* Clients should override abstract methods on this class and attach it to the * host view using {@link ViewCompat#setAccessibilityDelegate}: *
*
* class MyCustomView extends View {
* private MyVirtualViewHelper mVirtualViewHelper;
*
* public MyCustomView(Context context, ...) {
* ...
* mVirtualViewHelper = new MyVirtualViewHelper(this);
* ViewCompat.setAccessibilityDelegate(this, mVirtualViewHelper);
* }
*
* @Override
* public boolean dispatchHoverEvent(MotionEvent event) {
* return mHelper.dispatchHoverEvent(this, event)
* || super.dispatchHoverEvent(event);
* }
*
* @Override
* public boolean dispatchKeyEvent(KeyEvent event) {
* return mHelper.dispatchKeyEvent(event)
* || super.dispatchKeyEvent(event);
* }
*
* @Override
* public boolean onFocusChanged(boolean gainFocus, int direction,
* Rect previouslyFocusedRect) {
* super.onFocusChanged(gainFocus, direction, previouslyFocusedRect);
* mHelper.onFocusChanged(gainFocus, direction, previouslyFocusedRect);
* }
* }
* mAccessHelper = new MyExploreByTouchHelper(someView);
* ViewCompat.setAccessibilityDelegate(someView, mAccessHelper);
*
*/
public abstract class ExploreByTouchHelper extends AccessibilityDelegateCompat {
/** Virtual node identifier value for invalid nodes. */
public static final int INVALID_ID = Integer.MIN_VALUE;
/** Virtual node identifier value for the host view's node. */
public static final int HOST_ID = View.NO_ID;
/** Default class name used for virtual views. */
private static final String DEFAULT_CLASS_NAME = "android.view.View";
/** Default bounds used to determine if the client didn't set any. */
private static final Rect INVALID_PARENT_BOUNDS = new Rect(
Integer.MAX_VALUE, Integer.MAX_VALUE, Integer.MIN_VALUE, Integer.MIN_VALUE);
// Temporary, reusable data structures.
private final Rect mTempScreenRect = new Rect();
private final Rect mTempParentRect = new Rect();
private final Rect mTempVisibleRect = new Rect();
private final int[] mTempGlobalRect = new int[2];
/** System accessibility manager, used to check state and send events. */
private final AccessibilityManager mManager;
/** View whose internal structure is exposed through this helper. */
private final View mHost;
/** Virtual node provider used to expose logical structure to services. */
private MyNodeProvider mNodeProvider;
/** Identifier for the virtual view that holds accessibility focus. */
private int mAccessibilityFocusedVirtualViewId = INVALID_ID;
/** Identifier for the virtual view that holds keyboard focus. */
private int mKeyboardFocusedVirtualViewId = INVALID_ID;
/** Identifier for the virtual view that is currently hovered. */
private int mHoveredVirtualViewId = INVALID_ID;
/**
* Constructs a new helper that can expose a virtual view hierarchy for the
* specified host view.
*
* @param host view whose virtual view hierarchy is exposed by this helper
*/
public ExploreByTouchHelper(View host) {
if (host == null) {
throw new IllegalArgumentException("View may not be null");
}
mHost = host;
final Context context = host.getContext();
mManager = (AccessibilityManager) context.getSystemService(Context.ACCESSIBILITY_SERVICE);
// Host view must be focusable so that we can delegate to virtual
// views.
host.setFocusable(true);
if (ViewCompat.getImportantForAccessibility(host)
== ViewCompat.IMPORTANT_FOR_ACCESSIBILITY_AUTO) {
ViewCompat.setImportantForAccessibility(
host, ViewCompat.IMPORTANT_FOR_ACCESSIBILITY_YES);
}
}
@Override
public AccessibilityNodeProviderCompat getAccessibilityNodeProvider(View host) {
if (mNodeProvider == null) {
mNodeProvider = new MyNodeProvider();
}
return mNodeProvider;
}
/**
* Delegates hover events from the host view.
