Refactor mouse hit testing system: Direct mouse hit test (#59883)

packages/flutter/lib/src/gestures/events.dart

@@ -908,7 +908,7 @@ class PointerEnterEvent extends PointerEvent {
     down: event?.down,
     synthesized: event?.synthesized,
     transform: event?.transform,
-    original: event?.original as PointerEnterEvent,
+    original: null,
   );
 
   @override
@@ -1054,7 +1054,7 @@ class PointerExitEvent extends PointerEvent {
     down: event?.down,
     synthesized: event?.synthesized,
     transform: event?.transform,
-    original: event?.original as PointerExitEvent,
+    original: null,
   );
 
   @override

packages/flutter/lib/src/gestures/hit_test.dart

@@ -4,8 +4,6 @@
 
 // @dart = 2.8
 
-import 'dart:collection';
-
 import 'package:flutter/foundation.dart';
 import 'package:vector_math/vector_math_64.dart';
 
@@ -73,12 +71,51 @@ class HitTestEntry {
   Matrix4 _transform;
 }
 
+// A type of data that can be applied to a matrix by left-multiplication.
+@immutable
+abstract class _TransformPart {
+  const _TransformPart();
+
+  // Apply this transform part to `rhs` from the left.
+  //
+  // This should work as if this transform part is first converted to a matrix
+  // and then left-multiplied to `rhs`.
+  //
+  // For example, if this transform part is a vector `v1`, whose corresponding
+  // matrix is `m1 = Matrix4.translation(v1)`, then the result of
+  // `_VectorTransformPart(v1).multiply(rhs)` should equal to `m1 * rhs`.
+  Matrix4 multiply(Matrix4 rhs);
+}
+
+class _MatrixTransformPart extends _TransformPart {
+  const _MatrixTransformPart(this.matrix);
+
+  final Matrix4 matrix;
+
+  @override
+  Matrix4 multiply(Matrix4 rhs) {
+    return matrix * rhs as Matrix4;
+  }
+}
+
+class _OffsetTransformPart extends _TransformPart {
+  const _OffsetTransformPart(this.offset);
+
+  final Offset offset;
+
+  @override
+  Matrix4 multiply(Matrix4 rhs) {
+    return rhs.clone()..leftTranslate(offset.dx, offset.dy);
+  }
+}
+
 /// The result of performing a hit test.
 class HitTestResult {
   /// Creates an empty hit test result.
   HitTestResult()
      : _path = <HitTestEntry>[],
-       _transforms = Queue<Matrix4>();
+       _transforms = <Matrix4>[Matrix4.identity()],
+       _localTransforms = <_TransformPart>[];
 
   /// Wraps `result` (usually a subtype of [HitTestResult]) to create a
   /// generic [HitTestResult].
@@ -88,7 +125,8 @@ class HitTestResult {
   /// structure to store [HitTestEntry]s).
   HitTestResult.wrap(HitTestResult result)
      : _path = result._path,
-       _transforms = result._transforms;
+       _transforms = result._transforms,
+       _localTransforms = result._localTransforms;
 
   /// An unmodifiable list of [HitTestEntry] objects recorded during the hit test.
   ///
@@ -98,7 +136,40 @@ class HitTestResult {
   Iterable<HitTestEntry> get path => _path;
   final List<HitTestEntry> _path;
 
-  final Queue<Matrix4> _transforms;
+  // A stack of transform parts.
+  //
+  // The transform part stack leading from global to the current object is stored
+  // in 2 parts:
+  //
+  //  * `_transforms` are globalized matrices, meaning they have been multiplied
+  //    by the ancestors and are thus relative to the global coordinate space.
+  //  * `_localTransforms` are local transform parts, which are relative to the
+  //    parent's coordinate space.
+  //
+  // When new transform parts are added they're appended to `_localTransforms`,
+  // and are converted to global ones and moved to `_transforms` only when used.
+  final List<Matrix4> _transforms;
+  final List<_TransformPart> _localTransforms;
+
+  // Globalize all transform parts in `_localTransforms` and move them to
+  // _transforms.
+  void _globalizeTransforms() {
+    if (_localTransforms.isEmpty) {
+      return;
+    }
+    Matrix4 last = _transforms.last;
+    for (final _TransformPart part in _localTransforms) {
+      last = part.multiply(last);
+      _transforms.add(last);
+    }
+    _localTransforms.clear();
+  }
+
+  Matrix4 get _lastTransform {
+    _globalizeTransforms();
+    assert(_localTransforms.isEmpty);
+    return _transforms.last;
+  }
 
