[flutter] reject mouse drags by default in scrollables (#81569)

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

@@ -69,6 +69,7 @@ abstract class DragGestureRecognizer extends OneSequenceGestureRecognizer {
     PointerDeviceKind? kind,
     this.dragStartBehavior = DragStartBehavior.start,
     this.velocityTrackerBuilder = _defaultBuilder,
+    this.supportedDevices = _kAllPointerDeviceKinds
   }) : assert(dragStartBehavior != null),
        super(debugOwner: debugOwner, kind: kind);
 
@@ -200,6 +201,11 @@ abstract class DragGestureRecognizer extends OneSequenceGestureRecognizer {
   ///    match the native behavior on that platform.
   GestureVelocityTrackerBuilder velocityTrackerBuilder;
 
+  /// The device types that this gesture recognizer will accept drags from.
+  ///
+  /// If not specified, defaults to all pointer kinds.
+  Set<PointerDeviceKind> supportedDevices;
+
   _DragState _state = _DragState.ready;
   late OffsetPair _initialPosition;
   late OffsetPair _pendingDragOffset;
@@ -230,6 +236,9 @@ abstract class DragGestureRecognizer extends OneSequenceGestureRecognizer {
 
   @override
   bool isPointerAllowed(PointerEvent event) {
+    if (!supportedDevices.contains(event.kind)) {
+      return false;
+    }
     if (_initialButtons == null) {
       switch (event.buttons) {
         case kPrimaryButton:
@@ -508,7 +517,8 @@ class VerticalDragGestureRecognizer extends DragGestureRecognizer {
   VerticalDragGestureRecognizer({
     Object? debugOwner,
     PointerDeviceKind? kind,
-  }) : super(debugOwner: debugOwner, kind: kind);
+    Set<PointerDeviceKind> supportedDevices = _kAllPointerDeviceKinds,
+  }) : super(debugOwner: debugOwner, kind: kind, supportedDevices: supportedDevices);
 
   @override
   bool isFlingGesture(VelocityEstimate estimate, PointerDeviceKind kind) {
@@ -532,6 +542,10 @@ class VerticalDragGestureRecognizer extends DragGestureRecognizer {
   String get debugDescription => 'vertical drag';
 }
 
+const Set<PointerDeviceKind> _kAllPointerDeviceKinds = <PointerDeviceKind>{
+  ...PointerDeviceKind.values,
+};
+
 /// Recognizes movement in the horizontal direction.
 ///
 /// Used for horizontal scrolling.
@@ -549,7 +563,8 @@ class HorizontalDragGestureRecognizer extends DragGestureRecognizer {
   HorizontalDragGestureRecognizer({
     Object? debugOwner,
     PointerDeviceKind? kind,
-  }) : super(debugOwner: debugOwner, kind: kind);
+    Set<PointerDeviceKind> supportedDevices = _kAllPointerDeviceKinds,
+  }) : super(debugOwner: debugOwner, kind: kind, supportedDevices: supportedDevices);
 
   @override
   bool isFlingGesture(VelocityEstimate estimate, PointerDeviceKind kind) {

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

@@ -14,6 +14,13 @@ import 'scrollbar.dart';
 
 const Color _kDefaultGlowColor = Color(0xFFFFFFFF);
 
+/// Device types that scrollables should accept drag gestures from by default.
+const Set<PointerDeviceKind> _kTouchLikeDeviceTypes = <PointerDeviceKind>{
+  PointerDeviceKind.touch,
+  PointerDeviceKind.stylus,
+  PointerDeviceKind.invertedStylus,
+};
+
 /// Describes how [Scrollable] widgets should behave.
 ///
 /// {@template flutter.widgets.scrollBehavior}
@@ -52,6 +59,7 @@ class ScrollBehavior {
   ScrollBehavior copyWith({
     bool scrollbars = true,
     bool overscroll = true,
+    Set<PointerDeviceKind>? dragDevices,
     ScrollPhysics? physics,
     TargetPlatform? platform,
   }) {
@@ -61,6 +69,7 @@ class ScrollBehavior {
       overscrollIndicator: overscroll,
       physics: physics,
       platform: platform,
+      dragDevices: dragDevices,
     );
   }
 
