DEV/flutter_flutter
1
0
Fork 0
mirror of https://github.com/flutter/flutter.git synced 2026-02-20 02:29:02 +08:00
Code Issues Packages Projects Releases Wiki Activity

Merge pull request #2227 from abarth/scroll_events

Browse Source 
Scrollable's callbacks should follow a state machine
This commit is contained in:
Adam Barth 2016-02-26 14:47:53 -08:00
commit 6ecbd548c4
4 changed files with 138 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

45
packages/flutter/lib/src/widgets/scrollable.dart
View File

@ -290,7 +290,8 @@ abstract class ScrollableState<T extends Scrollable> extends State<T> {
Future _animateTo(double newScrollOffset, Duration duration, Curve curve) {
_controller.stop();
_controller.value = scrollOffset;
return _controller.animateTo(newScrollOffset, duration: duration, curve: curve);
_dispatchOnScrollStartIfNeeded();
return _controller.animateTo(newScrollOffset, duration: duration, curve: curve).then(_dispatchOnScrollEndIfNeeded);
}
bool _scrollOffsetIsInBounds(double scrollOffset) {
@ -303,7 +304,7 @@ abstract class ScrollableState<T extends Scrollable> extends State<T> {
Simulation _createFlingSimulation(double scrollVelocity) {
final Simulation simulation = scrollBehavior.createFlingScrollSimulation(scrollOffset, scrollVelocity);
if (simulation != null) {
final double endVelocity = pixelOffsetToScrollOffset(kPixelScrollTolerance.velocity) * scrollVelocity.sign;
final double endVelocity = pixelOffsetToScrollOffset(kPixelScrollTolerance.velocity).abs() * (scrollVelocity < 0.0 ? -1.0 : 1.0);
final double endDistance = pixelOffsetToScrollOffset(kPixelScrollTolerance.distance).abs();
simulation.tolerance = new Tolerance(velocity: endVelocity, distance: endDistance);
}
@ -336,7 +337,7 @@ abstract class ScrollableState<T extends Scrollable> extends State<T> {
return null;
final double snapVelocity = scrollVelocity.abs() * (snappedScrollOffset - scrollOffset).sign;
final double endVelocity = pixelOffsetToScrollOffset(kPixelScrollTolerance.velocity).abs() * scrollVelocity.sign;
final double endVelocity = pixelOffsetToScrollOffset(kPixelScrollTolerance.velocity).abs() * (scrollVelocity < 0.0 ? -1.0 : 1.0);
Simulation toSnapSimulation = scrollBehavior.createSnapScrollSimulation(
scrollOffset, snappedScrollOffset, snapVelocity, endVelocity
);
@ -353,7 +354,8 @@ abstract class ScrollableState<T extends Scrollable> extends State<T> {
Simulation simulation = _createSnapSimulation(scrollVelocity) ?? _createFlingSimulation(scrollVelocity);
if (simulation == null)
return new Future.value();
return _controller.animateWith(simulation);
_dispatchOnScrollStartIfNeeded();
return _controller.animateWith(simulation).then(_dispatchOnScrollEndIfNeeded);
}
void dispose() {
@ -373,7 +375,15 @@ abstract class ScrollableState<T extends Scrollable> extends State<T> {
});
PageStorage.of(context)?.writeState(context, _scrollOffset);
new ScrollNotification(this, _scrollOffset).dispatch(context);
final needsScrollStart = !_isBetweenOnScrollStartAndOnScrollEnd;
if (needsScrollStart) {
dispatchOnScrollStart();
assert(_isBetweenOnScrollStartAndOnScrollEnd);
}
dispatchOnScroll();
assert(_isBetweenOnScrollStartAndOnScrollEnd);
if (needsScrollStart)
dispatchOnScrollEnd();
}
/// Scroll this widget to the given scroll offset.
@ -413,10 +423,8 @@ abstract class ScrollableState<T extends Scrollable> extends State<T> {
/// offset with the given value as the initial velocity. The physics
/// simulation used is determined by the scroll behavior.
Future fling(double scrollVelocity) {
if (scrollVelocity != 0.0)
if (scrollVelocity != 0.0 || !_controller.isAnimating)
return _startToEndAnimation(scrollVelocity);
if (!_controller.isAnimating)
return settleScrollOffset();
return new Future.value();
}
@ -429,10 +437,24 @@ abstract class ScrollableState<T extends Scrollable> extends State<T> {
return _startToEndAnimation(0.0);
}
bool _isBetweenOnScrollStartAndOnScrollEnd = false;
void _dispatchOnScrollStartIfNeeded() {
if (!_isBetweenOnScrollStartAndOnScrollEnd)
dispatchOnScrollStart();
}
void _dispatchOnScrollEndIfNeeded(_) {
if (_isBetweenOnScrollStartAndOnScrollEnd)
dispatchOnScrollEnd();
}
/// Calls the onScrollStart callback.
///
/// Subclasses can override this function to hook the scroll start callback.
void dispatchOnScrollStart() {
assert(!_isBetweenOnScrollStartAndOnScrollEnd);
_isBetweenOnScrollStartAndOnScrollEnd = true;
if (config.onScrollStart != null)
config.onScrollStart(_scrollOffset);
}
@ -441,6 +463,7 @@ abstract class ScrollableState<T extends Scrollable> extends State<T> {
///
/// Subclasses can override this function to hook the scroll callback.
void dispatchOnScroll() {
assert(_isBetweenOnScrollStartAndOnScrollEnd);
if (config.onScroll != null)
config.onScroll(_scrollOffset);
}
@ -449,6 +472,8 @@ abstract class ScrollableState<T extends Scrollable> extends State<T> {
///
/// Subclasses can override this function to hook the scroll end callback.
void dispatchOnScrollEnd() {
assert(_isBetweenOnScrollStartAndOnScrollEnd);
_isBetweenOnScrollStartAndOnScrollEnd = false;
if (config.onScrollEnd != null)
config.onScrollEnd(_scrollOffset);
}
@ -458,7 +483,7 @@ abstract class ScrollableState<T extends Scrollable> extends State<T> {
}
void _handleDragStart(_) {
dispatchOnScrollStart();
_dispatchOnScrollStartIfNeeded();
}
void _handleDragUpdate(double delta) {
@ -468,9 +493,7 @@ abstract class ScrollableState<T extends Scrollable> extends State<T> {
Future _handleDragEnd(Velocity velocity) {
double scrollVelocity = pixelDeltaToScrollOffset(velocity.pixelsPerSecond) / Duration.MILLISECONDS_PER_SECOND;
// The gesture velocity properties are pixels/second, config min,max limits are pixels/ms
return fling(scrollVelocity.clamp(-kMaxFlingVelocity, kMaxFlingVelocity)).then((_) {
dispatchOnScrollEnd();
});
return fling(scrollVelocity.clamp(-kMaxFlingVelocity, kMaxFlingVelocity)).then(_dispatchOnScrollEndIfNeeded);
}
}

