Extract common PlatformView functionality: Gesture and PointerEvent (#37497)

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

@@ -75,12 +75,12 @@ Set<Type> _factoriesTypeSet<T>(Set<Factory<T>> factories) {
 ///
 ///  * [AndroidView] which is a widget that is used to show an Android view.
 ///  * [PlatformViewsService] which is a service for controlling platform views.
-class RenderAndroidView extends RenderBox {
+class RenderAndroidView extends RenderBox with _PlatformViewGestureMixin {
 
   /// Creates a render object for an Android view.
   RenderAndroidView({
     @required AndroidViewController viewController,
-    @required this.hitTestBehavior,
+    @required PlatformViewHitTestBehavior hitTestBehavior,
     @required Set<Factory<OneSequenceGestureRecognizer>> gestureRecognizers,
   }) : assert(viewController != null),
        assert(hitTestBehavior != null),
@@ -89,6 +89,7 @@ class RenderAndroidView extends RenderBox {
     _motionEventsDispatcher = _MotionEventsDispatcher(globalToLocal, viewController);
     updateGestureRecognizers(gestureRecognizers);
     _viewController.addOnPlatformViewCreatedListener(_onPlatformViewCreated);
+    this.hitTestBehavior = hitTestBehavior;
   }
 
   _PlatformViewState _state = _PlatformViewState.uninitialized;
@@ -117,11 +118,6 @@ class RenderAndroidView extends RenderBox {
     markNeedsSemanticsUpdate();
   }
 
-  /// How to behave during hit testing.
-  // The implicit setter is enough here as changing this value will just affect
-  // any newly arriving events there's nothing we need to invalidate.
-  PlatformViewHitTestBehavior hitTestBehavior;
-
   /// {@template flutter.rendering.platformView.updateGestureRecognizers}
   /// Updates which gestures should be forwarded to the platform view.
   ///
@@ -139,16 +135,7 @@ class RenderAndroidView extends RenderBox {
   /// Any active gesture arena the Android view participates in is rejected when the
   /// set of gesture recognizers is changed.
   void updateGestureRecognizers(Set<Factory<OneSequenceGestureRecognizer>> gestureRecognizers) {
-    assert(gestureRecognizers != null);
+    _updateGestureRecognizersWithCallBack(gestureRecognizers, _motionEventsDispatcher.handlePointerEvent);
-    assert(
-    _factoriesTypeSet(gestureRecognizers).length == gestureRecognizers.length,
-    'There were multiple gesture recognizer factories for the same type, there must only be a single '
-        'gesture recognizer factory for each gesture recognizer type.',);
-    if (_factoryTypesSetEquals(gestureRecognizers, _gestureRecognizer?.gestureRecognizerFactories)) {
-      return;
-    }
-    _gestureRecognizer?.dispose();
-    _gestureRecognizer = _AndroidViewGestureRecognizer(_motionEventsDispatcher, gestureRecognizers);
   }
 
   @override
@@ -162,8 +149,6 @@ class RenderAndroidView extends RenderBox {
 
   _MotionEventsDispatcher _motionEventsDispatcher;
 
-  _AndroidViewGestureRecognizer _gestureRecognizer;
-
   @override
   void performResize() {
     size = constraints.biggest;
@@ -229,24 +214,6 @@ class RenderAndroidView extends RenderBox {
     ));
   }
 
-  @override
-  bool hitTest(BoxHitTestResult result, { Offset position }) {
-    if (hitTestBehavior == PlatformViewHitTestBehavior.transparent || !size.contains(position))
-      return false;
-    result.add(BoxHitTestEntry(this, position));
-    return hitTestBehavior == PlatformViewHitTestBehavior.opaque;
-  }
-
-  @override
-  bool hitTestSelf(Offset position) => hitTestBehavior != PlatformViewHitTestBehavior.transparent;
-
-  @override
-  void handleEvent(PointerEvent event, HitTestEntry entry) {
-    if (event is PointerDownEvent) {
-      _gestureRecognizer.addPointer(event);
-    }
-  }
-
   @override
   void describeSemanticsConfiguration (SemanticsConfiguration config) {
     super.describeSemanticsConfiguration(config);
@@ -257,12 +224,6 @@ class RenderAndroidView extends RenderBox {
       config.platformViewId = _viewController.id;
     }
   }
-
-  @override
-  void detach() {
-    _gestureRecognizer.reset();
-    super.detach();
-  }
 }
 