   /// Add a [HitTestEntry] to the path.
   ///
@@ -107,7 +178,7 @@ class HitTestResult {
   /// upward walk of the tree being hit tested.
   void add(HitTestEntry entry) {
     assert(entry._transform == null);
-    entry._transform = _transforms.isEmpty ? null : _transforms.last;
+    entry._transform = _lastTransform;
     _path.add(entry);
   }
 
@@ -125,6 +196,9 @@ class HitTestResult {
   /// through [PointerEvent.removePerspectiveTransform] to remove
   /// the perspective component.
   ///
+  /// If the provided `transform` is a translation matrix, it is much faster
+  /// to use [pushOffset] with the translation offset instead.
+  ///
   /// [HitTestable]s need to call this method indirectly through a convenience
   /// method defined on a subclass before hit testing a child that does not
   /// have the same origin as the parent. After hit testing the child,
@@ -132,10 +206,10 @@ class HitTestResult {
   ///
   /// See also:
   ///
+  ///  * [pushOffset], which is similar to [pushTransform] but is limited to
+  ///    translations, and is faster in such cases.
   ///  * [BoxHitTestResult.addWithPaintTransform], which is a public wrapper
   ///    around this function for hit testing on [RenderBox]s.
-  ///  * [SliverHitTestResult.addWithAxisOffset], which is a public wrapper
-  ///    around this function for hit testing on [RenderSliver]s.
   @protected
   void pushTransform(Matrix4 transform) {
     assert(transform != null);
@@ -148,26 +222,60 @@ class HitTestResult {
       'matrix through PointerEvent.removePerspectiveTransform? '
       'The provided matrix is:\n$transform'
     );
-    _transforms.add(_transforms.isEmpty ? transform : (transform * _transforms.last as Matrix4));
+    _localTransforms.add(_MatrixTransformPart(transform));
+  }
+
+  /// Pushes a new translation offset that is to be applied to all future
+  /// [HitTestEntry]s added via [add] until it is removed via [popTransform].
+  ///
+  /// This method is only to be used by subclasses, which must provide
+  /// coordinate space specific public wrappers around this function for their
+  /// users (see [BoxHitTestResult.addWithPaintOffset] for such an example).
+  ///
+  /// The provided `offset` should describe how to transform [PointerEvent]s from
+  /// the coordinate space of the method caller to the coordinate space of its
+  /// children. Usually `offset` is the inverse of the offset of the child
+  /// relative to the parent.
+  ///
+  /// [HitTestable]s need to call this method indirectly through a convenience
+  /// method defined on a subclass before hit testing a child that does not
+  /// have the same origin as the parent. After hit testing the child,
+  /// [popTransform] has to be called to remove the child-specific `transform`.
+  ///
+  /// See also:
+  ///
+  ///  * [pushTransform], which is similar to [pushOffset] but allows general
+  ///    transform besides translation.
+  ///  * [BoxHitTestResult.addWithPaintOffset], which is a public wrapper
+  ///    around this function for hit testing on [RenderBox]s.
+  ///  * [SliverHitTestResult.addWithAxisOffset], which is a public wrapper
+  ///    around this function for hit testing on [RenderSliver]s.
+  @protected
+  void pushOffset(Offset offset) {
+    assert(offset != null);
+    _localTransforms.add(_OffsetTransformPart(offset));
   }
 
-  /// Removes the last transform added via [pushTransform].
+  /// Removes the last transform added via [pushTransform] or [pushOffset].
   ///
   /// This method is only to be used by subclasses, which must provide
   /// coordinate space specific public wrappers around this function for their
   /// users (see [BoxHitTestResult.addWithPaintTransform] for such an example).
   ///
   /// This method must be called after hit testing is done on a child that
-  /// required a call to [pushTransform].
+  /// required a call to [pushTransform] or [pushOffset].
   ///
   /// See also:
   ///
-  ///  * [pushTransform], which describes the use case of this function pair in
-  ///    more details.
+  ///  * [pushTransform] and [pushOffset], which describes the use case of this
+  ///    function pair in more details.
   @protected
   void popTransform() {
+    if (_localTransforms.isNotEmpty)
+      _localTransforms.removeLast();
+    else
+      _transforms.removeLast();
     assert(_transforms.isNotEmpty);
-    _transforms.removeLast();
   }
 
