Reland "Remove single-view assumption from ScrollPhysics (#117503)" (#117916)

This reverts commit c956121a.

dev/integration_tests/flutter_gallery/lib/demo/animation/home.dart

@@ -371,14 +371,14 @@ class _SnappingScrollPhysics extends ClampingScrollPhysics {
     return _SnappingScrollPhysics(parent: buildParent(ancestor), midScrollOffset: midScrollOffset);
   }
 
-  Simulation _toMidScrollOffsetSimulation(double offset, double dragVelocity) {
+  Simulation _toMidScrollOffsetSimulation(double offset, double dragVelocity, ScrollMetrics metrics) {
     final double velocity = math.max(dragVelocity, minFlingVelocity);
-    return ScrollSpringSimulation(spring, offset, midScrollOffset, velocity, tolerance: tolerance);
+    return ScrollSpringSimulation(spring, offset, midScrollOffset, velocity, tolerance: toleranceFor(metrics));
   }
 
-  Simulation _toZeroScrollOffsetSimulation(double offset, double dragVelocity) {
+  Simulation _toZeroScrollOffsetSimulation(double offset, double dragVelocity, ScrollMetrics metrics) {
     final double velocity = math.max(dragVelocity, minFlingVelocity);
-    return ScrollSpringSimulation(spring, offset, 0.0, velocity, tolerance: tolerance);
+    return ScrollSpringSimulation(spring, offset, 0.0, velocity, tolerance: toleranceFor(metrics));
   }
 
   @override
@@ -396,10 +396,10 @@ class _SnappingScrollPhysics extends ClampingScrollPhysics {
         return simulation;
       }
       if (dragVelocity > 0.0) {
-        return _toMidScrollOffsetSimulation(offset, dragVelocity);
+        return _toMidScrollOffsetSimulation(offset, dragVelocity, position);
       }
       if (dragVelocity < 0.0) {
-        return _toZeroScrollOffsetSimulation(offset, dragVelocity);
+        return _toZeroScrollOffsetSimulation(offset, dragVelocity, position);
       }
     } else {
       // The user ended the drag with little or no velocity. If they
@@ -408,10 +408,10 @@ class _SnappingScrollPhysics extends ClampingScrollPhysics {
       // otherwise snap to zero.
       final double snapThreshold = midScrollOffset / 2.0;
       if (offset >= snapThreshold && offset < midScrollOffset) {
-        return _toMidScrollOffsetSimulation(offset, dragVelocity);
+        return _toMidScrollOffsetSimulation(offset, dragVelocity, position);
       }
       if (offset > 0.0 && offset < snapThreshold) {
-        return _toZeroScrollOffsetSimulation(offset, dragVelocity);
+        return _toZeroScrollOffsetSimulation(offset, dragVelocity, position);
       }
     }
     return simulation;

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

@@ -902,7 +902,7 @@ class _DraggableScrollableSheetScrollPosition extends ScrollPositionWithSingleCo
   bool get _isAtSnapSize {
     return extent.snapSizes.any(
       (double snapSize) {
-        return (extent.currentSize - snapSize).abs() <= extent.pixelsToSize(physics.tolerance.distance);
+        return (extent.currentSize - snapSize).abs() <= extent.pixelsToSize(physics.toleranceFor(this).distance);
       },
     );
   }
@@ -937,7 +937,7 @@ class _DraggableScrollableSheetScrollPosition extends ScrollPositionWithSingleCo
         initialVelocity: velocity,
         pixelSnapSize: extent.pixelSnapSizes,
         snapAnimationDuration: extent.snapAnimationDuration,
-        tolerance: physics.tolerance,
+        tolerance: physics.toleranceFor(this),
       );
     } else {
       // The iOS bouncing simulation just isn't right here - once we delegate
@@ -946,7 +946,7 @@ class _DraggableScrollableSheetScrollPosition extends ScrollPositionWithSingleCo
         // Run the simulation in terms of pixels, not extent.
         position: extent.currentPixels,
         velocity: velocity,
-        tolerance: physics.tolerance,
+        tolerance: physics.toleranceFor(this),
       );
     }
 