 /// A render object for an iOS UIKit UIView.
@@ -486,15 +447,17 @@ class _UiKitViewGestureRecognizer extends OneSequenceGestureRecognizer {
   }
 }
 
+typedef _HandlePointerEvent = void Function(PointerEvent event);
+
 // This recognizer constructs gesture recognizers from a set of gesture recognizer factories
-// it was give, adds all of them to a gesture arena team with the _AndroidViewGestureRecognizer
+// it was give, adds all of them to a gesture arena team with the _PlatformViewGestureRecognizer
 // as the team captain.
-// As long as ta gesture arena is unresolved the recognizer caches all pointer events.
+// As long as the gesture arena is unresolved, the recognizer caches all pointer events.
-// When the team wins the recognizer sends all the cached point events to the embedded Android view, and
+// When the team wins, the recognizer sends all the cached pointer events to `_handlePointerEvent`, and
-// sets itself to a "forwarding mode" where it will forward any new pointer event to the Android view.
+// sets itself to a "forwarding mode" where it will forward any new pointer event to `_handlePointerEvent`.
-class _AndroidViewGestureRecognizer extends OneSequenceGestureRecognizer {
+class _PlatformViewGestureRecognizer extends OneSequenceGestureRecognizer {
-  _AndroidViewGestureRecognizer(
+  _PlatformViewGestureRecognizer(
-    this.dispatcher,
+    _HandlePointerEvent handlePointerEvent,
     this.gestureRecognizerFactories, {
     PointerDeviceKind kind,
   }) : super(kind: kind) {
@@ -505,18 +468,19 @@ class _AndroidViewGestureRecognizer extends OneSequenceGestureRecognizer {
         return recognizerFactory.constructor()..team = team;
       },
     ).toSet();
+    _handlePointerEvent = handlePointerEvent;
   }
 
-  final _MotionEventsDispatcher dispatcher;
+  _HandlePointerEvent _handlePointerEvent;
 
   // Maps a pointer to a list of its cached pointer events.
   // Before the arena for a pointer is resolved all events are cached here, if we win the arena
-  // the cached events are dispatched to the view, if we lose the arena we clear the cache for
+  // the cached events are dispatched to `_handlePointerEvent`, if we lose the arena we clear the cache for
   // the pointer.
   final Map<int, List<PointerEvent>> cachedEvents = <int, List<PointerEvent>>{};
 
   // Pointer for which we have already won the arena, events for pointers in this set are
-  // immediately dispatched to the Android view.
+  // immediately dispatched to `_handlePointerEvent`.
   final Set<int> forwardedPointers = <int>{};
 
   // We use OneSequenceGestureRecognizers as they support gesture arena teams.
@@ -534,7 +498,7 @@ class _AndroidViewGestureRecognizer extends OneSequenceGestureRecognizer {
   }
 
   @override
-  String get debugDescription => 'Android view';
+  String get debugDescription => 'Platform view';
 
   @override
   void didStopTrackingLastPointer(int pointer) { }
@@ -542,16 +506,16 @@ class _AndroidViewGestureRecognizer extends OneSequenceGestureRecognizer {
   @override
   void handleEvent(PointerEvent event) {
     if (!forwardedPointers.contains(event.pointer)) {
-      cacheEvent(event);
+      _cacheEvent(event);
     } else {
-      dispatcher.handlePointerEvent(event);
+      _handlePointerEvent(event);
     }
     stopTrackingIfPointerNoLongerDown(event);
   }
 
   @override
   void acceptGesture(int pointer) {
-    flushPointerCache(pointer);
+    _flushPointerCache(pointer);
     forwardedPointers.add(pointer);
   }
 
@@ -561,15 +525,15 @@ class _AndroidViewGestureRecognizer extends OneSequenceGestureRecognizer {
     cachedEvents.remove(pointer);
   }
 
