Move semantic-related bindings to SemanticsBinding (#121289)

Move semantic-related bindings to SemanticsBinding

dev/integration_tests/flutter_gallery/test/smoke_test.dart

@@ -184,8 +184,8 @@ void main() {
   );
 
   testWidgets('Flutter Gallery app smoke test with semantics', (WidgetTester tester) async {
-    RendererBinding.instance.setSemanticsEnabled(true);
+    final SemanticsHandle handle = SemanticsBinding.instance.ensureSemantics();
     await smokeGallery(tester);
-    RendererBinding.instance.setSemanticsEnabled(false);
+    handle.dispose();
   });
 }

dev/integration_tests/ios_add2app_life_cycle/flutterapp/lib/main.dart

@@ -3,19 +3,16 @@
 // found in the LICENSE file.
 
 import 'package:collection/collection.dart';
+import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
-import 'package:flutter/rendering.dart';
 import 'package:flutter/services.dart';
 
-VoidCallback? originalSemanticsListener;
-
 void main() {
-  WidgetsFlutterBinding.ensureInitialized();
   // Disconnects semantics listener for testing purposes.
-  originalSemanticsListener = WidgetsBinding.instance.platformDispatcher.onSemanticsEnabledChanged;
-  RendererBinding.instance.platformDispatcher.onSemanticsEnabledChanged = null;
-  RendererBinding.instance.setSemanticsEnabled(false);
   // If the test passes, LifeCycleSpy will rewire the semantics listener back.
+  SwitchableSemanticsBinding.ensureInitialized();
+  assert(!SwitchableSemanticsBinding.instance.semanticsEnabled);
+
   runApp(const LifeCycleSpy());
 }
 
@@ -68,8 +65,7 @@ class _LifeCycleSpyState extends State<LifeCycleSpy> with WidgetsBindingObserver
   Widget build(BuildContext context) {
     if (const ListEquality<AppLifecycleState?>().equals(_actualLifeCycleSequence, _expectedLifeCycleSequence)) {
       // Rewires the semantics harness if test passes.
-      RendererBinding.instance.setSemanticsEnabled(true);
-      RendererBinding.instance.platformDispatcher.onSemanticsEnabledChanged = originalSemanticsListener;
+      SwitchableSemanticsBinding.instance.semanticsEnabled = true;
     }
     return const MaterialApp(
       title: 'Flutter View',
@@ -77,3 +73,52 @@ class _LifeCycleSpyState extends State<LifeCycleSpy> with WidgetsBindingObserver
     );
   }
 }
+
+class SwitchableSemanticsBinding extends WidgetsFlutterBinding {
+  static SwitchableSemanticsBinding get instance => BindingBase.checkInstance(_instance);
+  static SwitchableSemanticsBinding? _instance;
+
+  static SwitchableSemanticsBinding ensureInitialized() {
+    if (_instance == null) {
+      SwitchableSemanticsBinding();
+    }
+    return SwitchableSemanticsBinding.instance;
+  }
+
+  VoidCallback? _originalSemanticsListener;
+
+  @override
+  void initInstances() {
+    super.initInstances();
+    _instance = this;
+    _updateHandler();
+  }
+
+  @override
+  bool get semanticsEnabled => _semanticsEnabled.value;
+  final ValueNotifier<bool> _semanticsEnabled = ValueNotifier<bool>(false);
+  set semanticsEnabled(bool value) {
+    _semanticsEnabled.value = value;
+    _updateHandler();
+  }
+
+  void _updateHandler() {
+    if (_semanticsEnabled.value) {
+      platformDispatcher.onSemanticsEnabledChanged = _originalSemanticsListener;
+      _originalSemanticsListener = null;
+    } else {
+      _originalSemanticsListener = platformDispatcher.onSemanticsEnabledChanged;
+      platformDispatcher.onSemanticsEnabledChanged = null;
+    }
+  }
+
+  @override
+  void addSemanticsEnabledListener(VoidCallback listener) {
+    _semanticsEnabled.addListener(listener);
+  }
+
+  @override
+  void removeSemanticsEnabledListener(VoidCallback listener) {
+    _semanticsEnabled.removeListener(listener);
+  }
+}