@@ -965,7 +965,7 @@ class _DraggableScrollableSheetScrollPosition extends ScrollPositionWithSingleCo
         // Make sure we pass along enough velocity to keep scrolling - otherwise
         // we just "bounce" off the top making it look like the list doesn't
         // have more to scroll.
-        velocity = ballisticController.velocity + (physics.tolerance.velocity * ballisticController.velocity.sign);
+        velocity = ballisticController.velocity + (physics.toleranceFor(this).velocity * ballisticController.velocity.sign);
         super.goBallistic(velocity);
         ballisticController.stop();
       } else if (ballisticController.isCompleted) {

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

@@ -316,6 +316,7 @@ class FixedExtentMetrics extends FixedScrollMetrics {
     required super.viewportDimension,
     required super.axisDirection,
     required this.itemIndex,
+    required super.devicePixelRatio,
   });
 
   @override
@@ -326,6 +327,7 @@ class FixedExtentMetrics extends FixedScrollMetrics {
     double? viewportDimension,
     AxisDirection? axisDirection,
     int? itemIndex,
+    double? devicePixelRatio,
   }) {
     return FixedExtentMetrics(
       minScrollExtent: minScrollExtent ?? (hasContentDimensions ? this.minScrollExtent : null),
@@ -334,6 +336,7 @@ class FixedExtentMetrics extends FixedScrollMetrics {
       viewportDimension: viewportDimension ?? (hasViewportDimension ? this.viewportDimension : null),
       axisDirection: axisDirection ?? this.axisDirection,
       itemIndex: itemIndex ?? this.itemIndex,
+      devicePixelRatio: devicePixelRatio ?? this.devicePixelRatio,
     );
   }
 
@@ -399,6 +402,7 @@ class _FixedExtentScrollPosition extends ScrollPositionWithSingleContext impleme
     double? viewportDimension,
     AxisDirection? axisDirection,
     int? itemIndex,
+    double? devicePixelRatio,
   }) {
     return FixedExtentMetrics(
       minScrollExtent: minScrollExtent ?? (hasContentDimensions ? this.minScrollExtent : null),
@@ -407,6 +411,7 @@ class _FixedExtentScrollPosition extends ScrollPositionWithSingleContext impleme
       viewportDimension: viewportDimension ?? (hasViewportDimension ? this.viewportDimension : null),
       axisDirection: axisDirection ?? this.axisDirection,
       itemIndex: itemIndex ?? this.itemIndex,
+      devicePixelRatio: devicePixelRatio ?? this.devicePixelRatio,
     );
   }
 }
@@ -505,8 +510,8 @@ class FixedExtentScrollPhysics extends ScrollPhysics {
     // Scenario 3:
     // If there's no velocity and we're already at where we intend to land,
     // do nothing.
-    if (velocity.abs() < tolerance.velocity
-        && (settlingPixels - metrics.pixels).abs() < tolerance.distance) {
+    if (velocity.abs() < toleranceFor(position).velocity
+        && (settlingPixels - metrics.pixels).abs() < toleranceFor(position).distance) {
       return null;
     }
 
@@ -519,7 +524,7 @@ class FixedExtentScrollPhysics extends ScrollPhysics {
         metrics.pixels,
         settlingPixels,
         velocity,
-        tolerance: tolerance,
+        tolerance: toleranceFor(position),
       );
     }
 
@@ -530,7 +535,7 @@ class FixedExtentScrollPhysics extends ScrollPhysics {
       metrics.pixels,
       settlingPixels,
       velocity,
-      tolerance.velocity * velocity.sign,
+      toleranceFor(position).velocity * velocity.sign,
     );
   }
 }

