android/widget/PopupWindow.java

/*
 * Copyright (C) 2007 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.widget;

import com.android.internal.R;

import android.content.Context;
import android.content.res.Resources;
import android.content.res.TypedArray;
import android.graphics.PixelFormat;
import android.graphics.Rect;
import android.graphics.drawable.Drawable;
import android.graphics.drawable.StateListDrawable;
import android.os.IBinder;
import android.util.AttributeSet;
import android.util.DisplayMetrics;
import android.view.Gravity;
import android.view.KeyEvent;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnTouchListener;
import android.view.ViewGroup;
import android.view.ViewTreeObserver;
import android.view.ViewTreeObserver.OnScrollChangedListener;
import android.view.WindowManager;

import java.lang.ref.WeakReference;

/**
 * <p>A popup window that can be used to display an arbitrary view. The popup
 * windows is a floating container that appears on top of the current
 * activity.</p>
 *
 * @see android.widget.AutoCompleteTextView
 * @see android.widget.Spinner
 */
public class PopupWindow {
    /**
     * Mode for {@link #setInputMethodMode(int)}: the requirements for the
     * input method should be based on the focusability of the popup.  That is
     * if it is focusable than it needs to work with the input method, else
     * it doesn't.
     */
    public static final int INPUT_METHOD_FROM_FOCUSABLE = 0;

    /**
     * Mode for {@link #setInputMethodMode(int)}: this popup always needs to
     * work with an input method, regardless of whether it is focusable.  This
     * means that it will always be displayed so that the user can also operate
     * the input method while it is shown.
     */
    public static final int INPUT_METHOD_NEEDED = 1;

    /**
     * Mode for {@link #setInputMethodMode(int)}: this popup never needs to
     * work with an input method, regardless of whether it is focusable.  This
     * means that it will always be displayed to use as much space on the
     * screen as needed, regardless of whether this covers the input method.
     */
    public static final int INPUT_METHOD_NOT_NEEDED = 2;

    private Context mContext;
    private WindowManager mWindowManager;

    private boolean mIsShowing;
    private boolean mIsDropdown;

    private View mContentView;
    private View mPopupView;
    private boolean mFocusable;
    private int mInputMethodMode = INPUT_METHOD_FROM_FOCUSABLE;
    private int mSoftInputMode;
    private boolean mTouchable = true;
    private boolean mOutsideTouchable = false;
    private boolean mClippingEnabled = true;
    private boolean mSplitTouchEnabled;
    private boolean mLayoutInScreen;
    private boolean mClipToScreen;

    private OnTouchListener mTouchInterceptor;

    private int mWidthMode;
    private int mWidth;
    private int mLastWidth;
    private int mHeightMode;
    private int mHeight;
    private int mLastHeight;

    private int mPopupWidth;
    private int mPopupHeight;

    private int[] mDrawingLocation = new int[2];
    private int[] mScreenLocation = new int[2];
    private Rect mTempRect = new Rect();

    private Drawable mBackground;
    private Drawable mAboveAnchorBackgroundDrawable;
    private Drawable mBelowAnchorBackgroundDrawable;

    private boolean mAboveAnchor;
    private int mWindowLayoutType = WindowManager.LayoutParams.TYPE_APPLICATION_PANEL;

    private OnDismissListener mOnDismissListener;
    private boolean mIgnoreCheekPress = false;

    private int mAnimationStyle = -1;

    private static final int[] ABOVE_ANCHOR_STATE_SET = new int[] {
        com.android.internal.R.attr.state_above_anchor
    };

    private WeakReference<View> mAnchor;
    private OnScrollChangedListener mOnScrollChangedListener =
        new OnScrollChangedListener() {
            public void onScrollChanged() {
                View anchor = mAnchor != null ? mAnchor.get() : null;
                if (anchor != null && mPopupView != null) {
                    WindowManager.LayoutParams p = (WindowManager.LayoutParams)
                            mPopupView.getLayoutParams();

                    updateAboveAnchor(findDropDownPosition(anchor, p, mAnchorXoff, mAnchorYoff));
                    update(p.x, p.y, -1, -1, true);
                }
            }
        };
    private int mAnchorXoff, mAnchorYoff;

    /**
     * <p>Create a new empty, non focusable popup window of dimension (0,0).</p>
     *
     * <p>The popup does provide a background.</p>
     */
    public PopupWindow(Context context) {
        this(context, null);
    }

    /**
     * <p>Create a new empty, non focusable popup window of dimension (0,0).</p>
     *
     * <p>The popup does provide a background.</p>
     */
    public PopupWindow(Context context, AttributeSet attrs) {
        this(context, attrs, com.android.internal.R.attr.popupWindowStyle);
    }

    /**
     * <p>Create a new empty, non focusable popup window of dimension (0,0).</p>
     *
     * <p>The popup does provide a background.</p>
     */
    public PopupWindow(Context context, AttributeSet attrs, int defStyle) {
        this(context, attrs, defStyle, 0);
    }

    /**
     * <p>Create a new, empty, non focusable popup window of dimension (0,0).</p>
     *
     * <p>The popup does not provide a background.</p>
     */
    public PopupWindow(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
        mContext = context;
        mWindowManager = (WindowManager)context.getSystemService(Context.WINDOW_SERVICE);

        TypedArray a =
            context.obtainStyledAttributes(
                attrs, com.android.internal.R.styleable.PopupWindow, defStyleAttr, defStyleRes);

        mBackground = a.getDrawable(R.styleable.PopupWindow_popupBackground);

        final int animStyle = a.getResourceId(R.styleable.PopupWindow_popupAnimationStyle, -1);
        mAnimationStyle = animStyle == com.android.internal.R.style.Animation_PopupWindow ? -1 :
                animStyle;

        // If this is a StateListDrawable, try to find and store the drawable to be
        // used when the drop-down is placed above its anchor view, and the one to be
        // used when the drop-down is placed below its anchor view. We extract
        // the drawables ourselves to work around a problem with using refreshDrawableState
        // that it will take into account the padding of all drawables specified in a
        // StateListDrawable, thus adding superfluous padding to drop-down views.
        //
        // We assume a StateListDrawable will have a drawable for ABOVE_ANCHOR_STATE_SET and
        // at least one other drawable, intended for the 'below-anchor state'.
        if (mBackground instanceof StateListDrawable) {
            StateListDrawable background = (StateListDrawable) mBackground;