-  void cacheEvent(PointerEvent event) {
+  void _cacheEvent(PointerEvent event) {
     if (!cachedEvents.containsKey(event.pointer)) {
       cachedEvents[event.pointer] = <PointerEvent> [];
     }
     cachedEvents[event.pointer].add(event);
   }
 
-  void flushPointerCache(int pointer) {
+  void _flushPointerCache(int pointer) {
-    cachedEvents.remove(pointer)?.forEach(dispatcher.handlePointerEvent);
+    cachedEvents.remove(pointer)?.forEach(_handlePointerEvent);
   }
 
   @override
@@ -728,18 +692,24 @@ class _MotionEventsDispatcher {
 
 /// A render object for embedding a platform view.
 ///
-/// [PlatformViewRenderBox] presents a platform view by adding a [PlatformViewLayer] layer, integrates it with the gesture arenas system
+/// [PlatformViewRenderBox] presents a platform view by adding a [PlatformViewLayer] layer,
-/// and adds relevant semantic nodes to the semantics tree.
+/// integrates it with the gesture arenas system and adds relevant semantic nodes to the semantics tree.
-class PlatformViewRenderBox extends RenderBox {
+class PlatformViewRenderBox extends RenderBox with _PlatformViewGestureMixin {
 
   /// Creating a render object for a [PlatformViewSurface].
   ///
   /// The `controller` parameter must not be null.
   PlatformViewRenderBox({
     @required PlatformViewController controller,
-
+    @required PlatformViewHitTestBehavior hitTestBehavior,
+    @required Set<Factory<OneSequenceGestureRecognizer>> gestureRecognizers,
   }) :  assert(controller != null && controller.viewId != null && controller.viewId > -1),
-       _controller = controller;
+        assert(hitTestBehavior != null),
+        assert(gestureRecognizers != null),
+        _controller = controller {
+          this.hitTestBehavior = hitTestBehavior;
+          updateGestureRecognizers(gestureRecognizers);
+        }
 
   /// Sets the [controller] for this render object.
   ///
@@ -759,6 +729,19 @@ class PlatformViewRenderBox extends RenderBox {
     }
   }
 
+  /// How to behave during hit testing.
+  // The implicit setter is enough here as changing this value will just affect
+  // any newly arriving events there's nothing we need to invalidate.
+  // PlatformViewHitTestBehavior hitTestBehavior;
+
+  /// {@macro  flutter.rendering.platformView.updateGestureRecognizers}
+  ///
+  /// Any active gesture arena the `PlatformView` participates in is rejected when the
+  /// set of gesture recognizers is changed.
+   void updateGestureRecognizers(Set<Factory<OneSequenceGestureRecognizer>> gestureRecognizers) {
+     _updateGestureRecognizersWithCallBack(gestureRecognizers, _controller.dispatchPointerEvent);
+  }
+
   PlatformViewController _controller;
 
