selection state of this view. A view can be selected or not.
     * Note that selection is not the same as focus. Views are typically
     * selected in the context of an AdapterView like ListView or GridView;
     * the selected view is the view that is highlighted.
     *
     * @param selected true if the view must be selected, false otherwise
     */
    public void setSelected(boolean selected) {
        if (((mPrivateFlags & SELECTED) != 0) != selected) {
            mPrivateFlags = (mPrivateFlags & ~SELECTED) | (selected ? SELECTED : 0);
            if (!selected) resetPressedState();
            invalidate(true);
            refreshDrawableState();
            dispatchSetSelected(selected);
        }
    }

    /**
     * Dispatch setSelected to all of this View's children.
     *
     * @see #setSelected(boolean)
     *
     * @param selected The new selected state
     */
    protected void dispatchSetSelected(boolean selected) {
    }

    /**
     * Indicates the selection state of this view.
     *
     * @return true if the view is selected, false otherwise
     */
    @ViewDebug.ExportedProperty
    public boolean isSelected() {
        return (mPrivateFlags & SELECTED) != 0;
    }

    /**
     * Changes the activated state of this view. A view can be activated or not.
     * Note that activation is not the same as selection.  Selection is
     * a transient property, representing the view (hierarchy) the user is
     * currently interacting with.  Activation is a longer-term state that the
     * user can move views in and out of.  For example, in a list view with
     * single or multiple selection enabled, the views in the current selection
     * set are activated.  (Um, yeah, we are deeply sorry about the terminology
     * here.)  The activated state is propagated down to children of the view it
     * is set on.
     *
     * @param activated true if the view must be activated, false otherwise
     */
    public void setActivated(boolean activated) {
        if (((mPrivateFlags & ACTIVATED) != 0) != activated) {
            mPrivateFlags = (mPrivateFlags & ~ACTIVATED) | (activated ? ACTIVATED : 0);
            invalidate(true);
            refreshDrawableState();
            dispatchSetActivated(activated);
        }
    }

    /**
     * Dispatch setActivated to all of this View's children.
     *
     * @see #setActivated(boolean)
     *
     * @param activated The new activated state
     */
    protected void dispatchSetActivated(boolean activated) {
    }

    /**
     * Indicates the activation state of this view.
     *
     * @return true if the view is activated, false otherwise
     */
    @ViewDebug.ExportedProperty
    public boolean isActivated() {
        return (mPrivateFlags & ACTIVATED) != 0;
    }

    /**
     * Returns the ViewTreeObserver for this view's hierarchy. The view tree
     * observer can be used to get notifications when global events, like
     * layout, happen.
     *
     * The returned ViewTreeObserver observer is not guaranteed to remain
     * valid for the lifetime of this View. If the caller of this method keeps
     * a long-lived reference to ViewTreeObserver, it should always check for
     * the return value of {@link ViewTreeObserver#isAlive()}.
     *
     * @return The ViewTreeObserver for this view's hierarchy.
     */
    public ViewTreeObserver getViewTreeObserver() {
        if (mAttachInfo != null) {
            return mAttachInfo.mTreeObserver;
        }
        if (mFloatingTreeObserver == null) {
            mFloatingTreeObserver = new ViewTreeObserver();
        }
        return mFloatingTreeObserver;
    }

    /**
     * <p>Finds the topmost view in the current view hierarchy.</p>
     *
     * @return the topmost view containing this view
     */
    public View getRootView() {
        if (mAttachInfo != null) {
            final View v = mAttachInfo.mRootView;
            if (v != null) {
                return v;
            }
        }

        View parent = this;

        while (parent.mParent != null && parent.mParent instanceof View) {
            parent = (View) parent.mParent;
        }

        return parent;
    }

    /**
     * <p>Computes the coordinates of this view on the screen. The argument
     * must be an array of two integers. After the method returns, the array
     * contains the x and y location in that order.</p>
     *
     * @param location an array of two integers in which to hold the coordinates
     */
    public void getLocationOnScreen(int[] location) {
        getLocationInWindow(location);

        final AttachInfo info = mAttachInfo;
        if (info != null) {
            location[0] += info.mWindowLeft;
            location[1] += info.mWindowTop;
        }
    }

    /**
     * <p>Computes the coordinates of this view in its window. The argument
     * must be an array of two integers. After the method returns, the array
     * contains the x and y location in that order.</p>
     *
     * @param location an array of two integers in which to hold the coordinates
     */
    public void getLocationInWindow(int[] location) {
        if (location == null || location.length < 2) {
            throw new IllegalArgumentException("location must be an array of "
                    + "two integers");
        }

        location[0] = mLeft + (int) (mTranslationX + 0.5f);
        location[1] = mTop + (int) (mTranslationY + 0.5f);

        ViewParent viewParent = mParent;
        while (viewParent instanceof View) {
            final View view = (View)viewParent;
            location[0] += view.mLeft + (int) (view.mTranslationX + 0.5f) - view.mScrollX;
            location[1] += view.mTop + (int) (view.mTranslationY + 0.5f) - view.mScrollY;
            viewParent = view.mParent;
        }

        if (viewParent instanceof ViewRoot) {
            // *cough*
            final ViewRoot vr = (ViewRoot)viewParent;
            location[1] -= vr.mCurScrollY;
        }
    }

    /**
     * {@hide}
     * @param id the id of the view to be found
     * @return the view of the specified id, null if cannot be found
     */
    protected View findViewTraversal(int id) {
        if (id == mID) {
            return this;
        }
        return null;
    }

    /**
     * {@hide}
     * @param tag the tag of the view to be found
     * @return the view of specified tag, null if cannot be found
     */
    protected View findViewWithTagTraversal(Object tag) {
        if (tag != null && tag.equals(mTag)) {
            return this;
        }
        return null;
    }

    /**
     * {@hide}
     * @param predicate The predicate to evaluate.
     * @return The first view that matches the predicate or null.
     */
    protected View findViewByPredicateTraversal(Predicate<View> predicate) {
        if (predicate.apply(this)) {
            return this;
        }
        return null;
    }

    /**
     * Look for a child view with the given id.  If this view has the given
     * id, return this view.
     *
     * @param id The id to search for.
     * @return The view that has the given id in the hierarchy or null
     */
    public final View findViewById(int id) {
        if (id < 0) {
            return null;
        }
        return findViewTraversal(id);
    }

    /**
     * Look for a child view with the given tag.  If this view has the given
     * tag, return this view.
     *
     * @param tag The tag to search for, using "tag.equals(getTag())".
     * @return The View that has the given tag in the hierarchy or null
     */
    public final View findViewWithTag(Object tag) {
        if (tag == null) {
            return null;
        }
        return findViewWithTagTraversal(tag);
    }

    /**
     * {@hide}
     * Look for a child view that matches the specified predicate.
     * If this view matches the predicate, return this view.
     *
     * @param predicate The predicate to evaluate.
     * @return The first view that matches the predicate or null.
     */
    public final View findViewByPredicate(Predicate<View> predicate) {
        return findViewByPredicateTraversal(predicate);
    }

    /**
     * Sets the identifier for this view. The identifier does not have to be
     * unique in this view's hierarchy. The identifier should be a positive
     * number.
     *
     * @see #NO_ID
     * @see #getId
     * @see #findViewById
     *
     * @param id a number used to identify the view
     *
     * @attr ref android.R.styleable#View_id
     */
    public void setId(int id) {
        mID = id;
    }

    /**
     * {@hide}
     *
     * @param isRoot true if the view belongs to the root namespace, false
     *        otherwise
     */
    public void setIsRootNamespace(boolean isRoot) {
        if (isRoot) {
            mPrivateFlags |= IS_ROOT_NAMESPACE;
        } else {
            mPrivateFlags &= ~IS_ROOT_NAMESPACE;
        }
    }

    /**
     * {@hide}
     *
     * @return true if the view belongs to the root namespace, false otherwise
     */
    public boolean isRootNamespace() {
        return (mPrivateFlags&IS_ROOT_NAMESPACE) != 0;
    }

    /**
     * Returns this view's identifier.
     *
     * @return a positive integer used to identify the view or {@link #NO_ID}
     *         if the view has no ID
     *
     * @see #setId
     * @see #findViewById
     * @attr ref android.R.styleable#View_id
     */
    @ViewDebug.CapturedViewProperty
    public int getId() {
        return mID;
    }

    /**
     * Returns this view's tag.
     *
     * @return the Object stored in this view as a tag
     *
     * @see #setTag(Object)
     * @see #getTag(int)
     */
    @ViewDebug.ExportedProperty
    public Object getTag() {
        return mTag;
    }

    /**
     * Sets the tag associated with this view. A tag can be used to mark
     * a view in its hierarchy and does not have to be unique within the
     * hierarchy. Tags can also be used to store data within a view without
     * resorting to another data structure.
     *
     * @param tag an Object to tag the view with
     *
     * @see #getTag()
     * @see #setTag(int, Object)
     */
    public void setTag(final Object tag) {
        mTag = tag;
    }