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

@@ -526,6 +526,7 @@ class _NestedScrollMetrics extends FixedScrollMetrics {
     required super.pixels,
     required super.viewportDimension,
     required super.axisDirection,
+    required super.devicePixelRatio,
     required this.minRange,
     required this.maxRange,
     required this.correctionOffset,
@@ -538,6 +539,7 @@ class _NestedScrollMetrics extends FixedScrollMetrics {
     double? pixels,
     double? viewportDimension,
     AxisDirection? axisDirection,
+    double? devicePixelRatio,
     double? minRange,
     double? maxRange,
     double? correctionOffset,
@@ -548,6 +550,7 @@ class _NestedScrollMetrics extends FixedScrollMetrics {
       pixels: pixels ?? (hasPixels ? this.pixels : null),
       viewportDimension: viewportDimension ?? (hasViewportDimension ? this.viewportDimension : null),
       axisDirection: axisDirection ?? this.axisDirection,
+      devicePixelRatio: devicePixelRatio ?? this.devicePixelRatio,
       minRange: minRange ?? this.minRange,
       maxRange: maxRange ?? this.maxRange,
       correctionOffset: correctionOffset ?? this.correctionOffset,
@@ -815,6 +818,7 @@ class _NestedScrollCoordinator implements ScrollActivityDelegate, ScrollHoldCont
       minRange: minRange,
       maxRange: maxRange,
       correctionOffset: correctionOffset,
+      devicePixelRatio: _outerPosition!.devicePixelRatio,
     );
   }
 

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

@@ -273,6 +273,7 @@ class PageMetrics extends FixedScrollMetrics {
     required super.viewportDimension,
     required super.axisDirection,
     required this.viewportFraction,
+    required super.devicePixelRatio,
   });
 
   @override
@@ -283,6 +284,7 @@ class PageMetrics extends FixedScrollMetrics {
     double? viewportDimension,
     AxisDirection? axisDirection,
     double? viewportFraction,
+    double? devicePixelRatio,
   }) {
     return PageMetrics(
       minScrollExtent: minScrollExtent ?? (hasContentDimensions ? this.minScrollExtent : null),
@@ -291,6 +293,7 @@ class PageMetrics extends FixedScrollMetrics {
       viewportDimension: viewportDimension ?? (hasViewportDimension ? this.viewportDimension : null),
       axisDirection: axisDirection ?? this.axisDirection,
       viewportFraction: viewportFraction ?? this.viewportFraction,
+      devicePixelRatio: devicePixelRatio ?? this.devicePixelRatio,
     );
   }
 
@@ -493,6 +496,7 @@ class _PagePosition extends ScrollPositionWithSingleContext implements PageMetri
     double? viewportDimension,
     AxisDirection? axisDirection,
     double? viewportFraction,
+    double? devicePixelRatio,
   }) {
     return PageMetrics(
       minScrollExtent: minScrollExtent ?? (hasContentDimensions ? this.minScrollExtent : null),
@@ -501,6 +505,7 @@ class _PagePosition extends ScrollPositionWithSingleContext implements PageMetri
       viewportDimension: viewportDimension ?? (hasViewportDimension ? this.viewportDimension : null),
       axisDirection: axisDirection ?? this.axisDirection,
       viewportFraction: viewportFraction ?? this.viewportFraction,
+      devicePixelRatio: devicePixelRatio ?? this.devicePixelRatio,
     );
   }
 }
@@ -573,7 +578,7 @@ class PageScrollPhysics extends ScrollPhysics {
         (velocity >= 0.0 && position.pixels >= position.maxScrollExtent)) {
       return super.createBallisticSimulation(position, velocity);
     }
-    final Tolerance tolerance = this.tolerance;
+    final Tolerance tolerance = toleranceFor(position);
     final double target = _getTargetPixels(position, tolerance, velocity);
     if (target != position.pixels) {
       return ScrollSpringSimulation(spring, position.pixels, target, velocity, tolerance: tolerance);

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

@@ -46,6 +46,7 @@ mixin ScrollMetrics {
     double? pixels,
     double? viewportDimension,
     AxisDirection? axisDirection,
+    double? devicePixelRatio,
   }) {
     return FixedScrollMetrics(
       minScrollExtent: minScrollExtent ?? (hasContentDimensions ? this.minScrollExtent : null),
@@ -53,6 +54,7 @@ mixin ScrollMetrics {
       pixels: pixels ?? (hasPixels ? this.pixels : null),
       viewportDimension: viewportDimension ?? (hasViewportDimension ? this.viewportDimension : null),
       axisDirection: axisDirection ?? this.axisDirection,
+      devicePixelRatio: devicePixelRatio ?? this.devicePixelRatio,
     );
   }
 