            // Find the above-anchor view - this one's easy, it should be labeled as such.
            int aboveAnchorStateIndex = background.getStateDrawableIndex(ABOVE_ANCHOR_STATE_SET);

            // Now, for the below-anchor view, look for any other drawable specified in the
            // StateListDrawable which is not for the above-anchor state and use that.
            int count = background.getStateCount();
            int belowAnchorStateIndex = -1;
            for (int i = 0; i < count; i++) {
                if (i != aboveAnchorStateIndex) {
                    belowAnchorStateIndex = i;
                    break;
                }
            }

            // Store the drawables we found, if we found them. Otherwise, set them both
            // to null so that we'll just use refreshDrawableState.
            if (aboveAnchorStateIndex != -1 && belowAnchorStateIndex != -1) {
                mAboveAnchorBackgroundDrawable = background.getStateDrawable(aboveAnchorStateIndex);
                mBelowAnchorBackgroundDrawable = background.getStateDrawable(belowAnchorStateIndex);
            } else {
                mBelowAnchorBackgroundDrawable = null;
                mAboveAnchorBackgroundDrawable = null;
            }
        }

        a.recycle();
    }

    /**
     * <p>Create a new empty, non focusable popup window of dimension (0,0).</p>
     *
     * <p>The popup does not provide any background. This should be handled
     * by the content view.</p>
     */
    public PopupWindow() {
        this(null, 0, 0);
    }

    /**
     * <p>Create a new non focusable popup window which can display the
     * <tt>contentView</tt>. The dimension of the window are (0,0).</p>
     *
     * <p>The popup does not provide any background. This should be handled
     * by the content view.</p>
     *
     * @param contentView the popup's content
     */
    public PopupWindow(View contentView) {
        this(contentView, 0, 0);
    }

    /**
     * <p>Create a new empty, non focusable popup window. The dimension of the
     * window must be passed to this constructor.</p>
     *
     * <p>The popup does not provide any background. This should be handled
     * by the content view.</p>
     *
     * @param width the popup's width
     * @param height the popup's height
     */
    public PopupWindow(int width, int height) {
        this(null, width, height);
    }

    /**
     * <p>Create a new non focusable popup window which can display the
     * <tt>contentView</tt>. The dimension of the window must be passed to
     * this constructor.</p>
     *
     * <p>The popup does not provide any background. This should be handled
     * by the content view.</p>
     *
     * @param contentView the popup's content
     * @param width the popup's width
     * @param height the popup's height
     */
    public PopupWindow(View contentView, int width, int height) {
        this(contentView, width, height, false);
    }

    /**
     * <p>Create a new popup window which can display the <tt>contentView</tt>.
     * The dimension of the window must be passed to this constructor.</p>
     *
     * <p>The popup does not provide any background. This should be handled
     * by the content view.</p>
     *
     * @param contentView the popup's content
     * @param width the popup's width
     * @param height the popup's height
     * @param focusable true if the popup can be focused, false otherwise
     */
    public PopupWindow(View contentView, int width, int height, boolean focusable) {
        if (contentView != null) {
            mContext = contentView.getContext();
            mWindowManager = (WindowManager) mContext.getSystemService(Context.WINDOW_SERVICE);
        }
        setContentView(contentView);
        setWidth(width);
        setHeight(height);
        setFocusable(focusable);
    }

    /**
     * <p>Return the drawable used as the popup window's background.</p>
     *
     * @return the background drawable or null
     */
    public Drawable getBackground() {
        return mBackground;
    }

    /**
     * <p>Change the background drawable for this popup window. The background
     * can be set to null.</p>
     *
     * @param background the popup's background
     */
    public void setBackgroundDrawable(Drawable background) {
        mBackground = background;
    }

    /**
     * <p>Return the animation style to use the popup appears and disappears</p>
     *
     * @return the animation style to use the popup appears and disappears
     */
    public int getAnimationStyle() {
        return mAnimationStyle;
    }

    /**
     * Set the flag on popup to ignore cheek press eventt; by default this flag
     * is set to false
     * which means the pop wont ignore cheek press dispatch events.
     *
     * <p>If the popup is showing, calling this method will take effect only
     * the next time the popup is shown or through a manual call to one of
     * the {@link #update()} methods.</p>
     *
     * @see #update()
     */
    public void setIgnoreCheekPress() {
        mIgnoreCheekPress = true;
    }


    /**
     * <p>Change the animation style resource for this popup.</p>
     *
     * <p>If the popup is showing, calling this method will take effect only
     * the next time the popup is shown or through a manual call to one of
     * the {@link #update()} methods.</p>
     *
     * @param animationStyle animation style to use when the popup appears
     *      and disappears.  Set to -1 for the default animation, 0 for no
     *      animation, or a resource identifier for an explicit animation.
     *
     * @see #update()
     */
    public void setAnimationStyle(int animationStyle) {
        mAnimationStyle = animationStyle;
    }

    /**
     * <p>Return the view used as the content of the popup window.</p>
     *
     * @return a {@link android.view.View} representing the popup's content
     *
     * @see #setContentView(android.view.View)
     */
    public View getContentView() {
        return mContentView;
    }

    /**
     * <p>Change the popup's content. The content is represented by an instance
     * of {@link android.view.View}.</p>
     *
     * <p>This method has no effect if called when the popup is showing.  To
     * apply it while a popup is showing, call </p>
     *
     * @param contentView the new content for the popup
     *
     * @see #getContentView()
     * @see #isShowing()
     */
    public void setContentView(View contentView) {
        if (isShowing()) {
            return;
        }

        mContentView = contentView;

        if (mContext == null) {
            mContext = mContentView.getContext();
        }

        if (mWindowManager == null) {
            mWindowManager = (WindowManager) mContext.getSystemService(Context.WINDOW_SERVICE);
        }
    }