   bool _debugVectorMoreOrLessEquals(Vector4 a, Vector4 b, { double epsilon = precisionErrorTolerance }) {

packages/flutter/lib/src/material/text_field.dart

@@ -1148,12 +1148,12 @@ class _TextFieldState extends State<TextField> implements TextSelectionGestureDe
       },
     );
 
-    return IgnorePointer(
-      ignoring: !_isEnabled,
-      child: MouseRegion(
-        cursor: effectiveMouseCursor,
-        onEnter: (PointerEnterEvent event) => _handleHover(true),
-        onExit: (PointerExitEvent event) => _handleHover(false),
+    return MouseRegion(
+      cursor: effectiveMouseCursor,
+      onEnter: (PointerEnterEvent event) => _handleHover(true),
+      onExit: (PointerExitEvent event) => _handleHover(false),
+      child: IgnorePointer(
+        ignoring: !_isEnabled,
         child: AnimatedBuilder(
           animation: controller, // changes the _currentLength
           builder: (BuildContext context, Widget child) {

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

@@ -764,11 +764,17 @@ class BoxHitTestResult extends HitTestResult {
     @required BoxHitTest hitTest,
   }) {
     assert(hitTest != null);
-    return addWithRawTransform(
-      transform: offset != null ? Matrix4.translationValues(-offset.dx, -offset.dy, 0.0) : null,
-      position: position,
-      hitTest: hitTest,
-    );
+    final Offset transformedPosition = position == null || offset == null
+        ? position
+        : position - offset;
+    if (offset != null) {
+      pushOffset(-offset);
+    }
+    final bool isHit = hitTest(this, transformedPosition);
+    if (offset != null) {
+      popTransform();
+    }
+    return isHit;
   }
 
   /// Transforms `position` to the local coordinate system of a child for

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

@@ -14,7 +14,6 @@ import 'package:flutter/painting.dart';
 import 'package:vector_math/vector_math_64.dart';
 
 import 'debug.dart';
-import 'mouse_tracking.dart';
 
 /// Information collected for an annotation that is found in the layer tree.
 ///
@@ -633,7 +632,6 @@ class PlatformViewLayer extends Layer {
   PlatformViewLayer({
     @required this.rect,
     @required this.viewId,
-    this.hoverAnnotation,
   }) : assert(rect != null),
        assert(viewId != null);
 
@@ -645,25 +643,6 @@ class PlatformViewLayer extends Layer {
   /// A UIView with this identifier must have been created by [PlatformViewsServices.initUiKitView].
   final int viewId;
 
-  /// [MouseTrackerAnnotation] that handles mouse events for this layer.
-  ///
-  /// If [hoverAnnotation] is non-null, [PlatformViewLayer] will annotate the
-  /// region of this platform view such that annotation callbacks will receive
-  /// mouse events, including mouse enter, exit, and hover, but not including
-  /// mouse down, move, and up. The layer will be treated as opaque during an
-  /// annotation search, which will prevent layers behind it from receiving
-  /// these events.
-  ///
-  /// By default, [hoverAnnotation] is null, and [PlatformViewLayer] will not
-  /// receive mouse events, and will therefore appear translucent during the
-  /// annotation search.
-  ///
-  /// See also:
-  ///
-  ///  * [MouseRegion], which explains more about the mouse events and opacity
-  ///    during annotation search.
-  final MouseTrackerAnnotation hoverAnnotation;
-
   @override
   void addToScene(ui.SceneBuilder builder, [ Offset layerOffset = Offset.zero ]) {
     final Rect shiftedRect = layerOffset == Offset.zero ? rect : rect.shift(layerOffset);
@@ -674,24 +653,6 @@ class PlatformViewLayer extends Layer {
       height: shiftedRect.height,
     );
   }
-
-  @override
-  @protected
-  bool findAnnotations<S>(AnnotationResult<S> result, Offset localPosition, { @required bool onlyFirst }) {
-    if (hoverAnnotation == null || !rect.contains(localPosition)) {
-      return false;
-    }
-    if (S == MouseTrackerAnnotation) {
-      final Object untypedValue = hoverAnnotation;
-      final S typedValue = untypedValue as S;
-      result.add(AnnotationEntry<S>(
-        annotation: typedValue,
-        localPosition: localPosition,
-      ));
-      return true;
-    }
-    return false;
-  }
 }
 
