Prevent TalkBack from announcing view in non-virtual a11y hierarchies (flutter/engine#34017)

engine/src/flutter/shell/platform/android/io/flutter/embedding/engine/mutatorsstack/FlutterMutatorView.java

@@ -3,6 +3,7 @@ package io.flutter.embedding.engine.mutatorsstack;
 import static android.view.View.OnFocusChangeListener;
 
 import android.annotation.SuppressLint;
+import android.annotation.TargetApi;
 import android.content.Context;
 import android.graphics.Canvas;
 import android.graphics.Matrix;
@@ -10,6 +11,7 @@ import android.graphics.Path;
 import android.view.MotionEvent;
 import android.view.View;
 import android.view.ViewTreeObserver;
+import android.view.accessibility.AccessibilityEvent;
 import android.widget.FrameLayout;
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
@@ -21,6 +23,7 @@ import io.flutter.util.ViewUtils;
  * A view that applies the {@link io.flutter.embedding.engine.mutatorsstack.FlutterMutatorsStack} to
  * its children.
  */
+@TargetApi(19)
 public class FlutterMutatorView extends FrameLayout {
   private FlutterMutatorsStack mutatorsStack;
   private float screenDensity;
@@ -160,6 +163,21 @@ public class FlutterMutatorView extends FrameLayout {
     return true;
   }
 
+  @Override
+  public boolean requestSendAccessibilityEvent(View child, AccessibilityEvent event) {
+    final View embeddedView = getChildAt(0);
+    if (embeddedView != null
+        && embeddedView.getImportantForAccessibility()
+            == View.IMPORTANT_FOR_ACCESSIBILITY_NO_HIDE_DESCENDANTS) {
+      return false;
+    }
+    // Forward the request only if the embedded view is in the Flutter accessibility tree.
+    // The embedded view may be ignored when the framework doesn't populate a SemanticNode
+    // for the current platform view.
+    // See AccessibilityBridge for more.
+    return super.requestSendAccessibilityEvent(child, event);
+  }
+
   @Override
   @SuppressLint("ClickableViewAccessibility")
   public boolean onTouchEvent(MotionEvent event) {

engine/src/flutter/shell/platform/android/io/flutter/plugin/platform/PlatformViewWrapper.java

@@ -21,6 +21,7 @@ import android.view.Surface;
 import android.view.View;
 import android.view.ViewParent;
 import android.view.ViewTreeObserver;
+import android.view.accessibility.AccessibilityEvent;
 import android.widget.FrameLayout;
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
@@ -242,6 +243,21 @@ class PlatformViewWrapper extends FrameLayout {
     return true;
   }
 
+  @Override
+  public boolean requestSendAccessibilityEvent(View child, AccessibilityEvent event) {
+    final View embeddedView = getChildAt(0);
+    if (embeddedView != null
+        && embeddedView.getImportantForAccessibility()
+            == View.IMPORTANT_FOR_ACCESSIBILITY_NO_HIDE_DESCENDANTS) {
+      return false;
+    }
+    // Forward the request only if the embedded view is in the Flutter accessibility tree.
+    // The embedded view may be ignored when the framework doesn't populate a SemanticNode
+    // for the current platform view.
+    // See AccessibilityBridge for more.
+    return super.requestSendAccessibilityEvent(child, event);
+  }
+
   /** Used on Android O+, {@link invalidateChildInParent} used for previous versions. */
   @SuppressLint("NewApi")
   @Override

engine/src/flutter/shell/platform/android/io/flutter/plugin/platform/PlatformViewsController.java

@@ -223,17 +223,28 @@ public class PlatformViewsController implements PlatformViewsAccessibilityDelega
           layoutParams.leftMargin = physicalLeft;
           wrapperView.setLayoutParams(layoutParams);
 
-          final View view = platformView.getView();
-          if (view == null) {
+          final View embeddedView = platformView.getView();
+          if (embeddedView == null) {
             throw new IllegalStateException(
                 "PlatformView#getView() returned null, but an Android view reference was expected.");
-          } else if (view.getParent() != null) {
+          } else if (embeddedView.getParent() != null) {
             throw new IllegalStateException(
                 "The Android view returned from PlatformView#getView() was already added to a parent view.");
           }
-          view.setLayoutParams(new FrameLayout.LayoutParams(physicalWidth, physicalHeight));
-          view.setLayoutDirection(request.direction);
-          wrapperView.addView(view);
+          embeddedView.setLayoutParams(new FrameLayout.LayoutParams(physicalWidth, physicalHeight));
+          embeddedView.setLayoutDirection(request.direction);
+
+          // Accessibility in the embedded view is initially disabled because if a Flutter app
+          // disabled accessibility in the first frame, the embedding won't receive an update to
+          // disable accessibility since the embedding never received an update to enable it.
+          // The AccessibilityBridge keeps track of the accessibility nodes, and handles the deltas
+          // when the framework sends a new a11y tree to the embedding.
+          // To prevent races, the framework populate the SemanticsNode after the platform view has
+          // been created.
+          embeddedView.setImportantForAccessibility(
+              View.IMPORTANT_FOR_ACCESSIBILITY_NO_HIDE_DESCENDANTS);
+
+          wrapperView.addView(embeddedView);
           wrapperView.setOnDescendantFocusChangeListener(
               (v, hasFocus) -> {
                 if (hasFocus) {
@@ -738,6 +749,7 @@ public class PlatformViewsController implements PlatformViewsAccessibilityDelega
    *     testing.
    */
   @VisibleForTesting
+  @TargetApi(Build.VERSION_CODES.KITKAT)
   void initializePlatformViewIfNeeded(int viewId) {
     final PlatformView platformView = platformViews.get(viewId);
     if (platformView == null) {
@@ -747,11 +759,12 @@ public class PlatformViewsController implements PlatformViewsAccessibilityDelega
     if (platformViewParent.get(viewId) != null) {
       return;
     }
-    if (platformView.getView() == null) {
+    final View embeddedView = platformView.getView();
+    if (embeddedView == null) {
       throw new IllegalStateException(
           "PlatformView#getView() returned null, but an Android view reference was expected.");
     }
-    if (platformView.getView().getParent() != null) {
+    if (embeddedView.getParent() != null) {
       throw new IllegalStateException(
           "The Android view returned from PlatformView#getView() was already added to a parent view.");
     }
@@ -769,7 +782,17 @@ public class PlatformViewsController implements PlatformViewsAccessibilityDelega
         });
 