@@ -69,6 +78,14 @@ class ScrollBehavior {
   /// Defaults to the current platform.
   TargetPlatform getPlatform(BuildContext context) => defaultTargetPlatform;
 
+  /// The device kinds that the scrollable will accept drag gestures from.
+  ///
+  /// By default only [PointerDeviceKind.touch], [PointerDeviceKind.stylus], and
+  /// [PointerDeviceKind.invertedStylus] are configured to create drag gestures.
+  /// Enabling this for [PointerDeviceKind.mouse] will make it difficult or
+  /// impossible to select text in scrollable containers and is not recommended.
+  Set<PointerDeviceKind> get dragDevices => _kTouchLikeDeviceTypes;
+
   /// Wraps the given widget, which scrolls in the given [AxisDirection].
   ///
   /// For example, on Android, this method wraps the given widget with a
@@ -200,13 +217,18 @@ class _WrappedScrollBehavior implements ScrollBehavior {
     this.overscrollIndicator = true,
     this.physics,
     this.platform,
-  });
+    Set<PointerDeviceKind>? dragDevices,
+  }) : _dragDevices = dragDevices;
 
   final ScrollBehavior delegate;
   final bool scrollbar;
   final bool overscrollIndicator;
   final ScrollPhysics? physics;
   final TargetPlatform? platform;
+  final Set<PointerDeviceKind>? _dragDevices;
+
+  @override
+  Set<PointerDeviceKind> get dragDevices => _dragDevices ?? delegate.dragDevices;
 
   @override
   Widget buildOverscrollIndicator(BuildContext context, Widget child, ScrollableDetails details) {
@@ -233,12 +255,14 @@ class _WrappedScrollBehavior implements ScrollBehavior {
     bool overscroll = true,
     ScrollPhysics? physics,
     TargetPlatform? platform,
+    Set<PointerDeviceKind>? dragDevices,
   }) {
     return delegate.copyWith(
       scrollbars: scrollbars,
       overscroll: overscroll,
       physics: physics,
       platform: platform,
+      dragDevices: dragDevices,
     );
   }
 
@@ -259,6 +283,7 @@ class _WrappedScrollBehavior implements ScrollBehavior {
         || oldDelegate.overscrollIndicator != overscrollIndicator
         || oldDelegate.physics != physics
         || oldDelegate.platform != platform
+        || setEquals<PointerDeviceKind>(oldDelegate.dragDevices, dragDevices)
         || delegate.shouldNotify(oldDelegate.delegate);
   }
 

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

@@ -565,7 +565,8 @@ class ScrollableState extends State<Scrollable> with TickerProviderStateMixin, R
                   ..minFlingVelocity = _physics?.minFlingVelocity
                   ..maxFlingVelocity = _physics?.maxFlingVelocity
                   ..velocityTrackerBuilder = _configuration.velocityTrackerBuilder(context)
-                  ..dragStartBehavior = widget.dragStartBehavior;
+                  ..dragStartBehavior = widget.dragStartBehavior
+                  ..supportedDevices = _configuration.dragDevices;
               },
             ),
           };
@@ -585,7 +586,8 @@ class ScrollableState extends State<Scrollable> with TickerProviderStateMixin, R
                   ..minFlingVelocity = _physics?.minFlingVelocity
                   ..maxFlingVelocity = _physics?.maxFlingVelocity
                   ..velocityTrackerBuilder = _configuration.velocityTrackerBuilder(context)
-                  ..dragStartBehavior = widget.dragStartBehavior;
+                  ..dragStartBehavior = widget.dragStartBehavior
+                  ..supportedDevices = _configuration.dragDevices;
               },
             ),
           };

packages/flutter/test/gestures/drag_test.dart

@@ -181,6 +181,106 @@ void main() {
     didEndDrag = false;
   });
 