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

@@ -38,16 +38,15 @@ mixin RendererBinding on BindingBase, ServicesBinding, SchedulerBinding, Gesture
     platformDispatcher
       ..onMetricsChanged = handleMetricsChanged
       ..onTextScaleFactorChanged = handleTextScaleFactorChanged
-      ..onPlatformBrightnessChanged = handlePlatformBrightnessChanged
-      ..onSemanticsEnabledChanged = _handleSemanticsEnabledChanged
-      ..onSemanticsAction = _handleSemanticsAction;
+      ..onPlatformBrightnessChanged = handlePlatformBrightnessChanged;
     initRenderView();
-    _handleSemanticsEnabledChanged();
     addPersistentFrameCallback(_handlePersistentFrameCallback);
     initMouseTracker();
     if (kIsWeb) {
       addPostFrameCallback(_handleWebFirstFrame);
     }
+    addSemanticsEnabledListener(_handleSemanticsEnabledChanged);
+    _handleSemanticsEnabledChanged();
   }
 
   /// The current [RendererBinding], if one has been created.
@@ -308,8 +307,6 @@ mixin RendererBinding on BindingBase, ServicesBinding, SchedulerBinding, Gesture
     );
   }
 
-  SemanticsHandle? _semanticsHandle;
-
   /// Creates a [MouseTracker] which manages state about currently connected
   /// mice, for hover notification.
   ///
@@ -333,14 +330,10 @@ mixin RendererBinding on BindingBase, ServicesBinding, SchedulerBinding, Gesture
     super.dispatchEvent(event, hitTestResult);
   }
 
-  void _handleSemanticsEnabledChanged() {
-    setSemanticsEnabled(platformDispatcher.semanticsEnabled);
-  }
+  SemanticsHandle? _semanticsHandle;
 
-  /// Whether the render tree associated with this binding should produce a tree
-  /// of [SemanticsNode] objects.
-  void setSemanticsEnabled(bool enabled) {
-    if (enabled) {
+  void _handleSemanticsEnabledChanged() {
+    if (semanticsEnabled) {
       _semanticsHandle ??= _pipelineOwner.ensureSemantics();
     } else {
       _semanticsHandle?.dispose();
@@ -348,18 +341,9 @@ mixin RendererBinding on BindingBase, ServicesBinding, SchedulerBinding, Gesture
     }
   }
 
-  void _handleWebFirstFrame(Duration _) {
-    assert(kIsWeb);
-    const MethodChannel methodChannel = MethodChannel('flutter/service_worker');
-    methodChannel.invokeMethod<void>('first-frame');
-  }
-
-  void _handleSemanticsAction(int id, SemanticsAction action, ByteData? args) {
-    _pipelineOwner.semanticsOwner?.performAction(
-      id,
-      action,
-      args != null ? const StandardMessageCodec().decodeMessage(args) : null,
-    );
+  @override
+  void performSemanticsAction(SemanticsActionEvent action) {
+    _pipelineOwner.semanticsOwner?.performAction(action.nodeId, action.type, action.arguments);
   }
 
   void _handleSemanticsOwnerCreated() {
@@ -374,6 +358,12 @@ mixin RendererBinding on BindingBase, ServicesBinding, SchedulerBinding, Gesture
     renderView.clearSemantics();
   }
 
+  void _handleWebFirstFrame(Duration _) {
+    assert(kIsWeb);
+    const MethodChannel methodChannel = MethodChannel('flutter/service_worker');
+    methodChannel.invokeMethod<void>('first-frame');
+  }
+
   void _handlePersistentFrameCallback(Duration timeStamp) {
     drawFrame();
     _scheduleMouseTrackerUpdate();

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

@@ -808,24 +808,8 @@ typedef RenderObjectVisitor = void Function(RenderObject child);
 /// Used by [RenderObject.invokeLayoutCallback].
 typedef LayoutCallback<T extends Constraints> = void Function(T constraints);
 
