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Revert "Timer based pointer event resampling (#73042)" (#76179)

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This reverts commit 9133deb9a714b0853faeed4892b220ae7a77e5a5.
This commit is contained in:
Jenn Magder 2021-02-16 20:13:53 -08:00 committed by GitHub
parent 9133deb9a7
commit 50897c98fc
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GPG Key ID: 4AEE18F83AFDEB23
4 changed files with 61 additions and 331 deletions
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122
packages/flutter/lib/src/gestures/binding.dart
View File

@ -21,24 +21,13 @@ import 'resampler.dart';
typedef _HandleSampleTimeChangedCallback = void Function(); typedef _HandleSampleTimeChangedCallback = void Function();
/// Class that implements clock used for sampling.
class SamplingClock {
/// Returns current time.
DateTime now() => DateTime.now();
/// Returns a new stopwatch that uses the current time as reported by `this`.
Stopwatch stopwatch() => Stopwatch();
}
// Class that handles resampling of touch events for multiple pointer // Class that handles resampling of touch events for multiple pointer
// devices. // devices.
// //
// The `samplingInterval` is used to determine the approximate next
// time for resampling.
// SchedulerBinding's `currentSystemFrameTimeStamp` is used to determine // SchedulerBinding's `currentSystemFrameTimeStamp` is used to determine
// sample time. // sample time.
class _Resampler { class _Resampler {
_Resampler(this._handlePointerEvent, this._handleSampleTimeChanged, this._samplingInterval); _Resampler(this._handlePointerEvent, this._handleSampleTimeChanged);
// Resamplers used to filter incoming pointer events. // Resamplers used to filter incoming pointer events.
final Map<int, PointerEventResampler> _resamplers = <int, PointerEventResampler>{}; final Map<int, PointerEventResampler> _resamplers = <int, PointerEventResampler>{};
@ -46,12 +35,9 @@ class _Resampler {
// Flag to track if a frame callback has been scheduled. // Flag to track if a frame callback has been scheduled.
bool _frameCallbackScheduled = false; bool _frameCallbackScheduled = false;
// Last frame time for resampling. // Current frame time for resampling.
Duration _frameTime = Duration.zero; Duration _frameTime = Duration.zero;
// Time since `_frameTime` was updated.
Stopwatch _frameTimeAge = Stopwatch();
// Last sample time and time stamp of last event. // Last sample time and time stamp of last event.
// //
// Only used for debugPrint of resampling margin. // Only used for debugPrint of resampling margin.
@ -64,12 +50,6 @@ class _Resampler {
// Callback used to handle sample time changes. // Callback used to handle sample time changes.
final _HandleSampleTimeChangedCallback _handleSampleTimeChanged; final _HandleSampleTimeChangedCallback _handleSampleTimeChanged;
// Interval used for sampling.
final Duration _samplingInterval;
// Timer used to schedule resampling.
Timer? _timer;
// Add `event` for resampling or dispatch it directly if // Add `event` for resampling or dispatch it directly if
// not a touch event. // not a touch event.
void addOrDispatch(PointerEvent event) { void addOrDispatch(PointerEvent event) {
@ -92,43 +72,25 @@ class _Resampler {
// Sample and dispatch events. // Sample and dispatch events.
// //
// The `samplingOffset` is relative to the current frame time, which // `samplingOffset` is relative to the current frame time, which
// can be in the past when we're not actively resampling. // can be in the past when we're not actively resampling.
// The `samplingClock` is the clock used to determine frame time age. // `samplingInterval` is used to determine the approximate next
void sample(Duration samplingOffset, SamplingClock clock) { // time for resampling.