 /// A layer that indicates to the compositor that it should display

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

@@ -622,7 +622,6 @@ class PlatformViewRenderBox extends RenderBox with _PlatformViewGestureMixin {
     context.addLayer(PlatformViewLayer(
       rect: offset & size,
       viewId: _controller.viewId,
-      hoverAnnotation: _hoverAnnotation,
     ));
   }
 
@@ -636,32 +635,13 @@ class PlatformViewRenderBox extends RenderBox with _PlatformViewGestureMixin {
 }
 
 /// The Mixin handling the pointer events and gestures of a platform view render box.
-mixin _PlatformViewGestureMixin on RenderBox {
+mixin _PlatformViewGestureMixin on RenderBox implements MouseTrackerAnnotation {
 
   /// 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;
 
-  /// [MouseTrackerAnnotation] associated with the platform view layer.
-  ///
-  /// Gesture recognizers don't receive hover events due to the performance
-  /// cost associated with hit testing a sequence of potentially thousands of
-  /// events -- move events only hit-test the down event, then cache the result
-  /// and apply it to all subsequent move events, but there is no down event
-  /// for a hover. To support native hover gesture handling by platform views,
-  /// we attach/detach this layer annotation as necessary.
-  MouseTrackerAnnotation get _hoverAnnotation {
-    return _cachedHoverAnnotation ??= MouseTrackerAnnotation(
-      onHover: (PointerHoverEvent event) {
-        if (_handlePointerEvent != null)
-          _handlePointerEvent(event);
-      },
-      cursor: MouseCursor.uncontrolled,
-    );
-  }
-  MouseTrackerAnnotation _cachedHoverAnnotation;
-
   _HandlePointerEvent _handlePointerEvent;
 
   /// {@macro  flutter.rendering.platformView.updateGestureRecognizers}
@@ -696,6 +676,22 @@ mixin _PlatformViewGestureMixin on RenderBox {
   @override
   bool hitTestSelf(Offset position) => hitTestBehavior != PlatformViewHitTestBehavior.transparent;
 
+  @override
+  PointerEnterEventListener get onEnter => null;
+
+  @override
+  PointerHoverEventListener get onHover => _handleHover;
+  void _handleHover(PointerHoverEvent event) {
+    if (_handlePointerEvent != null)
+      _handlePointerEvent(event);
+  }
+
+  @override
+  PointerExitEventListener get onExit => null;
+
+  @override
+  MouseCursor get cursor => MouseCursor.uncontrolled;
+
   @override
   void handleEvent(PointerEvent event, HitTestEntry entry) {
     if (event is PointerDownEvent) {

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

@@ -2720,6 +2720,15 @@ class RenderMouseRegion extends RenderProxyBox implements MouseTrackerAnnotation
        _annotationIsActive = false,
        super(child);
 
+  @protected
+  @override
+  bool hitTestSelf(Offset position) => true;
+
+  @override
+  bool hitTest(BoxHitTestResult result, { @required Offset position }) {
+    return super.hitTest(result, position: position) && _opaque;
+  }
+
   /// Whether this object should prevent [RenderMouseRegion]s visually behind it
   /// from detecting the pointer, thus affecting how their [onHover], [onEnter],
   /// and [onExit] behave.
@@ -2838,25 +2847,6 @@ class RenderMouseRegion extends RenderProxyBox implements MouseTrackerAnnotation
     super.detach();
   }
 
-  @override
-  bool get needsCompositing => super.needsCompositing || _annotationIsActive;
-
-  @override
-  void paint(PaintingContext context, Offset offset) {
-    if (_annotationIsActive) {
-      // Annotated region layers are not retained because they do not create engine layers.
-      final AnnotatedRegionLayer<MouseTrackerAnnotation> layer = AnnotatedRegionLayer<MouseTrackerAnnotation>(
-        this,
-        size: size,
-        offset: offset,
-        opaque: opaque,
-      );
-      context.pushLayer(layer, super.paint, offset);
-    } else {
-      super.paint(context, offset);
-    }
-  }
-
   @override
   void performResize() {
     size = constraints.biggest;