   @override
@@ -791,3 +774,56 @@ class PlatformViewRenderBox extends RenderBox {
     config.platformViewId = _controller.viewId;
   }
 }
+
+/// The Mixin handling the pointer events and gestures of a platform view render box.
+mixin _PlatformViewGestureMixin on RenderBox {
+
+  /// How to behave during hit testing.
+  // The implicit setter is enough here as changing this value will just affect
+  // any newly arriving events there's nothing we need to invalidate.
+  PlatformViewHitTestBehavior hitTestBehavior;
+
+  /// {@macro  flutter.rendering.platformView.updateGestureRecognizers}
+  ///
+  /// Any active gesture arena the `PlatformView` participates in is rejected when the
+  /// set of gesture recognizers is changed.
+  void _updateGestureRecognizersWithCallBack(Set<Factory<OneSequenceGestureRecognizer>> gestureRecognizers, _HandlePointerEvent _handlePointerEvent) {
+    assert(gestureRecognizers != null);
+    assert(
+    _factoriesTypeSet(gestureRecognizers).length == gestureRecognizers.length,
+    'There were multiple gesture recognizer factories for the same type, there must only be a single '
+        'gesture recognizer factory for each gesture recognizer type.',);
+    if (_factoryTypesSetEquals(gestureRecognizers, _gestureRecognizer?.gestureRecognizerFactories)) {
+      return;
+    }
+    _gestureRecognizer?.dispose();
+    _gestureRecognizer = _PlatformViewGestureRecognizer(_handlePointerEvent, gestureRecognizers);
+  }
+
+  _PlatformViewGestureRecognizer _gestureRecognizer;
+
+  @override
+  bool hitTest(BoxHitTestResult result, { Offset position }) {
+    if (hitTestBehavior == PlatformViewHitTestBehavior.transparent || !size.contains(position)) {
+      return false;
+    }
+    result.add(BoxHitTestEntry(this, position));
+    return hitTestBehavior == PlatformViewHitTestBehavior.opaque;
+  }
+
+  @override
+  bool hitTestSelf(Offset position) => hitTestBehavior != PlatformViewHitTestBehavior.transparent;
+
+  @override
+  void handleEvent(PointerEvent event, HitTestEntry entry) {
+    if (event is PointerDownEvent) {
+      _gestureRecognizer.addPointer(event);
+    }
+  }
+
+  @override
+  void detach() {
+    _gestureRecognizer.reset();
+    super.detach();
+  }
+}

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

@@ -7,6 +7,7 @@ import 'dart:typed_data';
 import 'dart:ui';
 
 import 'package:flutter/foundation.dart';
+import 'package:flutter/gestures.dart';
 
 import 'message_codec.dart';
 import 'system_channels.dart';
@@ -725,4 +726,7 @@ abstract class PlatformViewController {
   ///
   /// See also [PlatformViewRegistry] which is a helper for managing platform view ids.
   int get viewId;
+
+  /// Dispatches the `event` to the platform view.
+  void dispatchPointerEvent(PointerEvent event);
 }

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

@@ -603,7 +603,11 @@ class PlatformViewSurface extends LeafRenderObjectWidget {
   /// The [controller] must not be null.
   const PlatformViewSurface({
     @required this.controller,
-  }) : assert(controller != null);
+    @required this.hitTestBehavior,
+    @required this.gestureRecognizers,
+  }) : assert(controller != null),
+       assert(hitTestBehavior != null),
+       assert(gestureRecognizers != null);
 
   /// The controller for the platform view integrated by this [PlatformViewSurface].
   ///
@@ -611,14 +615,60 @@ class PlatformViewSurface extends LeafRenderObjectWidget {
   /// [PlatformViewController.viewId] identifies the platform view whose contents are painted by this widget.
   final PlatformViewController controller;
 
+  /// Which gestures should be forwarded to the PlatformView.
+  ///
+  /// {@macro flutter.widgets.platformViews.gestureRecognizersDescHead}
+  ///
+  /// For example, with the following setup vertical drags will not be dispatched to the platform view
+  /// as the vertical drag gesture is claimed by the parent [GestureDetector].
+  ///
+  /// ```dart
+  /// GestureDetector(
+  ///   onVerticalDragStart: (DragStartDetails details) {},
+  ///   child: PlatformViewSurface(
+  ///   ),
+  /// )
+  /// ```
+  ///
+  /// To get the [PlatformViewSurface] to claim the vertical drag gestures we can pass a vertical drag
+  /// gesture recognizer factory in [gestureRecognizers] e.g:
+  ///
+  /// ```dart
+  /// GestureDetector(
+  ///   onVerticalDragStart: (DragStartDetails details) {},
+  ///   child: SizedBox(
+  ///     width: 200.0,
+  ///     height: 100.0,
+  ///     child: PlatformViewSurface(
+  ///       gestureRecognizers: <Factory<OneSequenceGestureRecognizer>>[
+  ///         new Factory<OneSequenceGestureRecognizer>(
+  ///           () => new EagerGestureRecognizer(),
+  ///         ),
+  ///       ].toSet(),
+  ///     ),
+  ///   ),
+  /// )
+  /// ```
+  ///
+  /// {@macro flutter.widgets.platformViews.gestureRecognizersDescFoot}
+  // We use OneSequenceGestureRecognizers as they support gesture arena teams.
+  // TODO(amirh): get a list of GestureRecognizers here.
+  // https://github.com/flutter/flutter/issues/20953
+  final Set<Factory<OneSequenceGestureRecognizer>> gestureRecognizers;
+
+  /// {@macro flutter.widgets.platformViews.hittestParam}
+  final PlatformViewHitTestBehavior hitTestBehavior;
+
   @override
   RenderObject createRenderObject(BuildContext context) {
-    return PlatformViewRenderBox(controller: controller);
+    return PlatformViewRenderBox(controller: controller, gestureRecognizers: gestureRecognizers, hitTestBehavior: hitTestBehavior);
   }
 