    /**
     * Returns the tag associated with this view and the specified key.
     *
     * @param key The key identifying the tag
     *
     * @return the Object stored in this view as a tag
     *
     * @see #setTag(int, Object)
     * @see #getTag()
     */
    public Object getTag(int key) {
        SparseArray<Object> tags = null;
        synchronized (sTagsLock) {
            if (sTags != null) {
                tags = sTags.get(this);
            }
        }

        if (tags != null) return tags.get(key);
        return null;
    }

    /**
     * Sets a tag associated with this view and a key. A tag can be used
     * to mark a view in its hierarchy and does not have to be unique within
     * the hierarchy. Tags can also be used to store data within a view
     * without resorting to another data structure.
     *
     * The specified key should be an id declared in the resources of the
     * application to ensure it is unique (see the <a
     * href={@docRoot}guide/topics/resources/more-resources.html#Id">ID resource type</a>).
     * Keys identified as belonging to
     * the Android framework or not associated with any package will cause
     * an {@link IllegalArgumentException} to be thrown.
     *
     * @param key The key identifying the tag
     * @param tag An Object to tag the view with
     *
     * @throws IllegalArgumentException If they specified key is not valid
     *
     * @see #setTag(Object)
     * @see #getTag(int)
     */
    public void setTag(int key, final Object tag) {
        // If the package id is 0x00 or 0x01, it's either an undefined package
        // or a framework id
        if ((key >>> 24) < 2) {
            throw new IllegalArgumentException("The key must be an application-specific "
                    + "resource id.");
        }

        setTagInternal(this, key, tag);
    }

    /**
     * Variation of {@link #setTag(int, Object)} that enforces the key to be a
     * framework id.
     *
     * @hide
     */
    public void setTagInternal(int key, Object tag) {
        if ((key >>> 24) != 0x1) {
            throw new IllegalArgumentException("The key must be a framework-specific "
                    + "resource id.");
        }

        setTagInternal(this, key, tag);
    }

    private static void setTagInternal(View view, int key, Object tag) {
        SparseArray<Object> tags = null;
        synchronized (sTagsLock) {
            if (sTags == null) {
                sTags = new WeakHashMap<View, SparseArray<Object>>();
            } else {
                tags = sTags.get(view);
            }
        }

        if (tags == null) {
            tags = new SparseArray<Object>(2);
            synchronized (sTagsLock) {
                sTags.put(view, tags);
            }
        }

        tags.put(key, tag);
    }

    /**
     * @param consistency The type of consistency. See ViewDebug for more information.
     *
     * @hide
     */
    protected boolean dispatchConsistencyCheck(int consistency) {
        return onConsistencyCheck(consistency);
    }

    /**
     * Method that subclasses should implement to check their consistency. The type of
     * consistency check is indicated by the bit field passed as a parameter.
     *
     * @param consistency The type of consistency. See ViewDebug for more information.
     *
     * @throws IllegalStateException if the view is in an inconsistent state.
     *
     * @hide
     */
    protected boolean onConsistencyCheck(int consistency) {
        boolean result = true;

        final boolean checkLayout = (consistency & ViewDebug.CONSISTENCY_LAYOUT) != 0;
        final boolean checkDrawing = (consistency & ViewDebug.CONSISTENCY_DRAWING) != 0;

        if (checkLayout) {
            if (getParent() == null) {
                result = false;
                android.util.Log.d(ViewDebug.CONSISTENCY_LOG_TAG,
                        "View " + this + " does not have a parent.");
            }

            if (mAttachInfo == null) {
                result = false;
                android.util.Log.d(ViewDebug.CONSISTENCY_LOG_TAG,
                        "View " + this + " is not attached to a window.");
            }
        }

        if (checkDrawing) {
            // Do not check the DIRTY/DRAWN flags because views can call invalidate()
            // from their draw() method

            if ((mPrivateFlags & DRAWN) != DRAWN &&
                    (mPrivateFlags & DRAWING_CACHE_VALID) == DRAWING_CACHE_VALID) {
                result = false;
                android.util.Log.d(ViewDebug.CONSISTENCY_LOG_TAG,
                        "View " + this + " was invalidated but its drawing cache is valid.");
            }
        }

        return result;
    }

    /**
     * Prints information about this view in the log output, with the tag
     * {@link #VIEW_LOG_TAG}.
     *
     * @hide
     */
    public void debug() {
        debug(0);
    }

    /**
     * Prints information about this view in the log output, with the tag
     * {@link #VIEW_LOG_TAG}. Each line in the output is preceded with an
     * indentation defined by the <code>depth</code>.
     *
     * @param depth the indentation level
     *
     * @hide
     */
    protected void debug(int depth) {
        String output = debugIndent(depth - 1);

        output += "+ " + this;
        int id = getId();
        if (id != -1) {
            output += " (id=" + id + ")";
        }
        Object tag = getTag();
        if (tag != null) {
            output += " (tag=" + tag + ")";
        }
        Log.d(VIEW_LOG_TAG, output);

        if ((mPrivateFlags & FOCUSED) != 0) {
            output = debugIndent(depth) + " FOCUSED";
            Log.d(VIEW_LOG_TAG, output);
        }

        output = debugIndent(depth);
        output += "frame={" + mLeft + ", " + mTop + ", " + mRight
                + ", " + mBottom + "} scroll={" + mScrollX + ", " + mScrollY
                + "} ";
        Log.d(VIEW_LOG_TAG, output);

        if (mPaddingLeft != 0 || mPaddingTop != 0 || mPaddingRight != 0
                || mPaddingBottom != 0) {
            output = debugIndent(depth);
            output += "padding={" + mPaddingLeft + ", " + mPaddingTop
                    + ", " + mPaddingRight + ", " + mPaddingBottom + "}";
            Log.d(VIEW_LOG_TAG, output);
        }

        output = debugIndent(depth);
        output += "mMeasureWidth=" + mMeasuredWidth +
                " mMeasureHeight=" + mMeasuredHeight;
        Log.d(VIEW_LOG_TAG, output);

        output = debugIndent(depth);
        if (mLayoutParams == null) {
            output += "BAD! no layout params";
        } else {
            output = mLayoutParams.debug(output);
        }
        Log.d(VIEW_LOG_TAG, output);

        output = debugIndent(depth);
        output += "flags={";
        output += View.printFlags(mViewFlags);
        output += "}";
        Log.d(VIEW_LOG_TAG, output);

        output = debugIndent(depth);
        output += "privateFlags={";
        output += View.printPrivateFlags(mPrivateFlags);
        output += "}";
        Log.d(VIEW_LOG_TAG, output);
    }

    /**
     * Creates an string of whitespaces used for indentation.
     *
     * @param depth the indentation level
     * @return a String containing (depth * 2 + 3) * 2 white spaces
     *
     * @hide
     */
    protected static String debugIndent(int depth) {
        StringBuilder spaces = new StringBuilder((depth * 2 + 3) * 2);
        for (int i = 0; i < (depth * 2) + 3; i++) {
            spaces.append(' ').append(' ');
        }
        return spaces.toString();
    }

    /**
     * <p>Return the offset of the widget's text baseline from the widget's top
     * boundary. If this widget does not support baseline alignment, this
     * method returns -1. </p>
     *
     * @return the offset of the baseline within the widget's bounds or -1
     *         if baseline alignment is not supported
     */
    @ViewDebug.ExportedProperty(category = "layout")
    public int getBaseline() {
        return -1;
    }

    /**
     * Call this when something has changed which has invalidated the
     * layout of this view. This will schedule a layout pass of the view
     * tree.
     */
    public void requestLayout() {
        if (ViewDebug.TRACE_HIERARCHY) {
            ViewDebug.trace(this, ViewDebug.HierarchyTraceType.REQUEST_LAYOUT);
        }

        mPrivateFlags |= FORCE_LAYOUT;
        mPrivateFlags |= INVALIDATED;

        if (mParent != null && !mParent.isLayoutRequested()) {
            mParent.requestLayout();
        }
    }

    /**
     * Forces this view to be laid out during the next layout pass.
     * This method does not call requestLayout() or forceLayout()
     * on the parent.
     */
    public void forceLayout() {
        mPrivateFlags |= FORCE_LAYOUT;
        mPrivateFlags |= INVALIDATED;
    }

    /**
     * <p>
     * This is called to find out how big a view should be. The parent
     * supplies constraint information in the width and height parameters.
     * </p>
     *
     * <p>
     * The actual mesurement work of a view is performed in
     * {@link #onMeasure(int, int)}, called by this method. Therefore, only
     * {@link #onMeasure(int, int)} can and must be overriden by subclasses.
     * </p>
     *
     *
     * @param widthMeasureSpec Horizontal space requirements as imposed by the
     *        parent
     * @param heightMeasureSpec Vertical space requirements as imposed by the
     *        parent
     *
     * @see #onMeasure(int, int)
     */
    public final void measure(int widthMeasureSpec, int heightMeasureSpec) {
        if ((mPrivateFlags & FORCE_LAYOUT) == FORCE_LAYOUT ||
                widthMeasureSpec != mOldWidthMeasureSpec ||
                heightMeasureSpec != mOldHeightMeasureSpec) {

