Include platformViewId in semantics tree (#28953)

packages/flutter/lib/src/rendering/platform_view.dart

@@ -7,6 +7,7 @@ import 'dart:ui';
 
 import 'package:flutter/foundation.dart';
 import 'package:flutter/gestures.dart';
+import 'package:flutter/semantics.dart';
 import 'package:flutter/services.dart';
 
 import 'box.dart';
@@ -87,6 +88,7 @@ class RenderAndroidView extends RenderBox {
        _viewController = viewController {
     _motionEventsDispatcher = _MotionEventsDispatcher(globalToLocal, viewController);
     updateGestureRecognizers(gestureRecognizers);
+    _viewController.addOnPlatformViewCreatedListener(_onPlatformViewCreated);
   }
 
   _PlatformViewState _state = _PlatformViewState.uninitialized;
@@ -99,10 +101,20 @@ class RenderAndroidView extends RenderBox {
   /// `viewController` must not be null.
   set viewController(AndroidViewController viewController) {
     assert(_viewController != null);
+    assert(viewController != null);
     if (_viewController == viewController)
       return;
+    _viewController.removeOnPlatformViewCreatedListener(_onPlatformViewCreated);
     _viewController = viewController;
     _sizePlatformView();
+    if (_viewController.isCreated) {
+      markNeedsSemanticsUpdate();
+    }
+    _viewController.addOnPlatformViewCreatedListener(_onPlatformViewCreated);
+  }
+
+  void _onPlatformViewCreated(int id) {
+    markNeedsSemanticsUpdate();
   }
 
   /// How to behave during hit testing.
@@ -235,6 +247,17 @@ class RenderAndroidView extends RenderBox {
     }
   }
 
+  @override
+  void describeSemanticsConfiguration (SemanticsConfiguration config) {
+    super.describeSemanticsConfiguration(config);
+
+    config.isSemanticBoundary = true;
+
+    if (_viewController.isCreated) {
+      config.platformViewId = _viewController.id;
+    }
+  }
+
   @override
   void detach() {
     _gestureRecognizer.reset();
@@ -286,9 +309,9 @@ class RenderUiKitView extends RenderBox {
   /// must have been created by calling [PlatformViewsService.initUiKitView].
   UiKitViewController get viewController => _viewController;
   UiKitViewController _viewController;
-  set viewController(UiKitViewController viewId) {
-    assert(viewId != null);
-    _viewController = viewId;
+  set viewController(UiKitViewController viewController) {
+    assert(viewController != null);
+    _viewController = viewController;
     markNeedsPaint();
   }
 

packages/flutter/lib/src/semantics/semantics.dart

@@ -196,6 +196,7 @@ class SemanticsData extends Diagnosticable {
     @required this.scrollPosition,
     @required this.scrollExtentMax,
     @required this.scrollExtentMin,
+    @required this.platformViewId,
     this.tags,
     this.transform,
     this.customSemanticsActionIds,
@@ -295,6 +296,19 @@ class SemanticsData extends Diagnosticable {
   ///  * [ScrollPosition.minScrollExtent], from where this value is usually taken.
   final double scrollExtentMin;
 
+  /// The id of the platform view, whose semantics nodes will be added as
+  /// children to this node.
+  ///
+  /// If this value is non-null, the SemanticsNode must not have any children
+  /// as those would be replaced by the semantics nodes of the referenced
+  /// platform view.
+  ///
+  /// See also:
+  ///
+  ///  * [AndroidView], which is the platform view for Android.
+  ///  * [UiKitView], which is the platform view for iOS.
+  final int platformViewId;
+
   /// The bounding box for this node in its coordinate system.
   final Rect rect;
 
