System mouse cursors (#54171)

Adds the basic framework for the mouse cursor system. 

* Adds MouseRegion.cursor
* Adds SystemMouseCursors
* Adds mouseCursor to some widgets

packages/flutter/lib/rendering.dart

@@ -45,6 +45,7 @@ export 'src/rendering/image.dart';
 export 'src/rendering/layer.dart';
 export 'src/rendering/list_body.dart';
 export 'src/rendering/list_wheel_viewport.dart';
+export 'src/rendering/mouse_cursor.dart';
 export 'src/rendering/mouse_tracking.dart';
 export 'src/rendering/object.dart';
 export 'src/rendering/paragraph.dart';

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

@@ -142,7 +142,7 @@ class HitTestResult {
       _debugVectorMoreOrLessEquals(transform.getColumn(2), Vector4(0, 0, 1, 0)),
       'The third row and third column of a transform matrix for pointer '
       'events must be Vector4(0, 0, 1, 0) to ensure that a transformed '
-      'point is directly under the pointer device. Did you forget to run the paint '
+      'point is directly under the pointing device. Did you forget to run the paint '
       'matrix through PointerEvent.removePerspectiveTransform? '
       'The provided matrix is:\n$transform'
     );

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

@@ -40,6 +40,7 @@ class RawMaterialButton extends StatefulWidget {
     @required this.onPressed,
     this.onLongPress,
     this.onHighlightChanged,
+    this.mouseCursor,
     this.textStyle,
     this.fillColor,
     this.focusColor,
@@ -102,6 +103,11 @@ class RawMaterialButton extends StatefulWidget {
   /// [State.setState] is not allowed).
   final ValueChanged<bool> onHighlightChanged;
 
+  /// {@macro flutter.material.inkwell.mousecursor}
+  ///
+  /// Defaults to null.
+  final MouseCursor mouseCursor;
+
   /// Defines the default text style, with [Material.textStyle], for the
   /// button's [child].
   ///
@@ -401,6 +407,7 @@ class _RawMaterialButtonState extends State<RawMaterialButton> {
           onLongPress: widget.onLongPress,
           enableFeedback: widget.enableFeedback,
           customBorder: effectiveShape,
+          mouseCursor: widget.mouseCursor,
           child: IconTheme.merge(
             data: IconThemeData(color: effectiveTextColor),
             child: Container(

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

@@ -144,6 +144,7 @@ class FloatingActionButton extends StatelessWidget {
     @required this.onPressed,
     this.mini = false,
     this.shape,
+    this.mouseCursor,
     this.clipBehavior = Clip.none,
     this.focusNode,
     this.autofocus = false,
@@ -183,6 +184,7 @@ class FloatingActionButton extends StatelessWidget {
     this.disabledElevation,
     @required this.onPressed,
     this.shape,
+    this.mouseCursor,
     this.isExtended = true,
     this.materialTapTargetSize,
     this.clipBehavior = Clip.none,
@@ -376,6 +378,11 @@ class FloatingActionButton extends StatelessWidget {
   /// shape as well.
   final ShapeBorder shape;
 
+  /// {@macro flutter.material.inkwell.mousecursor}
+  ///
+  /// Defaults to null.
+  final MouseCursor mouseCursor;
+
   /// {@macro flutter.widgets.Clip}
   ///
   /// Defaults to [Clip.none], and must not be null.
@@ -484,6 +491,7 @@ class FloatingActionButton extends StatelessWidget {
 
     Widget result = RawMaterialButton(
       onPressed: onPressed,
+      mouseCursor: mouseCursor,
       elevation: elevation,
       focusElevation: focusElevation,
       hoverElevation: hoverElevation,

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

@@ -295,6 +295,7 @@ class InkResponse extends StatelessWidget {
     this.onLongPress,
     this.onHighlightChanged,
     this.onHover,
+    this.mouseCursor,
     this.containedInkWell = false,
     this.highlightShape = BoxShape.circle,
     this.radius,
@@ -361,6 +362,17 @@ class InkResponse extends StatelessWidget {
   /// material.
   final ValueChanged<bool> onHover;
 