* * Dispatches hover {@link MotionEvent}s to the virtual view hierarchy when * the Explore by Touch feature is enabled. *
* This method should be called by overriding the host view's * {@link View#dispatchHoverEvent(MotionEvent)} method: *
@Override
* public boolean dispatchHoverEvent(MotionEvent event) {
* return mHelper.dispatchHoverEvent(this, event)
* || super.dispatchHoverEvent(event);
* }
*
*
* @param event The hover event to dispatch to the virtual view hierarchy.
* @return Whether the hover event was handled.
*/
public final boolean dispatchHoverEvent(@NonNull MotionEvent event) {
if (!mManager.isEnabled()
|| !AccessibilityManagerCompat.isTouchExplorationEnabled(mManager)) {
return false;
}
switch (event.getAction()) {
case MotionEventCompat.ACTION_HOVER_MOVE:
case MotionEventCompat.ACTION_HOVER_ENTER:
final int virtualViewId = getVirtualViewAt(event.getX(), event.getY());
updateHoveredVirtualView(virtualViewId);
return (virtualViewId != INVALID_ID);
case MotionEventCompat.ACTION_HOVER_EXIT:
if (mAccessibilityFocusedVirtualViewId != INVALID_ID) {
updateHoveredVirtualView(INVALID_ID);
return true;
}
return false;
default:
return false;
}
}
/**
* Delegates key events from the host view.
* * This method should be called by overriding the host view's * {@link View#dispatchKeyEvent(KeyEvent)} method: *
@Override
* public boolean dispatchKeyEvent(KeyEvent event) {
* return mHelper.dispatchKeyEvent(event)
* || super.dispatchKeyEvent(event);
* }
*
*/
public final boolean dispatchKeyEvent(@NonNull KeyEvent event) {
boolean handled = false;
final int action = event.getAction();
if (action != KeyEvent.ACTION_UP) {
final int keyCode = event.getKeyCode();
switch (keyCode) {
case KeyEvent.KEYCODE_DPAD_LEFT:
case KeyEvent.KEYCODE_DPAD_UP:
case KeyEvent.KEYCODE_DPAD_RIGHT:
case KeyEvent.KEYCODE_DPAD_DOWN:
if (KeyEventCompat.hasNoModifiers(event)) {
final int direction = keyToDirection(keyCode);
final int count = 1 + event.getRepeatCount();
for (int i = 0; i < count; i++) {
if (moveFocus(direction, null)) {
handled = true;
} else {
break;
}
}
}
break;
case KeyEvent.KEYCODE_DPAD_CENTER:
case KeyEvent.KEYCODE_ENTER:
if (KeyEventCompat.hasNoModifiers(event)) {
if (event.getRepeatCount() == 0) {
clickKeyboardFocusedVirtualView();
handled = true;
}
}
break;
case KeyEvent.KEYCODE_TAB:
if (KeyEventCompat.hasNoModifiers(event)) {
handled = moveFocus(View.FOCUS_FORWARD, null);
} else if (KeyEventCompat.hasModifiers(event, KeyEvent.META_SHIFT_ON)) {
handled = moveFocus(View.FOCUS_BACKWARD, null);
}
break;
}
}
return handled;
}
/**
* Delegates focus changes from the host view.