@@ -374,6 +388,7 @@ class SemanticsData extends Diagnosticable {
     properties.add(EnumProperty<TextDirection>('textDirection', textDirection, defaultValue: null));
     if (textSelection?.isValid == true)
       properties.add(MessageProperty('textSelection', '[${textSelection.start}, ${textSelection.end}]'));
+    properties.add(IntProperty('platformViewId', platformViewId, defaultValue: null));
     properties.add(IntProperty('scrollChildren', scrollChildCount, defaultValue: null));
     properties.add(IntProperty('scrollIndex', scrollIndex, defaultValue: null));
     properties.add(DoubleProperty('scrollExtentMin', scrollExtentMin, defaultValue: null));
@@ -402,6 +417,7 @@ class SemanticsData extends Diagnosticable {
         && typedOther.scrollPosition == scrollPosition
         && typedOther.scrollExtentMax == scrollExtentMax
         && typedOther.scrollExtentMin == scrollExtentMin
+        && typedOther.platformViewId == platformViewId
         && typedOther.transform == transform
         && typedOther.elevation == elevation
         && typedOther.thickness == thickness
@@ -411,6 +427,7 @@ class SemanticsData extends Diagnosticable {
   @override
   int get hashCode {
     return ui.hashValues(
+      ui.hashValues(
         flags,
         actions,
         label,
@@ -427,9 +444,11 @@ class SemanticsData extends Diagnosticable {
         scrollPosition,
         scrollExtentMax,
         scrollExtentMin,
+        platformViewId,
         transform,
         elevation,
         thickness,
+      ),
       ui.hashList(customSemanticsActionIds),
     );
   }
@@ -1464,6 +1483,7 @@ class SemanticsNode extends AbstractNode with DiagnosticableTreeMixin {
         _scrollExtentMin != config._scrollExtentMin ||
         _actionsAsBits != config._actionsAsBits ||
         indexInParent != config.indexInParent ||
+        platformViewId != config.platformViewId ||
         _mergeAllDescendantsIntoThisNode != config.isMergingSemanticsOfDescendants;
   }
 
@@ -1663,6 +1683,20 @@ class SemanticsNode extends AbstractNode with DiagnosticableTreeMixin {
   double get scrollExtentMin => _scrollExtentMin;
   double _scrollExtentMin;
 
+  /// The id of the platform view, whose semantics nodes will be added as
+  /// children to this node.
+  ///
+  /// If this value is non-null, the SemanticsNode must not have any children
+  /// as those would be replaced by the semantics nodes of the referenced
+  /// platform view.
+  ///
+  /// See also:
+  ///
+  ///  * [AndroidView], which is the platform view for Android.
+  ///  * [UiKitView], which is the platform view for iOS.
+  int get platformViewId => _platformViewId;
+  int _platformViewId;
+
   bool _canPerformAction(SemanticsAction action) => _actions.containsKey(action);
 
   static final SemanticsConfiguration _kEmptyConfig = SemanticsConfiguration();
@@ -1684,6 +1718,11 @@ class SemanticsNode extends AbstractNode with DiagnosticableTreeMixin {
     if (_isDifferentFromCurrentSemanticAnnotation(config))
       _markDirty();
 
+    assert(
+      config.platformViewId == null || childrenInInversePaintOrder.isEmpty,
+      'SemanticsNodes with children must not specify a platformViewId.'
+    );
+
     _label = config.label;
     _decreasedValue = config.decreasedValue;
     _value = config.value;
@@ -1706,6 +1745,7 @@ class SemanticsNode extends AbstractNode with DiagnosticableTreeMixin {
     _scrollChildCount = config.scrollChildCount;
     _scrollIndex = config.scrollIndex;
     indexInParent = config.indexInParent;
+    _platformViewId = config._platformViewId;
     _replaceChildren(childrenInInversePaintOrder ?? const <SemanticsNode>[]);
 