+  /// {@template flutter.material.inkwell.mousecursor}
+  /// The cursor for a mouse pointer when it enters or is hovering over the
+  /// region.
+  ///
+  /// If the [mouseCursor] is null, then the hovering pointer's cursor will be
+  /// decided by the widget behind it on the screen in hit-test order.
+  /// {@endtemplate}
+  ///
+  /// Defaults to null.
+  final MouseCursor mouseCursor;
+
   /// Whether this ink response should be clipped its bounds.
   ///
   /// This flag also controls whether the splash migrates to the center of the
@@ -543,6 +555,7 @@ class InkResponse extends StatelessWidget {
       onLongPress: onLongPress,
       onHighlightChanged: onHighlightChanged,
       onHover: onHover,
+      mouseCursor: mouseCursor,
       containedInkWell: containedInkWell,
       highlightShape: highlightShape,
       radius: radius,
@@ -590,6 +603,7 @@ class _InnerInkResponse extends StatefulWidget {
     this.onLongPress,
     this.onHighlightChanged,
     this.onHover,
+    this.mouseCursor,
     this.containedInkWell = false,
     this.highlightShape = BoxShape.circle,
     this.radius,
@@ -624,6 +638,7 @@ class _InnerInkResponse extends StatefulWidget {
   final GestureLongPressCallback onLongPress;
   final ValueChanged<bool> onHighlightChanged;
   final ValueChanged<bool> onHover;
+  final MouseCursor mouseCursor;
   final bool containedInkWell;
   final BoxShape highlightShape;
   final double radius;
@@ -997,6 +1012,7 @@ class _InkResponseState extends State<_InnerInkResponse>
           onFocusChange: _handleFocusUpdate,
           autofocus: widget.autofocus,
           child: MouseRegion(
+            cursor: widget.mouseCursor,
             onEnter: enabled ? _handleMouseEnter : null,
             onExit: enabled ? _handleMouseExit : null,
             child: GestureDetector(
@@ -1121,6 +1137,7 @@ class InkWell extends InkResponse {
     GestureTapCancelCallback onTapCancel,
     ValueChanged<bool> onHighlightChanged,
     ValueChanged<bool> onHover,
+    MouseCursor mouseCursor,
     Color focusColor,
     Color hoverColor,
     Color highlightColor,
@@ -1145,6 +1162,7 @@ class InkWell extends InkResponse {
     onTapCancel: onTapCancel,
     onHighlightChanged: onHighlightChanged,
     onHover: onHover,
+    mouseCursor: mouseCursor,
     containedInkWell: true,
     highlightShape: BoxShape.rectangle,
     focusColor: focusColor,

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

@@ -12,6 +12,7 @@ import 'package:flutter/services.dart';
 
 import 'box.dart';
 import 'layer.dart';
+import 'mouse_cursor.dart';
 import 'mouse_tracking.dart';
 import 'object.dart';
 
@@ -757,9 +758,10 @@ class PlatformViewRenderBox extends RenderBox with _PlatformViewGestureMixin {
   void paint(PaintingContext context, Offset offset) {
     assert(_controller.viewId != null);
     context.addLayer(PlatformViewLayer(
-            rect: offset & size,
-            viewId: _controller.viewId,
-            hoverAnnotation: _hoverAnnotation));
+      rect: offset & size,
+      viewId: _controller.viewId,
+      hoverAnnotation: _hoverAnnotation,
+    ));
   }
 
   @override
@@ -787,7 +789,16 @@ mixin _PlatformViewGestureMixin on RenderBox {
   /// 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 _hoverAnnotation;
+  MouseTrackerAnnotation get _hoverAnnotation {
+    return _cachedHoverAnnotation ??= MouseTrackerAnnotation(
+      onHover: (PointerHoverEvent event) {
+        if (_handlePointerEvent != null)
+          _handlePointerEvent(event);
+      },
+      cursor: SystemMouseCursors.uncontrolled,
+    );
+  }
+  MouseTrackerAnnotation _cachedHoverAnnotation;
 
   _HandlePointerEvent _handlePointerEvent;
 
@@ -830,20 +841,9 @@ mixin _PlatformViewGestureMixin on RenderBox {
     }
   }
 
-  @override
-  void attach(PipelineOwner owner) {
-    super.attach(owner);
-    assert(_hoverAnnotation == null);
-    _hoverAnnotation = MouseTrackerAnnotation(onHover: (PointerHoverEvent event) {
-      if (_handlePointerEvent != null)
-        _handlePointerEvent(event);
-    });
-  }
-
   @override
   void detach() {
     _gestureRecognizer.reset();
-    _hoverAnnotation = null;
     super.detach();
   }
 }

