Clear focus if a platform view goes away (#17381)

shell/platform/android/io/flutter/view/AccessibilityBridge.java

@@ -26,6 +26,7 @@
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 import androidx.annotation.RequiresApi;
+import androidx.annotation.VisibleForTesting;
 import io.flutter.BuildConfig;
 import io.flutter.embedding.engine.systemchannels.AccessibilityChannel;
 import io.flutter.plugin.platform.PlatformViewsAccessibilityDelegate;
@@ -333,10 +334,32 @@ public AccessibilityBridge(
       // TODO(mattcarrol): Add the annotation once the plumbing is done.
       // https://github.com/flutter/flutter/issues/29618
       PlatformViewsAccessibilityDelegate platformViewsAccessibilityDelegate) {
+    this(
+        rootAccessibilityView,
+        accessibilityChannel,
+        accessibilityManager,
+        contentResolver,
+        new AccessibilityViewEmbedder(rootAccessibilityView, MIN_ENGINE_GENERATED_NODE_ID),
+        platformViewsAccessibilityDelegate);
+  }
+
+  @VisibleForTesting
+  public AccessibilityBridge(
+      @NonNull View rootAccessibilityView,
+      @NonNull AccessibilityChannel accessibilityChannel,
+      @NonNull AccessibilityManager accessibilityManager,
+      @NonNull ContentResolver contentResolver,
+      @NonNull AccessibilityViewEmbedder accessibilityViewEmbedder,
+      // This should be @NonNull once the plumbing for
+      // io.flutter.embedding.engine.android.FlutterView is done.
+      // TODO(mattcarrol): Add the annotation once the plumbing is done.
+      // https://github.com/flutter/flutter/issues/29618
+      PlatformViewsAccessibilityDelegate platformViewsAccessibilityDelegate) {
     this.rootAccessibilityView = rootAccessibilityView;
     this.accessibilityChannel = accessibilityChannel;
     this.accessibilityManager = accessibilityManager;
     this.contentResolver = contentResolver;
+    this.accessibilityViewEmbedder = accessibilityViewEmbedder;
     this.platformViewsAccessibilityDelegate = platformViewsAccessibilityDelegate;
 
     // Tell Flutter whether accessibility is initially active or not. Then register a listener
@@ -388,8 +411,6 @@ public void onTouchExplorationStateChanged(boolean isTouchExplorationEnabled) {
     if (platformViewsAccessibilityDelegate != null) {
       platformViewsAccessibilityDelegate.attachAccessibilityBridge(this);
     }
-    accessibilityViewEmbedder =
-        new AccessibilityViewEmbedder(rootAccessibilityView, MIN_ENGINE_GENERATED_NODE_ID);
   }
 
   /**
@@ -1580,15 +1601,31 @@ private void willRemoveSemanticsNode(SemanticsNode semanticsNodeToBeRemoved) {
     //                    for null'ing accessibilityFocusedSemanticsNode, inputFocusedSemanticsNode,
     //                    and hoveredObject.  Is this a hook method or a command?
     semanticsNodeToBeRemoved.parent = null;
+
+    if (semanticsNodeToBeRemoved.platformViewId != -1
+        && embeddedAccessibilityFocusedNodeId != null
+        && accessibilityViewEmbedder.platformViewOfNode(embeddedAccessibilityFocusedNodeId)
+            == platformViewsAccessibilityDelegate.getPlatformViewById(
+                semanticsNodeToBeRemoved.platformViewId)) {
+      // If the currently focused a11y node is within a platform view that is
+      // getting removed: clear it's a11y focus.
+      sendAccessibilityEvent(
+          embeddedAccessibilityFocusedNodeId,
+          AccessibilityEvent.TYPE_VIEW_ACCESSIBILITY_FOCUS_CLEARED);
+      embeddedAccessibilityFocusedNodeId = null;
+    }
+
     if (accessibilityFocusedSemanticsNode == semanticsNodeToBeRemoved) {
       sendAccessibilityEvent(
           accessibilityFocusedSemanticsNode.id,
           AccessibilityEvent.TYPE_VIEW_ACCESSIBILITY_FOCUS_CLEARED);
       accessibilityFocusedSemanticsNode = null;
     }
+
     if (inputFocusedSemanticsNode == semanticsNodeToBeRemoved) {
       inputFocusedSemanticsNode = null;
     }
+
     if (hoveredObject == semanticsNodeToBeRemoved) {
       hoveredObject = null;
     }

shell/platform/android/io/flutter/view/AccessibilityViewEmbedder.java

@@ -44,7 +44,7 @@
  * corresponding platform view and `originId`.
  */
 @Keep
-final class AccessibilityViewEmbedder {
+class AccessibilityViewEmbedder {
   private static final String TAG = "AccessibilityBridge";
 
   private final ReflectionAccessors reflectionAccessors;
@@ -387,6 +387,18 @@ public boolean onAccessibilityHoverEvent(int rootFlutterId, @NonNull MotionEvent
     return origin.view.dispatchGenericMotionEvent(translatedEvent);
   }
 