     assert(
@@ -1740,6 +1780,7 @@ class SemanticsNode extends AbstractNode with DiagnosticableTreeMixin {
     double scrollPosition = _scrollPosition;
     double scrollExtentMax = _scrollExtentMax;
     double scrollExtentMin = _scrollExtentMin;
+    int platformViewId = _platformViewId;
     final double elevation = _elevation;
     double thickness = _thickness;
     final Set<int> customSemanticsActionIds = <int>{};
@@ -1774,6 +1815,7 @@ class SemanticsNode extends AbstractNode with DiagnosticableTreeMixin {
         scrollPosition ??= node._scrollPosition;
         scrollExtentMax ??= node._scrollExtentMax;
         scrollExtentMin ??= node._scrollExtentMin;
+        platformViewId ??= node._platformViewId;
         if (value == '' || value == null)
           value = node._value;
         if (increasedValue == '' || increasedValue == null)
@@ -1843,6 +1885,7 @@ class SemanticsNode extends AbstractNode with DiagnosticableTreeMixin {
       scrollPosition: scrollPosition,
       scrollExtentMax: scrollExtentMax,
       scrollExtentMin: scrollExtentMin,
+      platformViewId: platformViewId,
       customSemanticsActionIds: customSemanticsActionIds.toList()..sort(),
     );
   }
@@ -1898,6 +1941,7 @@ class SemanticsNode extends AbstractNode with DiagnosticableTreeMixin {
       textDirection: data.textDirection,
       textSelectionBase: data.textSelection != null ? data.textSelection.baseOffset : -1,
       textSelectionExtent: data.textSelection != null ? data.textSelection.extentOffset : -1,
+      platformViewId: data.platformViewId != null ? data.platformViewId : -1,
       scrollChildren: data.scrollChildCount != null ? data.scrollChildCount : 0,
       scrollIndex: data.scrollIndex != null ? data.scrollIndex : 0 ,
       scrollPosition: data.scrollPosition != null ? data.scrollPosition : double.nan,
@@ -2038,6 +2082,7 @@ class SemanticsNode extends AbstractNode with DiagnosticableTreeMixin {
     properties.add(DiagnosticsProperty<SemanticsSortKey>('sortKey', sortKey, defaultValue: null));
     if (_textSelection?.isValid == true)
       properties.add(MessageProperty('text selection', '[${_textSelection.start}, ${_textSelection.end}]'));
+    properties.add(IntProperty('platformViewId', platformViewId, defaultValue: null));
     properties.add(IntProperty('scrollChildren', scrollChildCount, defaultValue: null));
     properties.add(IntProperty('scrollIndex', scrollIndex, defaultValue: null));
     properties.add(DoubleProperty('scrollExtentMin', scrollExtentMin, defaultValue: null));
@@ -3100,6 +3145,16 @@ class SemanticsConfiguration {
     _hasBeenAnnotated = true;
   }
 
+  /// The id of the platform view, whose semantics nodes will be added as
+  /// children to this node.
+  int get platformViewId => _platformViewId;
+  int _platformViewId;
+  set platformViewId(int value) {
+    if (value == platformViewId)
+      return;
+    _platformViewId = value;
+    _hasBeenAnnotated = true;
+  }
 
   /// Whether the semantic information provided by the owning [RenderObject] and
   /// all of its descendants should be treated as one logical entity.
@@ -3583,6 +3638,9 @@ class SemanticsConfiguration {
       return false;
     if ((_flags & other._flags) != 0)
       return false;
+    if (_platformViewId != null && other._platformViewId != null) {
+      return false;
+    }
     if (_value != null && _value.isNotEmpty && other._value != null && other._value.isNotEmpty)
       return false;
     return true;
@@ -3617,6 +3675,7 @@ class SemanticsConfiguration {
     _indexInParent ??= child.indexInParent;
     _scrollIndex ??= child._scrollIndex;
     _scrollChildCount ??= child._scrollChildCount;
+    _platformViewId ??= child._platformViewId;
 
     textDirection ??= child.textDirection;
     _sortKey ??= child._sortKey;
@@ -3672,6 +3731,7 @@ class SemanticsConfiguration {
       .._indexInParent = indexInParent
       .._scrollIndex = _scrollIndex
       .._scrollChildCount = _scrollChildCount
+      .._platformViewId = _platformViewId
       .._actions.addAll(_actions)
       .._customSemanticsActions.addAll(_customSemanticsActions);
   }

packages/flutter/lib/src/services/platform_views.dart

@@ -25,6 +25,8 @@ final PlatformViewsRegistry platformViewsRegistry = PlatformViewsRegistry._insta
 class PlatformViewsRegistry {
   PlatformViewsRegistry._instance();
 