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

@@ -11,12 +11,14 @@ import 'package:flutter/foundation.dart';
 import 'package:flutter/gestures.dart';
 import 'package:flutter/painting.dart';
 import 'package:flutter/semantics.dart';
+import 'package:flutter/services.dart';
 
 import 'package:vector_math/vector_math_64.dart';
 
 import 'binding.dart';
 import 'box.dart';
 import 'layer.dart';
+import 'mouse_cursor.dart';
 import 'mouse_tracking.dart';
 import 'object.dart';
 
@@ -2676,7 +2678,7 @@ class RenderPointerListener extends RenderProxyBoxWithHitTestBehavior {
 ///
 ///  * [MouseRegion], a widget that listens to hover events using
 ///    [RenderMouseRegion].
-class RenderMouseRegion extends RenderProxyBox {
+class RenderMouseRegion extends RenderProxyBox implements MouseTrackerAnnotation {
   /// Creates a render object that forwards pointer events to callbacks.
   ///
   /// All parameters are optional. By default this method creates an opaque
@@ -2685,21 +2687,17 @@ class RenderMouseRegion extends RenderProxyBox {
     PointerEnterEventListener onEnter,
     PointerHoverEventListener onHover,
     PointerExitEventListener onExit,
+    MouseCursor cursor,
     bool opaque = true,
     RenderBox child,
   }) : assert(opaque != null),
        _onEnter = onEnter,
        _onHover = onHover,
        _onExit = onExit,
+       _cursor = cursor,
        _opaque = opaque,
        _annotationIsActive = false,
-       super(child) {
-    _hoverAnnotation = MouseTrackerAnnotation(
-      onEnter: _handleEnter,
-      onHover: _handleHover,
-      onExit: _handleExit,
-    );
-  }
+       super(child);
 
   /// Whether this object should prevent [RenderMouseRegion]s visually behind it
   /// from detecting the pointer, thus affecting how their [onHover], [onEnter],
@@ -2720,77 +2718,53 @@ class RenderMouseRegion extends RenderProxyBox {
   set opaque(bool value) {
     if (_opaque != value) {
       _opaque = value;
+      // A repaint is needed in order to propagate the new value to
+      // AnnotatedRegionLayer via [paint].
       _markPropertyUpdated(mustRepaint: true);
     }
   }
 
-  /// Called when a mouse pointer starts being contained by the region (with or
-  /// without buttons pressed) for any reason.
-  ///
-  /// This callback is always matched by a later [onExit].
-  ///
-  /// See also:
-  ///
-  ///  * [MouseRegion.onEnter], which uses this callback.
+  @override
   PointerEnterEventListener get onEnter => _onEnter;
+  PointerEnterEventListener _onEnter;
   set onEnter(PointerEnterEventListener value) {
     if (_onEnter != value) {
       _onEnter = value;
       _markPropertyUpdated(mustRepaint: false);
     }
   }
-  PointerEnterEventListener _onEnter;
-  void _handleEnter(PointerEnterEvent event) {
-    if (_onEnter != null)
-      _onEnter(event);
-  }
 
-  /// Called when a pointer changes position without buttons pressed and the end
-  /// position is within the region.
+  @override
   PointerHoverEventListener get onHover => _onHover;
+  PointerHoverEventListener _onHover;
   set onHover(PointerHoverEventListener value) {
     if (_onHover != value) {
       _onHover = value;
       _markPropertyUpdated(mustRepaint: false);
     }
   }
-  PointerHoverEventListener _onHover;
-  void _handleHover(PointerHoverEvent event) {
-    if (_onHover != null)
-      _onHover(event);
-  }
 
-  /// Called when a pointer is no longer contained by the region (with or
-  /// without buttons pressed) for any reason.
-  ///
-  /// This callback is always matched by an earlier [onEnter].
-  ///
-  /// See also:
-  ///
-  ///  * [MouseRegion.onExit], which uses this callback, but is not triggered in
-  ///    certain cases and does not always match its earier [MouseRegion.onEnter].
+  @override
   PointerExitEventListener get onExit => _onExit;
+  PointerExitEventListener _onExit;
   set onExit(PointerExitEventListener value) {
     if (_onExit != value) {
       _onExit = value;
       _markPropertyUpdated(mustRepaint: false);
     }
   }
-  PointerExitEventListener _onExit;
-  void _handleExit(PointerExitEvent event) {
-    if (_onExit != null)
-      _onExit(event);
-  }
 