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

@@ -861,7 +861,7 @@ class SliverHitTestResult extends HitTestResult {
     assert(crossAxisPosition != null);
     assert(hitTest != null);
     if (paintOffset != null) {
-      pushTransform(Matrix4.translationValues(-paintOffset.dx, -paintOffset.dy, 0));
+      pushOffset(-paintOffset);
     }
     final bool isHit = hitTest(
       this,

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

@@ -9,6 +9,7 @@ import 'dart:io' show Platform;
 import 'dart:ui' as ui show Scene, SceneBuilder, Window;
 
 import 'package:flutter/foundation.dart';
+import 'package:flutter/gestures.dart';
 import 'package:flutter/services.dart';
 import 'package:vector_math/vector_math_64.dart';
 
@@ -201,9 +202,17 @@ class RenderView extends RenderObject with RenderObjectWithChildMixin<RenderBox>
     // Layer hit testing is done using device pixels, so we have to convert
     // the logical coordinates of the event location back to device pixels
     // here.
-    return layer.findAllAnnotations<MouseTrackerAnnotation>(
-      position * configuration.devicePixelRatio
-    ).annotations;
+    final BoxHitTestResult result = BoxHitTestResult();
+    if (child != null)
+      child.hitTest(result, position: position);
+    result.add(HitTestEntry(this));
+    final List<MouseTrackerAnnotation> annotations = <MouseTrackerAnnotation>[];
+    for (final HitTestEntry entry in result.path) {
+      if (entry.target is MouseTrackerAnnotation) {
+        annotations.add(entry.target as MouseTrackerAnnotation);
+      }
+    }
+    return annotations;
   }
 
   @override

packages/flutter/test/gestures/hit_test_test.dart

@@ -36,6 +36,94 @@ void main() {
     expect(wrapped.path, equals(<HitTestEntry>[entry1, entry2, entry3]));
     expect(entry3.transform, transform);
   });
+
+  test('HitTestResult should correctly push and pop transforms', () {
+    Matrix4 currentTransform(HitTestResult targetResult) {
+      final HitTestEntry entry = HitTestEntry(_DummyHitTestTarget());
+      targetResult.add(entry);
+      return entry.transform;
+    }
+
+    final MyHitTestResult result = MyHitTestResult();
+
+    final Matrix4 m1 = Matrix4.translationValues(10, 20, 0);
+    final Matrix4 m2 = Matrix4.rotationZ(1);
+    final Matrix4 m3 = Matrix4.diagonal3Values(1.1, 1.2, 1.0);
+
+    result.publicPushTransform(m1);
+    expect(currentTransform(result), equals(m1));
+
+    result.publicPushTransform(m2);
+    expect(currentTransform(result), equals(m2 * m1));
+    expect(currentTransform(result), equals(m2 * m1)); // Test repeated add
+
+    // The `wrapped` is wrapped at [m1, m2]
+    final MyHitTestResult wrapped = MyHitTestResult.wrap(result);
+    expect(currentTransform(wrapped), equals(m2 * m1));
+
+    result.publicPushTransform(m3);
+    expect(currentTransform(result), equals(m3 * m2 * m1));
+    expect(currentTransform(wrapped), equals(m3 * m2 * m1));
+
+    result.publicPopTransform();
+    result.publicPopTransform();
+    expect(currentTransform(result), equals(m1));
+
+    result.publicPopTransform();
+    result.publicPushTransform(m3);
+    expect(currentTransform(result), equals(m3));
+
+    result.publicPushTransform(m2);
+    expect(currentTransform(result), equals(m2 * m3));
+  });
+
+  test('HitTestResult should correctly push and pop offsets', () {
+    Matrix4 currentTransform(HitTestResult targetResult) {
+      final HitTestEntry entry = HitTestEntry(_DummyHitTestTarget());
+      targetResult.add(entry);
+      return entry.transform;
+    }
+
+    final MyHitTestResult result = MyHitTestResult();
+
+    final Matrix4 m1 = Matrix4.rotationZ(1);
+    final Matrix4 m2 = Matrix4.diagonal3Values(1.1, 1.2, 1.0);
+    const Offset o3 = Offset(10, 20);
+    final Matrix4 m3 = Matrix4.translationValues(o3.dx, o3.dy, 0.0);
+
+    // Test pushing offset as the first element
+    result.publicPushOffset(o3);
+    expect(currentTransform(result), equals(m3));
+    result.publicPopTransform();
+
+    result.publicPushOffset(o3);
+    result.publicPushTransform(m1);
+    expect(currentTransform(result), equals(m1 * m3));
+    expect(currentTransform(result), equals(m1 * m3)); // Test repeated add
+
+    // The `wrapped` is wrapped at [m1, m2]
+    final MyHitTestResult wrapped = MyHitTestResult.wrap(result);
+    expect(currentTransform(wrapped), equals(m1 * m3));
+
+    result.publicPushTransform(m2);
+    expect(currentTransform(result), equals(m2 * m1 * m3));
+    expect(currentTransform(wrapped), equals(m2 * m1 * m3));
+
+    result.publicPopTransform();
+    result.publicPopTransform();
+    result.publicPopTransform();
+    expect(currentTransform(result), equals(Matrix4.identity()));
+
+    result.publicPushTransform(m2);
+    result.publicPushOffset(o3);
+    result.publicPushTransform(m1);
+
+    expect(currentTransform(result), equals(m1 * m3 * m2));
+
+    result.publicPopTransform();
+
+    expect(currentTransform(result), equals(m3 * m2));
+  });
 }
 
