view/accessibility/AccessibilityNodeInfo.java

/*
 * Copyright (C) 2011 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.accessibility;

import android.graphics.Rect;
import android.os.Parcel;
import android.os.Parcelable;
import android.text.TextUtils;
import android.util.SparseLongArray;
import android.view.View;

import java.util.Collections;
import java.util.List;

/**
 * This class represents a node of the window content as well as actions that
 * can be requested from its source. From the point of view of an
 * {@link android.accessibilityservice.AccessibilityService} a window content is
 * presented as tree of accessibility node info which may or may not map one-to-one
 * to the view hierarchy. In other words, a custom view is free to report itself as
 * a tree of accessibility node info.
 * </p>
 * <p>
 * Once an accessibility node info is delivered to an accessibility service it is
 * made immutable and calling a state mutation method generates an error.
 * </p>
 * <p>
 * Please refer to {@link android.accessibilityservice.AccessibilityService} for
 * details about how to obtain a handle to window content as a tree of accessibility
 * node info as well as familiarizing with the security model.
 * </p>
 *
 * @see android.accessibilityservice.AccessibilityService
 * @see AccessibilityEvent
 * @see AccessibilityManager
 */
public class AccessibilityNodeInfo implements Parcelable {

    private static final boolean DEBUG = false;

    private static final int UNDEFINED = -1;

    // Actions.

    /**
     * Action that focuses the node.
     */
    public static final int ACTION_FOCUS =  0x00000001;

    /**
     * Action that unfocuses the node.
     */
    public static final int ACTION_CLEAR_FOCUS =  0x00000002;

    /**
     * Action that selects the node.
     */
    public static final int ACTION_SELECT =  0x00000004;

    /**
     * Action that unselects the node.
     */
    public static final int ACTION_CLEAR_SELECTION =  0x00000008;

    // Boolean attributes.

    private static final int PROPERTY_CHECKABLE = 0x00000001;

    private static final int PROPERTY_CHECKED = 0x00000002;

    private static final int PROPERTY_FOCUSABLE = 0x00000004;

    private static final int PROPERTY_FOCUSED = 0x00000008;

    private static final int PROPERTY_SELECTED = 0x00000010;

    private static final int PROPERTY_CLICKABLE = 0x00000020;

    private static final int PROPERTY_LONG_CLICKABLE = 0x00000040;

    private static final int PROPERTY_ENABLED = 0x00000080;

    private static final int PROPERTY_PASSWORD = 0x00000100;

    private static final int PROPERTY_SCROLLABLE = 0x00000200;

    /**
     * Bits that provide the id of a virtual descendant of a view.
     */
    private static final long VIRTUAL_DESCENDANT_ID_MASK = 0xffffffff00000000L;

    /**
     * Bit shift of {@link #VIRTUAL_DESCENDANT_ID_MASK} to get to the id for a
     * virtual descendant of a view. Such a descendant does not exist in the view
     * hierarchy and is only reported via the accessibility APIs.
     */
    private static final int VIRTUAL_DESCENDANT_ID_SHIFT = 32;

    /**
     * Gets the accessibility view id which identifies a View in the view three.
     *
     * @param accessibilityNodeId The id of an {@link AccessibilityNodeInfo}.
     * @return The accessibility view id part of the node id.
     *
     * @hide
     */
    public static int getAccessibilityViewId(long accessibilityNodeId) {
        return (int) accessibilityNodeId;
    }

    /**
     * Gets the virtual descendant id which identifies an imaginary view in a
     * containing View.
     *
     * @param accessibilityNodeId The id of an {@link AccessibilityNodeInfo}.
     * @return The virtual view id part of the node id.
     *
     * @hide
     */
    public static int getVirtualDescendantId(long accessibilityNodeId) {
        return (int) ((accessibilityNodeId & VIRTUAL_DESCENDANT_ID_MASK)
                >> VIRTUAL_DESCENDANT_ID_SHIFT);
    }

    /**
     * Makes a node id by shifting the <code>virtualDescendantId</code>
     * by {@link #VIRTUAL_DESCENDANT_ID_SHIFT} and taking
     * the bitwise or with the <code>accessibilityViewId</code>.
     *
     * @param accessibilityViewId A View accessibility id.
     * @param virtualDescendantId A virtual descendant id.
     * @return The node id.
     *
     * @hide
     */
    public static long makeNodeId(int accessibilityViewId, int virtualDescendantId) {
        return (((long) virtualDescendantId) << VIRTUAL_DESCENDANT_ID_SHIFT) | accessibilityViewId;
    }

    // Housekeeping.
    private static final int MAX_POOL_SIZE = 50;
    private static final Object sPoolLock = new Object();
    private static AccessibilityNodeInfo sPool;
    private static int sPoolSize;
    private AccessibilityNodeInfo mNext;
    private boolean mIsInPool;
    private boolean mSealed;