-  // Object used for annotation of the layer used for hover hit detection.
-  MouseTrackerAnnotation _hoverAnnotation;
-
-  /// Object used for annotation of the layer used for hover hit detection.
-  ///
-  /// This is only public to allow for testing of Listener widgets. Do not call
-  /// in other contexts.
-  @visibleForTesting
-  MouseTrackerAnnotation get hoverAnnotation => _hoverAnnotation;
+  @override
+  MouseCursor get cursor => _cursor;
+  MouseCursor _cursor;
+  set cursor(MouseCursor value) {
+    if (_cursor != value) {
+      _cursor = value;
+      // A repaint is needed in order to trigger a device update of
+      // [MouseTracker] so that this new value can be found.
+      _markPropertyUpdated(mustRepaint: true);
+    }
+  }
 
   // Call this method when a property has changed and might affect the
   // `_annotationIsActive` bit.
@@ -2807,6 +2781,7 @@ class RenderMouseRegion extends RenderProxyBox {
         _onEnter != null ||
         _onHover != null ||
         _onExit != null ||
+        _cursor != null ||
         opaque
       ) && RendererBinding.instance.mouseTracker.mouseIsConnected;
     _setAnnotationIsActive(newAnnotationIsActive);
@@ -2814,6 +2789,7 @@ class RenderMouseRegion extends RenderProxyBox {
       markNeedsPaint();
   }
 
+  bool _annotationIsActive = false;
   void _setAnnotationIsActive(bool value) {
     final bool annotationWasActive = _annotationIsActive;
     _annotationIsActive = value;
@@ -2841,8 +2817,6 @@ class RenderMouseRegion extends RenderProxyBox {
     super.detach();
   }
 
-  bool _annotationIsActive;
-
   @override
   bool get needsCompositing => super.needsCompositing || _annotationIsActive;
 
@@ -2851,7 +2825,7 @@ class RenderMouseRegion extends RenderProxyBox {
     if (_annotationIsActive) {
       // Annotated region layers are not retained because they do not create engine layers.
       final AnnotatedRegionLayer<MouseTrackerAnnotation> layer = AnnotatedRegionLayer<MouseTrackerAnnotation>(
-        _hoverAnnotation,
+        this,
         size: size,
         offset: offset,
         opaque: opaque,
@@ -2879,6 +2853,7 @@ class RenderMouseRegion extends RenderProxyBox {
       },
       ifEmpty: '<none>',
     ));
+    properties.add(DiagnosticsProperty<MouseCursor>('cursor', cursor, defaultValue: null));
     properties.add(DiagnosticsProperty<bool>('opaque', opaque, defaultValue: true));
   }
 }

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

@@ -270,4 +270,18 @@ class SystemChannels {
     'flutter/skia',
     JSONMethodCodec(),
   );
+
+  /// A [MethodChannel] for configuring mouse cursors.
+  ///
+  /// All outgoing methods defined for this channel uses a `Map<String, dynamic>`
+  /// to contain multiple parameters, including the following methods (invoked
+  /// using [OptionalMethodChannel.invokeMethod]):
+  ///
+  ///  * `activateSystemCursor`: Request to set the cursor of a pointer
+  ///    device to a system cursor. The parameters are
+  ///    integer `device`, and string `kind`.
+  static const MethodChannel mouseCursor = OptionalMethodChannel(
+    'flutter/mousecursor',
+    StandardMethodCodec(),
+  );
 }

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

@@ -9,6 +9,7 @@ import 'package:flutter/gestures.dart';
 import 'package:flutter/rendering.dart';
 import 'package:flutter/services.dart';
 
+import 'binding.dart';
 import 'debug.dart';
 import 'framework.dart';
 import 'localizations.dart';
@@ -5878,17 +5879,21 @@ class _PointerListener extends SingleChildRenderObjectWidget {
 ///    have buttons pressed.
 class MouseRegion extends StatefulWidget {
   /// Creates a widget that forwards mouse events to callbacks.
+  ///
+  /// By default, all callbacks are empty, `cursor` is unset, and `opaque` is
+  /// `true`.
   const MouseRegion({
     Key key,
     this.onEnter,
     this.onExit,
     this.onHover,
+    this.cursor,
     this.opaque = true,
     this.child,
   }) : assert(opaque != null),
        super(key: key);
 
