Reland VelocityTracker update (again) (#138843)

This updates the implementation to use the stopwatch from the Clock object and piping it through to the TestWidgetsFlutterBinding so it will be kept in sync with FakeAsync. Relands #137381 which attempted to reland #132291 Fixes #97761 The original change was reverted due to flakiness it introduced in tests that use fling gestures. * #135728 It was reverted again due to a change in the leak tracking tests that broke it.
flutter · Nov 21, 2023 · 3e4e280 · 3e4e280
1 parent 50c9a37
commit 3e4e280
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Showing 7 changed files with 141 additions and 43 deletions.
diff --git a/packages/flutter/lib/src/gestures/binding.dart b/packages/flutter/lib/src/gestures/binding.dart
@@ -366,7  366,7 @@ mixin GestureBinding on BindingBase implements HitTestable, HitTestDispatcher, H
 
     if (resamplingEnabled) {
       _resampler.addOrDispatch(event);
-      _resampler.sample(samplingOffset, _samplingClock);
       _resampler.sample(samplingOffset, samplingClock);
       return;
     }
 
@@ -505,24  505,29 @@ mixin GestureBinding on BindingBase implements HitTestable, HitTestDispatcher, H
     _hitTests.clear();
   }
 
-  /// Overrides the sampling clock for debugging and testing.
-  ///
-  /// This value is ignored in non-debug builds.
-  @protected
-  SamplingClock? get debugSamplingClock => null;
-
   void _handleSampleTimeChanged() {
     if (!locked) {
       if (resamplingEnabled) {
-        _resampler.sample(samplingOffset, _samplingClock);
         _resampler.sample(samplingOffset, samplingClock);
       }
       else {
         _resampler.stop();
       }
     }
   }
 
-  SamplingClock get _samplingClock {
   /// Overrides the [samplingClock] for debugging and testing.
   ///
   /// This value is ignored in non-debug builds.
   @protected
   SamplingClock? get debugSamplingClock => null;
 
   /// Provides access to the current [DateTime] and `StopWatch` objects for
   /// sampling.
   ///
   /// Overridden by [debugSamplingClock] for debug builds and testing. Using
   /// this object under test will maintain synchronization with [FakeAsync].
   SamplingClock get samplingClock {
     SamplingClock value = SamplingClock();
     assert(() {
       final SamplingClock? debugValue = debugSamplingClock;

diff --git a/packages/flutter/lib/src/gestures/velocity_tracker.dart b/packages/flutter/lib/src/gestures/velocity_tracker.dart
@@ -5,6  5,7 @@
 
 import 'package:flutter/foundation.dart';
 
 import 'binding.dart';
 import 'events.dart';
 import 'lsq_solver.dart';
 
@@ -149,12  150,21 @@ class VelocityTracker {
   /// The kind of pointer this tracker is for.
   final PointerDeviceKind kind;
 
   // Time difference since the last sample was added
   Stopwatch get _sinceLastSample {
     _stopwatch ??= GestureBinding.instance.samplingClock.stopwatch();
     return _stopwatch!;
   }
   Stopwatch? _stopwatch;
 
   // Circular buffer; current sample at _index.
   final List<_PointAtTime?> _samples = List<_PointAtTime?>.filled(_historySize, null);
   int _index = 0;
 
   /// Adds a position as the given time to the tracker.
   void addPosition(Duration time, Offset position) {
     _sinceLastSample.start();
     _sinceLastSample.reset();
     _index  = 1;
     if (_index == _historySize) {
       _index = 0;
@@ -169,6  179,16 @@ class VelocityTracker {
   ///
   /// Returns null if there is no data on which to base an estimate.
   VelocityEstimate? getVelocityEstimate() {
     // Has user recently moved since last sample?
     if (_sinceLastSample.elapsedMilliseconds > VelocityTracker._assumePointerMoveStoppedMilliseconds) {
       return const VelocityEstimate(
         pixelsPerSecond: Offset.zero,
         confidence: 1.0,
         duration: Duration.zero,
         offset: Offset.zero,
       );
     }
 
     final List<double> x = <double>[];
     final List<double> y = <double>[];
     final List<double> w = <double>[];
@@ -195,7  215,7 @@ class VelocityTracker {
       final double age = (newestSample.time - sample.time).inMicroseconds.toDouble() / 1000;
       final double delta = (sample.time - previousSample.time).inMicroseconds.abs().toDouble() / 1000;
       previousSample = sample;
-      if (age > _horizonMilliseconds || delta > _assumePointerMoveStoppedMilliseconds) {
       if (age > _horizonMilliseconds || delta > VelocityTracker._assumePointerMoveStoppedMilliseconds) {
         break;
       }
 