-/// A reference to the semantics tree.
-///
-/// The framework maintains the semantics tree (used for accessibility and
-/// indexing) only when there is at least one client holding an open
-/// [SemanticsHandle].
-///
-/// The framework notifies the client that it has updated the semantics tree by
-/// calling the [listener] callback. When the client no longer needs the
-/// semantics tree, the client can call [dispose] on the [SemanticsHandle],
-/// which stops these callbacks and closes the [SemanticsHandle]. When all the
-/// outstanding [SemanticsHandle] objects are closed, the framework stops
-/// updating the semantics tree.
-///
-/// To obtain a [SemanticsHandle], call [PipelineOwner.ensureSemantics] on the
-/// [PipelineOwner] for the render tree from which you wish to read semantics.
-/// You can obtain the [PipelineOwner] using the [RenderObject.owner] property.
-class SemanticsHandle {
-  SemanticsHandle._(PipelineOwner owner, this.listener)
+class _LocalSemanticsHandle implements SemanticsHandle {
+  _LocalSemanticsHandle._(PipelineOwner owner, this.listener)
       : _owner = owner {
     if (listener != null) {
       _owner.semanticsOwner!.addListener(listener!);
@@ -837,13 +821,7 @@ class SemanticsHandle {
   /// The callback that will be notified when the semantics tree updates.
   final VoidCallback? listener;
 
-  /// Closes the semantics handle and stops calling [listener] when the
-  /// semantics updates.
-  ///
-  /// When all the outstanding [SemanticsHandle] objects for a given
-  /// [PipelineOwner] are closed, the [PipelineOwner] will stop updating the
-  /// semantics tree.
-  @mustCallSuper
+  @override
   void dispose() {
     if (listener != null) {
       _owner.semanticsOwner!.removeListener(listener!);
@@ -1171,7 +1149,12 @@ class PipelineOwner {
   int _outstandingSemanticsHandles = 0;
 
   /// Opens a [SemanticsHandle] and calls [listener] whenever the semantics tree
-  /// updates.
+  /// generated from the render tree owned by this [PipelineOwner] updates.
+  ///
+  /// Calling this method only ensures that this particular [PipelineOwner] will
+  /// generate a semantics tree. Consider calling
+  /// [SemanticsBinding.ensureSemantics] instead to turn on semantics globally
+  /// for the entire app.
   ///
   /// The [PipelineOwner] updates the semantics tree only when there are clients
   /// that wish to use the semantics tree. These clients express their interest
@@ -1190,7 +1173,7 @@ class PipelineOwner {
       _semanticsOwner = SemanticsOwner(onSemanticsUpdate: onSemanticsUpdate!);
       onSemanticsOwnerCreated?.call();
     }
-    return SemanticsHandle._(this, listener);
+    return _LocalSemanticsHandle._(this, listener);
   }
 
   void _didDisposeSemanticsHandle() {

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

@@ -2,22 +2,27 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:ui' as ui show AccessibilityFeatures, SemanticsUpdateBuilder;
+import 'dart:ui' as ui show AccessibilityFeatures, SemanticsAction, SemanticsUpdateBuilder;
 
 import 'package:flutter/foundation.dart';
+import 'package:flutter/services.dart';
 
 import 'debug.dart';
 
 export 'dart:ui' show AccessibilityFeatures, SemanticsUpdateBuilder;
 
 /// The glue between the semantics layer and the Flutter engine.
-// TODO(zanderso): move the remaining semantic related bindings here.
 mixin SemanticsBinding on BindingBase {
   @override
   void initInstances() {
     super.initInstances();
     _instance = this;
     _accessibilityFeatures = platformDispatcher.accessibilityFeatures;
+    platformDispatcher
+      ..onSemanticsEnabledChanged = _handleSemanticsEnabledChanged
+      ..onSemanticsAction = _handleSemanticsAction
+      ..onAccessibilityFeaturesChanged = handleAccessibilityFeaturesChanged;
+    _handleSemanticsEnabledChanged();
   }
 
   /// The current [SemanticsBinding], if one has been created.
@@ -28,10 +33,118 @@ mixin SemanticsBinding on BindingBase {
   static SemanticsBinding get instance => BindingBase.checkInstance(_instance);
   static SemanticsBinding? _instance;
 