+  /**
+   * Returns the View that contains the accessibility node identified by the provided flutterId or
+   * null if it doesn't belong to a view.
+   */
+  public View platformViewOfNode(int flutterId) {
+    ViewAndId viewAndId = flutterIdToOrigin.get(flutterId);
+    if (viewAndId == null) {
+      return null;
+    }
+    return viewAndId.view;
+  }
+
   private static class ViewAndId {
     final View view;
     final int id;

shell/platform/android/test/io/flutter/view/AccessibilityBridgeTest.java

@@ -5,20 +5,27 @@
 package io.flutter.view;
 
 import static org.junit.Assert.assertEquals;
+import static org.mockito.Matchers.eq;
 import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.when;
 
 import android.content.ContentResolver;
 import android.content.Context;
 import android.view.View;
+import android.view.ViewParent;
+import android.view.accessibility.AccessibilityEvent;
 import android.view.accessibility.AccessibilityManager;
 import android.view.accessibility.AccessibilityNodeInfo;
 import io.flutter.embedding.engine.systemchannels.AccessibilityChannel;
 import io.flutter.plugin.platform.PlatformViewsAccessibilityDelegate;
 import java.nio.ByteBuffer;
 import java.util.ArrayList;
+import java.util.List;
 import org.junit.Test;
 import org.junit.runner.RunWith;
+import org.mockito.ArgumentCaptor;
 import org.robolectric.RobolectricTestRunner;
 import org.robolectric.annotation.Config;
 
@@ -73,24 +80,103 @@ public void itDoesNotContainADescriptionIfScopesRoute() {
     assertEquals(nodeInfo.getText(), null);
   }
 