// `currentSystemFrameTimeStamp` is used to determine the current
// frame time.
void sample(Duration samplingOffset, Duration samplingInterval) {
final SchedulerBinding? scheduler = SchedulerBinding.instance; final SchedulerBinding? scheduler = SchedulerBinding.instance;
assert(scheduler != null); assert(scheduler != null);
// Initialize `_frameTime` if needed. This will be used for periodic
// sampling when frame callbacks are not received.
if (_frameTime == Duration.zero) {
_frameTime = Duration(milliseconds: clock.now().millisecondsSinceEpoch);
_frameTimeAge = clock.stopwatch()..start();
}
// Schedule periodic resampling if `_timer` is not already active.
if (_timer?.isActive == false) {
_timer = Timer.periodic(_samplingInterval, (_) => _onSampleTimeChanged());
}
// Calculate the effective frame time by taking the number
// of sampling intervals since last time `_frameTime` was
// updated into account. This allows us to advance sample
// time without having to receive frame callbacks.
final int samplingIntervalUs = _samplingInterval.inMicroseconds;
final int elapsedIntervals = _frameTimeAge.elapsedMicroseconds ~/ samplingIntervalUs;
final int elapsedUs = elapsedIntervals * samplingIntervalUs;
final Duration frameTime = _frameTime + Duration(microseconds: elapsedUs);
// Determine sample time by adding the offset to the current // Determine sample time by adding the offset to the current
// frame time. This is expected to be in the past and not // frame time. This is expected to be in the past and not
// result in any dispatched events unless we're actively // result in any dispatched events unless we're actively
// resampling events. // resampling events.
final Duration sampleTime = frameTime + samplingOffset; final Duration sampleTime = _frameTime + samplingOffset;
// Determine next sample time by adding the sampling interval // Determine next sample time by adding the sampling interval
// to the current sample time. // to the current sample time.
final Duration nextSampleTime = sampleTime + _samplingInterval; final Duration nextSampleTime = sampleTime + samplingInterval;
// Iterate over active resamplers and sample pointer events for // Iterate over active resamplers and sample pointer events for
// current sample time. // current sample time.
@ -144,30 +106,23 @@ class _Resampler {
// Save last sample time for debugPrint of resampling margin. // Save last sample time for debugPrint of resampling margin.
_lastSampleTime = sampleTime; _lastSampleTime = sampleTime;
// Early out if another call to `sample` isn't needed.
if (_resamplers.isEmpty) {
_timer!.cancel();
return;
}
// Schedule a frame callback if another call to `sample` is needed. // Schedule a frame callback if another call to `sample` is needed.
if (!_frameCallbackScheduled) { if (!_frameCallbackScheduled && _resamplers.isNotEmpty) {
_frameCallbackScheduled = true; _frameCallbackScheduled = true;
// Add a post frame callback as this avoids producing unnecessary scheduler?.scheduleFrameCallback((_) {
// frames but ensures that sampling phase is adjusted to frame
// time when frames are produced.
scheduler?.addPostFrameCallback((_) {
_frameCallbackScheduled = false; _frameCallbackScheduled = false;
// We use `currentSystemFrameTimeStamp` here as it's critical that // We use `currentSystemFrameTimeStamp` here as it's critical that
// sample time is in the same clock as the event time stamps, and // sample time is in the same clock as the event time stamps, and
// never adjusted or scaled like `currentFrameTimeStamp`. // never adjusted or scaled like `currentFrameTimeStamp`.
_frameTime = scheduler.currentSystemFrameTimeStamp; _frameTime = scheduler.currentSystemFrameTimeStamp;
_frameTimeAge.reset(); assert(() {
// Reset timer to match phase of latest frame callback. if (debugPrintResamplingMargin) {
_timer?.cancel(); final Duration resamplingMargin = _lastEventTime - _lastSampleTime;
_timer = Timer.periodic(_samplingInterval, (_) => _onSampleTimeChanged()); debugPrint('$resamplingMargin');
// Trigger an immediate sample time change. }
_onSampleTimeChanged(); return true;
}());
_handleSampleTimeChanged();
}); });
} }
} }
@ -178,18 +133,6 @@ class _Resampler {
resampler.stop(_handlePointerEvent); resampler.stop(_handlePointerEvent);
} }
_resamplers.clear(); _resamplers.clear();
_frameTime = Duration.zero;
}
void _onSampleTimeChanged() {
assert(() {
if (debugPrintResamplingMargin) {
final Duration resamplingMargin = _lastEventTime - _lastSampleTime;
debugPrint('$resamplingMargin');
}
return true;
}());
_handleSampleTimeChanged();
} }
} }
@ -204,8 +147,7 @@ const Duration _defaultSamplingOffset = Duration(milliseconds: -38);
// The sampling interval. // The sampling interval.