 class _DummyHitTestTarget implements HitTestTarget {
@@ -46,5 +134,10 @@ class _DummyHitTestTarget implements HitTestTarget {
 }
 
 class MyHitTestResult extends HitTestResult {
+  MyHitTestResult();
+  MyHitTestResult.wrap(HitTestResult result) : super.wrap(result);
+
   void publicPushTransform(Matrix4 transform) => pushTransform(transform);
+  void publicPushOffset(Offset offset) => pushOffset(offset);
+  void publicPopTransform() => popTransform();
 }

packages/flutter/test/widgets/basic_test.dart

@@ -5,6 +5,7 @@
 // @dart = 2.8
 
 import 'dart:math' as math;
+import 'package:flutter/gestures.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter/widgets.dart';
@@ -398,6 +399,162 @@ void main() {
     );
     // TODO(Piinks): Remove skip once web goldens are supported, https://github.com/flutter/flutter/issues/40297
   }, skip: isBrowser);
+
+  testWidgets('IgnorePointer ignores pointers', (WidgetTester tester) async {
+    final List<String> logs = <String>[];
+    Widget target({bool ignoring}) => Align(
+      alignment: Alignment.topLeft,
+      child: Directionality(
+        textDirection: TextDirection.ltr,
+        child: SizedBox(
+          width: 100,
+          height: 100,
+          child: Listener(
+            onPointerDown: (_) { logs.add('down1'); },
+            child: MouseRegion(
+              onEnter: (_) { logs.add('enter1'); },
+              onExit: (_) { logs.add('exit1'); },
+              cursor: SystemMouseCursors.forbidden,
+              child: Stack(
+                children: <Widget>[
+                  Listener(
+                    onPointerDown: (_) { logs.add('down2'); },
+                    child: MouseRegion(
+                      cursor: SystemMouseCursors.click,
+                      onEnter: (_) { logs.add('enter2'); },
+                      onExit: (_) { logs.add('exit2'); },
+                    ),
+                  ),
+                  IgnorePointer(
+                    ignoring: ignoring,
+                    child: Listener(
+                      onPointerDown: (_) { logs.add('down3'); },
+                      child: MouseRegion(
+                        cursor: SystemMouseCursors.text,
+                        onEnter: (_) { logs.add('enter3'); },
+                        onExit: (_) { logs.add('exit3'); },
+                      ),
+                    ),
+                  )
+                ],
+              ),
+            ),
+          ),
+        ),
+      ),
+    );
+
+    final TestGesture gesture = await tester.createGesture(pointer: 1, kind: PointerDeviceKind.mouse);
+    await gesture.addPointer(location: const Offset(200, 200));
+    addTearDown(gesture.removePointer);
+
+    await tester.pumpWidget(target(ignoring: true));
+    expect(logs, isEmpty);
+
+    await gesture.moveTo(const Offset(50, 50));
+    expect(logs, <String>['enter1', 'enter2']);
+    logs.clear();
+
+    await gesture.down(const Offset(50, 50));
+    expect(logs, <String>['down2', 'down1']);
+    logs.clear();
+
+    await gesture.up();
+    expect(logs, isEmpty);
+
+    await tester.pumpWidget(target(ignoring: false));