-  /// Called when a mouse pointer has entered this widget.
+  /// Triggered when a mouse pointer has entered this widget.
   ///
   /// This callback is triggered when the pointer, with or without buttons
   /// pressed, has started to be contained by the region of this widget. More
@@ -5916,16 +5921,16 @@ class MouseRegion extends StatefulWidget {
   ///    internally implemented.
   final PointerEnterEventListener onEnter;
 
-  /// Called when a mouse pointer moves within this widget without buttons
-  /// pressed.
+  /// Triggered when a mouse pointer has moved onto or within the widget without
+  /// buttons pressed.
   ///
-  /// This callback is not triggered when the [MouseRegion] has moved
-  /// while being hovered by the mouse pointer.
+  /// This callback is not triggered by the movement of an annotation.
   ///
-  /// {@macro flutter.mouseRegion.triggerTime}
+  /// The time that this callback is triggered is during the callback of a
+  /// pointer event, which is always between frames.
   final PointerHoverEventListener onHover;
 
-  /// Called when a mouse pointer has exited this widget when the widget is
+  /// Triggered when a mouse pointer has exited this widget when the widget is
   /// still mounted.
   ///
   /// This callback is triggered when the pointer, with or without buttons
@@ -6094,9 +6099,22 @@ class MouseRegion extends StatefulWidget {
   ///    this callback is internally implemented, but without the restriction.
   final PointerExitEventListener onExit;
 
+  /// The mouse cursor for mouse pointers that are hovering over the annotated
+  /// region.
+  ///
+  /// When a mouse enters the region, its cursor will be changed to the [cursor].
+  /// The [cursor] defaults to null, meaning the region does not control cursors,
+  /// but defers the choice to the next region behind this one on the screen in
+  /// hit-test order, or [SystemMouseCursors.basic] if no others can be found.
+  /// When the mouse leaves the region, the cursor will be decided by the region
+  /// found at the new location.
+  final MouseCursor cursor;
+
   /// Whether this widget should prevent other [MouseRegion]s visually behind it
-  /// from detecting the pointer, thus affecting how their [onHover], [onEnter],
-  /// and [onExit] behave.
+  /// from detecting the pointer.
+  ///
+  /// This changes the list of regions that a pointer hovers, thus affecting how
+  /// their [onHover], [onEnter], [onExit], and [cursor] behave.
   ///
   /// If [opaque] is true, this widget will absorb the mouse pointer and
   /// prevent this widget's siblings (or any other widgets that are not
@@ -6129,6 +6147,7 @@ class MouseRegion extends StatefulWidget {
     if (onHover != null)
       listeners.add('hover');
     properties.add(IterableProperty<String>('listeners', listeners, ifEmpty: '<none>'));
+    properties.add(DiagnosticsProperty<MouseCursor>('cursor', cursor, defaultValue: null));
     properties.add(DiagnosticsProperty<bool>('opaque', opaque, defaultValue: true));
   }
 }
@@ -6161,6 +6180,7 @@ class _RawMouseRegion extends SingleChildRenderObjectWidget {
       onEnter: widget.onEnter,
       onHover: widget.onHover,
       onExit: owner.getHandleExit(),
+      cursor: widget.cursor,
       opaque: widget.opaque,
     );
   }
@@ -6172,6 +6192,7 @@ class _RawMouseRegion extends SingleChildRenderObjectWidget {
       ..onEnter = widget.onEnter
       ..onHover = widget.onHover
       ..onExit = owner.getHandleExit()
+      ..cursor = widget.cursor
       ..opaque = widget.opaque;
   }
 }

packages/flutter/test/rendering/mouse_tracking_test.dart

@@ -72,13 +72,25 @@ void main() {
     RendererBinding.instance.initMouseTracker(mouseTracker);
   }
 