@@ -124,6 +126,10 @@ mixin ScrollMetrics {
   /// The quantity of content conceptually "below" the viewport in the scrollable.
   /// This is the content below the content described by [extentInside].
   double get extentAfter => math.max(maxScrollExtent - pixels, 0.0);
+
+  /// The [FlutterView.devicePixelRatio] of the view that the [Scrollable]
+  /// associated with this metrics object is drawn into.
+  double get devicePixelRatio;
 }
 
 /// An immutable snapshot of values associated with a [Scrollable] viewport.
@@ -137,6 +143,7 @@ class FixedScrollMetrics with ScrollMetrics {
     required double? pixels,
     required double? viewportDimension,
     required this.axisDirection,
+    required this.devicePixelRatio,
   }) : _minScrollExtent = minScrollExtent,
        _maxScrollExtent = maxScrollExtent,
        _pixels = pixels,
@@ -170,6 +177,9 @@ class FixedScrollMetrics with ScrollMetrics {
   @override
   final AxisDirection axisDirection;
 
+  @override
+  final double devicePixelRatio;
+
   @override
   String toString() {
     return '${objectRuntimeType(this, 'FixedScrollMetrics')}(${extentBefore.toStringAsFixed(1)}..[${extentInside.toStringAsFixed(1)}]..${extentAfter.toStringAsFixed(1)})';

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

@@ -6,6 +6,7 @@ import 'dart:math' as math;
 
 import 'package:flutter/foundation.dart';
 import 'package:flutter/gestures.dart';
+import 'package:flutter/painting.dart' show AxisDirection;
 import 'package:flutter/physics.dart';
 
 import 'binding.dart' show WidgetsBinding;
@@ -383,16 +384,29 @@ class ScrollPhysics {
   /// The spring to use for ballistic simulations.
   SpringDescription get spring => parent?.spring ?? _kDefaultSpring;
 
-  /// The default accuracy to which scrolling is computed.
-  static final Tolerance _kDefaultTolerance = Tolerance(
-    // TODO(ianh): Handle the case of the device pixel ratio changing.
-    // TODO(ianh): Get this from the local MediaQuery not dart:ui's window object.
-    velocity: 1.0 / (0.050 * WidgetsBinding.instance.window.devicePixelRatio), // logical pixels per second
-    distance: 1.0 / WidgetsBinding.instance.window.devicePixelRatio, // logical pixels
-  );
+  /// Deprecated. Call [toleranceFor] instead.
+  @Deprecated(
+    'Call toleranceFor instead. '
+    'This feature was deprecated after v3.7.0-13.0.pre.',
+  )
+  Tolerance get tolerance {
+    return toleranceFor(FixedScrollMetrics(
+      minScrollExtent: null,
+      maxScrollExtent: null,
+      pixels: null,
+      viewportDimension: null,
+      axisDirection: AxisDirection.down,
+      devicePixelRatio: WidgetsBinding.instance.window.devicePixelRatio,
+    ));
+  }
 
   /// The tolerance to use for ballistic simulations.
-  Tolerance get tolerance => parent?.tolerance ?? _kDefaultTolerance;
+  Tolerance toleranceFor(ScrollMetrics metrics) {
+    return parent?.toleranceFor(metrics) ?? Tolerance(
+      velocity: 1.0 / (0.050 * metrics.devicePixelRatio), // logical pixels per second
+      distance: 1.0 / metrics.devicePixelRatio, // logical pixels
+    );
+  }
 
   /// The minimum distance an input pointer drag must have moved to
   /// to be considered a scroll fling gesture.
@@ -696,7 +710,7 @@ class BouncingScrollPhysics extends ScrollPhysics {
 
   @override
   Simulation? createBallisticSimulation(ScrollMetrics position, double velocity) {
-    final Tolerance tolerance = this.tolerance;
+    final Tolerance tolerance = toleranceFor(position);
     if (velocity.abs() >= tolerance.velocity || position.outOfRange) {
       double constantDeceleration;
       switch (decelerationRate) {
@@ -840,7 +854,7 @@ class ClampingScrollPhysics extends ScrollPhysics {
 