+  testGesture('Should reject mouse drag when configured to ignore mouse pointers - Horizontal', (GestureTester tester) {
+    final HorizontalDragGestureRecognizer drag = HorizontalDragGestureRecognizer(supportedDevices: <PointerDeviceKind>{
+      PointerDeviceKind.touch,
+    }) ..dragStartBehavior = DragStartBehavior.down;
+    addTearDown(drag.dispose);
+
+    bool didStartDrag = false;
+    drag.onStart = (_) {
+      didStartDrag = true;
+    };
+
+    double? updatedDelta;
+    drag.onUpdate = (DragUpdateDetails details) {
+      updatedDelta = details.primaryDelta;
+    };
+
+    bool didEndDrag = false;
+    drag.onEnd = (DragEndDetails details) {
+      didEndDrag = true;
+    };
+
+    final TestPointer pointer = TestPointer(5, PointerDeviceKind.mouse);
+    final PointerDownEvent down = pointer.down(const Offset(10.0, 10.0));
+    drag.addPointer(down);
+    tester.closeArena(5);
+    expect(didStartDrag, isFalse);
+    expect(updatedDelta, isNull);
+    expect(didEndDrag, isFalse);
+
+    tester.route(down);
+    expect(didStartDrag, isFalse);
+    expect(updatedDelta, isNull);
+    expect(didEndDrag, isFalse);
+
+    tester.route(pointer.move(const Offset(20.0, 25.0)));
+    expect(didStartDrag, isFalse);
+    expect(updatedDelta, isNull);
+    expect(didEndDrag, isFalse);
+
+    tester.route(pointer.move(const Offset(20.0, 25.0)));
+    expect(didStartDrag, isFalse);
+    expect(updatedDelta, isNull);
+    expect(didEndDrag, isFalse);
+
+    tester.route(pointer.up());
+    expect(didStartDrag, isFalse);
+    expect(updatedDelta, isNull);
+    expect(didEndDrag, isFalse);
+  });
+
+  testGesture('Should reject mouse drag when configured to ignore mouse pointers - Vertical', (GestureTester tester) {
+    final VerticalDragGestureRecognizer drag = VerticalDragGestureRecognizer(supportedDevices: <PointerDeviceKind>{
+      PointerDeviceKind.touch,
+    })..dragStartBehavior = DragStartBehavior.down;
+    addTearDown(drag.dispose);
+
+    bool didStartDrag = false;
+    drag.onStart = (_) {
+      didStartDrag = true;
+    };
+
+    double? updatedDelta;
+    drag.onUpdate = (DragUpdateDetails details) {
+      updatedDelta = details.primaryDelta;
+    };
+
+    bool didEndDrag = false;
+    drag.onEnd = (DragEndDetails details) {
+      didEndDrag = true;
+    };
+
+    final TestPointer pointer = TestPointer(5, PointerDeviceKind.mouse);
+    final PointerDownEvent down = pointer.down(const Offset(10.0, 10.0));
+    drag.addPointer(down);
+    tester.closeArena(5);
+    expect(didStartDrag, isFalse);
+    expect(updatedDelta, isNull);
+    expect(didEndDrag, isFalse);
+
+    tester.route(down);
+    expect(didStartDrag, isFalse);
+    expect(updatedDelta, isNull);
+    expect(didEndDrag, isFalse);
+
+    tester.route(pointer.move(const Offset(25.0, 20.0)));
+    expect(didStartDrag, isFalse);
+    expect(updatedDelta, isNull);
+    expect(didEndDrag, isFalse);
+
+    tester.route(pointer.move(const Offset(25.0, 20.0)));
+    expect(didStartDrag, isFalse);
+    expect(updatedDelta, isNull);
+    expect(didEndDrag, isFalse);
+
+    tester.route(pointer.up());
+    expect(didStartDrag, isFalse);
+    expect(updatedDelta, isNull);
+    expect(didEndDrag, isFalse);
+  });
+
   testGesture('Should report original timestamps', (GestureTester tester) {
     final HorizontalDragGestureRecognizer drag = HorizontalDragGestureRecognizer() ..dragStartBehavior = DragStartBehavior.down;
     addTearDown(drag.dispose);