-  // Set up a trivial test environment that includes one annotation, which adds
-  // the enter, hover, and exit events it received to [logEvents].
+  // Set up a trivial test environment that includes one annotation.
+  // This annotation records the enter, hover, and exit events it receives to
+  // `logEvents`.
+  // This annotation also contains a cursor with a value of `testCursor`.
+  // The mouse tracker records the cursor requests it receives to `logCursors`.
   MouseTrackerAnnotation _setUpWithOneAnnotation({List<PointerEvent> logEvents}) {
     final MouseTrackerAnnotation annotation = MouseTrackerAnnotation(
-      onEnter: (PointerEnterEvent event) => logEvents.add(event),
-      onHover: (PointerHoverEvent event) => logEvents.add(event),
-      onExit: (PointerExitEvent event) => logEvents.add(event),
+      onEnter: (PointerEnterEvent event) {
+        if (logEvents != null)
+          logEvents.add(event);
+      },
+      onHover: (PointerHoverEvent event) {
+        if (logEvents != null)
+          logEvents.add(event);
+      },
+      onExit: (PointerExitEvent event) {
+        if (logEvents != null)
+          logEvents.add(event);
+      },
     );
     _setUpMouseAnnotationFinder(
       (Offset position) sync* {
@@ -109,6 +121,15 @@ void main() {
       annotation2.toString(),
       equals('MouseTrackerAnnotation#${shortHash(annotation2)}(callbacks: <none>)'),
     );
+
+    final MouseTrackerAnnotation annotation3 = MouseTrackerAnnotation(
+      onEnter: (_) {},
+      cursor: SystemMouseCursors.grab,
+    );
+    expect(
+      annotation3.toString(),
+      equals('MouseTrackerAnnotation#${shortHash(annotation3)}(callbacks: [enter], cursor: SystemMouseCursor(grab))'),
+    );
   });
 
   test('should detect enter, hover, and exit from Added, Hover, and Removed events', () {
@@ -126,6 +147,7 @@ void main() {
     ui.window.onPointerDataPacket(ui.PointerDataPacket(data: <ui.PointerData>[
       _pointerData(PointerChange.add, const Offset(0.0, 0.0)),
     ]));
+
     expect(events, _equalToEventsOnCriticalFields(<PointerEvent>[
       const PointerEnterEvent(position: Offset(0.0, 0.0)),
     ]));
@@ -141,7 +163,7 @@ void main() {
       const PointerHoverEvent(position: Offset(1.0, 101.0)),
     ]));
     expect(_mouseTracker.mouseIsConnected, isTrue);
-    expect(listenerLogs, <bool>[]);
+    expect(listenerLogs, isEmpty);
     events.clear();
 
     // Pointer is removed while on the annotation.
@@ -489,7 +511,6 @@ void main() {
 
     isInHitRegionOne = false;
     isInHitRegionTwo = true;
-
     ui.window.onPointerDataPacket(ui.PointerDataPacket(data: <ui.PointerData>[
       _pointerData(PointerChange.add, const Offset(0.0, 101.0)),
       _pointerData(PointerChange.hover, const Offset(1.0, 101.0)),

packages/flutter/test/widgets/mouse_region_test.dart

@@ -2,8 +2,10 @@
 // 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/material.dart';
 import 'package:flutter/rendering.dart';
+import 'package:flutter/services.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter/gestures.dart';
 
@@ -536,6 +538,28 @@ void main() {
     expect(exit2, isEmpty);
   });
 
+  testWidgets('applies mouse cursor', (WidgetTester tester) async {
+    await tester.pumpWidget(_Scaffold(
+      topLeft: MouseRegion(
+        cursor: SystemMouseCursors.text,
+        child: Container(width: 10, height: 10),
+      ),
+    ));
+
+    final TestGesture gesture = await tester.createGesture(kind: PointerDeviceKind.mouse);
+    await gesture.addPointer(location: const Offset(100, 100));
+    addTearDown(gesture.removePointer);
+
+    await tester.pump();
+    expect(RendererBinding.instance.mouseTracker.debugDeviceActiveCursor(1), SystemMouseCursors.basic);
+
+    await gesture.moveTo(const Offset(5, 5));
+    expect(RendererBinding.instance.mouseTracker.debugDeviceActiveCursor(1), SystemMouseCursors.text);
+
+    await gesture.moveTo(const Offset(100, 100));
+    expect(RendererBinding.instance.mouseTracker.debugDeviceActiveCursor(1), SystemMouseCursors.basic);
+  });
+
   testWidgets('MouseRegion uses updated callbacks', (WidgetTester tester) async {
     final List<String> logs = <String>[];
     Widget hoverableContainer({
@@ -1358,7 +1382,7 @@ void main() {
     expect(logs, <String>['hover2']);
     logs.clear();
 