* * This method should be called by overriding the host view's * {@link View#onFocusChanged(boolean, int, Rect)} method: *
@Override
* public boolean onFocusChanged(boolean gainFocus, int direction,
* Rect previouslyFocusedRect) {
* super.onFocusChanged(gainFocus, direction, previouslyFocusedRect);
* mHelper.onFocusChanged(gainFocus, direction, previouslyFocusedRect);
* }
*
*/
public final void onFocusChanged(boolean gainFocus, int direction,
@Nullable Rect previouslyFocusedRect) {
if (mKeyboardFocusedVirtualViewId != INVALID_ID) {
clearKeyboardFocusForVirtualView(mKeyboardFocusedVirtualViewId);
}
if (gainFocus) {
moveFocus(direction, previouslyFocusedRect);
}
}
/**
* @return the identifier of the virtual view that has accessibility focus
* or {@link #INVALID_ID} if no virtual view has accessibility
* focus
*/
public final int getAccessibilityFocusedVirtualViewId() {
return mAccessibilityFocusedVirtualViewId;
}
/**
* @return the identifier of the virtual view that has keyboard focus
* or {@link #INVALID_ID} if no virtual view has keyboard focus
*/
public final int getKeyboardFocusedVirtualViewId() {
return mKeyboardFocusedVirtualViewId;
}
/**
* Maps key event codes to focus directions.
*
* @param keyCode the key event code
* @return the corresponding focus direction
*/
@FocusRealDirection
private static int keyToDirection(int keyCode) {
switch (keyCode) {
case KeyEvent.KEYCODE_DPAD_LEFT:
return View.FOCUS_LEFT;
case KeyEvent.KEYCODE_DPAD_UP:
return View.FOCUS_UP;
case KeyEvent.KEYCODE_DPAD_RIGHT:
return View.FOCUS_RIGHT;
default:
return View.FOCUS_DOWN;
}
}
/**
* Obtains the bounds for the specified virtual view.
*
* @param virtualViewId the identifier of the virtual view
* @param outBounds the rect to populate with virtual view bounds
*/
private void getBoundsInParent(int virtualViewId, Rect outBounds) {
final AccessibilityNodeInfoCompat node = obtainAccessibilityNodeInfo(virtualViewId);
node.getBoundsInParent(outBounds);
}
/**
* Adapts AccessibilityNodeInfoCompat for obtaining bounds.
*/
private static final FocusStrategy.BoundsAdapter* You should call this method after performing a user action that normally * fires an accessibility event, such as clicking on an item. *
*
public void performItemClick(T item) {
* ...
* sendEventForVirtualViewId(item.id, AccessibilityEvent.TYPE_VIEW_CLICKED);
* }
*
*
* @param virtualViewId the identifier of the virtual view for which to
* send an event
* @param eventType the type of event to send
* @return {@code true} if the event was sent successfully, {@code false}
* otherwise
*/
public final boolean sendEventForVirtualView(int virtualViewId, int eventType) {
if ((virtualViewId == INVALID_ID) || !mManager.isEnabled()) {
return false;
}
final ViewParent parent = mHost.getParent();
if (parent == null) {
return false;
}
final AccessibilityEvent event = createEvent(virtualViewId, eventType);
return ViewParentCompat.requestSendAccessibilityEvent(parent, mHost, event);
}
/**
* Notifies the accessibility framework that the properties of the parent
* view have changed.
* * You must call this method after adding or removing * items from the parent view. */ public final void invalidateRoot() { invalidateVirtualView(HOST_ID, AccessibilityEventCompat.CONTENT_CHANGE_TYPE_SUBTREE); } /** * Notifies the accessibility framework that the properties of a particular * item have changed. *
* You must call this method after changing any of the * properties set in * {@link #onPopulateNodeForVirtualView(int, AccessibilityNodeInfoCompat)}. * * @param virtualViewId the virtual view id to invalidate, or * {@link #HOST_ID} to invalidate the root view * @see #invalidateVirtualView(int, int) */ public final void invalidateVirtualView(int virtualViewId) { invalidateVirtualView(virtualViewId, AccessibilityEventCompat.CONTENT_CHANGE_TYPE_UNDEFINED); } /** * Notifies the accessibility framework that the properties of a particular * item have changed. *
* You must call this method after changing any of the * properties set in * {@link #onPopulateNodeForVirtualView(int, AccessibilityNodeInfoCompat)}. * * @param virtualViewId the virtual view id to invalidate, or * {@link #HOST_ID} to invalidate the root view * @param changeTypes the bit mask of change types. May be {@code 0} for the * default (undefined) change type or one or more of: *
* This method may be called with identifier {@link #HOST_ID} to obtain a
* node for the host view.