    // Data.
    private int mWindowId = UNDEFINED;
    private long mSourceNodeId = makeNodeId(UNDEFINED, UNDEFINED);
    private long mParentNodeId = makeNodeId(UNDEFINED, UNDEFINED);

    private int mBooleanProperties;
    private final Rect mBoundsInParent = new Rect();
    private final Rect mBoundsInScreen = new Rect();

    private CharSequence mPackageName;
    private CharSequence mClassName;
    private CharSequence mText;
    private CharSequence mContentDescription;

    private SparseLongArray mChildIds = new SparseLongArray();
    private int mActions;

    private int mConnectionId = UNDEFINED;

    /**
     * Hide constructor from clients.
     */
    private AccessibilityNodeInfo() {
        /* do nothing */
    }

    /**
     * Sets the source.
     * <p>
     *   <strong>Note:</strong> Cannot be called from an
     *   {@link android.accessibilityservice.AccessibilityService}.
     *   This class is made immutable before being delivered to an AccessibilityService.
     * </p>
     *
     * @param source The info source.
     */
    public void setSource(View source) {
        setSource(source, UNDEFINED);
    }

    /**
     * Sets the source to be a virtual descendant of the given <code>root</code>.
     * If <code>virtualDescendantId</code> is {@link View#NO_ID} the root
     * is set as the source.
     * <p>
     * A virtual descendant is an imaginary View that is reported as a part of the view
     * hierarchy for accessibility purposes. This enables custom views that draw complex
     * content to report themselves as a tree of virtual views, thus conveying their
     * logical structure.
     * </p>
     * <p>
     *   <strong>Note:</strong> Cannot be called from an
     *   {@link android.accessibilityservice.AccessibilityService}.
     *   This class is made immutable before being delivered to an AccessibilityService.
     * </p>
     *
     * @param root The root of the virtual subtree.
     * @param virtualDescendantId The id of the virtual descendant.
     */
    public void setSource(View root, int virtualDescendantId) {
        enforceNotSealed();
        mWindowId = (root != null) ? root.getAccessibilityWindowId() : UNDEFINED;
        final int rootAccessibilityViewId =
            (root != null) ? root.getAccessibilityViewId() : UNDEFINED;
        mSourceNodeId = makeNodeId(rootAccessibilityViewId, virtualDescendantId);
    }

    /**
     * Gets the id of the window from which the info comes from.
     *
     * @return The window id.
     */
    public int getWindowId() {
        return mWindowId;
    }

    /**
     * Gets the number of children.
     *
     * @return The child count.
     */
    public int getChildCount() {
        return mChildIds.size();
    }

    /**
     * Get the child at given index.
     * <p>
     *   <strong>Note:</strong> It is a client responsibility to recycle the
     *     received info by calling {@link AccessibilityNodeInfo#recycle()}
     *     to avoid creating of multiple instances.
     * </p>
     *
     * @param index The child index.
     * @return The child node.
     *
     * @throws IllegalStateException If called outside of an AccessibilityService.
     *
     */
    public AccessibilityNodeInfo getChild(int index) {
        enforceSealed();
        if (!canPerformRequestOverConnection(mSourceNodeId)) {
            return null;
        }
        final long childId = mChildIds.get(index);
        AccessibilityInteractionClient client = AccessibilityInteractionClient.getInstance();
        return client.findAccessibilityNodeInfoByAccessibilityId(mConnectionId, mWindowId, childId);
    }

    /**
     * Adds a child.
     * <p>
     * <strong>Note:</strong> Cannot be called from an
     * {@link android.accessibilityservice.AccessibilityService}.
     * This class is made immutable before being delivered to an AccessibilityService.
     * </p>
     *
     * @param child The child.
     *
     * @throws IllegalStateException If called from an AccessibilityService.
     */
    public void addChild(View child) {
        addChild(child, UNDEFINED);
    }

    /**
     * Adds a virtual child which is a descendant of the given <code>root</code>.
     * If <code>virtualDescendantId</code> is {@link View#NO_ID} the root
     * is added as a child.
     * <p>
     * A virtual descendant is an imaginary View that is reported as a part of the view
     * hierarchy for accessibility purposes. This enables custom views that draw complex
     * content to report them selves as a tree of virtual views, thus conveying their
     * logical structure.
     * </p>
     *
     * @param root The root of the virtual subtree.
     * @param virtualDescendantId The id of the virtual child.
     */
    public void addChild(View root, int virtualDescendantId) {
        enforceNotSealed();
        final int index = mChildIds.size();
        final int rootAccessibilityViewId =
            (root != null) ? root.getAccessibilityViewId() : UNDEFINED;
        final long childNodeId = makeNodeId(rootAccessibilityViewId, virtualDescendantId);
        mChildIds.put(index, childNodeId);
    }

