Adding an announcement type accessibility event and a method on View to announce.

1. The need for sending an accessibility event to announce a context change
   which does not cleanly fit into the existing UI transition UI events has
   come quite a few time in application development. To avoid retrofitting
   accessibility event types that do not semantically match the intent to
   just announce a short message this patch is adding specialized event type.
   Also a helper method on View is added to sheild developers from knowing
   how to construct and send such an event.

bug:5977979

Change-Id: Iaf5f620426f8616be67fbf243a02ad5b606c949b

1 files changed, 18 insertions, 0 deletions

diff --git a/core/java/android/view/View.java b/core/java/android/view/View.java
index ecfca74..7cadee8 100644
--- a/core/java/android/view/View.java
+++ b/core/java/android/view/View.java
@@ -3934,6 +3934,24 @@ public class View implements Drawable.Callback, Drawable.Callback2, KeyEvent.Cal
     }
 
     /**
+     * Convenience method for sending a {@link AccessibilityEvent#TYPE_ANNOUNCEMENT}
+     * {@link AccessibilityEvent} to make an announcement which is related to some
+     * sort of a context change for which none of the events representing UI transitions
+     * is a good fit. For example, announcing a new page in a book. If accessibility
+     * is not enabled this method does nothing.
+     *
+     * @param text The announcement text.
+     */
+    public void announceForAccessibility(CharSequence text) {
+        if (AccessibilityManager.getInstance(mContext).isEnabled()) {
+            AccessibilityEvent event = AccessibilityEvent.obtain(
+                    AccessibilityEvent.TYPE_ANNOUNCEMENT);
+            event.getText().add(text);
+            sendAccessibilityEventUnchecked(event);
+        }
+    }
+
+    /**
      * @see #sendAccessibilityEvent(int)
      *
      * Note: Called from the default {@link AccessibilityDelegate}.