    /**
     * Set a callback for all touch events being dispatched to the popup
     * window.
     */
    public void setTouchInterceptor(OnTouchListener l) {
        mTouchInterceptor = l;
    }

    /**
     * <p>Indicate whether the popup window can grab the focus.</p>
     *
     * @return true if the popup is focusable, false otherwise
     *
     * @see #setFocusable(boolean)
     */
    public boolean isFocusable() {
        return mFocusable;
    }

    /**
     * <p>Changes the focusability of the popup window. When focusable, the
     * window will grab the focus from the current focused widget if the popup
     * contains a focusable {@link android.view.View}.  By default a popup
     * window is not focusable.</p>
     *
     * <p>If the popup is showing, calling this method will take effect only
     * the next time the popup is shown or through a manual call to one of
     * the {@link #update()} methods.</p>
     *
     * @param focusable true if the popup should grab focus, false otherwise.
     *
     * @see #isFocusable()
     * @see #isShowing()
     * @see #update()
     */
    public void setFocusable(boolean focusable) {
        mFocusable = focusable;
    }

    /**
     * Return the current value in {@link #setInputMethodMode(int)}.
     *
     * @see #setInputMethodMode(int)
     */
    public int getInputMethodMode() {
        return mInputMethodMode;

    }

    /**
     * Control how the popup operates with an input method: one of
     * {@link #INPUT_METHOD_FROM_FOCUSABLE}, {@link #INPUT_METHOD_NEEDED},
     * or {@link #INPUT_METHOD_NOT_NEEDED}.
     *
     * <p>If the popup is showing, calling this method will take effect only
     * the next time the popup is shown or through a manual call to one of
     * the {@link #update()} methods.</p>
     *
     * @see #getInputMethodMode()
     * @see #update()
     */
    public void setInputMethodMode(int mode) {
        mInputMethodMode = mode;
    }

    /**
     * Sets the operating mode for the soft input area.
     *
     * @param mode The desired mode, see
     *        {@link android.view.WindowManager.LayoutParams#softInputMode}
     *        for the full list
     *
     * @see android.view.WindowManager.LayoutParams#softInputMode
     * @see #getSoftInputMode()
     */
    public void setSoftInputMode(int mode) {
        mSoftInputMode = mode;
    }

    /**
     * Returns the current value in {@link #setSoftInputMode(int)}.
     *
     * @see #setSoftInputMode(int)
     * @see android.view.WindowManager.LayoutParams#softInputMode
     */
    public int getSoftInputMode() {
        return mSoftInputMode;
    }

    /**
     * <p>Indicates whether the popup window receives touch events.</p>
     *
     * @return true if the popup is touchable, false otherwise
     *
     * @see #setTouchable(boolean)
     */
    public boolean isTouchable() {
        return mTouchable;
    }

    /**
     * <p>Changes the touchability of the popup window. When touchable, the
     * window will receive touch events, otherwise touch events will go to the
     * window below it. By default the window is touchable.</p>
     *
     * <p>If the popup is showing, calling this method will take effect only
     * the next time the popup is shown or through a manual call to one of
     * the {@link #update()} methods.</p>
     *
     * @param touchable true if the popup should receive touch events, false otherwise
     *
     * @see #isTouchable()
     * @see #isShowing()
     * @see #update()
     */
    public void setTouchable(boolean touchable) {
        mTouchable = touchable;
    }

    /**
     * <p>Indicates whether the popup window will be informed of touch events
     * outside of its window.</p>
     *
     * @return true if the popup is outside touchable, false otherwise
     *
     * @see #setOutsideTouchable(boolean)
     */
    public boolean isOutsideTouchable() {
        return mOutsideTouchable;
    }

    /**
     * <p>Controls whether the pop-up will be informed of touch events outside
     * of its window.  This only makes sense for pop-ups that are touchable
     * but not focusable, which means touches outside of the window will
     * be delivered to the window behind.  The default is false.</p>
     *
     * <p>If the popup is showing, calling this method will take effect only
     * the next time the popup is shown or through a manual call to one of
     * the {@link #update()} methods.</p>
     *
     * @param touchable true if the popup should receive outside
     * touch events, false otherwise
     *
     * @see #isOutsideTouchable()
     * @see #isShowing()
     * @see #update()
     */
    public void setOutsideTouchable(boolean touchable) {
        mOutsideTouchable = touchable;
    }

    /**
     * <p>Indicates whether clipping of the popup window is enabled.</p>
     *
     * @return true if the clipping is enabled, false otherwise
     *
     * @see #setClippingEnabled(boolean)
     */
    public boolean isClippingEnabled() {
        return mClippingEnabled;
    }

    /**
     * <p>Allows the popup window to extend beyond the bounds of the screen. By default the
     * window is clipped to the screen boundaries. Setting this to false will allow windows to be
     * accurately positioned.</p>
     *
     * <p>If the popup is showing, calling this method will take effect only
     * the next time the popup is shown or through a manual call to one of
     * the {@link #update()} methods.</p>
     *
     * @param enabled false if the window should be allowed to extend outside of the screen
     * @see #isShowing()
     * @see #isClippingEnabled()
     * @see #update()
     */
    public void setClippingEnabled(boolean enabled) {
        mClippingEnabled = enabled;
    }

    /**
     * Clip this popup window to the screen, but not to the containing window.
     *
     * @param enabled True to clip to the screen.
     * @hide
     */
    public void setClipToScreenEnabled(boolean enabled) {
        mClipToScreen = enabled;
        setClippingEnabled(!enabled);
    }

    /**
     * <p>Indicates whether the popup window supports splitting touches.</p>
     *
     * @return true if the touch splitting is enabled, false otherwise
     *
     * @see #setSplitTouchEnabled(boolean)
     * @hide
     */
    public boolean isSplitTouchEnabled() {
        return mSplitTouchEnabled;
    }