-    // Compare: It repaints if the MouseRegion is unactivated.
+    // Compare: It repaints if the MouseRegion is deactivated.
     await tester.pumpWidget(_Scaffold(
       topLeft: Container(
         height: 10,
@@ -1420,6 +1444,215 @@ void main() {
     expect(logs, <String>['paint', 'hover-enter']);
   });
 
+  testWidgets('Changing MouseRegion.cursor is effective and repaints', (WidgetTester tester) async {
+    final List<String> logPaints = <String>[];
+    final List<String> logEnters = <String>[];
+
+    final TestGesture gesture = await tester.createGesture(kind: PointerDeviceKind.mouse);
+    await gesture.addPointer(location: const Offset(100, 100));
+    addTearDown(gesture.removePointer);
+
+    final VoidCallback onPaintChild = () { logPaints.add('paint'); };
+
+    await tester.pumpWidget(_Scaffold(
+      topLeft: Container(
+        height: 10,
+        width: 10,
+        child: MouseRegion(
+          cursor: SystemMouseCursors.forbidden,
+          onEnter: (_) { logEnters.add('enter'); },
+          opaque: true,
+          child: CustomPaint(painter: _DelegatedPainter(onPaint: onPaintChild)),
+        ),
+      ),
+    ));
+    await gesture.moveTo(const Offset(5, 5));
+
+    expect(logPaints, <String>['paint']);
+    expect(RendererBinding.instance.mouseTracker.debugDeviceActiveCursor(1), SystemMouseCursors.forbidden);
+    expect(logEnters, <String>['enter']);
+    logPaints.clear();
+    logEnters.clear();
+
+    await tester.pumpWidget(_Scaffold(
+      topLeft: Container(
+        height: 10,
+        width: 10,
+        child: MouseRegion(
+          cursor: SystemMouseCursors.text,
+          onEnter: (_) { logEnters.add('enter'); },
+          opaque: true,
+          child: CustomPaint(painter: _DelegatedPainter(onPaint: onPaintChild)),
+        ),
+      ),
+    ));
+
+    expect(logPaints, <String>['paint']);
+    expect(RendererBinding.instance.mouseTracker.debugDeviceActiveCursor(1), SystemMouseCursors.text);
+    expect(logEnters, isEmpty);
+    logPaints.clear();
+    logEnters.clear();
+  });
+
+  testWidgets('Changing whether MouseRegion.cursor is null is effective and repaints', (WidgetTester tester) async {
+    final List<String> logEnters = <String>[];
+    final List<String> logPaints = <String>[];
+
+    final TestGesture gesture = await tester.createGesture(kind: PointerDeviceKind.mouse);
+    await gesture.addPointer(location: const Offset(100, 100));
+    addTearDown(gesture.removePointer);
+
+    final VoidCallback onPaintChild = () { logPaints.add('paint'); };
+
+    await tester.pumpWidget(_Scaffold(
+      topLeft: Container(
+        height: 10,
+        width: 10,
+        child: MouseRegion(
+          cursor: SystemMouseCursors.forbidden,
+          child: MouseRegion(
+            cursor: SystemMouseCursors.text,
+            onEnter: (_) { logEnters.add('enter'); },
+            child: CustomPaint(painter: _DelegatedPainter(onPaint: onPaintChild)),
+          ),
+        ),
+      ),
+    ));
+    await gesture.moveTo(const Offset(5, 5));
+
+    expect(logPaints, <String>['paint']);
+    expect(logEnters, <String>['enter']);
+    expect(RendererBinding.instance.mouseTracker.debugDeviceActiveCursor(1), SystemMouseCursors.text);
+    logPaints.clear();
+    logEnters.clear();
+
+    await tester.pumpWidget(_Scaffold(
+      topLeft: Container(
+        height: 10,
+        width: 10,
+        child: MouseRegion(
+          cursor: SystemMouseCursors.forbidden,
+          child: MouseRegion(
+            cursor: null,
+            onEnter: (_) { logEnters.add('enter'); },
+            child: CustomPaint(painter: _DelegatedPainter(onPaint: onPaintChild)),
+          ),
+        ),
+      ),
+    ));
+
+    expect(logPaints, <String>['paint']);
+    expect(logEnters, isEmpty);
+    expect(RendererBinding.instance.mouseTracker.debugDeviceActiveCursor(1), SystemMouseCursors.forbidden);
+    logPaints.clear();