            // first clears the measured dimension flag
            mPrivateFlags &= ~MEASURED_DIMENSION_SET;

            if (ViewDebug.TRACE_HIERARCHY) {
                ViewDebug.trace(this, ViewDebug.HierarchyTraceType.ON_MEASURE);
            }

            // measure ourselves, this should set the measured dimension flag back
            onMeasure(widthMeasureSpec, heightMeasureSpec);

            // flag not set, setMeasuredDimension() was not invoked, we raise
            // an exception to warn the developer
            if ((mPrivateFlags & MEASURED_DIMENSION_SET) != MEASURED_DIMENSION_SET) {
                throw new IllegalStateException("onMeasure() did not set the"
                        + " measured dimension by calling"
                        + " setMeasuredDimension()");
            }

            mPrivateFlags |= LAYOUT_REQUIRED;
        }

        mOldWidthMeasureSpec = widthMeasureSpec;
        mOldHeightMeasureSpec = heightMeasureSpec;
    }

    /**
     * <p>
     * Measure the view and its content to determine the measured width and the
     * measured height. This method is invoked by {@link #measure(int, int)} and
     * should be overriden by subclasses to provide accurate and efficient
     * measurement of their contents.
     * </p>
     *
     * <p>
     * <strong>CONTRACT:</strong> When overriding this method, you
     * <em>must</em> call {@link #setMeasuredDimension(int, int)} to store the
     * measured width and height of this view. Failure to do so will trigger an
     * <code>IllegalStateException</code>, thrown by
     * {@link #measure(int, int)}. Calling the superclass'
     * {@link #onMeasure(int, int)} is a valid use.
     * </p>
     *
     * <p>
     * The base class implementation of measure defaults to the background size,
     * unless a larger size is allowed by the MeasureSpec. Subclasses should
     * override {@link #onMeasure(int, int)} to provide better measurements of
     * their content.
     * </p>
     *
     * <p>
     * If this method is overridden, it is the subclass's responsibility to make
     * sure the measured height and width are at least the view's minimum height
     * and width ({@link #getSuggestedMinimumHeight()} and
     * {@link #getSuggestedMinimumWidth()}).
     * </p>
     *
     * @param widthMeasureSpec horizontal space requirements as imposed by the parent.
     *                         The requirements are encoded with
     *                         {@link android.view.View.MeasureSpec}.
     * @param heightMeasureSpec vertical space requirements as imposed by the parent.
     *                         The requirements are encoded with
     *                         {@link android.view.View.MeasureSpec}.
     *
     * @see #getMeasuredWidth()
     * @see #getMeasuredHeight()
     * @see #setMeasuredDimension(int, int)
     * @see #getSuggestedMinimumHeight()
     * @see #getSuggestedMinimumWidth()
     * @see android.view.View.MeasureSpec#getMode(int)
     * @see android.view.View.MeasureSpec#getSize(int)
     */
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        setMeasuredDimension(getDefaultSize(getSuggestedMinimumWidth(), widthMeasureSpec),
                getDefaultSize(getSuggestedMinimumHeight(), heightMeasureSpec));
    }

    /**
     * <p>This mehod must be called by {@link #onMeasure(int, int)} to store the
     * measured width and measured height. Failing to do so will trigger an
     * exception at measurement time.</p>
     *
     * @param measuredWidth The measured width of this view.  May be a complex
     * bit mask as defined by {@link #MEASURED_SIZE_MASK} and
     * {@link #MEASURED_STATE_TOO_SMALL}.
     * @param measuredHeight The measured height of this view.  May be a complex
     * bit mask as defined by {@link #MEASURED_SIZE_MASK} and
     * {@link #MEASURED_STATE_TOO_SMALL}.
     */
    protected final void setMeasuredDimension(int measuredWidth, int measuredHeight) {
        mMeasuredWidth = measuredWidth;
        mMeasuredHeight = measuredHeight;

        mPrivateFlags |= MEASURED_DIMENSION_SET;
    }

    /**
     * Merge two states as returned by {@link #getMeasuredState()}.
     * @param curState The current state as returned from a view or the result
     * of combining multiple views.
     * @param newState The new view state to combine.
     * @return Returns a new integer reflecting the combination of the two
     * states.
     */
    public static int combineMeasuredStates(int curState, int newState) {
        return curState | newState;
    }

    /**
     * Version of {@link #resolveSizeAndState(int, int, int)}
     * returning only the {@link #MEASURED_SIZE_MASK} bits of the result.
     */
    public static int resolveSize(int size, int measureSpec) {
        return resolveSizeAndState(size, measureSpec, 0) & MEASURED_SIZE_MASK;
    }

    /**
     * Utility to reconcile a desired size and state, with constraints imposed
     * by a MeasureSpec.  Will take the desired size, unless a different size
     * is imposed by the constraints.  The returned value is a compound integer,
     * with the resolved size in the {@link #MEASURED_SIZE_MASK} bits and
     * optionally the bit {@link #MEASURED_STATE_TOO_SMALL} set if the resulting
     * size is smaller than the size the view wants to be.
     *
     * @param size How big the view wants to be
     * @param measureSpec Constraints imposed by the parent
     * @return Size information bit mask as defined by
     * {@link #MEASURED_SIZE_MASK} and {@link #MEASURED_STATE_TOO_SMALL}.
     */
    public static int resolveSizeAndState(int size, int measureSpec, int childMeasuredState) {
        int result = size;
        int specMode = MeasureSpec.getMode(measureSpec);
        int specSize =  MeasureSpec.getSize(measureSpec);
        switch (specMode) {
        case MeasureSpec.UNSPECIFIED:
            result = size;
            break;
        case MeasureSpec.AT_MOST:
            if (specSize < size) {
                result = specSize | MEASURED_STATE_TOO_SMALL;
            } else {
                result = size;
            }
            break;
        case MeasureSpec.EXACTLY:
            result = specSize;
            break;
        }
        return result | (childMeasuredState&MEASURED_STATE_MASK);
    }

    /**
     * Utility to return a default size. Uses the supplied size if the
     * MeasureSpec imposed no contraints. Will get larger if allowed
     * by the MeasureSpec.
     *
     * @param size Default size for this view
     * @param measureSpec Constraints imposed by the parent
     * @return The size this view should be.
     */
    public static int getDefaultSize(int size, int measureSpec) {
        int result = size;
        int specMode = MeasureSpec.getMode(measureSpec);
        int specSize =  MeasureSpec.getSize(measureSpec);

        switch (specMode) {
        case MeasureSpec.UNSPECIFIED:
            result = size;
            break;
        case MeasureSpec.AT_MOST:
        case MeasureSpec.EXACTLY:
            result = specSize;
            break;
        }
        return result;
    }

    /**
     * Returns the suggested minimum height that the view should use. This
     * returns the maximum of the view's minimum height
     * and the background's minimum height
     * ({@link android.graphics.drawable.Drawable#getMinimumHeight()}).
     * <p>
     * When being used in {@link #onMeasure(int, int)}, the caller should still
     * ensure the returned height is within the requirements of the parent.
     *
     * @return The suggested minimum height of the view.
     */
    protected int getSuggestedMinimumHeight() {
        int suggestedMinHeight = mMinHeight;

        if (mBGDrawable != null) {
            final int bgMinHeight = mBGDrawable.getMinimumHeight();
            if (suggestedMinHeight < bgMinHeight) {
                suggestedMinHeight = bgMinHeight;
            }
        }

        return suggestedMinHeight;
    }

    /**
     * Returns the suggested minimum width that the view should use. This
     * returns the maximum of the view's minimum width)
     * and the background's minimum width
     *  ({@link android.graphics.drawable.Drawable#getMinimumWidth()}).
     * <p>
     * When being used in {@link #onMeasure(int, int)}, the caller should still
     * ensure the returned width is within the requirements of the parent.
     *
     * @return The suggested minimum width of the view.
     */
    protected int getSuggestedMinimumWidth() {
        int suggestedMinWidth = mMinWidth;

        if (mBGDrawable != null) {
            final int bgMinWidth = mBGDrawable.getMinimumWidth();
            if (suggestedMinWidth < bgMinWidth) {
                suggestedMinWidth = bgMinWidth;
            }
        }

        return suggestedMinWidth;
    }

    /**
     * Sets the minimum height of the view. It is not guaranteed the view will
     * be able to achieve this minimum height (for example, if its parent layout
     * constrains it with less available height).
     *
     * @param minHeight The minimum height the view will try to be.
     */
    public void setMinimumHeight(int minHeight) {
        mMinHeight = minHeight;
    }