+  /// Whether semantics information must be collected.
+  ///
+  /// Returns true if either the platform has requested semantics information
+  /// to be generated or if [ensureSemantics] has been called otherwise.
+  ///
+  /// To get notified when this value changes register a listener with
+  /// [addSemanticsEnabledListener].
+  bool get semanticsEnabled {
+    assert(_semanticsEnabled.value == (_outstandingHandles > 0));
+    return _semanticsEnabled.value;
+  }
+  late final ValueNotifier<bool> _semanticsEnabled = ValueNotifier<bool>(platformDispatcher.semanticsEnabled);
+
+  /// Adds a `listener` to be called when [semanticsEnabled] changes.
+  ///
+  /// See also:
+  ///
+  ///  * [removeSemanticsEnabledListener] to remove the listener again.
+  ///  * [ValueNotifier.addListener], which documents how and when listeners are
+  ///    called.
+  void addSemanticsEnabledListener(VoidCallback listener) {
+    _semanticsEnabled.addListener(listener);
+  }
+
+  /// Removes a `listener` added by [addSemanticsEnabledListener].
+  ///
+  /// See also:
+  ///
+  ///  * [ValueNotifier.removeListener], which documents how listeners are
+  ///    removed.
+  void removeSemanticsEnabledListener(VoidCallback listener) {
+    _semanticsEnabled.removeListener(listener);
+  }
+
+  int _outstandingHandles = 0;
+
+  /// Creates a new [SemanticsHandle] and requests the collection of semantics
+  /// information.
+  ///
+  /// Semantics information are only collected when there are clients interested
+  /// in them. These clients express their interest by holding a
+  /// [SemanticsHandle].
+  ///
+  /// Clients can close their [SemanticsHandle] by calling
+  /// [SemanticsHandle.dispose]. Once all outstanding [SemanticsHandle] objects
+  /// are closed, semantics information are no longer collected.
+  SemanticsHandle ensureSemantics() {
+    assert(_outstandingHandles >= 0);
+    _outstandingHandles++;
+    assert(_outstandingHandles > 0);
+    _semanticsEnabled.value = true;
+    return SemanticsHandle._(_didDisposeSemanticsHandle);
+  }
+
+  void _didDisposeSemanticsHandle() {
+    assert(_outstandingHandles > 0);
+    _outstandingHandles--;
+    assert(_outstandingHandles >= 0);
+    _semanticsEnabled.value = _outstandingHandles > 0;
+  }
+
+  // Handle for semantics request from the platform.
+  SemanticsHandle? _semanticsHandle;
+
+  void _handleSemanticsEnabledChanged() {
+    if (platformDispatcher.semanticsEnabled) {
+      _semanticsHandle ??= ensureSemantics();
+    } else {
+      _semanticsHandle?.dispose();
+      _semanticsHandle = null;
+    }
+  }
+
+  void _handleSemanticsAction(int id, ui.SemanticsAction action, ByteData? args) {
+    performSemanticsAction(SemanticsActionEvent(
+      nodeId: id,
+      type: action,
+      arguments: args != null ? const StandardMessageCodec().decodeMessage(args) : null,
+    ));
+  }
+
+  /// Called whenever the platform requests an action to be performed on a
+  /// [SemanticsNode].
+  ///
+  /// This callback is invoked when a user interacts with the app via an
+  /// accessibility service (e.g. TalkBack and VoiceOver) and initiates an
+  /// action on the focused node.
+  ///
+  /// Bindings that mixin the [SemanticsBinding] must implement this method and
+  /// perform the given `action` on the [SemanticsNode] specified by
+  /// [SemanticsActionEvent.nodeId].
+  ///
+  /// See [dart:ui.PlatformDispatcher.onSemanticsAction].
+  @protected
+  void performSemanticsAction(SemanticsActionEvent action);
+
+  /// The currently active set of [AccessibilityFeatures].
+  ///
+  /// This is set when the binding is first initialized and updated whenever a
+  /// flag is changed.
+  ///
+  /// To listen to changes to accessibility features, create a
+  /// [WidgetsBindingObserver] and listen to
+  /// [WidgetsBindingObserver.didChangeAccessibilityFeatures].
+  ui.AccessibilityFeatures get accessibilityFeatures => _accessibilityFeatures;
+  late ui.AccessibilityFeatures _accessibilityFeatures;
+
   /// Called when the platform accessibility features change.
   ///
   /// See [dart:ui.PlatformDispatcher.onAccessibilityFeaturesChanged].
   @protected
+  @mustCallSuper
   void handleAccessibilityFeaturesChanged() {
     _accessibilityFeatures = platformDispatcher.accessibilityFeatures;
   }
@@ -46,17 +159,6 @@ mixin SemanticsBinding on BindingBase {
     return ui.SemanticsUpdateBuilder();
   }
 