+  // Always non-negative. The id value -1 is used in the accessibility bridge
+  // to indicate the absence of a platform view.
   int _nextPlatformViewId = 0;
 
   /// Allocates a unique identifier for a platform view.
@@ -77,7 +79,6 @@ class PlatformViewsService {
     @required TextDirection layoutDirection,
     dynamic creationParams,
     MessageCodec<dynamic> creationParamsCodec,
-    PlatformViewCreatedCallback onPlatformViewCreated,
   }) {
     assert(id != null);
     assert(viewType != null);
@@ -89,7 +90,6 @@ class PlatformViewsService {
       creationParams,
       creationParamsCodec,
       layoutDirection,
-      onPlatformViewCreated,
     );
   }
 
@@ -406,7 +406,6 @@ class AndroidViewController {
     dynamic creationParams,
     MessageCodec<dynamic> creationParamsCodec,
     TextDirection layoutDirection,
-    PlatformViewCreatedCallback onPlatformViewCreated,
   ) : assert(id != null),
       assert(viewType != null),
       assert(layoutDirection != null),
@@ -415,7 +414,6 @@ class AndroidViewController {
       _creationParams = creationParams,
       _creationParamsCodec = creationParamsCodec,
       _layoutDirection = layoutDirection,
-      _onPlatformViewCreated = onPlatformViewCreated,
       _state = _AndroidViewState.waitingForSize;
 
   /// Action code for when a primary pointer touched the screen.
@@ -459,8 +457,6 @@ class AndroidViewController {
 
   final String _viewType;
 
-  final PlatformViewCreatedCallback _onPlatformViewCreated;
-
   /// The texture entry id into which the Android view is rendered.
   int _textureId;
 
@@ -478,6 +474,25 @@ class AndroidViewController {
 
   MessageCodec<dynamic> _creationParamsCodec;
 
+  final List<PlatformViewCreatedCallback> _platformViewCreatedCallbacks = <PlatformViewCreatedCallback>[];
+
+  /// Whether the platform view has already been created.
+  bool get isCreated => _state == _AndroidViewState.created;
+
+  /// Adds a callback that will get invoke after the platform view has been
+  /// created.
+  void addOnPlatformViewCreatedListener(PlatformViewCreatedCallback listener) {
+    assert(listener != null);
+    assert(_state != _AndroidViewState.disposed);
+    _platformViewCreatedCallbacks.add(listener);
+  }
+
+  /// Removes a callback added with [addOnPlatformViewCreatedListener].
+  void removeOnPlatformViewCreatedListener(PlatformViewCreatedCallback listener) {
+    assert(_state != _AndroidViewState.disposed);
+    _platformViewCreatedCallbacks.remove(listener);
+  }
+
   /// Disposes the Android view.
   ///
   /// The [AndroidViewController] object is unusable after calling this.
@@ -486,6 +501,7 @@ class AndroidViewController {
   Future<void> dispose() async {
     if (_state == _AndroidViewState.creating || _state == _AndroidViewState.created)
       await SystemChannels.platform_views.invokeMethod<void>('dispose', id);
+    _platformViewCreatedCallbacks.clear();
     _state = _AndroidViewState.disposed;
   }
 
@@ -578,9 +594,10 @@ class AndroidViewController {
       );
     }
     _textureId = await SystemChannels.platform_views.invokeMethod('create', args);
-    if (_onPlatformViewCreated != null)
-      _onPlatformViewCreated(id);
     _state = _AndroidViewState.created;
+    for (PlatformViewCreatedCallback callback in _platformViewCreatedCallbacks) {
+      callback(id);
+    }
   }
 }
 