    /**
     * <p>Allows the popup window to split touches across other windows that also
     * support split touch.  When this flag is not set, the first pointer
     * that goes down determines the window to which all subsequent touches
     * go until all pointers go up.  When this flag is set, each pointer
     * (not necessarily the first) that goes down determines the window
     * to which all subsequent touches of that pointer will go until that
     * pointer goes up thereby enabling touches with multiple pointers
     * to be split across multiple windows.</p>
     *
     * @param enabled true if the split touches should be enabled, false otherwise
     * @see #isSplitTouchEnabled()
     * @hide
     */
    public void setSplitTouchEnabled(boolean enabled) {
        mSplitTouchEnabled = enabled;
    }

    /**
     * <p>Indicates whether the popup window will be forced into using absolute screen coordinates
     * for positioning.</p>
     *
     * @return true if the window will always be positioned in screen coordinates.
     * @hide
     */
    public boolean isLayoutInScreenEnabled() {
        return mLayoutInScreen;
    }

    /**
     * <p>Allows the popup window to force the flag
     * {@link WindowManager.LayoutParams#FLAG_LAYOUT_IN_SCREEN}, overriding default behavior.
     * This will cause the popup to be positioned in absolute screen coordinates.</p>
     *
     * @param enabled true if the popup should always be positioned in screen coordinates
     * @hide
     */
    public void setLayoutInScreenEnabled(boolean enabled) {
        mLayoutInScreen = enabled;
    }

    /**
     * Set the layout type for this window. Should be one of the TYPE constants defined in
     * {@link WindowManager.LayoutParams}.
     *
     * @param layoutType Layout type for this window.
     * @hide
     */
    public void setWindowLayoutType(int layoutType) {
        mWindowLayoutType = layoutType;
    }

    /**
     * @return The layout type for this window.
     * @hide
     */
    public int getWindowLayoutType() {
        return mWindowLayoutType;
    }

    /**
     * <p>Change the width and height measure specs that are given to the
     * window manager by the popup.  By default these are 0, meaning that
     * the current width or height is requested as an explicit size from
     * the window manager.  You can supply
     * {@link ViewGroup.LayoutParams#WRAP_CONTENT} or
     * {@link ViewGroup.LayoutParams#MATCH_PARENT} to have that measure
     * spec supplied instead, replacing the absolute width and height that
     * has been set in the popup.</p>
     *
     * <p>If the popup is showing, calling this method will take effect only
     * the next time the popup is shown.</p>
     *
     * @param widthSpec an explicit width measure spec mode, either
     * {@link ViewGroup.LayoutParams#WRAP_CONTENT},
     * {@link ViewGroup.LayoutParams#MATCH_PARENT}, or 0 to use the absolute
     * width.
     * @param heightSpec an explicit height measure spec mode, either
     * {@link ViewGroup.LayoutParams#WRAP_CONTENT},
     * {@link ViewGroup.LayoutParams#MATCH_PARENT}, or 0 to use the absolute
     * height.
     */
    public void setWindowLayoutMode(int widthSpec, int heightSpec) {
        mWidthMode = widthSpec;
        mHeightMode = heightSpec;
    }

    /**
     * <p>Return this popup's height MeasureSpec</p>
     *
     * @return the height MeasureSpec of the popup
     *
     * @see #setHeight(int)
     */
    public int getHeight() {
        return mHeight;
    }

    /**
     * <p>Change the popup's height MeasureSpec</p>
     *
     * <p>If the popup is showing, calling this method will take effect only
     * the next time the popup is shown.</p>
     *
     * @param height the height MeasureSpec of the popup
     *
     * @see #getHeight()
     * @see #isShowing()
     */
    public void setHeight(int height) {
        mHeight = height;
    }

    /**
     * <p>Return this popup's width MeasureSpec</p>
     *
     * @return the width MeasureSpec of the popup
     *
     * @see #setWidth(int)
     */
    public int getWidth() {
        return mWidth;
    }

    /**
     * <p>Change the popup's width MeasureSpec</p>
     *
     * <p>If the popup is showing, calling this method will take effect only
     * the next time the popup is shown.</p>
     *
     * @param width the width MeasureSpec of the popup
     *
     * @see #getWidth()
     * @see #isShowing()
     */
    public void setWidth(int width) {
        mWidth = width;
    }

    /**
     * <p>Indicate whether this popup window is showing on screen.</p>
     *
     * @return true if the popup is showing, false otherwise
     */
    public boolean isShowing() {
        return mIsShowing;
    }

    /**
     * <p>
     * Display the content view in a popup window at the specified location. If the popup window
     * cannot fit on screen, it will be clipped. See {@link android.view.WindowManager.LayoutParams}
     * for more information on how gravity and the x and y parameters are related. Specifying
     * a gravity of {@link android.view.Gravity#NO_GRAVITY} is similar to specifying
     * <code>Gravity.LEFT | Gravity.TOP</code>.
     * </p>
     *
     * @param parent a parent view to get the {@link android.view.View#getWindowToken()} token from
     * @param gravity the gravity which controls the placement of the popup window
     * @param x the popup's x location offset
     * @param y the popup's y location offset
     */
    public void showAtLocation(View parent, int gravity, int x, int y) {
        if (isShowing() || mContentView == null) {
            return;
        }

        unregisterForScrollChanged();

        mIsShowing = true;
        mIsDropdown = false;

        WindowManager.LayoutParams p = createPopupLayout(parent.getWindowToken());
        p.windowAnimations = computeAnimationResource();

        preparePopup(p);
        if (gravity == Gravity.NO_GRAVITY) {
            gravity = Gravity.TOP | Gravity.LEFT;
        }
        p.gravity = gravity;
        p.x = x;
        p.y = y;
        invokePopup(p);
    }

    /**
     * <p>Display the content view in a popup window anchored to the bottom-left
     * corner of the anchor view. If there is not enough room on screen to show
     * the popup in its entirety, this method tries to find a parent scroll
     * view to scroll. If no parent scroll view can be scrolled, the bottom-left
     * corner of the popup is pinned at the top left corner of the anchor view.</p>
     *
     * @param anchor the view on which to pin the popup window
     *
     * @see #dismiss()
     */
    public void showAsDropDown(View anchor) {
        showAsDropDown(anchor, 0, 0);
    }