    /**
     * Gets the actions that can be performed on the node.
     *
     * @return The bit mask of with actions.
     *
     * @see AccessibilityNodeInfo#ACTION_FOCUS
     * @see AccessibilityNodeInfo#ACTION_CLEAR_FOCUS
     * @see AccessibilityNodeInfo#ACTION_SELECT
     * @see AccessibilityNodeInfo#ACTION_CLEAR_SELECTION
     */
    public int getActions() {
        return mActions;
    }

    /**
     * Adds an action that can be performed on the node.
     * <p>
     *   <strong>Note:</strong> Cannot be called from an
     *   {@link android.accessibilityservice.AccessibilityService}.
     *   This class is made immutable before being delivered to an AccessibilityService.
     * </p>
     *
     * @param action The action.
     *
     * @throws IllegalStateException If called from an AccessibilityService.
     */
    public void addAction(int action) {
        enforceNotSealed();
        mActions |= action;
    }

    /**
     * Performs an action on the node.
     * <p>
     *   <strong>Note:</strong> An action can be performed only if the request is made
     *   from an {@link android.accessibilityservice.AccessibilityService}.
     * </p>
     *
     * @param action The action to perform.
     * @return True if the action was performed.
     *
     * @throws IllegalStateException If called outside of an AccessibilityService.
     */
    public boolean performAction(int action) {
        enforceSealed();
        if (!canPerformRequestOverConnection(mSourceNodeId)) {
            return false;
        }
        AccessibilityInteractionClient client = AccessibilityInteractionClient.getInstance();
        return client.performAccessibilityAction(mConnectionId, mWindowId, mSourceNodeId, action);
    }

    /**
     * Finds {@link AccessibilityNodeInfo}s by text. The match is case
     * insensitive containment. The search is relative to this info i.e.
     * this info is the root of the traversed tree.
     *
     * <p>
     *   <strong>Note:</strong> It is a client responsibility to recycle the
     *     received info by calling {@link AccessibilityNodeInfo#recycle()}
     *     to avoid creating of multiple instances.
     * </p>
     *
     * @param text The searched text.
     * @return A list of node info.
     */
    public List<AccessibilityNodeInfo> findAccessibilityNodeInfosByText(String text) {
        enforceSealed();
        if (!canPerformRequestOverConnection(mSourceNodeId)) {
            return Collections.emptyList();
        }
        AccessibilityInteractionClient client = AccessibilityInteractionClient.getInstance();
        return client.findAccessibilityNodeInfosByText(mConnectionId, text, mWindowId,
                mSourceNodeId);
    }

    /**
     * Gets the parent.
     * <p>
     *   <strong>Note:</strong> It is a client responsibility to recycle the
     *     received info by calling {@link AccessibilityNodeInfo#recycle()}
     *     to avoid creating of multiple instances.
     * </p>
     *
     * @return The parent.
     */
    public AccessibilityNodeInfo getParent() {
        enforceSealed();
        if (!canPerformRequestOverConnection(mParentNodeId)) {
            return null;
        }
        AccessibilityInteractionClient client = AccessibilityInteractionClient.getInstance();
        return client.findAccessibilityNodeInfoByAccessibilityId(mConnectionId,
                mWindowId, mParentNodeId);
    }

    /**
     * Sets the parent.
     * <p>
     *   <strong>Note:</strong> Cannot be called from an
     *   {@link android.accessibilityservice.AccessibilityService}.
     *   This class is made immutable before being delivered to an AccessibilityService.
     * </p>
     *
     * @param parent The parent.
     *
     * @throws IllegalStateException If called from an AccessibilityService.
     */
    public void setParent(View parent) {
        setParent(parent, UNDEFINED);
    }

    /**
     * Sets the parent to be a virtual descendant of the given <code>root</code>.
     * If <code>virtualDescendantId</code> equals to {@link View#NO_ID} the root
     * is set as the parent.
     * <p>
     * A virtual descendant is an imaginary View that is reported as a part of the view
     * hierarchy for accessibility purposes. This enables custom views that draw complex
     * content to report them selves as a tree of virtual views, thus conveying their
     * logical structure.
     * </p>
     * <p>
     *   <strong>Note:</strong> Cannot be called from an
     *   {@link android.accessibilityservice.AccessibilityService}.
     *   This class is made immutable before being delivered to an AccessibilityService.
     * </p>
     *
     * @param root The root of the virtual subtree.
     * @param virtualDescendantId The id of the virtual descendant.
     */
    public void setParent(View root, int virtualDescendantId) {
        enforceNotSealed();
        final int rootAccessibilityViewId =
            (root != null) ? root.getAccessibilityViewId() : UNDEFINED;
        mParentNodeId = makeNodeId(rootAccessibilityViewId, virtualDescendantId);
    }

    /**
     * Gets the node bounds in parent coordinates.
     *
     * @param outBounds The output node bounds.
     */
    public void getBoundsInParent(Rect outBounds) {
        outBounds.set(mBoundsInParent.left, mBoundsInParent.top,
                mBoundsInParent.right, mBoundsInParent.bottom);
    }