    /**
     * Sets the minimum width of the view. It is not guaranteed the view will
     * be able to achieve this minimum width (for example, if its parent layout
     * constrains it with less available width).
     *
     * @param minWidth The minimum width the view will try to be.
     */
    public void setMinimumWidth(int minWidth) {
        mMinWidth = minWidth;
    }

    /**
     * Get the animation currently associated with this view.
     *
     * @return The animation that is currently playing or
     *         scheduled to play for this view.
     */
    public Animation getAnimation() {
        return mCurrentAnimation;
    }

    /**
     * Start the specified animation now.
     *
     * @param animation the animation to start now
     */
    public void startAnimation(Animation animation) {
        animation.setStartTime(Animation.START_ON_FIRST_FRAME);
        setAnimation(animation);
        invalidateParentCaches();
        invalidate(true);
    }

    /**
     * Cancels any animations for this view.
     */
    public void clearAnimation() {
        if (mCurrentAnimation != null) {
            mCurrentAnimation.detach();
        }
        mCurrentAnimation = null;
        invalidateParentIfNeeded();
    }

    /**
     * Sets the next animation to play for this view.
     * If you want the animation to play immediately, use
     * startAnimation. This method provides allows fine-grained
     * control over the start time and invalidation, but you
     * must make sure that 1) the animation has a start time set, and
     * 2) the view will be invalidated when the animation is supposed to
     * start.
     *
     * @param animation The next animation, or null.
     */
    public void setAnimation(Animation animation) {
        mCurrentAnimation = animation;
        if (animation != null) {
            animation.reset();
        }
    }

    /**
     * Invoked by a parent ViewGroup to notify the start of the animation
     * currently associated with this view. If you override this method,
     * always call super.onAnimationStart();
     *
     * @see #setAnimation(android.view.animation.Animation)
     * @see #getAnimation()
     */
    protected void onAnimationStart() {
        mPrivateFlags |= ANIMATION_STARTED;
    }

    /**
     * Invoked by a parent ViewGroup to notify the end of the animation
     * currently associated with this view. If you override this method,
     * always call super.onAnimationEnd();
     *
     * @see #setAnimation(android.view.animation.Animation)
     * @see #getAnimation()
     */
    protected void onAnimationEnd() {
        mPrivateFlags &= ~ANIMATION_STARTED;
    }

    /**
     * Invoked if there is a Transform that involves alpha. Subclass that can
     * draw themselves with the specified alpha should return true, and then
     * respect that alpha when their onDraw() is called. If this returns false
     * then the view may be redirected to draw into an offscreen buffer to
     * fulfill the request, which will look fine, but may be slower than if the
     * subclass handles it internally. The default implementation returns false.
     *
     * @param alpha The alpha (0..255) to apply to the view's drawing
     * @return true if the view can draw with the specified alpha.
     */
    protected boolean onSetAlpha(int alpha) {
        return false;
    }

    /**
     * This is used by the RootView to perform an optimization when
     * the view hierarchy contains one or several SurfaceView.
     * SurfaceView is always considered transparent, but its children are not,
     * therefore all View objects remove themselves from the global transparent
     * region (passed as a parameter to this function).
     *
     * @param region The transparent region for this ViewRoot (window).
     *
     * @return Returns true if the effective visibility of the view at this
     * point is opaque, regardless of the transparent region; returns false
     * if it is possible for underlying windows to be seen behind the view.
     *
     * {@hide}
     */
    public boolean gatherTransparentRegion(Region region) {
        final AttachInfo attachInfo = mAttachInfo;
        if (region != null && attachInfo != null) {
            final int pflags = mPrivateFlags;
            if ((pflags & SKIP_DRAW) == 0) {
                // The SKIP_DRAW flag IS NOT set, so this view draws. We need to
                // remove it from the transparent region.
                final int[] location = attachInfo.mTransparentLocation;
                getLocationInWindow(location);
                region.op(location[0], location[1], location[0] + mRight - mLeft,
                        location[1] + mBottom - mTop, Region.Op.DIFFERENCE);
            } else if ((pflags & ONLY_DRAWS_BACKGROUND) != 0 && mBGDrawable != null) {
                // The ONLY_DRAWS_BACKGROUND flag IS set and the background drawable
                // exists, so we remove the background drawable's non-transparent
                // parts from this transparent region.
                applyDrawableToTransparentRegion(mBGDrawable, region);
            }
        }
        return true;
    }

    /**
     * Play a sound effect for this view.
     *
     * <p>The framework will play sound effects for some built in actions, such as
     * clicking, but you may wish to play these effects in your widget,
     * for instance, for internal navigation.
     *
     * <p>The sound effect will only be played if sound effects are enabled by the user, and
     * {@link #isSoundEffectsEnabled()} is true.
     *
     * @param soundConstant One of the constants defined in {@link SoundEffectConstants}
     */
    public void playSoundEffect(int soundConstant) {
        if (mAttachInfo == null || mAttachInfo.mRootCallbacks == null || !isSoundEffectsEnabled()) {
            return;
        }
        mAttachInfo.mRootCallbacks.playSoundEffect(soundConstant);
    }

    /**
     * BZZZTT!!1!
     *
     * <p>Provide haptic feedback to the user for this view.
     *
     * <p>The framework will provide haptic feedback for some built in actions,
     * such as long presses, but you may wish to provide feedback for your
     * own widget.
     *
     * <p>The feedback will only be performed if
     * {@link #isHapticFeedbackEnabled()} is true.
     *
     * @param feedbackConstant One of the constants defined in
     * {@link HapticFeedbackConstants}
     */
    public boolean performHapticFeedback(int feedbackConstant) {
        return performHapticFeedback(feedbackConstant, 0);
    }

    /**
     * BZZZTT!!1!
     *
     * <p>Like {@link #performHapticFeedback(int)}, with additional options.
     *
     * @param feedbackConstant One of the constants defined in
     * {@link HapticFeedbackConstants}
     * @param flags Additional flags as per {@link HapticFeedbackConstants}.
     */
    public boolean performHapticFeedback(int feedbackConstant, int flags) {
        if (mAttachInfo == null) {
            return false;
        }
        //noinspection SimplifiableIfStatement
        if ((flags & HapticFeedbackConstants.FLAG_IGNORE_VIEW_SETTING) == 0
                && !isHapticFeedbackEnabled()) {
            return false;
        }
        return mAttachInfo.mRootCallbacks.performHapticFeedback(feedbackConstant,
                (flags & HapticFeedbackConstants.FLAG_IGNORE_GLOBAL_SETTING) != 0);
    }

    /**
     * Request that the visibility of the status bar be changed.
     */
    public void setSystemUiVisibility(int visibility) {
        if (visibility != mSystemUiVisibility) {
            mSystemUiVisibility = visibility;
            if (mParent != null && mAttachInfo != null && !mAttachInfo.mRecomputeGlobalAttributes) {
                mParent.recomputeViewAttributes(this);
            }
        }
    }

    /**
     * Returns the status bar visibility that this view has requested.
     */
    public int getSystemUiVisibility() {
        return mSystemUiVisibility;
    }

    public void setOnSystemUiVisibilityChangeListener(OnSystemUiVisibilityChangeListener l) {
        mOnSystemUiVisibilityChangeListener = l;
        if (mParent != null && mAttachInfo != null && !mAttachInfo.mRecomputeGlobalAttributes) {
            mParent.recomputeViewAttributes(this);
        }
    }

    /**
     */
    public void dispatchSystemUiVisibilityChanged(int visibility) {
        mSystemUiVisibility = visibility;
        if (mOnSystemUiVisibilityChangeListener != null) {
            mOnSystemUiVisibilityChangeListener.onSystemUiVisibilityChange(visibility);
        }
    }

    /**
     * !!! TODO: real docs
     *
     * The base class implementation makes the shadow the same size and appearance
     * as the view itself, and positions it with its center at the touch point.
     */
    public static class DragShadowBuilder {
        private final WeakReference<View> mView;

        /**
         * Construct a shadow builder object for use with the given View object.  The
         * default implementation will construct a drag shadow the same size and
         * appearance as the supplied View.
         *
         * @param view A view within the application's layout whose appearance
         *        should be replicated as the drag shadow.
         */
        public DragShadowBuilder(View view) {
            mView = new WeakReference<View>(view);
        }

        /**
         * Construct a shadow builder object with no associated View.  This
         * constructor variant is only useful when the {@link #onProvideShadowMetrics(Point, Point)}
         * and {@link #onDrawShadow(Canvas)} methods are also overridden in order
         * to supply the drag shadow's dimensions and appearance without
         * reference to any View object.
         */
        public DragShadowBuilder() {
            mView = new WeakReference<View>(null);
        }

