Touch exploration feature, event bubling, refactor

1. Added an Input Filter that interprets the touch screen motion
   events to perfrom accessibility exploration. One finger explores.
   Tapping within a given time and distance slop on the last exlopred
   location does click and long press, respectively. Two fingers close
   and in the same diretion drag. Multiple finglers or two fingers in
   different directions or two fingers too far away are delegated to
   the view hierarchy. Non moving fingers "accidentally grabbed the
   device for the scrren" are ignored.

2. Added accessibility events for hover enter, hover exit, touch
   exoloration gesture start, and end. Accessibility hover events
   are fired by the hover pipeline. An accessibility event is
   dispatched up the view tree and the topmost view fires it.
   Thus predecessors can augment the fired event. An accessibility
   event has several records and a predecessor can optionally
   modify, delete, and add such to the event.

3. Added onPopulateAccessibilityEvent and refactored the existing
   accessibility code to use it.

4. Added API for querying the currently enabled accessibility services
   by feedback type.

Change-Id: Iec03c6c3fe298de3f14cb6efdbb9b198cd531a0c

1 files changed, 19 insertions, 0 deletions

diff --git a/core/java/android/view/ViewParent.java b/core/java/android/view/ViewParent.java
index d7d4c3f02d0d..655df391ed4f 100644
--- a/core/java/android/view/ViewParent.java
+++ b/core/java/android/view/ViewParent.java
@@ -17,6 +17,7 @@
 package android.view;
 
 import android.graphics.Rect;
+import android.view.accessibility.AccessibilityEvent;
 
 /**
  * Defines the responsibilities for a class that will be a parent of a View.
@@ -222,4 +223,22 @@ public interface ViewParent {
      */
     public boolean requestChildRectangleOnScreen(View child, Rect rectangle,
             boolean immediate);
+
+    /**
+     * Called by a child to request from its parent to send an {@link AccessibilityEvent}.
+     * The child has already populated a record for itself in the event and is delegating
+     * to its parent to send the event. The parent can optionally add a record for itself.
+     * <p>
+     * Note: An accessibility event is fired by an individual view which populates the
+     *       event with a record for its state and requests from its parent to perform
+     *       the sending. The parent can optionally add a record for itself before
+     *       dispatching the request to its parent. A parent can also choose not to
+     *       respect the request for sending the event. The accessibility event is sent
+     *       by the topmost view in the view tree.
+     *
+     * @param child The child which requests sending the event.
+     * @param event The event to be sent.
+     * @return True if the event was sent.
+     */
+    public boolean requestSendAccessibilityEvent(View child, AccessibilityEvent event);
 }