    /**
     * Sets the node bounds in parent coordinates.
     * <p>
     *   <strong>Note:</strong> Cannot be called from an
     *   {@link android.accessibilityservice.AccessibilityService}.
     *   This class is made immutable before being delivered to an AccessibilityService.
     * </p>
     *
     * @param bounds The node bounds.
     *
     * @throws IllegalStateException If called from an AccessibilityService.
     */
    public void setBoundsInParent(Rect bounds) {
        enforceNotSealed();
        mBoundsInParent.set(bounds.left, bounds.top, bounds.right, bounds.bottom);
    }

    /**
     * Gets the node bounds in screen coordinates.
     *
     * @param outBounds The output node bounds.
     */
    public void getBoundsInScreen(Rect outBounds) {
        outBounds.set(mBoundsInScreen.left, mBoundsInScreen.top,
                mBoundsInScreen.right, mBoundsInScreen.bottom);
    }

    /**
     * Sets the node bounds in screen coordinates.
     * <p>
     *   <strong>Note:</strong> Cannot be called from an
     *   {@link android.accessibilityservice.AccessibilityService}.
     *   This class is made immutable before being delivered to an AccessibilityService.
     * </p>
     *
     * @param bounds The node bounds.
     *
     * @throws IllegalStateException If called from an AccessibilityService.
     */
    public void setBoundsInScreen(Rect bounds) {
        enforceNotSealed();
        mBoundsInScreen.set(bounds.left, bounds.top, bounds.right, bounds.bottom);
    }

    /**
     * Gets whether this node is checkable.
     *
     * @return True if the node is checkable.
     */
    public boolean isCheckable() {
        return getBooleanProperty(PROPERTY_CHECKABLE);
    }

    /**
     * Sets whether this node is checkable.
     * <p>
     *   <strong>Note:</strong> Cannot be called from an
     *   {@link android.accessibilityservice.AccessibilityService}.
     *   This class is made immutable before being delivered to an AccessibilityService.
     * </p>
     *
     * @param checkable True if the node is checkable.
     *
     * @throws IllegalStateException If called from an AccessibilityService.
     */
    public void setCheckable(boolean checkable) {
        setBooleanProperty(PROPERTY_CHECKABLE, checkable);
    }

    /**
     * Gets whether this node is checked.
     *
     * @return True if the node is checked.
     */
    public boolean isChecked() {
        return getBooleanProperty(PROPERTY_CHECKED);
    }

    /**
     * Sets whether this node is checked.
     * <p>
     *   <strong>Note:</strong> Cannot be called from an
     *   {@link android.accessibilityservice.AccessibilityService}.
     *   This class is made immutable before being delivered to an AccessibilityService.
     * </p>
     *
     * @param checked True if the node is checked.
     *
     * @throws IllegalStateException If called from an AccessibilityService.
     */
    public void setChecked(boolean checked) {
        setBooleanProperty(PROPERTY_CHECKED, checked);
    }

    /**
     * Gets whether this node is focusable.
     *
     * @return True if the node is focusable.
     */
    public boolean isFocusable() {
        return getBooleanProperty(PROPERTY_FOCUSABLE);
    }

    /**
     * Sets whether this node is focusable.
     * <p>
     *   <strong>Note:</strong> Cannot be called from an
     *   {@link android.accessibilityservice.AccessibilityService}.
     *   This class is made immutable before being delivered to an AccessibilityService.
     * </p>
     *
     * @param focusable True if the node is focusable.
     *
     * @throws IllegalStateException If called from an AccessibilityService.
     */
    public void setFocusable(boolean focusable) {
        setBooleanProperty(PROPERTY_FOCUSABLE, focusable);
    }

    /**
     * Gets whether this node is focused.
     *
     * @return True if the node is focused.
     */
    public boolean isFocused() {
        return getBooleanProperty(PROPERTY_FOCUSED);
    }

    /**
     * Sets whether this node is focused.
     * <p>
     *   <strong>Note:</strong> Cannot be called from an
     *   {@link android.accessibilityservice.AccessibilityService}.
     *   This class is made immutable before being delivered to an AccessibilityService.
     * </p>
     *
     * @param focused True if the node is focused.
     *
     * @throws IllegalStateException If called from an AccessibilityService.
     */
    public void setFocused(boolean focused) {
        setBooleanProperty(PROPERTY_FOCUSED, focused);
    }

    /**
     * Gets whether this node is selected.
     *
     * @return True if the node is selected.
     */
    public boolean isSelected() {
        return getBooleanProperty(PROPERTY_SELECTED);
    }

    /**
     * Sets whether this node is selected.
     * <p>
     *   <strong>Note:</strong> Cannot be called from an
     *   {@link android.accessibilityservice.AccessibilityService}.
     *   This class is made immutable before being delivered to an AccessibilityService.
     * </p>
     *
     * @param selected True if the node is selected.
     *
     * @throws IllegalStateException If called from an AccessibilityService.
     */
    public void setSelected(boolean selected) {
        setBooleanProperty(PROPERTY_SELECTED, selected);
    }