        /**
         * Returns the View object that had been passed to the
         * {@link #View.DragShadowBuilder(View)}
         * constructor.  If that View parameter was {@code null} or if the
         * {@link #View.DragShadowBuilder()}
         * constructor was used to instantiate the builder object, this method will return
         * null.
         *
         * @return The View object associate with this builder object.
         */
        final public View getView() {
            return mView.get();
        }

        /**
         * Provide the draggable-shadow metrics for the operation: the dimensions of
         * the shadow image itself, and the point within that shadow that should
         * be centered under the touch location while dragging.
         * <p>
         * The default implementation sets the dimensions of the shadow to be the
         * same as the dimensions of the View object that had been supplied to the
         * {@link #View.DragShadowBuilder(View)} constructor
         * when the builder object was instantiated, and centers the shadow under the touch
         * point.
         *
         * @param shadowSize The application should set the {@code x} member of this
         *        parameter to the desired shadow width, and the {@code y} member to
         *        the desired height.
         * @param shadowTouchPoint The application should set this point to be the
         *        location within the shadow that should track directly underneath
         *        the touch point on the screen during a drag.
         */
        public void onProvideShadowMetrics(Point shadowSize, Point shadowTouchPoint) {
            final View view = mView.get();
            if (view != null) {
                shadowSize.set(view.getWidth(), view.getHeight());
                shadowTouchPoint.set(shadowSize.x / 2, shadowSize.y / 2);
            } else {
                Log.e(View.VIEW_LOG_TAG, "Asked for drag thumb metrics but no view");
            }
        }

        /**
         * Draw the shadow image for the upcoming drag.  The shadow canvas was
         * created with the dimensions supplied by the
         * {@link #onProvideShadowMetrics(Point, Point)} callback.
         * <p>
         * The default implementation replicates the appearance of the View object
         * that had been supplied to the
         * {@link #View.DragShadowBuilder(View)}
         * constructor when the builder object was instantiated.
         *
         * @param canvas
         */
        public void onDrawShadow(Canvas canvas) {
            final View view = mView.get();
            if (view != null) {
                view.draw(canvas);
            } else {
                Log.e(View.VIEW_LOG_TAG, "Asked to draw drag shadow but no view");
            }
        }
    }

    /**
     * Drag and drop.  App calls startDrag(), then callbacks to the shadow builder's
     * {@link DragShadowBuilder#onProvideShadowMetrics(Point, Point)} and
     * {@link DragShadowBuilder#onDrawShadow(Canvas)} methods happen, then the drag
     * operation is handed over to the OS.
     * !!! TODO: real docs
     *
     * @param data !!! TODO
     * @param shadowBuilder !!! TODO
     * @param myLocalState An arbitrary object that will be passed as part of every DragEvent
     *     delivered to the calling application during the course of the current drag operation.
     *     This object is private to the application that called startDrag(), and is not
     *     visible to other applications. It provides a lightweight way for the application to
     *     propagate information from the initiator to the recipient of a drag within its own
     *     application; for example, to help disambiguate between 'copy' and 'move' semantics.
     * @param flags Flags affecting the drag operation.  At present no flags are defined;
     *     pass 0 for this parameter.
     * @return {@code true} if the drag operation was initiated successfully; {@code false} if
     *     an error prevented the drag from taking place.
     */
    public final boolean startDrag(ClipData data, DragShadowBuilder shadowBuilder,
            Object myLocalState, int flags) {
        if (ViewDebug.DEBUG_DRAG) {
            Log.d(VIEW_LOG_TAG, "startDrag: data=" + data + " flags=" + flags);
        }
        boolean okay = false;

        Point shadowSize = new Point();
        Point shadowTouchPoint = new Point();
        shadowBuilder.onProvideShadowMetrics(shadowSize, shadowTouchPoint);

        if ((shadowSize.x < 0) || (shadowSize.y < 0) ||
                (shadowTouchPoint.x < 0) || (shadowTouchPoint.y < 0)) {
            throw new IllegalStateException("Drag shadow dimensions must not be negative");
        }

        if (ViewDebug.DEBUG_DRAG) {
            Log.d(VIEW_LOG_TAG, "drag shadow: width=" + shadowSize.x + " height=" + shadowSize.y
                    + " shadowX=" + shadowTouchPoint.x + " shadowY=" + shadowTouchPoint.y);
        }
        Surface surface = new Surface();
        try {
            IBinder token = mAttachInfo.mSession.prepareDrag(mAttachInfo.mWindow,
                    flags, shadowSize.x, shadowSize.y, surface);
            if (ViewDebug.DEBUG_DRAG) Log.d(VIEW_LOG_TAG, "prepareDrag returned token=" + token
                    + " surface=" + surface);
            if (token != null) {
                Canvas canvas = surface.lockCanvas(null);
                try {
                    canvas.drawColor(0, PorterDuff.Mode.CLEAR);
                    shadowBuilder.onDrawShadow(canvas);
                } finally {
                    surface.unlockCanvasAndPost(canvas);
                }

                final ViewRoot root = getViewRoot();

                // Cache the local state object for delivery with DragEvents
                root.setLocalDragState(myLocalState);

                // repurpose 'shadowSize' for the last touch point
                root.getLastTouchPoint(shadowSize);

                okay = mAttachInfo.mSession.performDrag(mAttachInfo.mWindow, token,
                        shadowSize.x, shadowSize.y,
                        shadowTouchPoint.x, shadowTouchPoint.y, data);
                if (ViewDebug.DEBUG_DRAG) Log.d(VIEW_LOG_TAG, "performDrag returned " + okay);
            }
        } catch (Exception e) {
            Log.e(VIEW_LOG_TAG, "Unable to initiate drag", e);
            surface.destroy();
        }

        return okay;
    }

    /**
     * Drag-and-drop event dispatch.  The event.getAction() verb is one of the DragEvent
     * constants DRAG_STARTED_EVENT, DRAG_EVENT, DROP_EVENT, and DRAG_ENDED_EVENT.
     *
     * For DRAG_STARTED_EVENT, event.getClipDescription() describes the content
     * being dragged.  onDragEvent() should return 'true' if the view can handle
     * a drop of that content.  A view that returns 'false' here will receive no
     * further calls to onDragEvent() about the drag/drop operation.
     *
     * For DRAG_ENTERED, event.getClipDescription() describes the content being
     * dragged.  This will be the same content description passed in the
     * DRAG_STARTED_EVENT invocation.
     *
     * For DRAG_EXITED, event.getClipDescription() describes the content being
     * dragged.  This will be the same content description passed in the
     * DRAG_STARTED_EVENT invocation.  The view should return to its approriate
     * drag-acceptance visual state.
     *
     * For DRAG_LOCATION_EVENT, event.getX() and event.getY() give the location in View
     * coordinates of the current drag point.  The view must return 'true' if it
     * can accept a drop of the current drag content, false otherwise.
     *
     * For DROP_EVENT, event.getX() and event.getY() give the location of the drop
     * within the view; also, event.getClipData() returns the full data payload
     * being dropped.  The view should return 'true' if it consumed the dropped
     * content, 'false' if it did not.
     *
     * For DRAG_ENDED_EVENT, the 'event' argument may be null.  The view should return
     * to its normal visual state.
     */
    public boolean onDragEvent(DragEvent event) {
        return false;
    }

    /**
     * Views typically don't need to override dispatchDragEvent(); it just calls
     * onDragEvent(event) and passes the result up appropriately.
     */
    public boolean dispatchDragEvent(DragEvent event) {
        if (mOnDragListener != null && (mViewFlags & ENABLED_MASK) == ENABLED
                && mOnDragListener.onDrag(this, event)) {
            return true;
        }
        return onDragEvent(event);
    }

    /**
     * This needs to be a better API (NOT ON VIEW) before it is exposed.  If
     * it is ever exposed at all.
     * @hide
     */
    public void onCloseSystemDialogs(String reason) {
    }