packages/flutter/test/widgets/scrollable_test.dart

@@ -17,9 +17,13 @@ Future<void> pumpTest(
   bool scrollable = true,
   bool reverse = false,
   ScrollController? controller,
+  bool enableMouseDrag = true,
 }) async {
   await tester.pumpWidget(MaterialApp(
-    scrollBehavior: const NoScrollbarBehavior(),
+    scrollBehavior: const NoScrollbarBehavior().copyWith(dragDevices: enableMouseDrag
+      ? <ui.PointerDeviceKind>{...ui.PointerDeviceKind.values}
+      : null,
+    ),
     theme: ThemeData(
       platform: platform,
     ),
@@ -1269,6 +1273,46 @@ void main() {
 
     expect(tester.takeException(), null);
   });
+
+  testWidgets('Does not scroll with mouse pointer drag when behavior is configured to ignore them', (WidgetTester tester) async {
+    await pumpTest(tester, debugDefaultTargetPlatformOverride, enableMouseDrag: false);
+    final TestGesture gesture = await tester.startGesture(tester.getCenter(find.byType(Scrollable), warnIfMissed: true), kind: ui.PointerDeviceKind.mouse);
+
+    await gesture.moveBy(const Offset(0.0, -200));
+    await tester.pump();
+    await tester.pumpAndSettle();
+
+    expect(getScrollOffset(tester), 0.0);
+
+    await gesture.moveBy(const Offset(0.0, 200));
+    await tester.pump();
+    await tester.pumpAndSettle();
+
+    expect(getScrollOffset(tester), 0.0);
+
+    await gesture.removePointer();
+    await tester.pump();
+  }, variant: const TargetPlatformVariant(<TargetPlatform>{ TargetPlatform.iOS, TargetPlatform.macOS, TargetPlatform.android }));
+
+  testWidgets('Does scroll with mouse pointer drag when behavior is not configured to ignore them', (WidgetTester tester) async {
+    await pumpTest(tester, debugDefaultTargetPlatformOverride, enableMouseDrag: true);
+    final TestGesture gesture = await tester.startGesture(tester.getCenter(find.byType(Scrollable), warnIfMissed: true), kind: ui.PointerDeviceKind.mouse);
+
+    await gesture.moveBy(const Offset(0.0, -200));
+    await tester.pump();
+    await tester.pumpAndSettle();
+
+    expect(getScrollOffset(tester), 200.0);
+
+    await gesture.moveBy(const Offset(0.0, 200));
+    await tester.pump();
+    await tester.pumpAndSettle();
+
+    expect(getScrollOffset(tester), 0.0);
+
+    await gesture.removePointer();
+    await tester.pump();
+  }, variant: const TargetPlatformVariant(<TargetPlatform>{ TargetPlatform.iOS, TargetPlatform.macOS, TargetPlatform.android }));
 }
 
 // ignore: must_be_immutable

packages/flutter_test/lib/src/controller.dart

@@ -530,6 +530,7 @@ abstract class WidgetController {
     double touchSlopX = kDragSlopDefault,
     double touchSlopY = kDragSlopDefault,
     bool warnIfMissed = true,
+    PointerDeviceKind kind = PointerDeviceKind.touch,
   }) {
     return dragFrom(
       getCenter(finder, warnIfMissed: warnIfMissed, callee: 'drag'),
@@ -538,6 +539,7 @@ abstract class WidgetController {
       buttons: buttons,
       touchSlopX: touchSlopX,
       touchSlopY: touchSlopY,
+      kind: kind,
     );
   }
 
@@ -559,10 +561,11 @@ abstract class WidgetController {
     int buttons = kPrimaryButton,
     double touchSlopX = kDragSlopDefault,
     double touchSlopY = kDragSlopDefault,
+    PointerDeviceKind kind = PointerDeviceKind.touch,
   }) {
     assert(kDragSlopDefault > kTouchSlop);
     return TestAsyncUtils.guard<void>(() async {
-      final TestGesture gesture = await startGesture(startLocation, pointer: pointer, buttons: buttons);
+      final TestGesture gesture = await startGesture(startLocation, pointer: pointer, buttons: buttons, kind: kind);
       assert(gesture != null);
 
       final double xSign = offset.dx.sign;