     platformViewParent.put(viewId, parentView);
-    parentView.addView(platformView.getView());
+
+    // Accessibility in the embedded view is initially disabled because if a Flutter app disabled
+    // accessibility in the first frame, the embedding won't receive an update to disable
+    // accessibility since the embedding never received an update to enable it.
+    // The AccessibilityBridge keeps track of the accessibility nodes, and handles the deltas when
+    // the framework sends a new a11y tree to the embedding.
+    // To prevent races, the framework populate the SemanticsNode after the platform view has been
+    // created.
+    embeddedView.setImportantForAccessibility(View.IMPORTANT_FOR_ACCESSIBILITY_NO_HIDE_DESCENDANTS);
+
+    parentView.addView(embeddedView);
     flutterView.addView(parentView);
   }
 

engine/src/flutter/shell/platform/android/test/io/flutter/embedding/engine/mutatorsstack/FlutterMutatorViewTest.java

@@ -7,7 +7,10 @@ import static org.mockito.Mockito.*;
 import android.content.Context;
 import android.graphics.Matrix;
 import android.view.MotionEvent;
+import android.view.View;
+import android.view.ViewGroup;
 import android.view.ViewTreeObserver;
+import android.view.accessibility.AccessibilityEvent;
 import androidx.test.core.app.ApplicationProvider;
 import androidx.test.ext.junit.runners.AndroidJUnit4;
 import io.flutter.embedding.android.AndroidTouchProcessor;
@@ -15,6 +18,8 @@ import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.mockito.ArgumentCaptor;
 import org.robolectric.annotation.Config;
+import org.robolectric.annotation.Implementation;
+import org.robolectric.annotation.Implements;
 
 @Config(manifest = Config.NONE)
 @RunWith(AndroidJUnit4.class)
@@ -206,4 +211,54 @@ public class FlutterMutatorViewTest {
     view.unsetOnDescendantFocusChangeListener();
     verify(viewTreeObserver, times(1)).removeOnGlobalFocusChangeListener(activeFocusListener);
   }
+
+  @Test
+  @Config(
+      shadows = {
+        ShadowViewGroup.class,
+      })
+  public void ignoreAccessibilityEvents() {
+    final FlutterMutatorView wrapperView = new FlutterMutatorView(ctx);
+
+    final View embeddedView = mock(View.class);
+    wrapperView.addView(embeddedView);
+
+    when(embeddedView.getImportantForAccessibility())
+        .thenReturn(View.IMPORTANT_FOR_ACCESSIBILITY_NO_HIDE_DESCENDANTS);
+    final boolean eventSent =
+        wrapperView.requestSendAccessibilityEvent(embeddedView, mock(AccessibilityEvent.class));
+    assertFalse(eventSent);
+  }
+
+  @Test
+  @Config(
+      shadows = {
+        ShadowViewGroup.class,
+      })
+  public void sendAccessibilityEvents() {
+    final FlutterMutatorView wrapperView = new FlutterMutatorView(ctx);
+
+    final View embeddedView = mock(View.class);
+    wrapperView.addView(embeddedView);
+
+    when(embeddedView.getImportantForAccessibility())
+        .thenReturn(View.IMPORTANT_FOR_ACCESSIBILITY_YES);
+    boolean eventSent =
+        wrapperView.requestSendAccessibilityEvent(embeddedView, mock(AccessibilityEvent.class));
+    assertTrue(eventSent);
+
+    when(embeddedView.getImportantForAccessibility())
+        .thenReturn(View.IMPORTANT_FOR_ACCESSIBILITY_AUTO);
+    eventSent =
+        wrapperView.requestSendAccessibilityEvent(embeddedView, mock(AccessibilityEvent.class));
+    assertTrue(eventSent);
+  }
+
+  @Implements(ViewGroup.class)
+  public static class ShadowViewGroup extends org.robolectric.shadows.ShadowView {
+    @Implementation
+    public boolean requestSendAccessibilityEvent(View child, AccessibilityEvent event) {
+      return true;
+    }
+  }
 }

engine/src/flutter/shell/platform/android/test/io/flutter/plugin/platform/PlatformViewWrapperTest.java