+    expect(logs, <String>['exit2', 'enter3']);
+    logs.clear();
+
+    await gesture.down(const Offset(50, 50));
+    expect(logs, <String>['down3', 'down1']);
+    logs.clear();
+
+    await gesture.up();
+    expect(logs, isEmpty);
+
+    await tester.pumpWidget(target(ignoring: true));
+    expect(logs, <String>['exit3', 'enter2']);
+    logs.clear();
+  });
+
+  testWidgets('AbsorbPointer absorbs pointers', (WidgetTester tester) async {
+    final List<String> logs = <String>[];
+    Widget target({bool absorbing}) => Align(
+      alignment: Alignment.topLeft,
+      child: Directionality(
+        textDirection: TextDirection.ltr,
+        child: SizedBox(
+          width: 100,
+          height: 100,
+          child: Listener(
+            onPointerDown: (_) { logs.add('down1'); },
+            child: MouseRegion(
+              onEnter: (_) { logs.add('enter1'); },
+              onExit: (_) { logs.add('exit1'); },
+              cursor: SystemMouseCursors.forbidden,
+              child: Stack(
+                children: <Widget>[
+                  Listener(
+                    onPointerDown: (_) { logs.add('down2'); },
+                    child: MouseRegion(
+                      cursor: SystemMouseCursors.click,
+                      onEnter: (_) { logs.add('enter2'); },
+                      onExit: (_) { logs.add('exit2'); },
+                    ),
+                  ),
+                  AbsorbPointer(
+                    absorbing: absorbing,
+                    child: Listener(
+                      onPointerDown: (_) { logs.add('down3'); },
+                      child: MouseRegion(
+                        cursor: SystemMouseCursors.text,
+                        onEnter: (_) { logs.add('enter3'); },
+                        onExit: (_) { logs.add('exit3'); },
+                      ),
+                    ),
+                  )
+                ],
+              ),
+            ),
+          ),
+        ),
+      ),
+    );
+
+    final TestGesture gesture = await tester.createGesture(pointer: 1, kind: PointerDeviceKind.mouse);
+    await gesture.addPointer(location: const Offset(200, 200));
+    addTearDown(gesture.removePointer);
+
+    await tester.pumpWidget(target(absorbing: true));
+    expect(logs, isEmpty);
+
+    await gesture.moveTo(const Offset(50, 50));
+    expect(logs, <String>['enter1']);
+    logs.clear();
+
+    await gesture.down(const Offset(50, 50));
+    expect(logs, <String>['down1']);
+    logs.clear();
+
+    await gesture.up();
+    expect(logs, isEmpty);
+
+    await tester.pumpWidget(target(absorbing: false));
+    expect(logs, <String>['enter3']);
+    logs.clear();
+
+    await gesture.down(const Offset(50, 50));
+    expect(logs, <String>['down3', 'down1']);
+    logs.clear();
+
+    await gesture.up();
+    expect(logs, isEmpty);
+
+    await tester.pumpWidget(target(absorbing: true));
+    expect(logs, <String>['exit3']);
+    logs.clear();
+  });
 }
 
 HitsRenderBox hits(RenderBox renderBox) => HitsRenderBox(renderBox);

packages/flutter/test/widgets/listener_deprecated_test.dart

@@ -436,7 +436,7 @@ void main() {
       events.clear();
     });
 