-  /// The currently active set of [AccessibilityFeatures].
-  ///
-  /// This is initialized the first time [runApp] is called and updated whenever
-  /// a flag is changed.
-  ///
-  /// To listen to changes to accessibility features, create a
-  /// [WidgetsBindingObserver] and listen to
-  /// [WidgetsBindingObserver.didChangeAccessibilityFeatures].
-  ui.AccessibilityFeatures get accessibilityFeatures => _accessibilityFeatures;
-  late ui.AccessibilityFeatures _accessibilityFeatures;
-
   /// The platform is requesting that animations be disabled or simplified.
   ///
   /// This setting can be overridden for testing or debugging by setting
@@ -72,3 +174,49 @@ mixin SemanticsBinding on BindingBase {
     return value;
   }
 }
+
+/// An event to request a [SemanticsAction] of [type] to be performed on the
+/// [SemanticsNode] identified by [nodeId].
+///
+/// Used by [SemanticsBinding.performSemanticsAction].
+@immutable
+class SemanticsActionEvent {
+  /// Creates a [SemanticsActionEvent].
+  ///
+  /// The [type] and [nodeId] are required.
+  const SemanticsActionEvent({required this.type, required this.nodeId, this.arguments});
+
+  /// The type of action to be performed.
+  final ui.SemanticsAction type;
+
+  /// The id of the [SemanticsNode] on which the action is to be performed.
+  final int nodeId;
+
+  /// Optional arguments for the action.
+  final Object? arguments;
+}
+
+/// A reference to the semantics information generated by the framework.
+///
+/// Semantics information are only collected when there are clients interested
+/// in them. These clients express their interest by holding a
+/// [SemanticsHandle]. When the client no longer needs the
+/// semantics information, it must call [dispose] on the [SemanticsHandle] to
+/// close it. When all open [SemanticsHandle]s are disposed, the framework will
+/// stop updating the semantics information.
+///
+/// To obtain a [SemanticsHandle], call [SemanticsBinding.ensureSemantics].
+class SemanticsHandle {
+  SemanticsHandle._(this._onDispose);
+
+  final VoidCallback _onDispose;
+
+  /// Closes the semantics handle.
+  ///
+  /// When all the outstanding [SemanticsHandle] objects are closed, the
+  /// framework will stop generating semantics information.
+  @mustCallSuper
+  void dispose() {
+    _onDispose();
+  }
+}

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

@@ -3129,9 +3129,9 @@ class _TraversalSortNode implements Comparable<_TraversalSortNode> {
 /// Owns [SemanticsNode] objects and notifies listeners of changes to the
 /// render tree semantics.
 ///
-/// To listen for semantic updates, call [PipelineOwner.ensureSemantics] to
-/// obtain a [SemanticsHandle]. This will create a [SemanticsOwner] if
-/// necessary.
+/// To listen for semantic updates, call [SemanticsBinding.ensureSemantics] or
+/// [PipelineOwner.ensureSemantics] to obtain a [SemanticsHandle]. This will
+/// create a [SemanticsOwner] if necessary.
 class SemanticsOwner extends ChangeNotifier {
   /// Creates a [SemanticsOwner] that manages zero or more [SemanticsNode] objects.
   SemanticsOwner({