    /**
     * <p>Display the content view in a popup window anchored to the bottom-left
     * corner of the anchor view offset by the specified x and y coordinates.
     * If there is not enough room on screen to show
     * the popup in its entirety, this method tries to find a parent scroll
     * view to scroll. If no parent scroll view can be scrolled, the bottom-left
     * corner of the popup is pinned at the top left corner of the anchor view.</p>
     * <p>If the view later scrolls to move <code>anchor</code> to a different
     * location, the popup will be moved correspondingly.</p>
     *
     * @param anchor the view on which to pin the popup window
     *
     * @see #dismiss()
     */
    public void showAsDropDown(View anchor, int xoff, int yoff) {
        if (isShowing() || mContentView == null) {
            return;
        }

        registerForScrollChanged(anchor, xoff, yoff);

        mIsShowing = true;
        mIsDropdown = true;

        WindowManager.LayoutParams p = createPopupLayout(anchor.getWindowToken());
        preparePopup(p);

        updateAboveAnchor(findDropDownPosition(anchor, p, xoff, yoff));

        if (mHeightMode < 0) p.height = mLastHeight = mHeightMode;
        if (mWidthMode < 0) p.width = mLastWidth = mWidthMode;

        p.windowAnimations = computeAnimationResource();

        invokePopup(p);
    }

    private void updateAboveAnchor(boolean aboveAnchor) {
        if (aboveAnchor != mAboveAnchor) {
            mAboveAnchor = aboveAnchor;

            if (mBackground != null) {
                // If the background drawable provided was a StateListDrawable with above-anchor
                // and below-anchor states, use those. Otherwise rely on refreshDrawableState to
                // do the job.
                if (mAboveAnchorBackgroundDrawable != null) {
                    if (mAboveAnchor) {
                        mPopupView.setBackgroundDrawable(mAboveAnchorBackgroundDrawable);
                    } else {
                        mPopupView.setBackgroundDrawable(mBelowAnchorBackgroundDrawable);
                    }
                } else {
                    mPopupView.refreshDrawableState();
                }
            }
        }
    }

    /**
     * Indicates whether the popup is showing above (the y coordinate of the popup's bottom
     * is less than the y coordinate of the anchor) or below the anchor view (the y coordinate
     * of the popup is greater than y coordinate of the anchor's bottom).
     *
     * The value returned
     * by this method is meaningful only after {@link #showAsDropDown(android.view.View)}
     * or {@link #showAsDropDown(android.view.View, int, int)} was invoked.
     *
     * @return True if this popup is showing above the anchor view, false otherwise.
     */
    public boolean isAboveAnchor() {
        return mAboveAnchor;
    }

    /**
     * <p>Prepare the popup by embedding in into a new ViewGroup if the
     * background drawable is not null. If embedding is required, the layout
     * parameters' height is mnodified to take into account the background's
     * padding.</p>
     *
     * @param p the layout parameters of the popup's content view
     */
    private void preparePopup(WindowManager.LayoutParams p) {
        if (mContentView == null || mContext == null || mWindowManager == null) {
            throw new IllegalStateException("You must specify a valid content view by "
                    + "calling setContentView() before attempting to show the popup.");
        }

        if (mBackground != null) {
            final ViewGroup.LayoutParams layoutParams = mContentView.getLayoutParams();
            int height = ViewGroup.LayoutParams.MATCH_PARENT;
            if (layoutParams != null &&
                    layoutParams.height == ViewGroup.LayoutParams.WRAP_CONTENT) {
                height = ViewGroup.LayoutParams.WRAP_CONTENT;
            }

            // when a background is available, we embed the content view
            // within another view that owns the background drawable
            PopupViewContainer popupViewContainer = new PopupViewContainer(mContext);
            PopupViewContainer.LayoutParams listParams = new PopupViewContainer.LayoutParams(
                    ViewGroup.LayoutParams.MATCH_PARENT, height
            );
            popupViewContainer.setBackgroundDrawable(mBackground);
            popupViewContainer.addView(mContentView, listParams);

            mPopupView = popupViewContainer;
        } else {
            mPopupView = mContentView;
        }
        mPopupWidth = p.width;
        mPopupHeight = p.height;
    }

    /**
     * <p>Invoke the popup window by adding the content view to the window
     * manager.</p>
     *
     * <p>The content view must be non-null when this method is invoked.</p>
     *
     * @param p the layout parameters of the popup's content view
     */
    private void invokePopup(WindowManager.LayoutParams p) {
        p.packageName = mContext.getPackageName();
        mWindowManager.addView(mPopupView, p);
    }

    /**
     * <p>Generate the layout parameters for the popup window.</p>
     *
     * @param token the window token used to bind the popup's window
     *
     * @return the layout parameters to pass to the window manager
     */
    private WindowManager.LayoutParams createPopupLayout(IBinder token) {
        // generates the layout parameters for the drop down
        // we want a fixed size view located at the bottom left of the anchor
        WindowManager.LayoutParams p = new WindowManager.LayoutParams();
        // these gravity settings put the view at the top left corner of the
        // screen. The view is then positioned to the appropriate location
        // by setting the x and y offsets to match the anchor's bottom
        // left corner
        p.gravity = Gravity.LEFT | Gravity.TOP;
        p.width = mLastWidth = mWidth;
        p.height = mLastHeight = mHeight;
        if (mBackground != null) {
            p.format = mBackground.getOpacity();
        } else {
            p.format = PixelFormat.TRANSLUCENT;
        }
        p.flags = computeFlags(p.flags);
        p.type = mWindowLayoutType;
        p.token = token;
        p.softInputMode = mSoftInputMode;
        p.setTitle("PopupWindow:" + Integer.toHexString(hashCode()));