    /**
     * Gets whether this node is clickable.
     *
     * @return True if the node is clickable.
     */
    public boolean isClickable() {
        return getBooleanProperty(PROPERTY_CLICKABLE);
    }

    /**
     * Sets whether this node is clickable.
     * <p>
     *   <strong>Note:</strong> Cannot be called from an
     *   {@link android.accessibilityservice.AccessibilityService}.
     *   This class is made immutable before being delivered to an AccessibilityService.
     * </p>
     *
     * @param clickable True if the node is clickable.
     *
     * @throws IllegalStateException If called from an AccessibilityService.
     */
    public void setClickable(boolean clickable) {
        setBooleanProperty(PROPERTY_CLICKABLE, clickable);
    }

    /**
     * Gets whether this node is long clickable.
     *
     * @return True if the node is long clickable.
     */
    public boolean isLongClickable() {
        return getBooleanProperty(PROPERTY_LONG_CLICKABLE);
    }

    /**
     * Sets whether this node is long clickable.
     * <p>
     *   <strong>Note:</strong> Cannot be called from an
     *   {@link android.accessibilityservice.AccessibilityService}.
     *   This class is made immutable before being delivered to an AccessibilityService.
     * </p>
     *
     * @param longClickable True if the node is long clickable.
     *
     * @throws IllegalStateException If called from an AccessibilityService.
     */
    public void setLongClickable(boolean longClickable) {
        setBooleanProperty(PROPERTY_LONG_CLICKABLE, longClickable);
    }

    /**
     * Gets whether this node is enabled.
     *
     * @return True if the node is enabled.
     */
    public boolean isEnabled() {
        return getBooleanProperty(PROPERTY_ENABLED);
    }

    /**
     * Sets whether this node is enabled.
     * <p>
     *   <strong>Note:</strong> Cannot be called from an
     *   {@link android.accessibilityservice.AccessibilityService}.
     *   This class is made immutable before being delivered to an AccessibilityService.
     * </p>
     *
     * @param enabled True if the node is enabled.
     *
     * @throws IllegalStateException If called from an AccessibilityService.
     */
    public void setEnabled(boolean enabled) {
        setBooleanProperty(PROPERTY_ENABLED, enabled);
    }

    /**
     * Gets whether this node is a password.
     *
     * @return True if the node is a password.
     */
    public boolean isPassword() {
        return getBooleanProperty(PROPERTY_PASSWORD);
    }

    /**
     * Sets whether this node is a password.
     * <p>
     *   <strong>Note:</strong> Cannot be called from an
     *   {@link android.accessibilityservice.AccessibilityService}.
     *   This class is made immutable before being delivered to an AccessibilityService.
     * </p>
     *
     * @param password True if the node is a password.
     *
     * @throws IllegalStateException If called from an AccessibilityService.
     */
    public void setPassword(boolean password) {
        setBooleanProperty(PROPERTY_PASSWORD, password);
    }

    /**
     * Gets if the node is scrollable.
     *
     * @return True if the node is scrollable, false otherwise.
     */
    public boolean isScrollable() {
        return getBooleanProperty(PROPERTY_SCROLLABLE);
    }

    /**
     * Sets if the node is scrollable.
     * <p>
     *   <strong>Note:</strong> Cannot be called from an
     *   {@link android.accessibilityservice.AccessibilityService}.
     *   This class is made immutable before being delivered to an AccessibilityService.
     * </p>
     *
     * @param scrollable True if the node is scrollable, false otherwise.
     *
     * @throws IllegalStateException If called from an AccessibilityService.
     */
    public void setScrollable(boolean scrollable) {
        enforceNotSealed();
        setBooleanProperty(PROPERTY_SCROLLABLE, scrollable);
    }

    /**
     * Gets the package this node comes from.
     *
     * @return The package name.
     */
    public CharSequence getPackageName() {
        return mPackageName;
    }

    /**
     * Sets the package this node comes from.
     * <p>
     *   <strong>Note:</strong> Cannot be called from an
     *   {@link android.accessibilityservice.AccessibilityService}.
     *   This class is made immutable before being delivered to an AccessibilityService.
     * </p>
     *
     * @param packageName The package name.
     *
     * @throws IllegalStateException If called from an AccessibilityService.
     */
    public void setPackageName(CharSequence packageName) {
        enforceNotSealed();
        mPackageName = packageName;
    }

    /**
     * Gets the class this node comes from.
     *
     * @return The class name.
     */
    public CharSequence getClassName() {
        return mClassName;
    }

    /**
     * Sets the class this node comes from.
     * <p>
     *   <strong>Note:</strong> Cannot be called from an
     *   {@link android.accessibilityservice.AccessibilityService}.
     *   This class is made immutable before being delivered to an AccessibilityService.
     * </p>
     *
     * @param className The class name.
     *
     * @throws IllegalStateException If called from an AccessibilityService.
     */
    public void setClassName(CharSequence className) {
        enforceNotSealed();
        mClassName = className;
    }