packages/flutter/lib/src/widgets/platform_view.dart

@@ -367,10 +367,12 @@ class _AndroidViewState extends State<AndroidView> {
       id: _id,
       viewType: widget.viewType,
       layoutDirection: _layoutDirection,
-      onPlatformViewCreated: widget.onPlatformViewCreated,
       creationParams: widget.creationParams,
       creationParamsCodec: widget.creationParamsCodec,
     );
+    if (widget.onPlatformViewCreated != null) {
+      _controller.addOnPlatformViewCreatedListener(widget.onPlatformViewCreated);
+    }
   }
 }
 

packages/flutter/test/semantics/semantics_test.dart

@@ -346,6 +346,7 @@ void main() {
       '   hint: ""\n'
       '   textDirection: null\n'
       '   sortKey: null\n'
+      '   platformViewId: null\n'
       '   scrollChildren: null\n'
       '   scrollIndex: null\n'
       '   scrollExtentMin: null\n'
@@ -440,6 +441,7 @@ void main() {
       '   hint: ""\n'
       '   textDirection: null\n'
       '   sortKey: null\n'
+      '   platformViewId: null\n'
       '   scrollChildren: null\n'
       '   scrollIndex: null\n'
       '   scrollExtentMin: null\n'

packages/flutter/test/services/fake_platform_views.dart

@@ -26,6 +26,8 @@ class FakeAndroidPlatformViewsController {
 
   Completer<void> resizeCompleter;
 
+  Completer<void> createCompleter;
+
   void registerViewType(String viewType) {
     _registeredViewTypes.add(viewType);
   }
@@ -46,7 +48,7 @@ class FakeAndroidPlatformViewsController {
     return Future<dynamic>.sync(() => null);
   }
 
-  Future<dynamic> _create(MethodCall call) {
+  Future<dynamic> _create(MethodCall call) async {
     final Map<dynamic, dynamic> args = call.arguments;
     final int id = args['id'];
     final String viewType = args['viewType'];
@@ -67,6 +69,10 @@ class FakeAndroidPlatformViewsController {
         message: 'Trying to create a platform view of unregistered type: $viewType',
       );
 
+    if (createCompleter != null) {
+      await createCompleter.future;
+    }
+
     _views[id] = FakeAndroidPlatformView(id, viewType, Size(width, height), layoutDirection, creationParams);
     final int textureId = _textureCounter++;
     return Future<int>.sync(() => textureId);

packages/flutter/test/services/platform_views_test.dart

@@ -105,14 +105,20 @@ void main() {
       final PlatformViewCreatedCallback callback = (int id) { createdViews.add(id); };
 
       final AndroidViewController controller1 = PlatformViewsService.initAndroidView(
-          id: 0, viewType: 'webview', layoutDirection: TextDirection.ltr, onPlatformViewCreated:  callback);
+        id: 0,
+        viewType: 'webview',
+        layoutDirection: TextDirection.ltr,
+      )..addOnPlatformViewCreatedListener(callback);
       expect(createdViews, isEmpty);
 
       await controller1.setSize(const Size(100.0, 100.0));
       expect(createdViews, orderedEquals(<int>[0]));
 
       final AndroidViewController controller2 = PlatformViewsService.initAndroidView(
-          id: 5, viewType: 'webview', layoutDirection: TextDirection.ltr, onPlatformViewCreated:  callback);
+        id: 5,
+        viewType: 'webview',
+        layoutDirection: TextDirection.ltr,
+      )..addOnPlatformViewCreatedListener(callback);
       expect(createdViews, orderedEquals(<int>[0]));
 
       await controller2.setSize(const Size(100.0, 200.0));