        return p;
    }

    private int computeFlags(int curFlags) {
        curFlags &= ~(
                WindowManager.LayoutParams.FLAG_IGNORE_CHEEK_PRESSES |
                WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE |
                WindowManager.LayoutParams.FLAG_NOT_TOUCHABLE |
                WindowManager.LayoutParams.FLAG_WATCH_OUTSIDE_TOUCH |
                WindowManager.LayoutParams.FLAG_LAYOUT_NO_LIMITS |
                WindowManager.LayoutParams.FLAG_ALT_FOCUSABLE_IM |
                WindowManager.LayoutParams.FLAG_SPLIT_TOUCH);
        if(mIgnoreCheekPress) {
            curFlags |= WindowManager.LayoutParams.FLAG_IGNORE_CHEEK_PRESSES;
        }
        if (!mFocusable) {
            curFlags |= WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE;
            if (mInputMethodMode == INPUT_METHOD_NEEDED) {
                curFlags |= WindowManager.LayoutParams.FLAG_ALT_FOCUSABLE_IM;
            }
        } else if (mInputMethodMode == INPUT_METHOD_NOT_NEEDED) {
            curFlags |= WindowManager.LayoutParams.FLAG_ALT_FOCUSABLE_IM;
        }
        if (!mTouchable) {
            curFlags |= WindowManager.LayoutParams.FLAG_NOT_TOUCHABLE;
        }
        if (mOutsideTouchable) {
            curFlags |= WindowManager.LayoutParams.FLAG_WATCH_OUTSIDE_TOUCH;
        }
        if (!mClippingEnabled) {
            curFlags |= WindowManager.LayoutParams.FLAG_LAYOUT_NO_LIMITS;
        }
        if (mSplitTouchEnabled) {
            curFlags |= WindowManager.LayoutParams.FLAG_SPLIT_TOUCH;
        }
        if (mLayoutInScreen) {
            curFlags |= WindowManager.LayoutParams.FLAG_LAYOUT_IN_SCREEN;
        }
        return curFlags;
    }

    private int computeAnimationResource() {
        if (mAnimationStyle == -1) {
            if (mIsDropdown) {
                return mAboveAnchor
                        ? com.android.internal.R.style.Animation_DropDownUp
                        : com.android.internal.R.style.Animation_DropDownDown;
            }
            return 0;
        }
        return mAnimationStyle;
    }

    /**
     * <p>Positions the popup window on screen. When the popup window is too
     * tall to fit under the anchor, a parent scroll view is seeked and scrolled
     * up to reclaim space. If scrolling is not possible or not enough, the
     * popup window gets moved on top of the anchor.</p>
     *
     * <p>The height must have been set on the layout parameters prior to
     * calling this method.</p>
     *
     * @param anchor the view on which the popup window must be anchored
     * @param p the layout parameters used to display the drop down
     *
     * @return true if the popup is translated upwards to fit on screen
     */
    private boolean findDropDownPosition(View anchor, WindowManager.LayoutParams p,
            int xoff, int yoff) {

        anchor.getLocationInWindow(mDrawingLocation);
        p.x = mDrawingLocation[0] + xoff;
        p.y = mDrawingLocation[1] + anchor.getHeight() + yoff;

        boolean onTop = false;

        p.gravity = Gravity.LEFT | Gravity.TOP;

        anchor.getLocationOnScreen(mScreenLocation);
        final Rect displayFrame = new Rect();
        anchor.getWindowVisibleDisplayFrame(displayFrame);

        final View root = anchor.getRootView();
        if (p.y + mPopupHeight > displayFrame.bottom || p.x + mPopupWidth - root.getWidth() > 0) {
            // if the drop down disappears at the bottom of the screen. we try to
            // scroll a parent scrollview or move the drop down back up on top of
            // the edit box
            int scrollX = anchor.getScrollX();
            int scrollY = anchor.getScrollY();
            Rect r = new Rect(scrollX, scrollY,  scrollX + mPopupWidth + xoff,
                    scrollY + mPopupHeight + anchor.getHeight() + yoff);
            anchor.requestRectangleOnScreen(r, true);

            // now we re-evaluate the space available, and decide from that
            // whether the pop-up will go above or below the anchor.
            anchor.getLocationInWindow(mDrawingLocation);
            p.x = mDrawingLocation[0] + xoff;
            p.y = mDrawingLocation[1] + anchor.getHeight() + yoff;

            // determine whether there is more space above or below the anchor
            anchor.getLocationOnScreen(mScreenLocation);

            onTop = (displayFrame.bottom - mScreenLocation[1] - anchor.getHeight() - yoff) <
                    (mScreenLocation[1] - yoff - displayFrame.top);
            if (onTop) {
                p.gravity = Gravity.LEFT | Gravity.BOTTOM;
                p.y = root.getHeight() - mDrawingLocation[1] + yoff;
            } else {
                p.y = mDrawingLocation[1] + anchor.getHeight() + yoff;
            }
        }

        if (mClipToScreen) {
            final int displayFrameWidth = displayFrame.right - displayFrame.left;

            int right = p.x + p.width;
            if (right > displayFrameWidth) {
                p.x -= right - displayFrameWidth;
            }
            if (p.x < displayFrame.left) {
                p.x = displayFrame.left;
                p.width = Math.min(p.width, displayFrameWidth);
            }

            p.y = Math.max(p.y, displayFrame.top);
        }

        p.gravity |= Gravity.DISPLAY_CLIP_VERTICAL;

        return onTop;
    }

    /**
     * Returns the maximum height that is available for the popup to be
     * completely shown. It is recommended that this height be the maximum for
     * the popup's height, otherwise it is possible that the popup will be
     * clipped.
     *
     * @param anchor The view on which the popup window must be anchored.
     * @return The maximum available height for the popup to be completely
     *         shown.
     */
    public int getMaxAvailableHeight(View anchor) {
        return getMaxAvailableHeight(anchor, 0);
    }

    /**
     * Returns the maximum height that is available for the popup to be
     * completely shown. It is recommended that this height be the maximum for
     * the popup's height, otherwise it is possible that the popup will be
     * clipped.
     *
     * @param anchor The view on which the popup window must be anchored.
     * @param yOffset y offset from the view's bottom edge
     * @return The maximum available height for the popup to be completely
     *         shown.
     */
    public int getMaxAvailableHeight(View anchor, int yOffset) {
        return getMaxAvailableHeight(anchor, yOffset, false);
    }