*
* @param virtualViewId the identifier of the virtual view for which to
* construct a node
* @return an {@link AccessibilityNodeInfoCompat} populated with information
* about the specified item
*/
@NonNull
private AccessibilityNodeInfoCompat obtainAccessibilityNodeInfo(int virtualViewId) {
if (virtualViewId == HOST_ID) {
return createNodeForHost();
}
return createNodeForChild(virtualViewId);
}
/**
* Constructs and returns an {@link AccessibilityNodeInfoCompat} for the
* host view populated with its virtual descendants.
*
* @return an {@link AccessibilityNodeInfoCompat} for the parent node
*/
@NonNull
private AccessibilityNodeInfoCompat createNodeForHost() {
final AccessibilityNodeInfoCompat info = AccessibilityNodeInfoCompat.obtain(mHost);
ViewCompat.onInitializeAccessibilityNodeInfo(mHost, info);
// Add the virtual descendants.
final ArrayList
* Allows the implementing class to specify most node properties, but
* overrides the following:
*
* Uses the bounds of the parent view and the parent-relative bounding
* rectangle specified by
* {@link AccessibilityNodeInfoCompat#getBoundsInParent} to automatically
* update the following properties:
*
* A virtual view will not actually take focus if
* {@link AccessibilityManager#isEnabled()} returns false,
* {@link AccessibilityManager#isTouchExplorationEnabled()} returns false,
* or the view already has accessibility focus.
*
* @param virtualViewId the identifier of the virtual view on which to
* place accessibility focus
* @return whether this virtual view actually took accessibility focus
*/
private boolean requestAccessibilityFocus(int virtualViewId) {
if (!mManager.isEnabled()
|| !AccessibilityManagerCompat.isTouchExplorationEnabled(mManager)) {
return false;
}
// TODO: Check virtual view visibility.
if (mAccessibilityFocusedVirtualViewId != virtualViewId) {
// Clear focus from the previously focused view, if applicable.
if (mAccessibilityFocusedVirtualViewId != INVALID_ID) {
clearAccessibilityFocus(mAccessibilityFocusedVirtualViewId);
}
// Set focus on the new view.
mAccessibilityFocusedVirtualViewId = virtualViewId;
// TODO: Only invalidate virtual view bounds.
mHost.invalidate();
sendEventForVirtualView(virtualViewId,
AccessibilityEventCompat.TYPE_VIEW_ACCESSIBILITY_FOCUSED);
return true;
}
return false;
}
/**
* Attempts to clear accessibility focus from a virtual view.
*
* @param virtualViewId the identifier of the virtual view from which to
* clear accessibility focus
* @return whether this virtual view actually cleared accessibility focus
*/
private boolean clearAccessibilityFocus(int virtualViewId) {
if (mAccessibilityFocusedVirtualViewId == virtualViewId) {
mAccessibilityFocusedVirtualViewId = INVALID_ID;
mHost.invalidate();
sendEventForVirtualView(virtualViewId,
AccessibilityEventCompat.TYPE_VIEW_ACCESSIBILITY_FOCUS_CLEARED);
return true;
}
return false;
}
/**
* Attempts to give keyboard focus to a virtual view.
*
* @param virtualViewId the identifier of the virtual view on which to
* place keyboard focus
* @return whether this virtual view actually took keyboard focus
*/
public final boolean requestKeyboardFocusForVirtualView(int virtualViewId) {
if (!mHost.isFocused() && !mHost.requestFocus()) {
// Host must have real keyboard focus.
return false;
}
if (mKeyboardFocusedVirtualViewId == virtualViewId) {
// The virtual view already has focus.
return false;
}
if (mKeyboardFocusedVirtualViewId != INVALID_ID) {
clearKeyboardFocusForVirtualView(mKeyboardFocusedVirtualViewId);
}
mKeyboardFocusedVirtualViewId = virtualViewId;
onVirtualViewKeyboardFocusChanged(virtualViewId, true);
sendEventForVirtualView(virtualViewId, AccessibilityEvent.TYPE_VIEW_FOCUSED);
return true;
}
/**
* Attempts to clear keyboard focus from a virtual view.