    /**
     * Given a Drawable whose bounds have been set to draw into this view,
     * update a Region being computed for {@link #gatherTransparentRegion} so
     * that any non-transparent parts of the Drawable are removed from the
     * given transparent region.
     *
     * @param dr The Drawable whose transparency is to be applied to the region.
     * @param region A Region holding the current transparency information,
     * where any parts of the region that are set are considered to be
     * transparent.  On return, this region will be modified to have the
     * transparency information reduced by the corresponding parts of the
     * Drawable that are not transparent.
     * {@hide}
     */
    public void applyDrawableToTransparentRegion(Drawable dr, Region region) {
        if (DBG) {
            Log.i("View", "Getting transparent region for: " + this);
        }
        final Region r = dr.getTransparentRegion();
        final Rect db = dr.getBounds();
        final AttachInfo attachInfo = mAttachInfo;
        if (r != null && attachInfo != null) {
            final int w = getRight()-getLeft();
            final int h = getBottom()-getTop();
            if (db.left > 0) {
                //Log.i("VIEW", "Drawable left " + db.left + " > view 0");
                r.op(0, 0, db.left, h, Region.Op.UNION);
            }
            if (db.right < w) {
                //Log.i("VIEW", "Drawable right " + db.right + " < view " + w);
                r.op(db.right, 0, w, h, Region.Op.UNION);
            }
            if (db.top > 0) {
                //Log.i("VIEW", "Drawable top " + db.top + " > view 0");
                r.op(0, 0, w, db.top, Region.Op.UNION);
            }
            if (db.bottom < h) {
                //Log.i("VIEW", "Drawable bottom " + db.bottom + " < view " + h);
                r.op(0, db.bottom, w, h, Region.Op.UNION);
            }
            final int[] location = attachInfo.mTransparentLocation;
            getLocationInWindow(location);
            r.translate(location[0], location[1]);
            region.op(r, Region.Op.INTERSECT);
        } else {
            region.op(db, Region.Op.DIFFERENCE);
        }
    }

    private void postCheckForLongClick(int delayOffset) {
        mHasPerformedLongPress = false;

        if (mPendingCheckForLongPress == null) {
            mPendingCheckForLongPress = new CheckForLongPress();
        }
        mPendingCheckForLongPress.rememberWindowAttachCount();
        postDelayed(mPendingCheckForLongPress,
                ViewConfiguration.getLongPressTimeout() - delayOffset);
    }

    /**
     * Inflate a view from an XML resource.  This convenience method wraps the {@link
     * LayoutInflater} class, which provides a full range of options for view inflation.
     *
     * @param context The Context object for your activity or application.
     * @param resource The resource ID to inflate
     * @param root A view group that will be the parent.  Used to properly inflate the
     * layout_* parameters.
     * @see LayoutInflater
     */
    public static View inflate(Context context, int resource, ViewGroup root) {
        LayoutInflater factory = LayoutInflater.from(context);
        return factory.inflate(resource, root);
    }

    /**
     * Scroll the view with standard behavior for scrolling beyond the normal
     * content boundaries. Views that call this method should override
     * {@link #onOverScrolled(int, int, boolean, boolean)} to respond to the
     * results of an over-scroll operation.
     *
     * Views can use this method to handle any touch or fling-based scrolling.
     *
     * @param deltaX Change in X in pixels
     * @param deltaY Change in Y in pixels
     * @param scrollX Current X scroll value in pixels before applying deltaX
     * @param scrollY Current Y scroll value in pixels before applying deltaY
     * @param scrollRangeX Maximum content scroll range along the X axis
     * @param scrollRangeY Maximum content scroll range along the Y axis
     * @param maxOverScrollX Number of pixels to overscroll by in either direction
     *          along the X axis.
     * @param maxOverScrollY Number of pixels to overscroll by in either direction
     *          along the Y axis.
     * @param isTouchEvent true if this scroll operation is the result of a touch event.
     * @return true if scrolling was clamped to an over-scroll boundary along either
     *          axis, false otherwise.
     */
    protected boolean overScrollBy(int deltaX, int deltaY,
            int scrollX, int scrollY,
            int scrollRangeX, int scrollRangeY,
            int maxOverScrollX, int maxOverScrollY,
            boolean isTouchEvent) {
        final int overScrollMode = mOverScrollMode;
        final boolean canScrollHorizontal =
                computeHorizontalScrollRange() > computeHorizontalScrollExtent();
        final boolean canScrollVertical =
                computeVerticalScrollRange() > computeVerticalScrollExtent();
        final boolean overScrollHorizontal = overScrollMode == OVER_SCROLL_ALWAYS ||
                (overScrollMode == OVER_SCROLL_IF_CONTENT_SCROLLS && canScrollHorizontal);
        final boolean overScrollVertical = overScrollMode == OVER_SCROLL_ALWAYS ||
                (overScrollMode == OVER_SCROLL_IF_CONTENT_SCROLLS && canScrollVertical);

        int newScrollX = scrollX + deltaX;
        if (!overScrollHorizontal) {
            maxOverScrollX = 0;
        }

        int newScrollY = scrollY + deltaY;
        if (!overScrollVertical) {
            maxOverScrollY = 0;
        }

        // Clamp values if at the limits and record
        final int left = -maxOverScrollX;
        final int right = maxOverScrollX + scrollRangeX;
        final int top = -maxOverScrollY;
        final int bottom = maxOverScrollY + scrollRangeY;

        boolean clampedX = false;
        if (newScrollX > right) {
            newScrollX = right;
            clampedX = true;
        } else if (newScrollX < left) {
            newScrollX = left;
            clampedX = true;
        }

        boolean clampedY = false;
        if (newScrollY > bottom) {
            newScrollY = bottom;
            clampedY = true;
        } else if (newScrollY < top) {
            newScrollY = top;
            clampedY = true;
        }

        onOverScrolled(newScrollX, newScrollY, clampedX, clampedY);

        return clampedX || clampedY;
    }

    /**
     * Called by {@link #overScrollBy(int, int, int, int, int, int, int, int, boolean)} to
     * respond to the results of an over-scroll operation.
     *
     * @param scrollX New X scroll value in pixels
     * @param scrollY New Y scroll value in pixels
     * @param clampedX True if scrollX was clamped to an over-scroll boundary
     * @param clampedY True if scrollY was clamped to an over-scroll boundary
     */
    protected void onOverScrolled(int scrollX, int scrollY,
            boolean clampedX, boolean clampedY) {
        // Intentionally empty.
    }

    /**
     * Returns the over-scroll mode for this view. The result will be
     * one of {@link #OVER_SCROLL_ALWAYS} (default), {@link #OVER_SCROLL_IF_CONTENT_SCROLLS}
     * (allow over-scrolling only if the view content is larger than the container),
     * or {@link #OVER_SCROLL_NEVER}.
     *
     * @return This view's over-scroll mode.
     */
    public int getOverScrollMode() {
        return mOverScrollMode;
    }

    /**
     * Set the over-scroll mode for this view. Valid over-scroll modes are
     * {@link #OVER_SCROLL_ALWAYS} (default), {@link #OVER_SCROLL_IF_CONTENT_SCROLLS}
     * (allow over-scrolling only if the view content is larger than the container),
     * or {@link #OVER_SCROLL_NEVER}.
     *
     * Setting the over-scroll mode of a view will have an effect only if the
     * view is capable of scrolling.
     *
     * @param overScrollMode The new over-scroll mode for this view.
     */
    public void setOverScrollMode(int overScrollMode) {
        if (overScrollMode != OVER_SCROLL_ALWAYS &&
                overScrollMode != OVER_SCROLL_IF_CONTENT_SCROLLS &&
                overScrollMode != OVER_SCROLL_NEVER) {
            throw new IllegalArgumentException("Invalid overscroll mode " + overScrollMode);
        }
        mOverScrollMode = overScrollMode;
    }

    /**
     * A MeasureSpec encapsulates the layout requirements passed from parent to child.
     * Each MeasureSpec represents a requirement for either the width or the height.
     * A MeasureSpec is comprised of a size and a mode. There are three possible
     * modes:
     * <dl>
     * <dt>UNSPECIFIED</dt>
     * <dd>
     * The parent has not imposed any constraint on the child. It can be whatever size
     * it wants.
     * </dd>
     *
     * <dt>EXACTLY</dt>
     * <dd>
     * The parent has determined an exact size for the child. The child is going to be
     * given those bounds regardless of how big it wants to be.
     * </dd>
     *
     * <dt>AT_MOST</dt>
     * <dd>
     * The child can be as large as it wants up to the specified size.
     * </dd>
     * </dl>
     *
     * MeasureSpecs are implemented as ints to reduce object allocation. This class
     * is provided to pack and unpack the &lt;size, mode&gt; tuple into the int.
     */
    public static class MeasureSpec {
        private static final int MODE_SHIFT = 30;
        private static final int MODE_MASK  = 0x3 << MODE_SHIFT;

        /**
         * Measure specification mode: The parent has not imposed any constraint
         * on the child. It can be whatever size it wants.
         */
        public static final int UNSPECIFIED = 0 << MODE_SHIFT;

        /**
         * Measure specification mode: The parent has determined an exact size
         * for the child. The child is going to be given those bounds regardless
         * of how big it wants to be.
         */
        public static final int EXACTLY     = 1 << MODE_SHIFT;

        /**
         * Measure specification mode: The child can be as large as it wants up
         * to the specified size.
         */
        public static final int AT_MOST     = 2 << MODE_SHIFT;

        /**
         * Creates a measure specification based on the supplied size and mode.
         *
         * The mode must always be one of the following:
         * <ul>
         *  <li>{@link android.view.View.MeasureSpec#UNSPECIFIED}</li>
         *  <li>{@link android.view.View.MeasureSpec#EXACTLY}</li>
         *  <li>{@link android.view.View.MeasureSpec#AT_MOST}</li>
         * </ul>
         *
         * @param size the size of the measure specification
         * @param mode the mode of the measure specification
         * @return the measure specification based on size and mode
         */
        public static int makeMeasureSpec(int size, int mode) {
            return size + mode;
        }