    /**
     * Returns the maximum height that is available for the popup to be
     * completely shown, optionally ignoring any bottom decorations such as
     * the input method. It is recommended that this height be the maximum for
     * the popup's height, otherwise it is possible that the popup will be
     * clipped.
     *
     * @param anchor The view on which the popup window must be anchored.
     * @param yOffset y offset from the view's bottom edge
     * @param ignoreBottomDecorations if true, the height returned will be
     *        all the way to the bottom of the display, ignoring any
     *        bottom decorations
     * @return The maximum available height for the popup to be completely
     *         shown.
     *
     * @hide Pending API council approval.
     */
    public int getMaxAvailableHeight(View anchor, int yOffset, boolean ignoreBottomDecorations) {
        final Rect displayFrame = new Rect();
        anchor.getWindowVisibleDisplayFrame(displayFrame);

        final int[] anchorPos = mDrawingLocation;
        anchor.getLocationOnScreen(anchorPos);

        int bottomEdge = displayFrame.bottom;
        if (ignoreBottomDecorations) {
            Resources res = anchor.getContext().getResources();
            bottomEdge = res.getDisplayMetrics().heightPixels -
                    (int) res.getDimension(com.android.internal.R.dimen.screen_margin_bottom);
        }
        final int distanceToBottom = bottomEdge - (anchorPos[1] + anchor.getHeight()) - yOffset;
        final int distanceToTop = anchorPos[1] - displayFrame.top + yOffset;

        // anchorPos[1] is distance from anchor to top of screen
        int returnedHeight = Math.max(distanceToBottom, distanceToTop);
        if (mBackground != null) {
            mBackground.getPadding(mTempRect);
            returnedHeight -= mTempRect.top + mTempRect.bottom;
        }

        return returnedHeight;
    }

    /**
     * <p>Dispose of the popup window. This method can be invoked only after
     * {@link #showAsDropDown(android.view.View)} has been executed. Failing that, calling
     * this method will have no effect.</p>
     *
     * @see #showAsDropDown(android.view.View)
     */
    public void dismiss() {
        if (isShowing() && mPopupView != null) {
            unregisterForScrollChanged();

            try {
                mWindowManager.removeView(mPopupView);
            } finally {
                if (mPopupView != mContentView && mPopupView instanceof ViewGroup) {
                    ((ViewGroup) mPopupView).removeView(mContentView);
                }
                mPopupView = null;
                mIsShowing = false;

                if (mOnDismissListener != null) {
                    mOnDismissListener.onDismiss();
                }
            }
        }
    }

    /**
     * Sets the listener to be called when the window is dismissed.
     *
     * @param onDismissListener The listener.
     */
    public void setOnDismissListener(OnDismissListener onDismissListener) {
        mOnDismissListener = onDismissListener;
    }

    /**
     * Updates the state of the popup window, if it is currently being displayed,
     * from the currently set state.  This include:
     * {@link #setClippingEnabled(boolean)}, {@link #setFocusable(boolean)},
     * {@link #setIgnoreCheekPress()}, {@link #setInputMethodMode(int)},
     * {@link #setTouchable(boolean)}, and {@link #setAnimationStyle(int)}.
     */
    public void update() {
        if (!isShowing() || mContentView == null) {
            return;
        }

        WindowManager.LayoutParams p = (WindowManager.LayoutParams)
                mPopupView.getLayoutParams();

        boolean update = false;

        final int newAnim = computeAnimationResource();
        if (newAnim != p.windowAnimations) {
            p.windowAnimations = newAnim;
            update = true;
        }

        final int newFlags = computeFlags(p.flags);
        if (newFlags != p.flags) {
            p.flags = newFlags;
            update = true;
        }

        if (update) {
            mWindowManager.updateViewLayout(mPopupView, p);
        }
    }

    /**
     * <p>Updates the dimension of the popup window. Calling this function
     * also updates the window with the current popup state as described
     * for {@link #update()}.</p>
     *
     * @param width the new width
     * @param height the new height
     */
    public void update(int width, int height) {
        WindowManager.LayoutParams p = (WindowManager.LayoutParams)
                mPopupView.getLayoutParams();
        update(p.x, p.y, width, height, false);
    }

    /**
     * <p>Updates the position and the dimension of the popup window. Width and
     * height can be set to -1 to update location only.  Calling this function
     * also updates the window with the current popup state as
     * described for {@link #update()}.</p>
     *
     * @param x the new x location
     * @param y the new y location
     * @param width the new width, can be -1 to ignore
     * @param height the new height, can be -1 to ignore
     */
    public void update(int x, int y, int width, int height) {
        update(x, y, width, height, false);
    }

    /**
     * <p>Updates the position and the dimension of the popup window. Width and
     * height can be set to -1 to update location only.  Calling this function
     * also updates the window with the current popup state as
     * described for {@link #update()}.</p>
     *
     * @param x the new x location
     * @param y the new y location
     * @param width the new width, can be -1 to ignore
     * @param height the new height, can be -1 to ignore
     * @param force reposition the window even if the specified position
     *              already seems to correspond to the LayoutParams
     */
    public void update(int x, int y, int width, int height, boolean force) {
        if (width != -1) {
            mLastWidth = width;
            setWidth(width);
        }

        if (height != -1) {
            mLastHeight = height;
            setHeight(height);
        }

        if (!isShowing() || mContentView == null) {
            return;
        }

        WindowManager.LayoutParams p = (WindowManager.LayoutParams) mPopupView.getLayoutParams();

        boolean update = force;

        final int finalWidth = mWidthMode < 0 ? mWidthMode : mLastWidth;
        if (width != -1 && p.width != finalWidth) {
            p.width = mLastWidth = finalWidth;
            update = true;
        }

        final int finalHeight = mHeightMode < 0 ? mHeightMode : mLastHeight;
        if (height != -1 && p.height != finalHeight) {
            p.height = mLastHeight = finalHeight;
            update = true;
        }

        if (p.x != x) {
            p.x = x;
            update = true;
        }

        if (p.y != y) {
            p.y = y;
            update = true;
        }

        final int newAnim = computeAnimationResource();
        if (newAnim != p.windowAnimations) {
            p.windowAnimations = newAnim;
            update = true;
        }

        final int newFlags = computeFlags(p.flags);
        if (newFlags != p.flags) {
            p.flags = newFlags;
            update = true;
        }

        if (update) {
            mWindowManager.updateViewLayout(mPopupView, p);
        }
    }