*
* @param virtualViewId the identifier of the virtual view from which to
* clear keyboard focus
* @return whether this virtual view actually cleared keyboard focus
*/
public final boolean clearKeyboardFocusForVirtualView(int virtualViewId) {
if (mKeyboardFocusedVirtualViewId != virtualViewId) {
// The virtual view is not focused.
return false;
}
mKeyboardFocusedVirtualViewId = INVALID_ID;
onVirtualViewKeyboardFocusChanged(virtualViewId, false);
sendEventForVirtualView(virtualViewId, AccessibilityEvent.TYPE_VIEW_FOCUSED);
return true;
}
/**
* Provides a mapping between view-relative coordinates and logical
* items.
*
* @param x The view-relative x coordinate
* @param y The view-relative y coordinate
* @return virtual view identifier for the logical item under
* coordinates (x,y) or {@link #HOST_ID} if there is no item at
* the given coordinates
*/
protected abstract int getVirtualViewAt(float x, float y);
/**
* Populates a list with the view's visible items. The ordering of items
* within {@code virtualViewIds} specifies order of accessibility focus
* traversal.
*
* @param virtualViewIds The list to populate with visible items
*/
protected abstract void getVisibleVirtualViews(List
* The helper class automatically populates the following fields based on
* the values set by
* {@link #onPopulateNodeForVirtualView(int, AccessibilityNodeInfoCompat)},
* but implementations may optionally override them:
*
* The following required fields are automatically populated by the
* helper class and may not be overridden:
*
* The default implementation is a no-op.
*
* @param event the event to populate with information about the host view
*/
protected void onPopulateEventForHost(AccessibilityEvent event) {
// Default implementation is no-op.
}
/**
* Populates an {@link AccessibilityNodeInfoCompat} with information
* about the specified item.
*
* Implementations must populate the following required
* fields:
*
* The helper class automatically populates the following fields with
* default values, but implementations may optionally override them:
*
* The following required fields are automatically populated by the
* helper class and may not be overridden:
*
* Additionally, the helper class automatically handles keyboard focus and
* accessibility focus management by adding the appropriate
* {@link AccessibilityNodeInfoCompat#ACTION_FOCUS},
* {@link AccessibilityNodeInfoCompat#ACTION_CLEAR_FOCUS},
* {@link AccessibilityNodeInfoCompat#ACTION_ACCESSIBILITY_FOCUS}, or
* {@link AccessibilityNodeInfoCompat#ACTION_CLEAR_ACCESSIBILITY_FOCUS}
* actions. Implementations must never manually add these
* actions.
*
* The helper class also automatically modifies parent- and
* screen-relative bounds to reflect the portion of the item visible
* within its parent.
*
* @param virtualViewId The virtual view identifier of the item for
* which to populate the node
* @param node The node to populate
*/
protected abstract void onPopulateNodeForVirtualView(
int virtualViewId, AccessibilityNodeInfoCompat node);
/**
* Populates an {@link AccessibilityNodeInfoCompat} with information
* about the host view.
*
* The default implementation is a no-op.
*
* @param node the node to populate with information about the host view
*/
protected void onPopulateNodeForHost(AccessibilityNodeInfoCompat node) {
// Default implementation is no-op.
}
/**
* Performs the specified accessibility action on the item associated
* with the virtual view identifier. See
* {@link AccessibilityNodeInfoCompat#performAction(int, Bundle)} for
* more information.
*
* Implementations must handle any actions added manually
* in
* {@link #onPopulateNodeForVirtualView(int, AccessibilityNodeInfoCompat)}.