// //
// Sampling interval is used to determine the approximate time for subsequent // Sampling interval is used to determine the approximate time for subsequent
// sampling. This is used to sample events when frame callbacks are not // sampling. This is used to decide if early processing of up and removed events
// being received and decide if early processing of up and removed events
// is appropriate. 16667 us for 60hz sampling interval. // is appropriate. 16667 us for 60hz sampling interval.
const Duration _samplingInterval = Duration(microseconds: 16667); const Duration _samplingInterval = Duration(microseconds: 16667);
@ -328,7 +270,7 @@ mixin GestureBinding on BindingBase implements HitTestable, HitTestDispatcher, H
if (resamplingEnabled) { if (resamplingEnabled) {
_resampler.addOrDispatch(event); _resampler.addOrDispatch(event);
_resampler.sample(samplingOffset, _samplingClock); _resampler.sample(samplingOffset, _samplingInterval);
return; return;
} }
@ -456,16 +398,10 @@ mixin GestureBinding on BindingBase implements HitTestable, HitTestDispatcher, H
_hitTests.clear(); _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() { void _handleSampleTimeChanged() {
if (!locked) { if (!locked) {
if (resamplingEnabled) { if (resamplingEnabled) {
_resampler.sample(samplingOffset, _samplingClock); _resampler.sample(samplingOffset, _samplingInterval);
} }
else { else {
_resampler.stop(); _resampler.stop();
@ -473,23 +409,11 @@ mixin GestureBinding on BindingBase implements HitTestable, HitTestDispatcher, H
} }
} }
SamplingClock get _samplingClock {
SamplingClock value = SamplingClock();
assert(() {
final SamplingClock? debugValue = debugSamplingClock;
if (debugValue != null)
value = debugValue;
return true;
}());
return value;
}
// Resampler used to filter incoming pointer events when resampling // Resampler used to filter incoming pointer events when resampling
// is enabled. // is enabled.
late final _Resampler _resampler = _Resampler( late final _Resampler _resampler = _Resampler(
_handlePointerEventImmediately, _handlePointerEventImmediately,
_handleSampleTimeChanged, _handleSampleTimeChanged,
_samplingInterval,
); );
/// Enable pointer event resampling for touch devices by setting /// Enable pointer event resampling for touch devices by setting

68
packages/flutter/test/gestures/gesture_binding_resample_event_on_widget_test.dart
View File

@ -10,35 +10,15 @@
import 'dart:ui' as ui; import 'dart:ui' as ui;
import 'package:clock/clock.dart';
import 'package:flutter/gestures.dart'; import 'package:flutter/gestures.dart';
import 'package:flutter/scheduler.dart';
import 'package:flutter/widgets.dart'; import 'package:flutter/widgets.dart';
import 'package:flutter_test/flutter_test.dart'; import 'package:flutter_test/flutter_test.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() { void main() {
final TestWidgetsFlutterBinding binding = TestResampleEventFlutterBinding(); final TestWidgetsFlutterBinding binding = AutomatedTestWidgetsFlutterBinding();
testWidgets('PointerEvent resampling on a widget', (WidgetTester tester) async { testWidgets('PointerEvent resampling on a widget', (WidgetTester tester) async {
assert(WidgetsBinding.instance == binding); assert(WidgetsBinding.instance == binding);
Duration currentTestFrameTime() => Duration(milliseconds: binding.clock.now().millisecondsSinceEpoch); Duration currentTestFrameTime() => Duration(milliseconds: binding.clock.now().millisecondsSinceEpoch);
void requestFrame() => SchedulerBinding.instance!.scheduleFrameCallback((_) {});
final Duration epoch = currentTestFrameTime(); final Duration epoch = currentTestFrameTime();
final ui.PointerDataPacket packet = ui.PointerDataPacket( final ui.PointerDataPacket packet = ui.PointerDataPacket(
data: <ui.PointerData>[ data: <ui.PointerData>[
@ -50,37 +30,37 @@ void main() {
ui.PointerData( ui.PointerData(