+    logEnters.clear();
+
+    await tester.pumpWidget(_Scaffold(
+      topLeft: Container(
+        height: 10,
+        width: 10,
+        child: MouseRegion(
+          cursor: SystemMouseCursors.forbidden,
+          child: MouseRegion(
+            cursor: SystemMouseCursors.text,
+            opaque: true,
+            child: CustomPaint(painter: _DelegatedPainter(onPaint: onPaintChild)),
+          ),
+        ),
+      ),
+    ));
+
+    expect(logPaints, <String>['paint']);
+    expect(RendererBinding.instance.mouseTracker.debugDeviceActiveCursor(1), SystemMouseCursors.text);
+    expect(logEnters, isEmpty);
+    logPaints.clear();
+    logEnters.clear();
+  });
+
+  testWidgets('Does not trigger side effects during a reparent', (WidgetTester tester) async {
+    final List<String> logEnters = <String>[];
+    final List<String> logExits = <String>[];
+    final List<String> logCursors = <String>[];
+
+    final TestGesture gesture = await tester.createGesture(kind: PointerDeviceKind.mouse);
+    await gesture.addPointer(location: const Offset(100, 100));
+    addTearDown(gesture.removePointer);
+    SystemChannels.mouseCursor.setMockMethodCallHandler((_) async {
+      logCursors.add('cursor');
+    });
+
+    final GlobalKey key = GlobalKey();
+
+    // Pump a row of 2 SizedBox's, each taking 50px of width.
+    await tester.pumpWidget(_Scaffold(
+      topLeft: SizedBox(
+        width: 100,
+        height: 50,
+        child: Row(
+          children: <Widget>[
+            SizedBox(
+              width: 50,
+              height: 50,
+              child: MouseRegion(
+                key: key,
+                onEnter: (_) { logEnters.add('enter'); },
+                onExit: (_) { logEnters.add('enter'); },
+                cursor: SystemMouseCursors.click,
+              ),
+            ),
+            const SizedBox(
+              width: 50,
+              height: 50,
+            ),
+          ],
+        ),
+      ),
+    ));
+
+    // Move to the mouse region inside the first box.
+    await gesture.moveTo(const Offset(40, 5));
+
+    expect(logEnters, <String>['enter']);
+    expect(logExits, isEmpty);
+    expect(logCursors, isNotEmpty);
+    expect(RendererBinding.instance.mouseTracker.debugDeviceActiveCursor(1), SystemMouseCursors.click);
+    logEnters.clear();
+    logExits.clear();
+    logCursors.clear();
+
+    // Move MouseRegion to the second box while resizing them so that the
+    // mouse is still on the MouseRegion
+    await tester.pumpWidget(_Scaffold(
+      topLeft: SizedBox(
+        width: 100,
+        height: 50,
+        child: Row(
+          children: <Widget>[
+            const SizedBox(
+              width: 30,
+              height: 50,
+            ),
+            SizedBox(
+              width: 70,
+              height: 50,
+              child: MouseRegion(
+                key: key,
+                onEnter: (_) { logEnters.add('enter'); },
+                onExit: (_) { logEnters.add('enter'); },
+                cursor: SystemMouseCursors.click,
+              ),
+            ),
+          ],
+        ),
+      ),
+    ));
+
+    expect(logEnters, isEmpty);
+    expect(logExits, isEmpty);
+    expect(logCursors, isEmpty);
+    expect(RendererBinding.instance.mouseTracker.debugDeviceActiveCursor(1), SystemMouseCursors.click);
+  });
+
   testWidgets("RenderMouseRegion's debugFillProperties when default", (WidgetTester tester) async {
     final DiagnosticPropertiesBuilder builder = DiagnosticPropertiesBuilder();
     RenderMouseRegion().debugFillProperties(builder);

packages/flutter_test/lib/src/test_pointer.dart

@@ -57,7 +57,7 @@ class TestPointer {
   /// Set when the object is constructed. Defaults to 1.
   final int pointer;
 
-  /// The kind of pointer device to simulate. Defaults to
+  /// The kind of pointing device to simulate. Defaults to
   /// [PointerDeviceKind.touch].
   final PointerDeviceKind kind;