@@ -288,6  308,8 @@ class IOSScrollViewFlingVelocityTracker extends VelocityTracker {
 
   @override
   void addPosition(Duration time, Offset position) {
     _sinceLastSample.start();
     _sinceLastSample.reset();
     assert(() {
       final _PointAtTime? previousPoint = _touchSamples[_index];
       if (previousPoint == null || previousPoint.time <= time) {
@@ -326,6  348,16 @@ class IOSScrollViewFlingVelocityTracker extends VelocityTracker {
 
   @override
   VelocityEstimate getVelocityEstimate() {
     // Has user recently moved since last sample?
     if (_sinceLastSample.elapsedMilliseconds > VelocityTracker._assumePointerMoveStoppedMilliseconds) {
       return const VelocityEstimate(
         pixelsPerSecond: Offset.zero,
         confidence: 1.0,
         duration: Duration.zero,
         offset: Offset.zero,
       );
     }
 
     // The velocity estimated using this expression is an approximation of the
     // scroll velocity of an iOS scroll view at the moment the user touch was
     // released, not the final velocity of the iOS pan gesture recognizer
@@ -387,6  419,16 @@ class MacOSScrollViewFlingVelocityTracker extends IOSScrollViewFlingVelocityTrac
 
   @override
   VelocityEstimate getVelocityEstimate() {
     // Has user recently moved since last sample?
     if (_sinceLastSample.elapsedMilliseconds > VelocityTracker._assumePointerMoveStoppedMilliseconds) {
       return const VelocityEstimate(
         pixelsPerSecond: Offset.zero,
         confidence: 1.0,
         duration: Duration.zero,
         offset: Offset.zero,
       );
     }
 
     // The velocity estimated using this expression is an approximation of the
     // scroll velocity of a macOS scroll view at the moment the user touch was
     // released.

diff --git a/packages/flutter/test/gestures/gesture_binding_resample_event_on_widget_test.dart b/packages/flutter/test/gestures/gesture_binding_resample_event_on_widget_test.dart
@@ -4,35  4,17 @@
 
 import 'dart:ui' as ui;
 
-import 'package:clock/clock.dart';
 import 'package:flutter/gestures.dart';
 import 'package:flutter/scheduler.dart';
 import 'package:flutter/widgets.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:leak_tracker_flutter_testing/leak_tracker_flutter_testing.dart';
 
-class TestResampleEventFlutterBinding extends AutomatedTestWidgetsFlutterBinding {
-  @override
-  SamplingClock? get debugSamplingClock => TestSamplingClock(this.clock);
-}
-
-class TestSamplingClock implements SamplingClock {
-  TestSamplingClock(this._clock);
-
-  @override
-  DateTime now() => _clock.now();
-
-  @override
-  Stopwatch stopwatch() => _clock.stopwatch();
-
-  final Clock _clock;
-}
-
 void main() {
-  final TestWidgetsFlutterBinding binding = TestResampleEventFlutterBinding();
   testWidgetsWithLeakTracking('PointerEvent resampling on a widget', (WidgetTester tester) async {
-    assert(WidgetsBinding.instance == binding);
-    Duration currentTestFrameTime() => Duration(milliseconds: binding.clock.now().millisecondsSinceEpoch);
     Duration currentTestFrameTime() => Duration(
       milliseconds: TestWidgetsFlutterBinding.instance.clock.now().millisecondsSinceEpoch,
     );
     void requestFrame() => SchedulerBinding.instance.scheduleFrameCallback((_) {});
     final Duration epoch = currentTestFrameTime();
     final ui.PointerDataPacket packet = ui.PointerDataPacket(

diff --git a/packages/flutter/test/gestures/gesture_tester.dart b/packages/flutter/test/gestures/gesture_tester.dart
@@ -4,7  4,7 @@
 
 import 'package:fake_async/fake_async.dart';
 import 'package:flutter/gestures.dart';
-import 'package:flutter_test/flutter_test.dart';
 import 'package:leak_tracker_flutter_testing/leak_tracker_flutter_testing.dart';
 import 'package:meta/meta.dart';
 
 class GestureTester {
@@ -26,7  26,7 @@ typedef GestureTest = void Function(GestureTester tester);
 