*
* The helper class automatically handles focus management resulting
* from {@link AccessibilityNodeInfoCompat#ACTION_ACCESSIBILITY_FOCUS}
* and
* {@link AccessibilityNodeInfoCompat#ACTION_CLEAR_ACCESSIBILITY_FOCUS}
* actions.
*
* @param virtualViewId The virtual view identifier of the item on which
* to perform the action
* @param action The accessibility action to perform
* @param arguments (Optional) A bundle with additional arguments, or
* null
* @return true if the action was performed
*/
protected abstract boolean onPerformActionForVirtualView(
int virtualViewId, int action, Bundle arguments);
/**
* Exposes a virtual view hierarchy to the accessibility framework.
*/
private class MyNodeProvider extends AccessibilityNodeProviderCompat {
@Override
public AccessibilityNodeInfoCompat createAccessibilityNodeInfo(int virtualViewId) {
// The caller takes ownership of the node and is expected to
// recycle it when done, so always return a copy.
final AccessibilityNodeInfoCompat node =
ExploreByTouchHelper.this.obtainAccessibilityNodeInfo(virtualViewId);
return AccessibilityNodeInfoCompat.obtain(node);
}
@Override
public boolean performAction(int virtualViewId, int action, Bundle arguments) {
return ExploreByTouchHelper.this.performAction(virtualViewId, action, arguments);
}
}
}
*
*
*
*
* @param virtualViewId the virtual view id for item for which to construct
* a node
* @return an {@link AccessibilityNodeInfoCompat} for the specified item
*/
@NonNull
private AccessibilityNodeInfoCompat createNodeForChild(int virtualViewId) {
final AccessibilityNodeInfoCompat node = AccessibilityNodeInfoCompat.obtain();
// Ensure the client has good defaults.
node.setEnabled(true);
node.setFocusable(true);
node.setClassName(DEFAULT_CLASS_NAME);
node.setBoundsInParent(INVALID_PARENT_BOUNDS);
node.setBoundsInScreen(INVALID_PARENT_BOUNDS);
// Allow the client to populate the node.
onPopulateNodeForVirtualView(virtualViewId, node);
// Make sure the developer is following the rules.
if ((node.getText() == null) && (node.getContentDescription() == null)) {
throw new RuntimeException("Callbacks must add text or a content description in "
+ "populateNodeForVirtualViewId()");
}
node.getBoundsInParent(mTempParentRect);
if (mTempParentRect.equals(INVALID_PARENT_BOUNDS)) {
throw new RuntimeException("Callbacks must set parent bounds in "
+ "populateNodeForVirtualViewId()");
}
final int actions = node.getActions();
if ((actions & AccessibilityNodeInfoCompat.ACTION_ACCESSIBILITY_FOCUS) != 0) {
throw new RuntimeException("Callbacks must not add ACTION_ACCESSIBILITY_FOCUS in "
+ "populateNodeForVirtualViewId()");
}
if ((actions & AccessibilityNodeInfoCompat.ACTION_CLEAR_ACCESSIBILITY_FOCUS) != 0) {
throw new RuntimeException("Callbacks must not add ACTION_CLEAR_ACCESSIBILITY_FOCUS in "
+ "populateNodeForVirtualViewId()");
}
// Don't allow the client to override these properties.
node.setPackageName(mHost.getContext().getPackageName());
node.setSource(mHost, virtualViewId);
node.setParent(mHost);
// Manage internal accessibility focus state.
if (mAccessibilityFocusedVirtualViewId == virtualViewId) {
node.setAccessibilityFocused(true);
node.addAction(AccessibilityNodeInfoCompat.ACTION_CLEAR_ACCESSIBILITY_FOCUS);
} else {
node.setAccessibilityFocused(false);
node.addAction(AccessibilityNodeInfoCompat.ACTION_ACCESSIBILITY_FOCUS);
}
// Manage internal keyboard focus state.