    /**
     * Gets the text of this node.
     *
     * @return The text.
     */
    public CharSequence getText() {
        return mText;
    }

    /**
     * Sets the text of this node.
     * <p>
     *   <strong>Note:</strong> Cannot be called from an
     *   {@link android.accessibilityservice.AccessibilityService}.
     *   This class is made immutable before being delivered to an AccessibilityService.
     * </p>
     *
     * @param text The text.
     *
     * @throws IllegalStateException If called from an AccessibilityService.
     */
    public void setText(CharSequence text) {
        enforceNotSealed();
        mText = text;
    }

    /**
     * Gets the content description of this node.
     *
     * @return The content description.
     */
    public CharSequence getContentDescription() {
        return mContentDescription;
    }

    /**
     * Sets the content description of this node.
     * <p>
     *   <strong>Note:</strong> Cannot be called from an
     *   {@link android.accessibilityservice.AccessibilityService}.
     *   This class is made immutable before being delivered to an AccessibilityService.
     * </p>
     *
     * @param contentDescription The content description.
     *
     * @throws IllegalStateException If called from an AccessibilityService.
     */
    public void setContentDescription(CharSequence contentDescription) {
        enforceNotSealed();
        mContentDescription = contentDescription;
    }

    /**
     * Gets the value of a boolean property.
     *
     * @param property The property.
     * @return The value.
     */
    private boolean getBooleanProperty(int property) {
        return (mBooleanProperties & property) != 0;
    }

    /**
     * Sets a boolean property.
     *
     * @param property The property.
     * @param value The value.
     *
     * @throws IllegalStateException If called from an AccessibilityService.
     */
    private void setBooleanProperty(int property, boolean value) {
        enforceNotSealed();
        if (value) {
            mBooleanProperties |= property;
        } else {
            mBooleanProperties &= ~property;
        }
    }

    /**
     * Sets the unique id of the IAccessibilityServiceConnection over which
     * this instance can send requests to the system.
     *
     * @param connectionId The connection id.
     *
     * @hide
     */
    public void setConnectionId(int connectionId) {
        enforceNotSealed();
        mConnectionId = connectionId;
    }

    /**
     * {@inheritDoc}
     */
    public int describeContents() {
        return 0;
    }

    /**
     * Sets if this instance is sealed.
     *
     * @param sealed Whether is sealed.
     *
     * @hide
     */
    public void setSealed(boolean sealed) {
        mSealed = sealed;
    }

    /**
     * Gets if this instance is sealed.
     *
     * @return Whether is sealed.
     *
     * @hide
     */
    public boolean isSealed() {
        return mSealed;
    }

    /**
     * Enforces that this instance is sealed.
     *
     * @throws IllegalStateException If this instance is not sealed.
     *
     * @hide
     */
    protected void enforceSealed() {
        if (!isSealed()) {
            throw new IllegalStateException("Cannot perform this "
                    + "action on a not sealed instance.");
        }
    }

    /**
     * Enforces that this instance is not sealed.
     *
     * @throws IllegalStateException If this instance is sealed.
     *
     * @hide
     */
    protected void enforceNotSealed() {
        if (isSealed()) {
            throw new IllegalStateException("Cannot perform this "
                    + "action on an sealed instance.");
        }
    }

    /**
     * Returns a cached instance if such is available otherwise a new one
     * and sets the source.
     *
     * @param source The source view.
     * @return An instance.
     *
     * @see #setSource(View)
     */
    public static AccessibilityNodeInfo obtain(View source) {
        AccessibilityNodeInfo info = AccessibilityNodeInfo.obtain();
        info.setSource(source);
        return info;
    }

    /**
     * Returns a cached instance if such is available otherwise a new one
     * and sets the source.
     *
     * @param root The root of the virtual subtree.
     * @param virtualDescendantId The id of the virtual descendant.
     * @return An instance.
     *
     * @see #setSource(View, int)
     */
    public static AccessibilityNodeInfo obtain(View root, int virtualDescendantId) {
        AccessibilityNodeInfo info = AccessibilityNodeInfo.obtain();
        info.setSource(root, virtualDescendantId);
        return info;
    }

    /**
     * Returns a cached instance if such is available otherwise a new one.
     *
     * @return An instance.
     */
    public static AccessibilityNodeInfo obtain() {
        synchronized (sPoolLock) {
            if (sPool != null) {
                AccessibilityNodeInfo info = sPool;
                sPool = sPool.mNext;
                sPoolSize--;
                info.mNext = null;
                info.mIsInPool = false;
                return info;
            }
            return new AccessibilityNodeInfo();
        }
    }