 @isTest
 void testGesture(String description, GestureTest callback) {
-  test(description, () {
   testWidgetsWithLeakTracking(description, (_) async {
     FakeAsync().run((FakeAsync async) {
       callback(GestureTester._(async));
     });

diff --git a/packages/flutter/test/gestures/velocity_tracker_test.dart b/packages/flutter/test/gestures/velocity_tracker_test.dart
@@ -4,6  4,8 @@
 
 import 'package:flutter/gestures.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:leak_tracker_flutter_testing/leak_tracker_flutter_testing.dart';
 
 import 'velocity_tracker_data.dart';
 
 bool _withinTolerance(double actual, double expected) {
@@ -34,7  36,7 @@ void main() {
     Offset(-71.51939428321249, 3716.7385187526947),
   ];
 
-  test('Velocity tracker gives expected results', () {
   testWidgetsWithLeakTracking('Velocity tracker gives expected results', (WidgetTester tester) async {
     final VelocityTracker tracker = VelocityTracker.withKind(PointerDeviceKind.touch);
     int i = 0;
     for (final PointerEvent event in velocityEventData) {
@@ -48,7  50,7 @@ void main() {
     }
   });
 
-  test('Velocity control test', () {
   testWidgetsWithLeakTracking('Velocity control test', (WidgetTester tester) async {
     const Velocity velocity1 = Velocity(pixelsPerSecond: Offset(7.0, 0.0));
     const Velocity velocity2 = Velocity(pixelsPerSecond: Offset(12.0, 0.0));
     expect(velocity1, equals(const Velocity(pixelsPerSecond: Offset(7.0, 0.0))));
@@ -60,7  62,7 @@ void main() {
     expect(velocity1, hasOneLineDescription);
   });
 
-  test('Interrupted velocity estimation', () {
   testWidgetsWithLeakTracking('Interrupted velocity estimation', (WidgetTester tester) async {
     // Regression test for https://github.com/flutter/flutter/pull/7510
     final VelocityTracker tracker = VelocityTracker.withKind(PointerDeviceKind.touch);
     for (final PointerEvent event in interruptedVelocityEventData) {
@@ -73,12  75,12 @@ void main() {
     }
   });
 
-  test('No data velocity estimation', () {
   testWidgetsWithLeakTracking('No data velocity estimation', (WidgetTester tester) async {
     final VelocityTracker tracker = VelocityTracker.withKind(PointerDeviceKind.touch);
     expect(tracker.getVelocity(), Velocity.zero);
   });
 
-  test('FreeScrollStartVelocityTracker.getVelocity throws when no points', () {
   testWidgetsWithLeakTracking('FreeScrollStartVelocityTracker.getVelocity throws when no points', (WidgetTester tester) async {
     final IOSScrollViewFlingVelocityTracker tracker = IOSScrollViewFlingVelocityTracker(PointerDeviceKind.touch);
     AssertionError? exception;
     try {
@@ -90,7  92,7 @@ void main() {
     expect(exception?.toString(), contains('at least 1 point'));
   });
 
-  test('FreeScrollStartVelocityTracker.getVelocity throws when the new point precedes the previous point', () {
   testWidgetsWithLeakTracking('FreeScrollStartVelocityTracker.getVelocity throws when the new point precedes the previous point', (WidgetTester tester) async {
     final IOSScrollViewFlingVelocityTracker tracker = IOSScrollViewFlingVelocityTracker(PointerDeviceKind.touch);
     AssertionError? exception;
 
@@ -105,7  107,7 @@ void main() {
     expect(exception?.toString(), contains('has a smaller timestamp'));
   });
 
-  test('Estimate does not throw when there are more than 1 point', () {
   testWidgetsWithLeakTracking('Estimate does not throw when there are more than 1 point', (WidgetTester tester) async {
     final IOSScrollViewFlingVelocityTracker tracker = IOSScrollViewFlingVelocityTracker(PointerDeviceKind.touch);
     Offset position = Offset.zero;
     Duration time = Duration.zero;
@@ -127,7  129,7 @@ void main() {
     }
   });
 