change: ui.PointerChange.down, change: ui.PointerChange.down,
physicalX: 0.0, physicalX: 0.0,
timeStamp: epoch + const Duration(milliseconds: 0),
),
ui.PointerData(
change: ui.PointerChange.move,
physicalX: 15.0,
timeStamp: epoch + const Duration(milliseconds: 10), timeStamp: epoch + const Duration(milliseconds: 10),
), ),
ui.PointerData( ui.PointerData(
change: ui.PointerChange.move, change: ui.PointerChange.move,
physicalX: 30.0, physicalX: 10.0,
timeStamp: epoch + const Duration(milliseconds: 20), timeStamp: epoch + const Duration(milliseconds: 20),
), ),
ui.PointerData( ui.PointerData(
change: ui.PointerChange.move, change: ui.PointerChange.move,
physicalX: 45.0, physicalX: 20.0,
timeStamp: epoch + const Duration(milliseconds: 30), timeStamp: epoch + const Duration(milliseconds: 30),
), ),
ui.PointerData( ui.PointerData(
change: ui.PointerChange.move, change: ui.PointerChange.move,
physicalX: 50.0, physicalX: 30.0,
timeStamp: epoch + const Duration(milliseconds: 40), timeStamp: epoch + const Duration(milliseconds: 40),
), ),
ui.PointerData(
change: ui.PointerChange.move,
physicalX: 40.0,
timeStamp: epoch + const Duration(milliseconds: 50),
),
ui.PointerData( ui.PointerData(
change: ui.PointerChange.up, change: ui.PointerChange.up,
physicalX: 60.0, physicalX: 40.0,
timeStamp: epoch + const Duration(milliseconds: 40), timeStamp: epoch + const Duration(milliseconds: 60),
), ),
ui.PointerData( ui.PointerData(
change: ui.PointerChange.remove, change: ui.PointerChange.remove,
physicalX: 60.0, physicalX: 40.0,
timeStamp: epoch + const Duration(milliseconds: 40), timeStamp: epoch + const Duration(milliseconds: 70),
), ),
], ],
); );
@ -104,31 +84,29 @@ void main() {
ui.window.onPointerDataPacket!(packet); ui.window.onPointerDataPacket!(packet);
expect(events.length, 0); expect(events.length, 0);
requestFrame(); await tester.pump(const Duration(milliseconds: 20));
await tester.pump(const Duration(milliseconds: 10));
expect(events.length, 1); expect(events.length, 1);
expect(events[0], isA<PointerDownEvent>()); expect(events[0], isA<PointerDownEvent>());
expect(events[0].timeStamp, currentTestFrameTime() + kSamplingOffset); expect(events[0].timeStamp, currentTestFrameTime() + kSamplingOffset);
expect(events[0].position, Offset(7.5 / ui.window.devicePixelRatio, 0.0)); expect(events[0].position, Offset(5.0 / ui.window.devicePixelRatio, 0.0));
// Now the system time is epoch + 20ms // Now the system time is epoch + 40ms
requestFrame(); await tester.pump(const Duration(milliseconds: 20));
await tester.pump(const Duration(milliseconds: 10));
expect(events.length, 2); expect(events.length, 2);
expect(events[1].timeStamp, currentTestFrameTime() + kSamplingOffset); expect(events[1].timeStamp, currentTestFrameTime() + kSamplingOffset);
expect(events[1], isA<PointerMoveEvent>()); expect(events[1], isA<PointerMoveEvent>());
expect(events[1].position, Offset(22.5 / ui.window.devicePixelRatio, 0.0)); expect(events[1].position, Offset(25.0 / ui.window.devicePixelRatio, 0.0));
expect(events[1].delta, Offset(15.0 / ui.window.devicePixelRatio, 0.0)); expect(events[1].delta, Offset(20.0 / ui.window.devicePixelRatio, 0.0));
// Now the system time is epoch + 30ms // Now the system time is epoch + 60ms
requestFrame(); await tester.pump(const Duration(milliseconds: 20));
await tester.pump(const Duration(milliseconds: 10));
expect(events.length, 4); expect(events.length, 4);
expect(events[2].timeStamp, currentTestFrameTime() + kSamplingOffset); expect(events[2].timeStamp, currentTestFrameTime() + kSamplingOffset);
expect(events[2], isA<PointerMoveEvent>()); expect(events[2], isA<PointerMoveEvent>());
expect(events[2].position, Offset(37.5 / ui.window.devicePixelRatio, 0.0)); expect(events[2].position, Offset(40.0 / ui.window.devicePixelRatio, 0.0));