-    testWidgets('needsCompositing updates correctly and is respected', (WidgetTester tester) async {
+    testWidgets('needsCompositing is always false', (WidgetTester tester) async {
       // Pretend that we have a mouse connected.
       final TestGesture gesture = await tester.createGesture(kind: PointerDeviceKind.mouse);
       await gesture.addPointer(location: Offset.zero);
@@ -467,22 +467,9 @@ void main() {
           ),
         ),
       );
-      expect(listener.needsCompositing, isTrue);
-      // Compositing is required, therefore a dedicated TransformLayer for
-      // `Transform.scale` is added.
-      expect(tester.layers.whereType<TransformLayer>(), hasLength(2));
-
-      await tester.pumpWidget(
-        Transform.scale(
-          scale: 2.0,
-          child: Listener(
-            onPointerDown: (PointerDownEvent _) { },
-          ),
-        ),
-      );
       expect(listener.needsCompositing, isFalse);
-      // TransformLayer for `Transform.scale` is removed again as transform is
-      // executed directly on the canvas.
+      // If compositing was required, a dedicated TransformLayer for
+      // `Transform.scale` would be added.
       expect(tester.layers.whereType<TransformLayer>(), hasLength(1));
     });
 

packages/flutter/test/widgets/mouse_region_test.dart

@@ -168,10 +168,6 @@ void main() {
     await gesture.addPointer(location: const Offset(400, 300));
     addTearDown(gesture.removePointer);
     expect(move, isNull);
-    expect(enter, isNull);
-    expect(exit, isNull);
-    await tester.pump();
-    expect(move, isNull);
     expect(enter, isNotNull);
     expect(enter.position, equals(const Offset(400.0, 300.0)));
     expect(exit, isNull);
@@ -585,13 +581,13 @@ void main() {
     }
 
     await tester.pumpWidget(hoverableContainer(
-      onEnter: (PointerEnterEvent details) => logs.add('enter1'),
-      onHover: (PointerHoverEvent details) => logs.add('hover1'),
-      onExit: (PointerExitEvent details) => logs.add('exit1'),
+      onEnter: (PointerEnterEvent details) { logs.add('enter1'); },
+      onHover: (PointerHoverEvent details) { logs.add('hover1'); },
+      onExit: (PointerExitEvent details) { logs.add('exit1'); },
     ));
 
     final TestGesture gesture = await tester.createGesture(kind: PointerDeviceKind.mouse);
-    await gesture.addPointer();
+    await gesture.addPointer(location: const Offset(150.0, 150.0));
     addTearDown(gesture.removePointer);
 
     // Start outside, move inside, then move outside
@@ -709,7 +705,7 @@ void main() {
     events.clear();
   });
 
-  testWidgets('needsCompositing updates correctly and is respected', (WidgetTester tester) async {
+  testWidgets('needsCompositing is always false', (WidgetTester tester) async {
     // Pretend that we have a mouse connected.
     final TestGesture gesture = await tester.createGesture(kind: PointerDeviceKind.mouse);
     await gesture.addPointer();
@@ -729,7 +725,7 @@ void main() {
     // transform.)
     expect(tester.layers.whereType<TransformLayer>(), hasLength(1));
 
-    // Test that needsCompositing updates correctly with callback change
+    // Test that needsCompositing stays false with callback change
     await tester.pumpWidget(
       Transform.scale(
         scale: 2.0,
@@ -739,35 +735,10 @@ void main() {
         ),
       ),
     );
-    expect(mouseRegion.needsCompositing, isTrue);
-    // Compositing is required, therefore a dedicated TransformLayer for
-    // `Transform.scale` is added.
-    expect(tester.layers.whereType<TransformLayer>(), hasLength(2));
-
-    await tester.pumpWidget(
-      Transform.scale(
-        scale: 2.0,
-        child: const MouseRegion(opaque: false),
-      ),
-    );
     expect(mouseRegion.needsCompositing, isFalse);
-    // TransformLayer for `Transform.scale` is removed again as transform is
-    // executed directly on the canvas.
+    // If compositing was required, a dedicated TransformLayer for
+    // `Transform.scale` would be added.
     expect(tester.layers.whereType<TransformLayer>(), hasLength(1));
-
-    // Test that needsCompositing updates correctly with `opaque` change
-    await tester.pumpWidget(
-      Transform.scale(
-        scale: 2.0,
-        child: const MouseRegion(
-          opaque: true,
-        ),
-      ),
-    );
-    expect(mouseRegion.needsCompositing, isTrue);
-    // Compositing is required, therefore a dedicated TransformLayer for
-    // `Transform.scale` is added.
-    expect(tester.layers.whereType<TransformLayer>(), hasLength(2));
   });
 
   testWidgets("Callbacks aren't called during build", (WidgetTester tester) async {