-  test('Makes consistent velocity estimates with consistent velocity', () {
   testWidgetsWithLeakTracking('Makes consistent velocity estimates with consistent velocity', (WidgetTester tester) async {
     final IOSScrollViewFlingVelocityTracker tracker = IOSScrollViewFlingVelocityTracker(PointerDeviceKind.touch);
     Offset position = Offset.zero;
     Duration time = Duration.zero;
@@ -144,4  146,55 @@ void main() {
       }
     }
   });
 
   testWidgetsWithLeakTracking('Assume zero velocity when there are no recent samples - base VelocityTracker', (WidgetTester tester) async {
     final VelocityTracker tracker = VelocityTracker.withKind(PointerDeviceKind.touch);
     Offset position = Offset.zero;
     Duration time = Duration.zero;
     const Offset positionDelta = Offset(0, -1);
     const Duration durationDelta = Duration(seconds: 1);
 
     for (int i = 0; i < 10; i =1) {
       position  = positionDelta;
       time  = durationDelta;
       tracker.addPosition(time, position);
     }
     await tester.pumpAndSettle();
 
     expect(tracker.getVelocity().pixelsPerSecond, Offset.zero);
   });
 
   testWidgetsWithLeakTracking('Assume zero velocity when there are no recent samples - IOS', (WidgetTester tester) async {
     final IOSScrollViewFlingVelocityTracker tracker = IOSScrollViewFlingVelocityTracker(PointerDeviceKind.touch);
     Offset position = Offset.zero;
     Duration time = Duration.zero;
     const Offset positionDelta = Offset(0, -1);
     const Duration durationDelta = Duration(seconds: 1);
 
     for (int i = 0; i < 10; i =1) {
       position  = positionDelta;
       time  = durationDelta;
       tracker.addPosition(time, position);
     }
     await tester.pumpAndSettle();
 
     expect(tracker.getVelocity().pixelsPerSecond, Offset.zero);
   });
 
   testWidgetsWithLeakTracking('Assume zero velocity when there are no recent samples - MacOS', (WidgetTester tester) async {
     final MacOSScrollViewFlingVelocityTracker tracker = MacOSScrollViewFlingVelocityTracker(PointerDeviceKind.touch);
     Offset position = Offset.zero;
     Duration time = Duration.zero;
     const Offset positionDelta = Offset(0, -1);
     const Duration durationDelta = Duration(seconds: 1);
 
     for (int i = 0; i < 10; i =1) {
       position  = positionDelta;
       time  = durationDelta;
       tracker.addPosition(time, position);
     }
     await tester.pumpAndSettle();
 
     expect(tracker.getVelocity().pixelsPerSecond, Offset.zero);
   });
 }
diff --git a/packages/flutter/test/rendering/editable_gesture_test.dart b/packages/flutter/test/rendering/editable_gesture_test.dart
@@ -8,9  8,10 @@ import 'package:flutter/rendering.dart';
 import 'package:flutter_test/flutter_test.dart';
 
 void main() {
-  setUp(() => _GestureBindingSpy());
   final TestWidgetsFlutterBinding binding = _GestureBindingSpy();
 
-  test('attach and detach correctly handle gesture', () {
   testWidgets('attach and detach correctly handle gesture', (_) async {
     assert(WidgetsBinding.instance == binding);
     final TextSelectionDelegate delegate = FakeEditableTextState();
     final RenderEditable editable = RenderEditable(
       backgroundCursorColor: Colors.grey,

diff --git a/packages/flutter_test/lib/src/binding.dart b/packages/flutter_test/lib/src/binding.dart
@@ -425,6  425,9 @@ abstract class TestWidgetsFlutterBinding extends BindingBase
   /// actual current wall-clock time.
   Clock get clock;
 
   @override
   SamplingClock? get debugSamplingClock => _TestSamplingClock(clock);
 
   /// Triggers a frame sequence (build/layout/paint/etc),
   /// then flushes microtasks.
   ///
@@ -2149,6  2152,18 @@ class TestViewConfiguration extends ViewConfiguration {
   String toString() => 'TestViewConfiguration';
 }
 
 class _TestSamplingClock implements SamplingClock {
   _TestSamplingClock(this._clock);
 
   @override
   DateTime now() => _clock.now();
 
   @override
   Stopwatch stopwatch() => _clock.stopwatch();
 
   final Clock _clock;
 }
 
 const int _kPointerDecay = -2;
 
 class _LiveTestPointerRecord {