    /**
     * Returns a cached instance if such is available or a new one is
     * create. The returned instance is initialized from the given
     * <code>info</code>.
     *
     * @param info The other info.
     * @return An instance.
     */
    public static AccessibilityNodeInfo obtain(AccessibilityNodeInfo info) {
        AccessibilityNodeInfo infoClone = AccessibilityNodeInfo.obtain();
        infoClone.init(info);
        return infoClone;
    }

    /**
     * Return an instance back to be reused.
     * <p>
     * <strong>Note:</strong> You must not touch the object after calling this function.
     *
     * @throws IllegalStateException If the info is already recycled.
     */
    public void recycle() {
        if (mIsInPool) {
            throw new IllegalStateException("Info already recycled!");
        }
        clear();
        synchronized (sPoolLock) {
            if (sPoolSize <= MAX_POOL_SIZE) {
                mNext = sPool;
                sPool = this;
                mIsInPool = true;
                sPoolSize++;
            }
        }
    }

    /**
     * {@inheritDoc}
     * <p>
     *   <strong>Note:</strong> After the instance is written to a parcel it
     *      is recycled. You must not touch the object after calling this function.
     * </p>
     */
    public void writeToParcel(Parcel parcel, int flags) {
        parcel.writeInt(isSealed() ? 1 : 0);
        parcel.writeLong(mSourceNodeId);
        parcel.writeInt(mWindowId);
        parcel.writeLong(mParentNodeId);
        parcel.writeInt(mConnectionId);

        SparseLongArray childIds = mChildIds;
        final int childIdsSize = childIds.size();
        parcel.writeInt(childIdsSize);
        for (int i = 0; i < childIdsSize; i++) {
            parcel.writeLong(childIds.valueAt(i));
        }

        parcel.writeInt(mBoundsInParent.top);
        parcel.writeInt(mBoundsInParent.bottom);
        parcel.writeInt(mBoundsInParent.left);
        parcel.writeInt(mBoundsInParent.right);

        parcel.writeInt(mBoundsInScreen.top);
        parcel.writeInt(mBoundsInScreen.bottom);
        parcel.writeInt(mBoundsInScreen.left);
        parcel.writeInt(mBoundsInScreen.right);

        parcel.writeInt(mActions);

        parcel.writeInt(mBooleanProperties);

        TextUtils.writeToParcel(mPackageName, parcel, flags);
        TextUtils.writeToParcel(mClassName, parcel, flags);
        TextUtils.writeToParcel(mText, parcel, flags);
        TextUtils.writeToParcel(mContentDescription, parcel, flags);

        // Since instances of this class are fetched via synchronous i.e. blocking
        // calls in IPCs we always recycle as soon as the instance is marshaled.
        recycle();
    }

    /**
     * Initializes this instance from another one.
     *
     * @param other The other instance.
     */
    private void init(AccessibilityNodeInfo other) {
        mSealed = other.mSealed;
        mSourceNodeId = other.mSourceNodeId;
        mParentNodeId = other.mParentNodeId;
        mWindowId = other.mWindowId;
        mConnectionId = other.mConnectionId;
        mBoundsInParent.set(other.mBoundsInParent);
        mBoundsInScreen.set(other.mBoundsInScreen);
        mPackageName = other.mPackageName;
        mClassName = other.mClassName;
        mText = other.mText;
        mContentDescription = other.mContentDescription;
        mActions= other.mActions;
        mBooleanProperties = other.mBooleanProperties;
        mChildIds = other.mChildIds.clone();
    }

    /**
     * Creates a new instance from a {@link Parcel}.
     *
     * @param parcel A parcel containing the state of a {@link AccessibilityNodeInfo}.
     */
    private void initFromParcel(Parcel parcel) {
        mSealed = (parcel.readInt()  == 1);
        mSourceNodeId = parcel.readLong();
        mWindowId = parcel.readInt();
        mParentNodeId = parcel.readLong();
        mConnectionId = parcel.readInt();

        SparseLongArray childIds = mChildIds;
        final int childrenSize = parcel.readInt();
        for (int i = 0; i < childrenSize; i++) {
            final long childId = parcel.readLong();
            childIds.put(i, childId);
        }

        mBoundsInParent.top = parcel.readInt();
        mBoundsInParent.bottom = parcel.readInt();
        mBoundsInParent.left = parcel.readInt();
        mBoundsInParent.right = parcel.readInt();

        mBoundsInScreen.top = parcel.readInt();
        mBoundsInScreen.bottom = parcel.readInt();
        mBoundsInScreen.left = parcel.readInt();
        mBoundsInScreen.right = parcel.readInt();

        mActions = parcel.readInt();

        mBooleanProperties = parcel.readInt();

        mPackageName = TextUtils.CHAR_SEQUENCE_CREATOR.createFromParcel(parcel);
        mClassName = TextUtils.CHAR_SEQUENCE_CREATOR.createFromParcel(parcel);
        mText = TextUtils.CHAR_SEQUENCE_CREATOR.createFromParcel(parcel);
        mContentDescription = TextUtils.CHAR_SEQUENCE_CREATOR.createFromParcel(parcel);
    }