   @override
   void updateRenderObject(BuildContext context, PlatformViewRenderBox renderObject) {
     renderObject
-      ..controller = controller;
+      ..controller = controller
+      ..hitTestBehavior = hitTestBehavior
+      ..updateGestureRecognizers(gestureRecognizers);
   }
 }

packages/flutter/test/rendering/platform_view_test.dart

@@ -2,6 +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/foundation.dart';
+import 'package:flutter/gestures.dart';
 import 'package:flutter/rendering.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter/material.dart';
@@ -15,7 +17,16 @@ void main() {
     PlatformViewRenderBox platformViewRenderBox;
     setUp((){
       fakePlatformViewController = FakePlatformViewController(0);
-      platformViewRenderBox = PlatformViewRenderBox(controller: fakePlatformViewController);
+      platformViewRenderBox = PlatformViewRenderBox(
+        controller: fakePlatformViewController,
+        hitTestBehavior: PlatformViewHitTestBehavior.opaque,
+        gestureRecognizers: <Factory<OneSequenceGestureRecognizer>>{
+                  Factory<VerticalDragGestureRecognizer>(
+                    () {
+                      return VerticalDragGestureRecognizer();
+                    },
+                  ),
+                },);
     });
 
     test('layout should size to max constraint', () {

packages/flutter/test/services/fake_platform_views.dart

@@ -8,6 +8,7 @@ import 'package:collection/collection.dart';
 
 import 'package:flutter/painting.dart';
 import 'package:flutter/services.dart';
+import 'package:flutter/widgets.dart';
 
 /// Used in internal testing.
 class FakePlatformViewController extends PlatformViewController {
@@ -16,10 +17,22 @@ class FakePlatformViewController extends PlatformViewController {
     _id = id;
   }
 
+  /// Events that are dispatched;
+  List<PointerEvent> dispatchedPointerEvents = <PointerEvent>[];
+
   int _id;
 
   @override
   int get viewId => _id;
+
+  @override
+  void dispatchPointerEvent(PointerEvent event) {
+    dispatchedPointerEvents.add(event);
+  }
+
+  void clearTestingVariables() {
+    dispatchedPointerEvents.clear();
+  }
 }
 
 class FakeAndroidPlatformViewsController {

packages/flutter/test/widgets/platform_view_test.dart

@@ -1676,12 +1676,261 @@ void main() {
     });
 