98
packages/flutter/test/widget/scroll_events_test.dart Normal file
View File

@ -0,0 +1,98 @@
// Copyright 2015 The Chromium 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 'package:flutter_test/flutter_test.dart';
import 'package:flutter/widgets.dart';
import 'package:test/test.dart';
Widget _buildScroller({Key key, List<String> log}) {
return new ScrollableViewport(
key: key,
onScrollStart: (double scrollOffset) {
log.add('scrollstart');
},
onScroll: (double scrollOffset) {
log.add('scroll');
},
onScrollEnd: (double scrollOffset) {
log.add('scrollend');
},
child: new Container(width: 1000.0, height: 1000.0)
);
}
void main() {
test('Scroll event drag', () {
testWidgets((WidgetTester tester) {
List<String> log = <String>[];
tester.pumpWidget(_buildScroller(log: log));
expect(log, equals([]));
TestGesture gesture = tester.startGesture(new Point(100.0, 100.0));
expect(log, equals(['scrollstart']));
tester.pump(const Duration(seconds: 1));
expect(log, equals(['scrollstart']));
gesture.moveBy(new Offset(-10.0, -10.0));
expect(log, equals(['scrollstart', 'scroll']));
tester.pump(const Duration(seconds: 1));
expect(log, equals(['scrollstart', 'scroll']));
gesture.up();
expect(log, equals(['scrollstart', 'scroll']));
tester.pump(const Duration(seconds: 1));
expect(log, equals(['scrollstart', 'scroll', 'scrollend']));
});
});
test('Scroll scrollTo animation', () {
testWidgets((WidgetTester tester) {
GlobalKey<ScrollableState> scrollKey = new GlobalKey<ScrollableState>();
List<String> log = <String>[];
tester.pumpWidget(_buildScroller(key: scrollKey, log: log));
expect(log, equals([]));
scrollKey.currentState.scrollTo(100.0, duration: const Duration(seconds: 1));
expect(log, equals(['scrollstart']));
tester.pump(const Duration(milliseconds: 100));
expect(log, equals(['scrollstart']));
tester.pump(const Duration(milliseconds: 100));
expect(log, equals(['scrollstart', 'scroll']));
tester.pump(const Duration(milliseconds: 1500));
expect(log, equals(['scrollstart', 'scroll', 'scroll', 'scrollend']));
});
});
test('Scroll scrollTo no animation', () {
testWidgets((WidgetTester tester) {
GlobalKey<ScrollableState> scrollKey = new GlobalKey<ScrollableState>();
List<String> log = <String>[];
tester.pumpWidget(_buildScroller(key: scrollKey, log: log));
expect(log, equals([]));
scrollKey.currentState.scrollTo(100.0);
expect(log, equals(['scrollstart', 'scroll', 'scrollend']));
});
});
test('Scroll during animation', () {
testWidgets((WidgetTester tester) {
GlobalKey<ScrollableState> scrollKey = new GlobalKey<ScrollableState>();
List<String> log = <String>[];
tester.pumpWidget(_buildScroller(key: scrollKey, log: log));
expect(log, equals([]));
scrollKey.currentState.scrollTo(100.0, duration: const Duration(seconds: 1));
expect(log, equals(['scrollstart']));
tester.pump(const Duration(milliseconds: 100));
expect(log, equals(['scrollstart']));
tester.pump(const Duration(milliseconds: 100));
expect(log, equals(['scrollstart', 'scroll']));
scrollKey.currentState.scrollTo(100.0);
expect(log, equals(['scrollstart', 'scroll', 'scroll']));
tester.pump(const Duration(milliseconds: 100));
expect(log, equals(['scrollstart', 'scroll', 'scroll', 'scrollend']));
tester.pump(const Duration(milliseconds: 1500));
expect(log, equals(['scrollstart', 'scroll', 'scroll', 'scrollend']));
});
});
}

4
packages/newton/lib/src/scroll_simulation.dart
View File

@ -64,4 +64,8 @@ class ScrollSimulation extends SimulationGroup {
return false;
}
String toString() {
return 'ScrollSimulation(leadingExtent: $_leadingExtent, trailingExtent: $_trailingExtent)';
}
}

2
packages/newton/lib/src/tolerance.dart
View File

@ -11,6 +11,8 @@ class Tolerance {
const Tolerance({this.distance: epsilonDefault, this.time: epsilonDefault,
this.velocity: epsilonDefault});
String toString() => 'Tolerance(distance: $distance, time=$time, velocity: $velocity)';
}
const double epsilonDefault = 1e-3;