@@ -13,7 +13,9 @@ import android.graphics.Color;
 import android.graphics.SurfaceTexture;
 import android.view.Surface;
 import android.view.View;
+import android.view.ViewGroup;
 import android.view.ViewTreeObserver;
+import android.view.accessibility.AccessibilityEvent;
 import androidx.annotation.NonNull;
 import androidx.test.core.app.ApplicationProvider;
 import androidx.test.ext.junit.runners.AndroidJUnit4;
@@ -21,6 +23,7 @@ import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.mockito.ArgumentCaptor;
 import org.robolectric.annotation.Config;
+import org.robolectric.annotation.Implementation;
 import org.robolectric.annotation.Implements;
 
 @TargetApi(31)
@@ -295,6 +298,56 @@ public class PlatformViewWrapperTest {
     verify(viewTreeObserver, times(1)).removeOnGlobalFocusChangeListener(activeFocusListener);
   }
 
+  @Test
+  @Config(
+      shadows = {
+        ShadowViewGroup.class,
+      })
+  public void ignoreAccessibilityEvents() {
+    final PlatformViewWrapper wrapperView = new PlatformViewWrapper(ctx);
+
+    final View embeddedView = mock(View.class);
+    wrapperView.addView(embeddedView);
+
+    when(embeddedView.getImportantForAccessibility())
+        .thenReturn(View.IMPORTANT_FOR_ACCESSIBILITY_NO_HIDE_DESCENDANTS);
+    final boolean eventSent =
+        wrapperView.requestSendAccessibilityEvent(embeddedView, mock(AccessibilityEvent.class));
+    assertFalse(eventSent);
+  }
+
+  @Test
+  @Config(
+      shadows = {
+        ShadowViewGroup.class,
+      })
+  public void sendAccessibilityEvents() {
+    final PlatformViewWrapper wrapperView = new PlatformViewWrapper(ctx);
+
+    final View embeddedView = mock(View.class);
+    wrapperView.addView(embeddedView);
+
+    when(embeddedView.getImportantForAccessibility())
+        .thenReturn(View.IMPORTANT_FOR_ACCESSIBILITY_YES);
+    boolean eventSent =
+        wrapperView.requestSendAccessibilityEvent(embeddedView, mock(AccessibilityEvent.class));
+    assertTrue(eventSent);
+
+    when(embeddedView.getImportantForAccessibility())
+        .thenReturn(View.IMPORTANT_FOR_ACCESSIBILITY_AUTO);
+    eventSent =
+        wrapperView.requestSendAccessibilityEvent(embeddedView, mock(AccessibilityEvent.class));
+    assertTrue(eventSent);
+  }
+
   @Implements(View.class)
   public static class ShadowView {}
+
+  @Implements(ViewGroup.class)
+  public static class ShadowViewGroup extends org.robolectric.shadows.ShadowView {
+    @Implementation
+    public boolean requestSendAccessibilityEvent(View child, AccessibilityEvent event) {
+      return true;
+    }
+  }
 }

engine/src/flutter/shell/platform/android/test/io/flutter/plugin/platform/PlatformViewsControllerTest.java

@@ -211,6 +211,33 @@ public class PlatformViewsControllerTest {
     assertEquals(capturedLayoutParams.get(0).height, 1);
   }
 
+  @Test
+  @Config(shadows = {ShadowFlutterJNI.class, ShadowPlatformTaskQueue.class})
+  public void createPlatformViewMessage__disablesAccessibility() {
+    PlatformViewsController platformViewsController = new PlatformViewsController();
+    platformViewsController.setSoftwareRendering(true);
+
+    int platformViewId = 0;
+    assertNull(platformViewsController.getPlatformViewById(platformViewId));
+
+    PlatformViewFactory viewFactory = mock(PlatformViewFactory.class);
+    PlatformView platformView = mock(PlatformView.class);
+
+    View androidView = mock(View.class);
+    when(platformView.getView()).thenReturn(androidView);
+    when(viewFactory.create(any(), eq(platformViewId), any())).thenReturn(platformView);
+    platformViewsController.getRegistry().registerViewFactory("testType", viewFactory);
+
+    FlutterJNI jni = new FlutterJNI();
+    attach(jni, platformViewsController);
+
+    // Simulate create call from the framework.
+    createPlatformView(
+        jni, platformViewsController, platformViewId, "testType", /* hybrid=*/ false);
+    verify(androidView, times(1))
+        .setImportantForAccessibility(View.IMPORTANT_FOR_ACCESSIBILITY_NO_HIDE_DESCENDANTS);
+  }
+
   @Test
   @Config(shadows = {ShadowFlutterJNI.class, ShadowPlatformTaskQueue.class})
   public void createPlatformViewMessage__throwsIfViewIsNull() {