packages/flutter/test/widgets/platform_view_test.dart

@@ -806,6 +806,53 @@ void main() {
 
       expect(factoryInvocationCount, 1);
     });
+
+    testWidgets('AndroidView has correct semantics', (WidgetTester tester) async {
+      final SemanticsHandle handle = tester.ensureSemantics();
+      final int currentViewId = platformViewsRegistry.getNextPlatformViewId();
+      expect(currentViewId, greaterThanOrEqualTo(0));
+      final FakeAndroidPlatformViewsController viewsController = FakeAndroidPlatformViewsController();
+      viewsController.registerViewType('webview');
+
+      viewsController.createCompleter = Completer<void>();
+
+      await tester.pumpWidget(
+        Semantics(
+          container: true,
+          child: const Align(
+            alignment: Alignment.bottomRight,
+            child: SizedBox(
+              width: 200.0,
+              height: 100.0,
+              child: AndroidView(
+                viewType: 'webview',
+                layoutDirection: TextDirection.ltr,
+              ),
+            ),
+          ),
+        ),
+      );
+
+      final SemanticsNode semantics =  tester.getSemantics(find.byType(AndroidView));
+
+      // Platform view has not been created yet, no platformViewId.
+      expect(semantics.platformViewId, null);
+      expect(semantics.rect, Rect.fromLTWH(0, 0, 200, 100));
+      // A 200x100 rect positioned at bottom right of a 800x600 box.
+      expect(semantics.transform, Matrix4.translationValues(600, 500, 0));
+      expect(semantics.childrenCount, 0);
+
+      viewsController.createCompleter.complete();
+      await tester.pumpAndSettle();
+
+      expect(semantics.platformViewId, currentViewId + 1);
+      expect(semantics.rect, Rect.fromLTWH(0, 0, 200, 100));
+      // A 200x100 rect positioned at bottom right of a 800x600 box.
+      expect(semantics.transform, Matrix4.translationValues(600, 500, 0));
+      expect(semantics.childrenCount, 0);
+
+      handle.dispose();
+    });
   });
 
   group('UiKitView', () {

packages/flutter_test/lib/src/matchers.dart

@@ -364,6 +364,7 @@ Matcher matchesSemantics({
   Size size,
   double elevation,
   double thickness,
+  int platformViewId,
   // Flags //
   bool hasCheckedState = false,
   bool isChecked = false,
@@ -514,6 +515,7 @@ Matcher matchesSemantics({
     size: size,
     elevation: elevation,
     thickness: thickness,
+    platformViewId: platformViewId,
     customActions: customActions,
     hintOverrides: hintOverrides,
     children: children,
@@ -1698,6 +1700,7 @@ class _MatchesSemanticsData extends Matcher {
     this.size,
     this.elevation,
     this.thickness,
+    this.platformViewId,
     this.customActions,
     this.hintOverrides,
     this.children,
@@ -1717,6 +1720,7 @@ class _MatchesSemanticsData extends Matcher {
   final Size size;
   final double elevation;
   final double thickness;
+  final int platformViewId;
   final List<Matcher> children;
 
   @override
@@ -1746,6 +1750,8 @@ class _MatchesSemanticsData extends Matcher {
       description.add(' with elevation: $elevation');
     if (thickness != null)
       description.add(' with thickness: $thickness');
+    if (platformViewId != null)
+      description.add(' with platformViewId: $platformViewId');
     if (customActions != null)
       description.add(' with custom actions: $customActions');
     if (hintOverrides != null)
@@ -1786,6 +1792,8 @@ class _MatchesSemanticsData extends Matcher {
       return failWithDescription(matchState, 'elevation was: ${data.elevation}');
     if (thickness != null && thickness != data.thickness)
       return failWithDescription(matchState, 'thickness was: ${data.thickness}');
+    if (platformViewId != null && platformViewId != data.platformViewId)
+      return failWithDescription(matchState, 'platformViewId was: ${data.platformViewId}');
     if (actions != null) {
       int actionBits = 0;
       for (SemanticsAction action in actions)

packages/flutter_test/test/matchers_test.dart

@@ -502,6 +502,7 @@ void main() {
         scrollPosition: null,
         scrollExtentMax: null,
         scrollExtentMin: null,
+        platformViewId: 105,
         customSemanticsActionIds: <int>[CustomSemanticsAction.getIdentifier(action)],
       );
       final _FakeSemanticsNode node = _FakeSemanticsNode();
@@ -512,6 +513,7 @@ void main() {
          size: const Size(10.0, 10.0),
          elevation: 3.0,
          thickness: 4.0,
+         platformViewId: 105,
          /* Flags */
          hasCheckedState: true,
          isChecked: true,