final boolean isFocused = mKeyboardFocusedVirtualViewId == virtualViewId;
if (isFocused) {
node.addAction(AccessibilityNodeInfoCompat.ACTION_CLEAR_FOCUS);
} else if (node.isFocusable()) {
node.addAction(AccessibilityNodeInfoCompat.ACTION_FOCUS);
}
node.setFocused(isFocused);
// Set the visibility based on the parent bound.
if (intersectVisibleToUser(mTempParentRect)) {
node.setVisibleToUser(true);
node.setBoundsInParent(mTempParentRect);
}
// If not explicitly specified, calculate screen-relative bounds and
// offset for scroll position based on bounds in parent.
node.getBoundsInScreen(mTempScreenRect);
if (mTempScreenRect.equals(INVALID_PARENT_BOUNDS)) {
mHost.getLocationOnScreen(mTempGlobalRect);
node.getBoundsInParent(mTempScreenRect);
mTempScreenRect.offset(mTempGlobalRect[0] - mHost.getScrollX(),
mTempGlobalRect[1] - mHost.getScrollY());
node.setBoundsInScreen(mTempScreenRect);
}
return node;
}
private boolean performAction(int virtualViewId, int action, Bundle arguments) {
switch (virtualViewId) {
case HOST_ID:
return performActionForHost(action, arguments);
default:
return performActionForChild(virtualViewId, action, arguments);
}
}
private boolean performActionForHost(int action, Bundle arguments) {
return ViewCompat.performAccessibilityAction(mHost, action, arguments);
}
private boolean performActionForChild(int virtualViewId, int action, Bundle arguments) {
switch (action) {
case AccessibilityNodeInfoCompat.ACTION_ACCESSIBILITY_FOCUS:
return requestAccessibilityFocus(virtualViewId);
case AccessibilityNodeInfoCompat.ACTION_CLEAR_ACCESSIBILITY_FOCUS:
return clearAccessibilityFocus(virtualViewId);
case AccessibilityNodeInfoCompat.ACTION_FOCUS:
return requestKeyboardFocusForVirtualView(virtualViewId);
case AccessibilityNodeInfoCompat.ACTION_CLEAR_FOCUS:
return clearKeyboardFocusForVirtualView(virtualViewId);
default:
return onPerformActionForVirtualView(virtualViewId, action, arguments);
}
}
/**
* Computes whether the specified {@link Rect} intersects with the visible
* portion of its parent {@link View}. Modifies {@code localRect} to contain
* only the visible portion.
*
* @param localRect a rectangle in local (parent) coordinates
* @return whether the specified {@link Rect} is visible on the screen
*/
private boolean intersectVisibleToUser(Rect localRect) {
// Missing or empty bounds mean this view is not visible.
if ((localRect == null) || localRect.isEmpty()) {
return false;
}
// Attached to invisible window means this view is not visible.
if (mHost.getWindowVisibility() != View.VISIBLE) {
return false;
}
// An invisible predecessor means that this view is not visible.
ViewParent viewParent = mHost.getParent();
while (viewParent instanceof View) {
final View view = (View) viewParent;
if ((ViewCompat.getAlpha(view) <= 0) || (view.getVisibility() != View.VISIBLE)) {
return false;
}
viewParent = view.getParent();
}
// A null parent implies the view is not visible.
if (viewParent == null) {
return false;
}
// If no portion of the parent is visible, this view is not visible.
if (!mHost.getLocalVisibleRect(mTempVisibleRect)) {
return false;
}
// Check if the view intersects the visible portion of the parent.
return localRect.intersect(mTempVisibleRect);
}
/**
* Attempts to give accessibility focus to a virtual view.
*
*
*
*
*
* @param virtualViewId The virtual view id for the item for which to
* populate the event
* @param event The event to populate
*/
protected void onPopulateEventForVirtualView(int virtualViewId, AccessibilityEvent event) {
// Default implementation is no-op.
}
/**
* Populates an {@link AccessibilityEvent} with information about the host
* view.
*
*
*
*
*
*
*