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

@@ -260,7 +260,6 @@ mixin WidgetsBinding on BindingBase, ServicesBinding, SchedulerBinding, GestureB
     _buildOwner = BuildOwner();
     buildOwner!.onBuildScheduled = _handleBuildScheduled;
     platformDispatcher.onLocaleChanged = handleLocaleChanged;
-    platformDispatcher.onAccessibilityFeaturesChanged = handleAccessibilityFeaturesChanged;
     SystemChannels.navigation.setMethodCallHandler(_handleNavigationInvocation);
     assert(() {
       FlutterErrorDetails.propertiesTransformers.add(debugTransformDebugCreator);

packages/flutter/test/semantics/semantics_binding_test.dart

+// Copyright 2014 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/semantics.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+void main() {
+  testWidgets('Listeners are called when semantics are turned on with ensureSemantics', (WidgetTester tester) async {
+    expect(SemanticsBinding.instance.semanticsEnabled, isFalse);
+
+    final List<bool> status = <bool>[];
+    void listener() {
+      status.add(SemanticsBinding.instance.semanticsEnabled);
+    }
+
+    SemanticsBinding.instance.addSemanticsEnabledListener(listener);
+    expect(SemanticsBinding.instance.semanticsEnabled, isFalse);
+
+    final SemanticsHandle handle1 = SemanticsBinding.instance.ensureSemantics();
+    expect(status.single, isTrue);
+    expect(SemanticsBinding.instance.semanticsEnabled, isTrue);
+    status.clear();
+
+    final SemanticsHandle handle2 = SemanticsBinding.instance.ensureSemantics();
+    expect(status, isEmpty); // Listener didn't fire again.
+    expect(SemanticsBinding.instance.semanticsEnabled, isTrue);
+
+    expect(tester.binding.platformDispatcher.semanticsEnabled, isFalse);
+    tester.binding.platformDispatcher.semanticsEnabledTestValue = true;
+    expect(tester.binding.platformDispatcher.semanticsEnabled, isTrue);
+    tester.binding.platformDispatcher.clearSemanticsEnabledTestValue();
+    expect(tester.binding.platformDispatcher.semanticsEnabled, isFalse);
+    expect(status, isEmpty); // Listener didn't fire again.
+    expect(SemanticsBinding.instance.semanticsEnabled, isTrue);
+
+    handle1.dispose();
+    expect(status, isEmpty); // Listener didn't fire.
+    expect(SemanticsBinding.instance.semanticsEnabled, isTrue);
+
+    handle2.dispose();
+    expect(status.single, isFalse);
+    expect(SemanticsBinding.instance.semanticsEnabled, isFalse);
+  }, semanticsEnabled: false);
+
+  testWidgets('Listeners are called when semantics are turned on by platform', (WidgetTester tester) async {
+    expect(SemanticsBinding.instance.semanticsEnabled, isFalse);
+
+    final List<bool> status = <bool>[];
+    void listener() {
+      status.add(SemanticsBinding.instance.semanticsEnabled);
+    }
+
+    SemanticsBinding.instance.addSemanticsEnabledListener(listener);
+    expect(SemanticsBinding.instance.semanticsEnabled, isFalse);
+
+    tester.binding.platformDispatcher.semanticsEnabledTestValue = true;
+    expect(status.single, isTrue);
+    expect(SemanticsBinding.instance.semanticsEnabled, isTrue);
+    status.clear();
+
+    final SemanticsHandle handle = SemanticsBinding.instance.ensureSemantics();
+    handle.dispose();
+    expect(status, isEmpty); // Listener didn't fire.
+    expect(SemanticsBinding.instance.semanticsEnabled, isTrue);
+
+    tester.binding.platformDispatcher.clearSemanticsEnabledTestValue();
+    expect(status.single, isFalse);
+    expect(SemanticsBinding.instance.semanticsEnabled, isFalse);
+  }, semanticsEnabled: false);
+
+  testWidgets('SemanticsBinding.ensureSemantics triggers creation of semantics owner.', (WidgetTester tester) async {
+    expect(SemanticsBinding.instance.semanticsEnabled, isFalse);
+    expect(tester.binding.pipelineOwner.semanticsOwner, isNull);
+
+    final SemanticsHandle handle = SemanticsBinding.instance.ensureSemantics();
+    expect(SemanticsBinding.instance.semanticsEnabled, isTrue);
+    expect(tester.binding.pipelineOwner.semanticsOwner, isNotNull);
+
+    handle.dispose();
+    expect(SemanticsBinding.instance.semanticsEnabled, isFalse);
+    expect(tester.binding.pipelineOwner.semanticsOwner, isNull);
+  }, semanticsEnabled: false);
+}