expect(events[2].delta, Offset(15.0 / ui.window.devicePixelRatio, 0.0)); expect(events[2].delta, Offset(15.0 / ui.window.devicePixelRatio, 0.0));
expect(events[3].timeStamp, currentTestFrameTime() + kSamplingOffset); expect(events[3].timeStamp, currentTestFrameTime() + kSamplingOffset);
expect(events[3], isA<PointerUpEvent>()); expect(events[3], isA<PointerUpEvent>());
expect(events[3].position, Offset(40.0 / ui.window.devicePixelRatio, 0.0));
}); });
} }

186
packages/flutter/test/gestures/gesture_binding_resample_event_test.dart
View File

@ -1,186 +0,0 @@
// Copyright 2014 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
import 'dart:ui' as ui;
import 'package:clock/clock.dart';
import 'package:fake_async/fake_async.dart';
import 'package:flutter/foundation.dart';
import 'package:flutter/gestures.dart';
import 'package:flutter/scheduler.dart';
import '../flutter_test_alternative.dart';
typedef HandleEventCallback = void Function(PointerEvent event);
class TestResampleEventFlutterBinding extends BindingBase with GestureBinding, SchedulerBinding {
HandleEventCallback? callback;
FrameCallback? postFrameCallback;
Duration? frameTime;
@override
void handleEvent(PointerEvent event, HitTestEntry entry) {
super.handleEvent(event, entry);
if (callback != null)
callback?.call(event);
}
@override
Duration get currentSystemFrameTimeStamp {
assert(frameTime != null);
return frameTime!;
}
@override
int addPostFrameCallback(FrameCallback callback) {
postFrameCallback = callback;
return 0;
}
@override
SamplingClock? get debugSamplingClock => TestSamplingClock();
}
class TestSamplingClock implements SamplingClock {
@override
DateTime now() => clock.now();
@override
Stopwatch stopwatch() => clock.stopwatch();
}
typedef ResampleEventTest = void Function(FakeAsync async);
void testResampleEvent(String description, ResampleEventTest callback) {
test(description, () {
fakeAsync((FakeAsync async) {
callback(async);
}, initialTime: DateTime.utc(2015, 1, 1));
}, skip: isBrowser); // Fake clock is not working with the web platform.
}
void main() {
final TestResampleEventFlutterBinding binding = TestResampleEventFlutterBinding();
testResampleEvent('Pointer event resampling', (FakeAsync async) {
Duration currentTime() => Duration(milliseconds: clock.now().millisecondsSinceEpoch);
final Duration epoch = currentTime();
final ui.PointerDataPacket packet = ui.PointerDataPacket(
data: <ui.PointerData>[
ui.PointerData(
change: ui.PointerChange.add,
physicalX: 0.0,
timeStamp: epoch + const Duration(milliseconds: 0),
),
ui.PointerData(
change: ui.PointerChange.down,
physicalX: 0.0,
timeStamp: epoch + const Duration(milliseconds: 10),
),
ui.PointerData(
change: ui.PointerChange.move,
physicalX: 10.0,
timeStamp: epoch + const Duration(milliseconds: 20),
),
ui.PointerData(
change: ui.PointerChange.move,
physicalX: 20.0,
timeStamp: epoch + const Duration(milliseconds: 30),
),
ui.PointerData(
change: ui.PointerChange.move,
physicalX: 30.0,
timeStamp: epoch + const Duration(milliseconds: 40),
),
ui.PointerData(
change: ui.PointerChange.move,
physicalX: 40.0,
timeStamp: epoch + const Duration(milliseconds: 50),
),
ui.PointerData(
change: ui.PointerChange.move,
physicalX: 50.0,
timeStamp: epoch + const Duration(milliseconds: 60),
),
ui.PointerData(
change: ui.PointerChange.up,
physicalX: 50.0,
timeStamp: epoch + const Duration(milliseconds: 70),
),
ui.PointerData(
change: ui.PointerChange.remove,
physicalX: 50.0,
timeStamp: epoch + const Duration(milliseconds: 70),
),
],
);
const Duration samplingOffset = Duration(milliseconds: -5);
const Duration frameInterval = Duration(microseconds: 16667);
GestureBinding.instance!.resamplingEnabled = true;
GestureBinding.instance!.samplingOffset = samplingOffset;
final List<PointerEvent> events = <PointerEvent>[];
binding.callback = events.add;
ui.window.onPointerDataPacket?.call(packet);
// No pointer events should have been dispatched yet.