    /**
     * <p>Updates the position and the dimension of the popup window. Calling this
     * function also updates the window with the current popup state as described
     * for {@link #update()}.</p>
     *
     * @param anchor the popup's anchor view
     * @param width the new width, can be -1 to ignore
     * @param height the new height, can be -1 to ignore
     */
    public void update(View anchor, int width, int height) {
        update(anchor, false, 0, 0, true, width, height);
    }

    /**
     * <p>Updates the position and the dimension of the popup window. Width and
     * height can be set to -1 to update location only.  Calling this function
     * also updates the window with the current popup state as
     * described for {@link #update()}.</p>
     * <p>If the view later scrolls to move <code>anchor</code> to a different
     * location, the popup will be moved correspondingly.</p>
     *
     * @param anchor the popup's anchor view
     * @param xoff x offset from the view's left edge
     * @param yoff y offset from the view's bottom edge
     * @param width the new width, can be -1 to ignore
     * @param height the new height, can be -1 to ignore
     */
    public void update(View anchor, int xoff, int yoff, int width, int height) {
        update(anchor, true, xoff, yoff, true, width, height);
    }

    private void update(View anchor, boolean updateLocation, int xoff, int yoff,
            boolean updateDimension, int width, int height) {

        if (!isShowing() || mContentView == null) {
            return;
        }

        WeakReference<View> oldAnchor = mAnchor;
        if (oldAnchor == null || oldAnchor.get() != anchor ||
                (updateLocation && (mAnchorXoff != xoff || mAnchorYoff != yoff))) {
            registerForScrollChanged(anchor, xoff, yoff);
        }

        WindowManager.LayoutParams p = (WindowManager.LayoutParams) mPopupView.getLayoutParams();

        if (updateDimension) {
            if (width == -1) {
                width = mPopupWidth;
            } else {
                mPopupWidth = width;
            }
            if (height == -1) {
                height = mPopupHeight;
            } else {
                mPopupHeight = height;
            }
        }

        int x = p.x;
        int y = p.y;

        if (updateLocation) {
            updateAboveAnchor(findDropDownPosition(anchor, p, xoff, yoff));
        } else {
            updateAboveAnchor(findDropDownPosition(anchor, p, mAnchorXoff, mAnchorYoff));
        }

        update(p.x, p.y, width, height, x != p.x || y != p.y);
    }

    /**
     * Listener that is called when this popup window is dismissed.
     */
    public interface OnDismissListener {
        /**
         * Called when this popup window is dismissed.
         */
        public void onDismiss();
    }

    private void unregisterForScrollChanged() {
        WeakReference<View> anchorRef = mAnchor;
        View anchor = null;
        if (anchorRef != null) {
            anchor = anchorRef.get();
        }
        if (anchor != null) {
            ViewTreeObserver vto = anchor.getViewTreeObserver();
            vto.removeOnScrollChangedListener(mOnScrollChangedListener);
        }
        mAnchor = null;
    }

    private void registerForScrollChanged(View anchor, int xoff, int yoff) {
        unregisterForScrollChanged();

        mAnchor = new WeakReference<View>(anchor);
        ViewTreeObserver vto = anchor.getViewTreeObserver();
        if (vto != null) {
            vto.addOnScrollChangedListener(mOnScrollChangedListener);
        }

        mAnchorXoff = xoff;
        mAnchorYoff = yoff;
    }

    private class PopupViewContainer extends FrameLayout {
        private static final String TAG = "PopupWindow.PopupViewContainer";

        public PopupViewContainer(Context context) {
            super(context);
        }

        @Override
        protected int[] onCreateDrawableState(int extraSpace) {
            if (mAboveAnchor) {
                // 1 more needed for the above anchor state
                final int[] drawableState = super.onCreateDrawableState(extraSpace + 1);
                View.mergeDrawableStates(drawableState, ABOVE_ANCHOR_STATE_SET);
                return drawableState;
            } else {
                return super.onCreateDrawableState(extraSpace);
            }
        }

        @Override
        public boolean dispatchKeyEvent(KeyEvent event) {
            if (event.getKeyCode() == KeyEvent.KEYCODE_BACK) {
                if (event.getAction() == KeyEvent.ACTION_DOWN
                        && event.getRepeatCount() == 0) {
                    getKeyDispatcherState().startTracking(event, this);
                    return true;
                } else if (event.getAction() == KeyEvent.ACTION_UP
                        && getKeyDispatcherState().isTracking(event) && !event.isCanceled()) {
                    dismiss();
                    return true;
                }
                return super.dispatchKeyEvent(event);
            } else {
                return super.dispatchKeyEvent(event);
            }
        }

        @Override
        public boolean dispatchTouchEvent(MotionEvent ev) {
            if (mTouchInterceptor != null && mTouchInterceptor.onTouch(this, ev)) {
                return true;
            }
            return super.dispatchTouchEvent(ev);
        }

        @Override
        public boolean onTouchEvent(MotionEvent event) {
            final int x = (int) event.getX();
            final int y = (int) event.getY();

            if ((event.getAction() == MotionEvent.ACTION_DOWN)
                    && ((x < 0) || (x >= getWidth()) || (y < 0) || (y >= getHeight()))) {
                dismiss();
                return true;
            } else if (event.getAction() == MotionEvent.ACTION_OUTSIDE) {
                dismiss();
                return true;
            } else {
                return super.onTouchEvent(event);
            }
        }

        @Override
        public void sendAccessibilityEvent(int eventType) {
            // clinets are interested in the content not the container, make it event source
            if (mContentView != null) {
                mContentView.sendAccessibilityEvent(eventType);
            } else {
                super.sendAccessibilityEvent(eventType);
            }
        }
    }

}