Scroll accessibility events should not populate text.

Scroll events are used to report position change and should not
contain the text content of the view that fires them because it
is usiually a containter for many other views and the text will
be long and not informative for accessibility purposes. Also
such evens are fired relatively frequently. If a client wants
to fetch some textual content for a scroll event he can use
the interrogation APIs.

bug:5352059

Change-Id: I43e02aca895c8ab16ba82ebe1cee3aea8ce7711a

4 files changed, 26 insertions, 29 deletions

diff --git a/core/java/android/view/View.java b/core/java/android/view/View.java
index ca06b9cf118a..0b9da11db77d 100644
--- a/core/java/android/view/View.java
+++ b/core/java/android/view/View.java
@@ -3900,6 +3900,12 @@ public class View implements Drawable.Callback, Drawable.Callback2, KeyEvent.Cal
      * Note: Called from the default {@link AccessibilityDelegate}.
      */
     boolean dispatchPopulateAccessibilityEventInternal(AccessibilityEvent event) {
+        // Do not populate text to scroll events. They describe position change
+        // and usually come from container with a lot of text which is not very
+        // informative for accessibility purposes. Also they are fired frequently.
+        if (event.getEventType() == AccessibilityEvent.TYPE_VIEW_SCROLLED) {
+            return true;
+        }
         onPopulateAccessibilityEvent(event);
         return false;
     }
diff --git a/core/java/android/view/ViewGroup.java b/core/java/android/view/ViewGroup.java
index b678c7dab894..a29cf13f4ef8 100644
--- a/core/java/android/view/ViewGroup.java
+++ b/core/java/android/view/ViewGroup.java
@@ -2176,13 +2176,15 @@ public abstract class ViewGroup extends View implements ViewParent, ViewManager
 
     @Override
     boolean dispatchPopulateAccessibilityEventInternal(AccessibilityEvent event) {
-        // We first get a chance to populate the event.
-        super.dispatchPopulateAccessibilityEventInternal(event);
+        boolean handled = super.dispatchPopulateAccessibilityEventInternal(event);
+        if (handled) {
+            return handled;
+        }
         // Let our children have a shot in populating the event.
         for (int i = 0, count = getChildCount(); i < count; i++) {
             View child = getChildAt(i);
             if ((child.mViewFlags & VISIBILITY_MASK) == VISIBLE) {
-                boolean handled = getChildAt(i).dispatchPopulateAccessibilityEvent(event);
+                handled = getChildAt(i).dispatchPopulateAccessibilityEvent(event);
                 if (handled) {
                     return handled;
                 }
diff --git a/core/java/android/widget/AbsListView.java b/core/java/android/widget/AbsListView.java
index ba89ef3e6cbd..7b8c7f218ddc 100644
--- a/core/java/android/widget/AbsListView.java
+++ b/core/java/android/widget/AbsListView.java
@@ -1304,16 +1304,6 @@ public abstract class AbsListView extends AdapterView<ListAdapter> implements Te
         }
     }
 
-    @Override
-    public boolean dispatchPopulateAccessibilityEvent(AccessibilityEvent event) {
-        // Do not append text content to scroll events they are fired frequently
-        // and the client has already received another event type with the text.
-        if (event.getEventType() != AccessibilityEvent.TYPE_VIEW_SCROLLED) {
-            super.dispatchPopulateAccessibilityEvent(event);
-        }
-        return false;
-    }
-
     /**
      * Indicates whether the children's drawing cache is used during a scroll.
      * By default, the drawing cache is enabled but this will consume more memory.
diff --git a/core/java/android/widget/AdapterView.java b/core/java/android/widget/AdapterView.java
index 5392c2e5f5ad..a4b4e783def9 100644
--- a/core/java/android/widget/AdapterView.java
+++ b/core/java/android/widget/AdapterView.java
@@ -881,31 +881,30 @@ public abstract class AdapterView<T extends Adapter> extends ViewGroup {
 
     @Override
     public boolean dispatchPopulateAccessibilityEvent(AccessibilityEvent event) {
-        // This is an exceptional case which occurs when a window gets the
-        // focus and sends a focus event via its focused child to announce
-        // current focus/selection. AdapterView fires selection but not focus
-        // events so we change the event type here.
-        if (event.getEventType() == AccessibilityEvent.TYPE_VIEW_FOCUSED) {
-            event.setEventType(AccessibilityEvent.TYPE_VIEW_SELECTED);
+        final int eventType = event.getEventType();
+        switch (eventType) {
+            case AccessibilityEvent.TYPE_VIEW_SCROLLED:
+                // Do not populate the text of scroll events.
+                return true;
+            case AccessibilityEvent.TYPE_VIEW_FOCUSED:
+                // This is an exceptional case which occurs when a window gets the
+                // focus and sends a focus event via its focused child to announce
+                // current focus/selection. AdapterView fires selection but not focus
+                // events so we change the event type here.
+                if (event.getEventType() == AccessibilityEvent.TYPE_VIEW_FOCUSED) {
+                    event.setEventType(AccessibilityEvent.TYPE_VIEW_SELECTED);
+                }
+                break;
         }
 
         View selectedView = getSelectedView();
         if (selectedView != null && selectedView.getVisibility() == VISIBLE) {
-            // We first get a chance to populate the event.
-            onPopulateAccessibilityEvent(event);
+            getSelectedView().dispatchPopulateAccessibilityEvent(event);
         }
         return false;
     }
 
     @Override
-    public void onPopulateAccessibilityEvent(AccessibilityEvent event) {
-        super.onPopulateAccessibilityEvent(event);
-        // We send selection events only from AdapterView to avoid
-        // generation of such event for each child.
-        getSelectedView().dispatchPopulateAccessibilityEvent(event);
-    }
-
-    @Override
     public boolean onRequestSendAccessibilityEvent(View child, AccessibilityEvent event) {
         if (super.onRequestSendAccessibilityEvent(child, event)) {
             // Add a record for ourselves as well.