expect(events.length, 0);
// Frame callback should have been requested.
FrameCallback? callback = binding.postFrameCallback;
binding.postFrameCallback = null;
expect(callback, isNotNull);
binding.frameTime = epoch + const Duration(milliseconds: 15);
callback!(Duration.zero);
// One pointer event should have been dispatched.
expect(events.length, 1);
expect(events[0], isA<PointerDownEvent>());
expect(events[0].timeStamp, binding.frameTime! + samplingOffset);
expect(events[0].position, Offset(0.0 / ui.window.devicePixelRatio, 0.0));
// Second frame callback should have been requested.
callback = binding.postFrameCallback;
binding.postFrameCallback = null;
expect(callback, isNotNull);
final Duration frameTime = epoch + const Duration(milliseconds: 25);
binding.frameTime = frameTime;
callback!(Duration.zero);
// Second pointer event should have been dispatched.
expect(events.length, 2);
expect(events[1], isA<PointerMoveEvent>());
expect(events[1].timeStamp, binding.frameTime! + samplingOffset);
expect(events[1].position, Offset(10.0 / ui.window.devicePixelRatio, 0.0));
expect(events[1].delta, Offset(10.0 / ui.window.devicePixelRatio, 0.0));
// Verify that resampling continues without a frame callback.
async.elapse(frameInterval * 1.5);
// Third pointer event should have been dispatched.
expect(events.length, 3);
expect(events[2], isA<PointerMoveEvent>());
expect(events[2].timeStamp, frameTime + frameInterval + samplingOffset);
async.elapse(frameInterval);
// Remaining pointer events should have been dispatched.
expect(events.length, 5);
expect(events[3], isA<PointerMoveEvent>());
expect(events[3].timeStamp, frameTime + frameInterval * 2 + samplingOffset);
expect(events[4], isA<PointerUpEvent>());
expect(events[4].timeStamp, frameTime + frameInterval * 2 + samplingOffset);
async.elapse(frameInterval);
// No more pointer events should have been dispatched.
expect(events.length, 5);
GestureBinding.instance!.resamplingEnabled = false;
});
}

14
packages/flutter/test/gestures/gesture_binding_test.dart
View File

@ -14,6 +14,8 @@ typedef HandleEventCallback = void Function(PointerEvent event);
class TestGestureFlutterBinding extends BindingBase with GestureBinding, SchedulerBinding { class TestGestureFlutterBinding extends BindingBase with GestureBinding, SchedulerBinding {
HandleEventCallback? callback; HandleEventCallback? callback;
FrameCallback? frameCallback;
Duration? frameTime;
@override @override
void handleEvent(PointerEvent event, HitTestEntry entry) { void handleEvent(PointerEvent event, HitTestEntry entry) {
@ -21,6 +23,18 @@ class TestGestureFlutterBinding extends BindingBase with GestureBinding, Schedul
if (callback != null) if (callback != null)
callback?.call(event); callback?.call(event);
} }
@override
Duration get currentSystemFrameTimeStamp {
assert(frameTime != null);
return frameTime!;
}
@override
int scheduleFrameCallback(FrameCallback callback, {bool rescheduling = false}) {
frameCallback = callback;
return 0;
}
} }
TestGestureFlutterBinding? _binding; TestGestureFlutterBinding? _binding;