     testWidgets('PlatformViewSurface should create platform view layer', (WidgetTester tester) async {
-      final PlatformViewSurface surface = PlatformViewSurface(controller: controller);
+      final PlatformViewSurface surface = PlatformViewSurface(
+        controller: controller,
+        hitTestBehavior: PlatformViewHitTestBehavior.opaque,
+        gestureRecognizers: const <Factory<OneSequenceGestureRecognizer>>{},);
       await tester.pumpWidget(surface);
       final PlatformViewLayer layer = tester.layers.firstWhere((Layer layer){
         return layer is PlatformViewLayer;
       });
       expect(layer, isNotNull);
     });
+
+    testWidgets('PlatformViewSurface can lose gesture arenas', (WidgetTester tester) async {
+      bool verticalDragAcceptedByParent = false;
+      await tester.pumpWidget(
+        Align(
+          alignment: Alignment.topLeft,
+          child: Container(
+            margin: const EdgeInsets.all(10.0),
+            child: GestureDetector(
+              onVerticalDragStart: (DragStartDetails d) {
+                verticalDragAcceptedByParent = true;
+              },
+              child: SizedBox(
+                width: 200.0,
+                height: 100.0,
+                child: PlatformViewSurface(
+                  controller: controller,
+                  gestureRecognizers: const <Factory<OneSequenceGestureRecognizer>>{},
+                  hitTestBehavior: PlatformViewHitTestBehavior.opaque),
+              ),
+            ),
+          ),
+        ),
+      );
+
+      final TestGesture gesture = await tester.startGesture(const Offset(50.0, 50.0));
+      await gesture.moveBy(const Offset(0.0, 100.0));
+      await gesture.up();
+
+      expect(verticalDragAcceptedByParent, true);
+      expect(
+        controller.dispatchedPointerEvents,
+        isEmpty,
+      );
+    });
+
+    testWidgets('PlatformViewSurface gesture recognizers dispatch events', (WidgetTester tester) async {
+      bool verticalDragAcceptedByParent = false;
+      await tester.pumpWidget(
+        Align(
+          alignment: Alignment.topLeft,
+          child: GestureDetector(
+            onVerticalDragStart: (DragStartDetails d) {
+              verticalDragAcceptedByParent = true;
+            },
+            child: SizedBox(
+              width: 200.0,
+              height: 100.0,
+              child: PlatformViewSurface(
+                controller: controller,
+                hitTestBehavior: PlatformViewHitTestBehavior.opaque,
+                gestureRecognizers: <Factory<OneSequenceGestureRecognizer>>{
+                  Factory<VerticalDragGestureRecognizer>(
+                    () {
+                      return VerticalDragGestureRecognizer()
+                        ..onStart = (_) {}; // Add callback to enable recognizer
+                    },
+                  ),
+                },
+              ),
+            ),
+          ),
+        ),
+      );
+
+      final TestGesture gesture = await tester.startGesture(const Offset(50.0, 50.0));
+      await gesture.moveBy(const Offset(0.0, 100.0));
+      await gesture.up();
+
+      expect(verticalDragAcceptedByParent, false);
+      expect(
+        controller.dispatchedPointerEvents.length,
+        3,
+      );
+
+    });
+
+    testWidgets(
+        'PlatformViewSurface can claim gesture after all pointers are up', (WidgetTester tester) async {
+      bool verticalDragAcceptedByParent = false;
+      // The long press recognizer rejects the gesture after the PlatformViewSurface gets the pointer up event.
+      // This test makes sure that the PlatformViewSurface can win the gesture after it got the pointer up event.
+      await tester.pumpWidget(
+        Align(
+          alignment: Alignment.topLeft,
+          child: GestureDetector(
+            onVerticalDragStart: (DragStartDetails d) {
+              verticalDragAcceptedByParent = true;
+            },
+            onLongPress: () { },
+            child: SizedBox(
+              width: 200.0,
+              height: 100.0,
+              child: PlatformViewSurface(
+                controller: controller,
+                hitTestBehavior: PlatformViewHitTestBehavior.opaque,
+                gestureRecognizers: const <Factory<OneSequenceGestureRecognizer>>{},
+              ),
+            ),
+          ),
+        ),
+      );
+
+      final TestGesture gesture = await tester.startGesture(const Offset(50.0, 50.0));
+      await gesture.up();
+
+      expect(verticalDragAcceptedByParent, false);
+      expect(
+        controller.dispatchedPointerEvents.length,
+        2,
+      );
+
+    });
+
