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Commit 510043d4 authored by Hiroki Sato's avatar Hiroki Sato
Browse files

Throttle content changed events only subtree changes 

Previously accessibility events of TYPE_WINDOW_CONTENT_CHANGED were
throttled in ViewRootImpl. It merges events from multiple nodes and
destroys source node information.

This makes multiple issues, for example:
- accessibility services cannot deliver proper feedback,
- view's onInitializeAccessibilityEvent is not correctly called,
- AccessibilityCache is not correctly updated.

This change limits the throttle only for subtree changes to prevent.

Bug: 143889012
Bug: 277305460
Test: CtsAccessibilityTestCases CtsAccessibilityServiceTestCases
Change-Id: Ic18cd4aa310ab37e40c6623625b59b4b9ebfea2f
parent 2a592601

core/java/android/view/View.java

+3 −3
Original line number Diff line number Diff line
@@ -14944,8 +14944,8 @@ public class View implements Drawable.Callback, KeyEvent.Callback, 
    /**

     * Notifies that the accessibility state of this view changed. The change

     * is local to this view and does not represent structural changes such

     * as children and parent. For example, the view became focusable. The

     * notification is at at most once every

     * as children and parent. For example, the view became focusable. Some of

     * the notification is at at most once every

     * {@link ViewConfiguration#getSendRecurringAccessibilityEventsInterval()}

     * to avoid unnecessary load to the system. Also once a view has a pending

     * notification this method is a NOP until the notification has been sent.
@@ -15007,7 +15007,7 @@ public class View implements Drawable.Callback, KeyEvent.Callback, 
    /**

     * Notifies that the accessibility state of this view changed. The change

     * is *not* local to this view and does represent structural changes such

     * as children and parent. For example, the view size changed. The

     * as children and parent. For example, the view size changed. Some of the

     * notification is at at most once every

     * {@link ViewConfiguration#getSendRecurringAccessibilityEventsInterval()}

     * to avoid unnecessary load to the system. Also once a view has a pending

core/java/android/view/ViewRootImpl.java

+24 −2
Original line number Diff line number Diff line
@@ -218,7 +218,6 @@ import com.android.internal.os.IResultReceiver; 
import com.android.internal.os.SomeArgs;

import com.android.internal.policy.DecorView;

import com.android.internal.policy.PhoneFallbackEventHandler;

import com.android.internal.util.Preconditions;

import com.android.internal.view.BaseSurfaceHolder;

import com.android.internal.view.RootViewSurfaceTaker;

import com.android.internal.view.SurfaceCallbackHelper;
@@ -808,6 +807,7 @@ public final class ViewRootImpl implements ViewParent, 
    final HighContrastTextManager mHighContrastTextManager;



    SendWindowContentChangedAccessibilityEvent mSendWindowContentChangedAccessibilityEvent;

    boolean mSendingAccessibilityWIndowContentChange = false;



    HashSet<View> mTempHashSet;
@@ -9867,7 +9867,29 @@ public final class ViewRootImpl implements ViewParent, 


    @Override

    public void notifySubtreeAccessibilityStateChanged(View child, View source, int changeType) {

        postSendWindowContentChangedCallback(Preconditions.checkNotNull(source), changeType);

        Objects.requireNonNull(source);

        if (changeType == AccessibilityEvent.CONTENT_CHANGE_TYPE_SUBTREE) {

            postSendWindowContentChangedCallback(source, changeType);

            return;

        }

        if (mSendingAccessibilityWIndowContentChange) {

            // This allows re-entering this method.

            // Some apps update views during an event dispatch, which triggers another a11y event.

            // In order to avoid an infinite loop, postpone second event dispatch.

            mHandler.post(() -> notifySubtreeAccessibilityStateChanged(child, source, changeType));

            return;

        }



        AccessibilityEvent event =

                new AccessibilityEvent(AccessibilityEvent.TYPE_WINDOW_CONTENT_CHANGED);

        event.setContentChangeTypes(changeType);

        event.setAction(mAccessibilityManager.getPerformingAction());

        mSendingAccessibilityWIndowContentChange = true;

        try {

            source.sendAccessibilityEventUnchecked(event);

        } finally {

            mSendingAccessibilityWIndowContentChange = false;

        }

    }



    @Override