packages/flutter/test/widgets/binding_cannot_schedule_frame_test.dart

@@ -18,7 +18,9 @@ void main() {
 
     // Enables the semantics should not schedule any frames if the root widget
     // has not been attached.
-    binding.setSemanticsEnabled(true);
+    expect(binding.semanticsEnabled, isFalse);
+    binding.ensureSemantics();
+    expect(binding.semanticsEnabled, isTrue);
     expect(SchedulerBinding.instance.framesEnabled, isFalse);
     expect(SchedulerBinding.instance.hasScheduledFrame, isFalse);
 

packages/flutter_driver/lib/src/common/handler_factory.dart

@@ -443,13 +443,13 @@ mixin CommandHandlerFactory {
   }
 
   SemanticsHandle? _semantics;
-  bool get _semanticsIsEnabled => RendererBinding.instance.pipelineOwner.semanticsOwner != null;
+  bool get _semanticsIsEnabled => SemanticsBinding.instance.semanticsEnabled;
 
   Future<SetSemanticsResult> _setSemantics(Command command) async {
     final SetSemantics setSemanticsCommand = command as SetSemantics;
     final bool semanticsWasEnabled = _semanticsIsEnabled;
     if (setSemanticsCommand.enabled && _semantics == null) {
-      _semantics = RendererBinding.instance.pipelineOwner.ensureSemantics();
+      _semantics = SemanticsBinding.instance.ensureSemantics();
       if (!semanticsWasEnabled) {
         // wait for the first frame where semantics is enabled.
         final Completer<void> completer = Completer<void>();

packages/flutter_test/lib/src/controller.dart

@@ -72,7 +72,7 @@ class SemanticsController {
   /// if no semantics are found or are not enabled.
   SemanticsNode find(Finder finder) {
     TestAsyncUtils.guardSync();
-    if (_binding.pipelineOwner.semanticsOwner == null) {
+    if (!_binding.semanticsEnabled) {
       throw StateError('Semantics are not enabled.');
     }
     final Iterable<Element> candidates = finder.evaluate();
@@ -241,7 +241,7 @@ abstract class WidgetController {
   /// use of the [Semantics] tree to determine the meaning of an application.
   /// If semantics has been disabled for the test, this will throw a [StateError].
   SemanticsController get semantics {
-    if (binding.pipelineOwner.semanticsOwner == null) {
+    if (!binding.semanticsEnabled) {
       throw StateError(
         'Semantics are not enabled. Enable them by passing '
         '`semanticsEnabled: true` to `testWidgets`, or by manually creating a '
@@ -1491,7 +1491,7 @@ abstract class WidgetController {
   ///
   /// The handle must be disposed at the end of the test.
   SemanticsHandle ensureSemantics() {
-    return binding.pipelineOwner.ensureSemantics();
+    return binding.ensureSemantics();
   }
 
   /// Given a widget `W` specified by [finder] and a [Scrollable] widget `S` in

packages/flutter_test/lib/src/finders.dart

@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'package:flutter/gestures.dart';
 import 'package:flutter/material.dart' show Tooltip;
+import 'package:flutter/rendering.dart';
 import 'package:flutter/widgets.dart';
 
 import 'all_elements.dart';
@@ -435,7 +435,7 @@ class CommonFinders {
   /// If the `skipOffstage` argument is true (the default), then this skips
   /// nodes that are [Offstage] or that are from inactive [Route]s.
   Finder bySemanticsLabel(Pattern label, { bool skipOffstage = true }) {
-    if (WidgetsBinding.instance.pipelineOwner.semanticsOwner == null) {
+    if (!SemanticsBinding.instance.semanticsEnabled) {
       throw StateError('Semantics are not enabled. '
                        'Make sure to call tester.ensureSemantics() before using '
                        'this finder, and call dispose on its return value after.');