        /**
         * Extracts the mode from the supplied measure specification.
         *
         * @param measureSpec the measure specification to extract the mode from
         * @return {@link android.view.View.MeasureSpec#UNSPECIFIED},
         *         {@link android.view.View.MeasureSpec#AT_MOST} or
         *         {@link android.view.View.MeasureSpec#EXACTLY}
         */
        public static int getMode(int measureSpec) {
            return (measureSpec & MODE_MASK);
        }

        /**
         * Extracts the size from the supplied measure specification.
         *
         * @param measureSpec the measure specification to extract the size from
         * @return the size in pixels defined in the supplied measure specification
         */
        public static int getSize(int measureSpec) {
            return (measureSpec & ~MODE_MASK);
        }

        /**
         * Returns a String representation of the specified measure
         * specification.
         *
         * @param measureSpec the measure specification to convert to a String
         * @return a String with the following format: "MeasureSpec: MODE SIZE"
         */
        public static String toString(int measureSpec) {
            int mode = getMode(measureSpec);
            int size = getSize(measureSpec);

            StringBuilder sb = new StringBuilder("MeasureSpec: ");

            if (mode == UNSPECIFIED)
                sb.append("UNSPECIFIED ");
            else if (mode == EXACTLY)
                sb.append("EXACTLY ");
            else if (mode == AT_MOST)
                sb.append("AT_MOST ");
            else
                sb.append(mode).append(" ");

            sb.append(size);
            return sb.toString();
        }
    }

    class CheckForLongPress implements Runnable {

        private int mOriginalWindowAttachCount;

        public void run() {
            if (isPressed() && (mParent != null)
                    && mOriginalWindowAttachCount == mWindowAttachCount) {
                if (performLongClick()) {
                    mHasPerformedLongPress = true;
                }
            }
        }

        public void rememberWindowAttachCount() {
            mOriginalWindowAttachCount = mWindowAttachCount;
        }
    }

    private final class CheckForTap implements Runnable {
        public void run() {
            mPrivateFlags &= ~PREPRESSED;
            mPrivateFlags |= PRESSED;
            refreshDrawableState();
            if ((mViewFlags & LONG_CLICKABLE) == LONG_CLICKABLE) {
                postCheckForLongClick(ViewConfiguration.getTapTimeout());
            }
        }
    }

    private final class PerformClick implements Runnable {
        public void run() {
            performClick();
        }
    }

    /** @hide */
    public void hackTurnOffWindowResizeAnim(boolean off) {
        mAttachInfo.mTurnOffWindowResizeAnim = off;
    }

    /**
     * Interface definition for a callback to be invoked when a key event is
     * dispatched to this view. The callback will be invoked before the key
     * event is given to the view.
     */
    public interface OnKeyListener {
        /**
         * Called when a key is dispatched to a view. This allows listeners to
         * get a chance to respond before the target view.
         *
         * @param v The view the key has been dispatched to.
         * @param keyCode The code for the physical key that was pressed
         * @param event The KeyEvent object containing full information about
         *        the event.
         * @return True if the listener has consumed the event, false otherwise.
         */
        boolean onKey(View v, int keyCode, KeyEvent event);
    }

    /**
     * Interface definition for a callback to be invoked when a touch event is
     * dispatched to this view. The callback will be invoked before the touch
     * event is given to the view.
     */
    public interface OnTouchListener {
        /**
         * Called when a touch event is dispatched to a view. This allows listeners to
         * get a chance to respond before the target view.
         *
         * @param v The view the touch event has been dispatched to.
         * @param event The MotionEvent object containing full information about
         *        the event.
         * @return True if the listener has consumed the event, false otherwise.
         */
        boolean onTouch(View v, MotionEvent event);
    }

    /**
     * Interface definition for a callback to be invoked when a view has been clicked and held.
     */
    public interface OnLongClickListener {
        /**
         * Called when a view has been clicked and held.
         *
         * @param v The view that was clicked and held.
         *
         * @return true if the callback consumed the long click, false otherwise.
         */
        boolean onLongClick(View v);
    }

    /**
     * Interface definition for a callback to be invoked when a drag is being dispatched
     * to this view.  The callback will be invoked before the hosting view's own
     * onDrag(event) method.  If the listener wants to fall back to the hosting view's
     * onDrag(event) behavior, it should return 'false' from this callback.
     */
    public interface OnDragListener {
        /**
         * Called when a drag event is dispatched to a view. This allows listeners
         * to get a chance to override base View behavior.
         *
         * @param v The view the drag has been dispatched to.
         * @param event The DragEvent object containing full information
         *        about the event.
         * @return true if the listener consumed the DragEvent, false in order to fall
         *         back to the view's default handling.
         */
        boolean onDrag(View v, DragEvent event);
    }

    /**
     * Interface definition for a callback to be invoked when the focus state of
     * a view changed.
     */
    public interface OnFocusChangeListener {
        /**
         * Called when the focus state of a view has changed.
         *
         * @param v The view whose state has changed.
         * @param hasFocus The new focus state of v.
         */
        void onFocusChange(View v, boolean hasFocus);
    }

    /**
     * Interface definition for a callback to be invoked when a view is clicked.
     */
    public interface OnClickListener {
        /**
         * Called when a view has been clicked.
         *
         * @param v The view that was clicked.
         */
        void onClick(View v);
    }

    /**
     * Interface definition for a callback to be invoked when the context menu
     * for this view is being built.
     */
    public interface OnCreateContextMenuListener {
        /**
         * Called when the context menu for this view is being built. It is not
         * safe to hold onto the menu after this method returns.
         *
         * @param menu The context menu that is being built
         * @param v The view for which the context menu is being built
         * @param menuInfo Extra information about the item for which the
         *            context menu should be shown. This information will vary
         *            depending on the class of v.
         */
        void onCreateContextMenu(ContextMenu menu, View v, ContextMenuInfo menuInfo);
    }

    /**
     * Interface definition for a callback to be invoked when the status bar changes
     * visibility.
     *
     * @see #setOnSystemUiVisibilityChangeListener
     */
    public interface OnSystemUiVisibilityChangeListener {
        /**
         * Called when the status bar changes visibility because of a call to
         * {@link #setSystemUiVisibility}.
         *
         * @param visibility {@link #STATUS_BAR_VISIBLE} or {@link #STATUS_BAR_HIDDEN}.
         */
        public void onSystemUiVisibilityChange(int visibility);
    }

    private final class UnsetPressedState implements Runnable {
        public void run() {
            setPressed(false);
        }
    }

    /**
     * Base class for derived classes that want to save and restore their own
     * state in {@link android.view.View#onSaveInstanceState()}.
     */
    public static class BaseSavedState extends AbsSavedState {
        /**
         * Constructor used when reading from a parcel. Reads the state of the superclass.
         *
         * @param source
         */
        public BaseSavedState(Parcel source) {
            super(source);
        }

        /**
         * Constructor called by derived classes when creating their SavedState objects
         *
         * @param superState The state of the superclass of this view
         */
        public BaseSavedState(Parcelable superState) {
            super(superState);
        }

        public static final Parcelable.Creator<BaseSavedState> CREATOR =
                new Parcelable.Creator<BaseSavedState>() {
            public BaseSavedState createFromParcel(Parcel in) {
                return new BaseSavedState(in);
            }

            public BaseSavedState[] newArray(int size) {
                return new BaseSavedState[size];
            }
        };
    }

    /**
     * A set of information given to a view when it is attached to its parent
     * window.
     */
    static class AttachInfo {
        interface Callbacks {
            void playSoundEffect(int effectId);
            boolean performHapticFeedback(int effectId, boolean always);
        }

        /**
         * InvalidateInfo is used to post invalidate(int, int, int, int) messages
         * to a Handler. This class contains the target (View) to invalidate and
         * the coordinates of the dirty rectangle.
         *
         * For performance purposes, this class also implements a pool of up to
         * POOL_LIMIT objects that get reused. This reduces memory allocations
         * whenever possible.
         */
        static class InvalidateInfo implements Poolable<InvalidateInfo> {
            private static final int POOL_LIMIT = 10;
            private static final Pool<InvalidateInfo> sPool = Pools.synchronizedPool(
                    Pools.finitePool(new PoolableManager<InvalidateInfo>() {
                        public InvalidateInfo newInstance() {
                            return new InvalidateInfo();
                        }

                        public void onAcquired(InvalidateInfo element) {
                        }

                        public void onReleased(InvalidateInfo element) {
                        }
                    }, POOL_LIMIT)
            );

            private InvalidateInfo mNext;

            View target;

            int left;
            int top;
            int right;
            int bottom;

            public void setNextPoolable(InvalidateInfo element) {
                mNext = element;
            }

            public InvalidateInfo getNextPoolable() {
                return mNext;
            }

            static InvalidateInfo acquire() {
                return sPool.acquire();
            }

            void release() {
                sPool.release(this);
            }
        }

        final IWindowSession mSession;

        final IWindow mWindow;

        final IBinder mWindowToken;

        final Callbacks mRootCallbacks;