-  AccessibilityBridge setUpBridge() {
-    View view = mock(View.class);
+  @Test
+  public void itUnfocusesPlatformViewWhenPlatformViewGoesAway() {
+    AccessibilityViewEmbedder mockViewEmbedder = mock(AccessibilityViewEmbedder.class);
+    AccessibilityManager mockManager = mock(AccessibilityManager.class);
+    View mockRootView = mock(View.class);
     Context context = mock(Context.class);
-    when(view.getContext()).thenReturn(context);
+    when(mockRootView.getContext()).thenReturn(context);
     when(context.getPackageName()).thenReturn("test");
-    AccessibilityChannel accessibilityChannel = mock(AccessibilityChannel.class);
-    AccessibilityManager accessibilityManager = mock(AccessibilityManager.class);
-    ContentResolver contentResolver = mock(ContentResolver.class);
-    PlatformViewsAccessibilityDelegate platformViewsAccessibilityDelegate =
-        mock(PlatformViewsAccessibilityDelegate.class);
     AccessibilityBridge accessibilityBridge =
-        new AccessibilityBridge(
-            view,
-            accessibilityChannel,
-            accessibilityManager,
-            contentResolver,
-            platformViewsAccessibilityDelegate);
-    return accessibilityBridge;
+        setUpBridge(mockRootView, mockManager, mockViewEmbedder);
+
+    // Sent a11y tree with platform view.
+    TestSemanticsNode root = new TestSemanticsNode();
+    root.id = 0;
+    TestSemanticsNode platformView = new TestSemanticsNode();
+    platformView.id = 1;
+    platformView.platformViewId = 42;
+    root.children.add(platformView);
+    TestSemanticsUpdate testSemanticsUpdate = root.toUpdate();
+    accessibilityBridge.updateSemantics(testSemanticsUpdate.buffer, testSemanticsUpdate.strings);
+
+    // Set a11y focus to platform view.
+    View mockView = mock(View.class);
+    AccessibilityEvent focusEvent = mock(AccessibilityEvent.class);
+    when(mockViewEmbedder.requestSendAccessibilityEvent(mockView, mockView, focusEvent))
+        .thenReturn(true);
+    when(mockViewEmbedder.getRecordFlutterId(mockView, focusEvent)).thenReturn(42);
+    when(focusEvent.getEventType()).thenReturn(AccessibilityEvent.TYPE_VIEW_ACCESSIBILITY_FOCUSED);
+    accessibilityBridge.externalViewRequestSendAccessibilityEvent(mockView, mockView, focusEvent);
+
+    // Replace the platform view.
+    TestSemanticsNode node = new TestSemanticsNode();
+    node.id = 2;
+    root.children.clear();
+    root.children.add(node);
+    testSemanticsUpdate = root.toUpdate();
+    when(mockManager.isEnabled()).thenReturn(true);
+    ViewParent mockParent = mock(ViewParent.class);
+    when(mockRootView.getParent()).thenReturn(mockParent);
+    accessibilityBridge.updateSemantics(testSemanticsUpdate.buffer, testSemanticsUpdate.strings);
+
+    // Check that unfocus event was sent.
+    ArgumentCaptor<AccessibilityEvent> eventCaptor =
+        ArgumentCaptor.forClass(AccessibilityEvent.class);
+    verify(mockParent, times(2))
+        .requestSendAccessibilityEvent(eq(mockRootView), eventCaptor.capture());
+    AccessibilityEvent event = eventCaptor.getAllValues().get(0);
+    assertEquals(event.getEventType(), AccessibilityEvent.TYPE_VIEW_ACCESSIBILITY_FOCUS_CLEARED);
+  }
+
+  AccessibilityBridge setUpBridge() {
+    return setUpBridge(null, null, null, null, null, null);
+  }
+
+  AccessibilityBridge setUpBridge(
+      View rootAccessibilityView,
+      AccessibilityManager accessibilityManager,
+      AccessibilityViewEmbedder accessibilityViewEmbedder) {
+    return setUpBridge(
+        rootAccessibilityView, null, accessibilityManager, null, accessibilityViewEmbedder, null);
+  }
+
+  AccessibilityBridge setUpBridge(
+      View rootAccessibilityView,
+      AccessibilityChannel accessibilityChannel,
+      AccessibilityManager accessibilityManager,
+      ContentResolver contentResolver,
+      AccessibilityViewEmbedder accessibilityViewEmbedder,
+      PlatformViewsAccessibilityDelegate platformViewsAccessibilityDelegate) {
+    if (rootAccessibilityView == null) {
+      rootAccessibilityView = mock(View.class);
+      Context context = mock(Context.class);
+      when(rootAccessibilityView.getContext()).thenReturn(context);
+      when(context.getPackageName()).thenReturn("test");
+    }
+    if (accessibilityChannel == null) {
+      accessibilityChannel = mock(AccessibilityChannel.class);
+    }
+    if (accessibilityManager == null) {
+      accessibilityManager = mock(AccessibilityManager.class);
+    }
+    if (contentResolver == null) {
+      contentResolver = mock(ContentResolver.class);
+    }
+    if (accessibilityViewEmbedder == null) {
+      accessibilityViewEmbedder = mock(AccessibilityViewEmbedder.class);
+    }
+    if (platformViewsAccessibilityDelegate == null) {
+      platformViewsAccessibilityDelegate = mock(PlatformViewsAccessibilityDelegate.class);
+    }
+    return new AccessibilityBridge(
+        rootAccessibilityView,
+        accessibilityChannel,
+        accessibilityManager,
+        contentResolver,
+        accessibilityViewEmbedder,
+        platformViewsAccessibilityDelegate);
   }
 
   /// The encoding for semantics is described in platform_view_android.cc
@@ -136,11 +222,18 @@ void addFlag(AccessibilityBridge.Flag flag) {
     float top = 0.0f;
     float right = 0.0f;
     float bottom = 0.0f;
-    // children and custom actions not supported.
+    final List<TestSemanticsNode> children = new ArrayList<TestSemanticsNode>();
+    // custom actions not supported.
 
     TestSemanticsUpdate toUpdate() {
       ArrayList<String> strings = new ArrayList<String>();
       ByteBuffer bytes = ByteBuffer.allocate(1000);
+      addToBuffer(bytes, strings);
+      bytes.flip();
+      return new TestSemanticsUpdate(bytes, strings.toArray(new String[strings.size()]));
+    }
+
+    protected void addToBuffer(ByteBuffer bytes, ArrayList<String> strings) {
       bytes.putInt(id);
       bytes.putInt(flags);
       bytes.putInt(actions);
@@ -169,11 +262,20 @@ TestSemanticsUpdate toUpdate() {
         bytes.putFloat(0);
       }
       // children in traversal order.
-      bytes.putInt(0);
+      bytes.putInt(children.size());
+      for (TestSemanticsNode node : children) {
+        bytes.putInt(node.id);
+      }
+      // children in hit test order.
+      for (TestSemanticsNode node : children) {
+        bytes.putInt(node.id);
+      }
       // custom actions
       bytes.putInt(0);
-      bytes.flip();
-      return new TestSemanticsUpdate(bytes, strings.toArray(new String[strings.size()]));
+      // child nodes
+      for (TestSemanticsNode node : children) {
+        node.addToBuffer(bytes, strings);
+      }
     }
   }