   @override
   Simulation? createBallisticSimulation(ScrollMetrics position, double velocity) {
-    final Tolerance tolerance = this.tolerance;
+    final Tolerance tolerance = toleranceFor(position);
     if (position.outOfRange) {
       double? end;
       if (position.pixels > position.maxScrollExtent) {

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

@@ -12,6 +12,7 @@ import 'package:flutter/scheduler.dart';
 
 import 'basic.dart';
 import 'framework.dart';
+import 'media_query.dart';
 import 'notification_listener.dart';
 import 'page_storage.dart';
 import 'scroll_activity.dart';
@@ -19,6 +20,7 @@ import 'scroll_context.dart';
 import 'scroll_metrics.dart';
 import 'scroll_notification.dart';
 import 'scroll_physics.dart';
+import 'view.dart';
 
 export 'scroll_activity.dart' show ScrollHoldController;
 
@@ -242,6 +244,9 @@ abstract class ScrollPosition extends ViewportOffset with ScrollMetrics {
     isScrollingNotifier.value = activity!.isScrolling;
   }
 
+  @override
+  double get devicePixelRatio => MediaQuery.maybeDevicePixelRatioOf(context.storageContext) ?? View.of(context.storageContext).devicePixelRatio;
+
   /// Update the scroll position ([pixels]) to a given pixel value.
   ///
   /// This should only be called by the current [ScrollActivity], either during

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

@@ -176,7 +176,7 @@ class ScrollPositionWithSingleContext extends ScrollPosition implements ScrollAc
     required Duration duration,
     required Curve curve,
   }) {
-    if (nearEqual(to, pixels, physics.tolerance.distance)) {
+    if (nearEqual(to, pixels, physics.toleranceFor(this).distance)) {
       // Skip the animation, go straight to the position as we are already close.
       jumpTo(to);
       return Future<void>.value();

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

@@ -727,6 +727,12 @@ class ScrollableState extends State<Scrollable> with TickerProviderStateMixin, R
   }
 
   void _handleDragCancel() {
+    if (_gestureDetectorKey.currentContext == null) {
+      // The cancel was caused by the GestureDetector getting disposed, which
+      // means we will get disposed momentarily as well and shouldn't do
+      // any work.
+      return;
+    }
     // _hold might be null if the drag started.
     // _drag might be null if the drag activity ended and called _disposeDrag.
     assert(_hold == null || _drag == null);

packages/flutter/test/material/scrollbar_test.dart

@@ -148,6 +148,7 @@ void main() {
       pixels: 0.0,
       viewportDimension: 100.0,
       axisDirection: AxisDirection.down,
+      devicePixelRatio: tester.binding.window.devicePixelRatio,
     );
     scrollPainter!.update(metrics, AxisDirection.down);
 

packages/flutter/test/widgets/page_view_test.dart

@@ -1048,6 +1048,7 @@ void main() {
       viewportDimension: 25.0,
       axisDirection: AxisDirection.right,
       viewportFraction: 1.0,
+      devicePixelRatio: tester.binding.window.devicePixelRatio,
     );
     expect(page.page, 6);
     final PageMetrics page2 = page.copyWith(

packages/flutter/test/widgets/scroll_physics_test.dart

@@ -107,6 +107,7 @@ void main() {
       pixels: 20.0,
       viewportDimension: 500.0,
       axisDirection: AxisDirection.down,
+      devicePixelRatio: 3.0,
     );
 
     const BouncingScrollPhysics bounce = BouncingScrollPhysics();
@@ -129,11 +130,12 @@ void main() {
 
     test('overscroll is progressively harder', () {
       final ScrollMetrics lessOverscrolledPosition = FixedScrollMetrics(
-          minScrollExtent: 0.0,
-          maxScrollExtent: 1000.0,
-          pixels: -20.0,
-          viewportDimension: 100.0,
-          axisDirection: AxisDirection.down,
+        minScrollExtent: 0.0,
+        maxScrollExtent: 1000.0,
+        pixels: -20.0,
+        viewportDimension: 100.0,
+        axisDirection: AxisDirection.down,
+        devicePixelRatio: 3.0,
       );
 