    /**
     * Clears the state of this instance.
     */
    private void clear() {
        mSealed = false;
        mSourceNodeId = makeNodeId(UNDEFINED, UNDEFINED);
        mParentNodeId = makeNodeId(UNDEFINED, UNDEFINED);
        mWindowId = UNDEFINED;
        mConnectionId = UNDEFINED;
        mChildIds.clear();
        mBoundsInParent.set(0, 0, 0, 0);
        mBoundsInScreen.set(0, 0, 0, 0);
        mBooleanProperties = 0;
        mPackageName = null;
        mClassName = null;
        mText = null;
        mContentDescription = null;
        mActions = 0;
    }

    /**
     * Gets the human readable action symbolic name.
     *
     * @param action The action.
     * @return The symbolic name.
     */
    private static String getActionSymbolicName(int action) {
        switch (action) {
            case ACTION_FOCUS:
                return "ACTION_FOCUS";
            case ACTION_CLEAR_FOCUS:
                return "ACTION_CLEAR_FOCUS";
            case ACTION_SELECT:
                return "ACTION_SELECT";
            case ACTION_CLEAR_SELECTION:
                return "ACTION_CLEAR_SELECTION";
            default:
                throw new IllegalArgumentException("Unknown action: " + action);
        }
    }

    private boolean canPerformRequestOverConnection(long accessibilityNodeId) {
        return (mWindowId != UNDEFINED
                && getAccessibilityViewId(accessibilityNodeId) != UNDEFINED
                && mConnectionId != UNDEFINED);
    }

    @Override
    public boolean equals(Object object) {
        if (this == object) {
            return true;
        }
        if (object == null) {
            return false;
        }
        if (getClass() != object.getClass()) {
            return false;
        }
        AccessibilityNodeInfo other = (AccessibilityNodeInfo) object;
        if (mSourceNodeId != other.mSourceNodeId) {
            return false;
        }
        if (mWindowId != other.mWindowId) {
            return false;
        }
        return true;
    }

    @Override
    public int hashCode() {
        final int prime = 31;
        int result = 1;
        result = prime * result + getAccessibilityViewId(mSourceNodeId);
        result = prime * result + getVirtualDescendantId(mSourceNodeId);
        result = prime * result + mWindowId;
        return result;
    }

    @Override
    public String toString() {
        StringBuilder builder = new StringBuilder();
        builder.append(super.toString());

        if (DEBUG) {
            builder.append("; accessibilityViewId: " + getAccessibilityViewId(mSourceNodeId));
            builder.append("; virtualDescendantId: " + getVirtualDescendantId(mSourceNodeId));
            builder.append("; mParentNodeId: " + mParentNodeId);
            SparseLongArray childIds = mChildIds;
            builder.append("; childAccessibilityIds: [");
            for (int i = 0, count = childIds.size(); i < count; i++) {
                builder.append(childIds.valueAt(i));
                if (i < count - 1) {
                    builder.append(", ");
                }
           }
           builder.append("]");
        }

        builder.append("; boundsInParent: " + mBoundsInParent);
        builder.append("; boundsInScreen: " + mBoundsInScreen);

        builder.append("; packageName: ").append(mPackageName);
        builder.append("; className: ").append(mClassName);
        builder.append("; text: ").append(mText);
        builder.append("; contentDescription: ").append(mContentDescription);

        builder.append("; checkable: ").append(isCheckable());
        builder.append("; checked: ").append(isChecked());
        builder.append("; focusable: ").append(isFocusable());
        builder.append("; focused: ").append(isFocused());
        builder.append("; selected: ").append(isSelected());
        builder.append("; clickable: ").append(isClickable());
        builder.append("; longClickable: ").append(isLongClickable());
        builder.append("; enabled: ").append(isEnabled());
        builder.append("; password: ").append(isPassword());
        builder.append("; scrollable: " + isScrollable());

        builder.append("; [");

        for (int actionBits = mActions; actionBits != 0;) {
            final int action = 1 << Integer.numberOfTrailingZeros(actionBits);
            actionBits &= ~action;
            builder.append(getActionSymbolicName(action));
            if (actionBits != 0) {
                builder.append(", ");
            }
        }

        builder.append("]");

        return builder.toString();
    }

    /**
     * @see Parcelable.Creator
     */
    public static final Parcelable.Creator<AccessibilityNodeInfo> CREATOR =
            new Parcelable.Creator<AccessibilityNodeInfo>() {
        public AccessibilityNodeInfo createFromParcel(Parcel parcel) {
            AccessibilityNodeInfo info = AccessibilityNodeInfo.obtain();
            info.initFromParcel(parcel);
            return info;
        }

        public AccessibilityNodeInfo[] newArray(int size) {
            return new AccessibilityNodeInfo[size];
        }
    };
}