        Canvas mHardwareCanvas;

        /**
         * The top view of the hierarchy.
         */
        View mRootView;

        IBinder mPanelParentWindowToken;
        Surface mSurface;

        boolean mHardwareAccelerated;
        boolean mHardwareAccelerationRequested;
        HardwareRenderer mHardwareRenderer;

        /**
         * Scale factor used by the compatibility mode
         */
        float mApplicationScale;

        /**
         * Indicates whether the application is in compatibility mode
         */
        boolean mScalingRequired;

        /**
         * If set, ViewRoot doesn't use its lame animation for when the window resizes.
         */
        boolean mTurnOffWindowResizeAnim;

        /**
         * Left position of this view's window
         */
        int mWindowLeft;

        /**
         * Top position of this view's window
         */
        int mWindowTop;

        /**
         * Indicates whether views need to use 32-bit drawing caches
         */
        boolean mUse32BitDrawingCache;

        /**
         * For windows that are full-screen but using insets to layout inside
         * of the screen decorations, these are the current insets for the
         * content of the window.
         */
        final Rect mContentInsets = new Rect();

        /**
         * For windows that are full-screen but using insets to layout inside
         * of the screen decorations, these are the current insets for the
         * actual visible parts of the window.
         */
        final Rect mVisibleInsets = new Rect();

        /**
         * The internal insets given by this window.  This value is
         * supplied by the client (through
         * {@link ViewTreeObserver.OnComputeInternalInsetsListener}) and will
         * be given to the window manager when changed to be used in laying
         * out windows behind it.
         */
        final ViewTreeObserver.InternalInsetsInfo mGivenInternalInsets
                = new ViewTreeObserver.InternalInsetsInfo();

        /**
         * All views in the window's hierarchy that serve as scroll containers,
         * used to determine if the window can be resized or must be panned
         * to adjust for a soft input area.
         */
        final ArrayList<View> mScrollContainers = new ArrayList<View>();

        final KeyEvent.DispatcherState mKeyDispatchState
                = new KeyEvent.DispatcherState();

        /**
         * Indicates whether the view's window currently has the focus.
         */
        boolean mHasWindowFocus;

        /**
         * The current visibility of the window.
         */
        int mWindowVisibility;

        /**
         * Indicates the time at which drawing started to occur.
         */
        long mDrawingTime;

        /**
         * Indicates whether or not ignoring the DIRTY_MASK flags.
         */
        boolean mIgnoreDirtyState;

        /**
         * Indicates whether the view's window is currently in touch mode.
         */
        boolean mInTouchMode;

        /**
         * Indicates that ViewRoot should trigger a global layout change
         * the next time it performs a traversal
         */
        boolean mRecomputeGlobalAttributes;

        /**
         * Set during a traveral if any views want to keep the screen on.
         */
        boolean mKeepScreenOn;

        /**
         * Bitwise-or of all of the values that views have passed to setSystemUiVisibility().
         */
        int mSystemUiVisibility;

        /**
         * True if a view in this hierarchy has an OnSystemUiVisibilityChangeListener
         * attached.
         */
        boolean mHasSystemUiListeners;

        /**
         * Set if the visibility of any views has changed.
         */
        boolean mViewVisibilityChanged;

        /**
         * Set to true if a view has been scrolled.
         */
        boolean mViewScrollChanged;

        /**
         * Global to the view hierarchy used as a temporary for dealing with
         * x/y points in the transparent region computations.
         */
        final int[] mTransparentLocation = new int[2];

        /**
         * Global to the view hierarchy used as a temporary for dealing with
         * x/y points in the ViewGroup.invalidateChild implementation.
         */
        final int[] mInvalidateChildLocation = new int[2];


        /**
         * Global to the view hierarchy used as a temporary for dealing with
         * x/y location when view is transformed.
         */
        final float[] mTmpTransformLocation = new float[2];

        /**
         * The view tree observer used to dispatch global events like
         * layout, pre-draw, touch mode change, etc.
         */
        final ViewTreeObserver mTreeObserver = new ViewTreeObserver();

        /**
         * A Canvas used by the view hierarchy to perform bitmap caching.
         */
        Canvas mCanvas;

        /**
         * A Handler supplied by a view's {@link android.view.ViewRoot}. This
         * handler can be used to pump events in the UI events queue.
         */
        final Handler mHandler;

        /**
         * Identifier for messages requesting the view to be invalidated.
         * Such messages should be sent to {@link #mHandler}.
         */
        static final int INVALIDATE_MSG = 0x1;

        /**
         * Identifier for messages requesting the view to invalidate a region.
         * Such messages should be sent to {@link #mHandler}.
         */
        static final int INVALIDATE_RECT_MSG = 0x2;

        /**
         * Temporary for use in computing invalidate rectangles while
         * calling up the hierarchy.
         */
        final Rect mTmpInvalRect = new Rect();

        /**
         * Temporary for use in computing hit areas with transformed views
         */
        final RectF mTmpTransformRect = new RectF();

        /**
         * Temporary list for use in collecting focusable descendents of a view.
         */
        final ArrayList<View> mFocusablesTempList = new ArrayList<View>(24);

        /**
         * Creates a new set of attachment information with the specified
         * events handler and thread.
         *
         * @param handler the events handler the view must use
         */
        AttachInfo(IWindowSession session, IWindow window,
                Handler handler, Callbacks effectPlayer) {
            mSession = session;
            mWindow = window;
            mWindowToken = window.asBinder();
            mHandler = handler;
            mRootCallbacks = effectPlayer;
        }
    }

    /**
     * <p>ScrollabilityCache holds various fields used by a View when scrolling
     * is supported. This avoids keeping too many unused fields in most
     * instances of View.</p>
     */
    private static class ScrollabilityCache implements Runnable {

        /**
         * Scrollbars are not visible
         */
        public static final int OFF = 0;

        /**
         * Scrollbars are visible
         */
        public static final int ON = 1;

        /**
         * Scrollbars are fading away
         */
        public static final int FADING = 2;

        public boolean fadeScrollBars;

        public int fadingEdgeLength;
        public int scrollBarDefaultDelayBeforeFade;
        public int scrollBarFadeDuration;

        public int scrollBarSize;
        public ScrollBarDrawable scrollBar;
        public float[] interpolatorValues;
        public View host;

        public final Paint paint;
        public final Matrix matrix;
        public Shader shader;

        public final Interpolator scrollBarInterpolator = new Interpolator(1, 2);

        private static final float[] OPAQUE = { 255 };
        private static final float[] TRANSPARENT = { 0.0f };

        /**
         * When fading should start. This time moves into the future every time
         * a new scroll happens. Measured based on SystemClock.uptimeMillis()
         */
        public long fadeStartTime;


        /**
         * The current state of the scrollbars: ON, OFF, or FADING
         */
        public int state = OFF;

        private int mLastColor;

        public ScrollabilityCache(ViewConfiguration configuration, View host) {
            fadingEdgeLength = configuration.getScaledFadingEdgeLength();
            scrollBarSize = configuration.getScaledScrollBarSize();
            scrollBarDefaultDelayBeforeFade = ViewConfiguration.getScrollDefaultDelay();
            scrollBarFadeDuration = ViewConfiguration.getScrollBarFadeDuration();

            paint = new Paint();
            matrix = new Matrix();
            // use use a height of 1, and then wack the matrix each time we
            // actually use it.
            shader = new LinearGradient(0, 0, 0, 1, 0xFF000000, 0, Shader.TileMode.CLAMP);

            paint.setShader(shader);
            paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.DST_OUT));
            this.host = host;
        }

        public void setFadeColor(int color) {
            if (color != 0 && color != mLastColor) {
                mLastColor = color;
                color |= 0xFF000000;

                shader = new LinearGradient(0, 0, 0, 1, color | 0xFF000000,
                        color & 0x00FFFFFF, Shader.TileMode.CLAMP);

                paint.setShader(shader);
                // Restore the default transfer mode (src_over)
                paint.setXfermode(null);
            }
        }

        public void run() {
            long now = AnimationUtils.currentAnimationTimeMillis();
            if (now >= fadeStartTime) {

                // the animation fades the scrollbars out by changing
                // the opacity (alpha) from fully opaque to fully
                // transparent
                int nextFrame = (int) now;
                int framesCount = 0;

                Interpolator interpolator = scrollBarInterpolator;

                // Start opaque
                interpolator.setKeyFrame(framesCount++, nextFrame, OPAQUE);

                // End transparent
                nextFrame += scrollBarFadeDuration;
                interpolator.setKeyFrame(framesCount, nextFrame, TRANSPARENT);

                state = FADING;

                // Kick off the fade animation
                host.invalidate(true);
            }
        }

    }
}