       final ScrollMetrics moreOverscrolledPosition = FixedScrollMetrics(
@@ -142,6 +144,7 @@ void main() {
         pixels: -40.0,
         viewportDimension: 100.0,
         axisDirection: AxisDirection.down,
+        devicePixelRatio: 3.0,
       );
 
       final double lessOverscrollApplied =
@@ -170,6 +173,7 @@ void main() {
         pixels: -20.0,
         viewportDimension: 100.0,
         axisDirection: AxisDirection.down,
+        devicePixelRatio: 3.0,
       );
 
       final double easingApplied =
@@ -186,6 +190,7 @@ void main() {
         pixels: 300.0,
         viewportDimension: 100.0,
         axisDirection: AxisDirection.down,
+        devicePixelRatio: 3.0,
       );
 
       expect(
@@ -205,6 +210,7 @@ void main() {
         pixels: -20.0,
         viewportDimension: 100.0,
         axisDirection: AxisDirection.down,
+        devicePixelRatio: 3.0,
       );
 
       final double easingApplied =
@@ -217,11 +223,12 @@ void main() {
 
     test('overscroll a small list and a big list works the same way', () {
       final ScrollMetrics smallListOverscrolledPosition = FixedScrollMetrics(
-          minScrollExtent: 0.0,
-          maxScrollExtent: 10.0,
-          pixels: -20.0,
-          viewportDimension: 100.0,
-          axisDirection: AxisDirection.down,
+        minScrollExtent: 0.0,
+        maxScrollExtent: 10.0,
+        pixels: -20.0,
+        viewportDimension: 100.0,
+        axisDirection: AxisDirection.down,
+        devicePixelRatio: 3.0,
       );
 
       final ScrollMetrics bigListOverscrolledPosition = FixedScrollMetrics(
@@ -230,6 +237,7 @@ void main() {
         pixels: -20.0,
         viewportDimension: 100.0,
         axisDirection: AxisDirection.down,
+        devicePixelRatio: 3.0,
       );
 
       final double smallListOverscrollApplied =
@@ -254,6 +262,7 @@ void main() {
       maxScrollExtent: 1000,
       viewportDimension: 0,
       axisDirection: AxisDirection.down,
+      devicePixelRatio: 3.0,
     );
     expect(position.pixels, pixels);
     late FlutterError error;

packages/flutter/test/widgets/scrollable_animations_test.dart

@@ -41,7 +41,7 @@ void main() {
 
     expectNoAnimation();
 
-    final double halfTolerance = controller.position.physics.tolerance.distance / 2;
+    final double halfTolerance = controller.position.physics.toleranceFor(controller.position).distance / 2;
     expect(halfTolerance, isNonZero);
     final double targetPosition = controller.position.pixels + halfTolerance;
     controller.position.animateTo(targetPosition, duration: const Duration(seconds: 10), curve: Curves.linear);
@@ -64,7 +64,7 @@ void main() {
 
     expectNoAnimation();
 
-    final double doubleTolerance = controller.position.physics.tolerance.distance * 2;
+    final double doubleTolerance = controller.position.physics.toleranceFor(controller.position).distance * 2;
     expect(doubleTolerance, isNonZero);
     final double targetPosition = controller.position.pixels + doubleTolerance;
     controller.position.animateTo(targetPosition, duration: const Duration(seconds: 10), curve: Curves.linear);

packages/flutter/test/widgets/scrollbar_test.dart

@@ -83,6 +83,7 @@ void main() {
     pixels: 0,
     viewportDimension: 100,
     axisDirection: AxisDirection.down,
+    devicePixelRatio: 3.0,
   );
 
   test(

packages/flutter/test/widgets/slivers_evil_test.dart

@@ -53,7 +53,7 @@ class TestScrollPhysics extends ClampingScrollPhysics {
   }
 
   @override
-  Tolerance get tolerance => const Tolerance(velocity: 20.0, distance: 1.0);
+  Tolerance toleranceFor(ScrollMetrics metrics) => const Tolerance(velocity: 20.0, distance: 1.0);
 }
 
 void main() {