+    testWidgets('PlatformViewSurface rebuilt during gesture', (WidgetTester tester) async {
+      await tester.pumpWidget(
+        Align(
+          alignment: Alignment.topLeft,
+          child: SizedBox(
+            width: 200.0,
+            height: 100.0,
+            child: PlatformViewSurface(
+                controller: controller,
+                hitTestBehavior: PlatformViewHitTestBehavior.opaque,
+                gestureRecognizers: const <Factory<OneSequenceGestureRecognizer>>{},
+            ),
+          ),
+        ),
+      );
+
+      final TestGesture gesture = await tester.startGesture(const Offset(50.0, 50.0));
+      await gesture.moveBy(const Offset(0.0, 100.0));
+
+      await tester.pumpWidget(
+        Align(
+          alignment: Alignment.topLeft,
+          child: SizedBox(
+            width: 200.0,
+            height: 100.0,
+            child: PlatformViewSurface(
+                controller: controller,
+                hitTestBehavior: PlatformViewHitTestBehavior.opaque,
+                gestureRecognizers: const <Factory<OneSequenceGestureRecognizer>>{},
+            ),
+          ),
+        ),
+      );
+
+      await gesture.up();
+
+      expect(
+        controller.dispatchedPointerEvents.length,
+        3,
+      );
+    });
+
+    testWidgets('PlatformViewSurface with eager gesture recognizer', (WidgetTester tester) async {
+      await tester.pumpWidget(
+        Align(
+          alignment: Alignment.topLeft,
+          child: GestureDetector(
+            onVerticalDragStart: (DragStartDetails d) { },
+            child: SizedBox(
+              width: 200.0,
+              height: 100.0,
+              child: PlatformViewSurface(
+                controller: controller,
+                hitTestBehavior: PlatformViewHitTestBehavior.opaque,
+                gestureRecognizers: <Factory<OneSequenceGestureRecognizer>>{
+                  Factory<OneSequenceGestureRecognizer>(
+                        () => EagerGestureRecognizer(),
+                  ),
+                },
+              ),
+            ),
+          ),
+        ),
+      );
+
+      await tester.startGesture(const Offset(50.0, 50.0));
+
+      // Normally (without the eager gesture recognizer) after just the pointer down event
+      // no gesture arena member will claim the arena (so no motion events will be dispatched to
+      // the PlatformViewSurface). Here we assert that with the eager recognizer in the gesture team the
+      // pointer down event is immediately dispatched.
+      expect(
+        controller.dispatchedPointerEvents.length,
+        1,
+      );
+    });
+
+    testWidgets('PlatformViewRenderBox reconstructed with same gestureRecognizers', (WidgetTester tester) async {
+
+      int factoryInvocationCount = 0;
+      final ValueGetter<EagerGestureRecognizer> constructRecognizer = () {
+        ++ factoryInvocationCount;
+        return EagerGestureRecognizer();
+      };
+
+      final PlatformViewSurface platformViewSurface = PlatformViewSurface(
+              controller: controller,
+              hitTestBehavior: PlatformViewHitTestBehavior.opaque,
+              gestureRecognizers: <Factory<OneSequenceGestureRecognizer>>{
+                Factory<OneSequenceGestureRecognizer>(
+                      constructRecognizer,
+                ),
+              });
+
+      await tester.pumpWidget(platformViewSurface);
+      await tester.pumpWidget(const SizedBox.shrink());
+      await tester.pumpWidget(platformViewSurface);
+
+      expect(factoryInvocationCount, 2);
+    });
+
+    testWidgets('PlatformViewSurface rebuilt with same gestureRecognizers', (WidgetTester tester) async {
+
+      int factoryInvocationCount = 0;
+      final ValueGetter<EagerGestureRecognizer> constructRecognizer = () {
+        ++ factoryInvocationCount;
+        return EagerGestureRecognizer();
+      };
+
+      await tester.pumpWidget(
+        PlatformViewSurface(
+          controller: controller,
+          hitTestBehavior: PlatformViewHitTestBehavior.opaque,
+          gestureRecognizers: <Factory<OneSequenceGestureRecognizer>>{
+            Factory<OneSequenceGestureRecognizer>(
+                  constructRecognizer,
+            ),
+          })
+      );
+
+      await tester.pumpWidget(
+        PlatformViewSurface(
+          controller: controller,
+          hitTestBehavior: PlatformViewHitTestBehavior.opaque,
+          gestureRecognizers: <Factory<OneSequenceGestureRecognizer>>{
+            Factory<OneSequenceGestureRecognizer>(
+                  constructRecognizer,
+            ),
+          })
+      );
+      expect(factoryInvocationCount, 1);
+    });
   });
 }