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Unverified Commit 32ee0084 authored by renyou's avatar renyou Committed by GitHub
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Revert "Fix RangeMaintainingScrollPhysics" (#63611)

parent 360023e2
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Showing with 16 additions and 414 deletions
packages/flutter/lib/src/widgets/scroll_physics.dart
View file @ 32ee0084
......@@ -412,45 +412,6 @@ class ScrollPhysics {
/// These physics should be combined with other scroll physics, e.g.
/// [BouncingScrollPhysics] or [ClampingScrollPhysics], to obtain a complete
/// description of typical scroll physics. See [applyTo].
///
/// ## Implementation details
///
/// Specifically, these physics perform two adjustments.
///
/// The first is to maintain overscroll when the position is out of range.
///
/// The second is to enforce the boundary when the position is in range.
///
/// If the current velocity is zero, neither adjustment is made. The
/// assumption is that there is an ongoing animation and therefore
/// further changing the scroll position would disrupt the experience.
///
/// If the extents haven't changed, then the overscroll adjustment is
/// not made. The assumption is that if the position is overscrolled,
/// it is intentional, otherwise the position could not have reached
/// that position. (Consider [ClampingScrollPhysics] vs
/// [BouncingScrollPhysics] for example.)
///
/// If the position itself changed since the last animation frame,
/// then the overscroll is not maintained. The assumption is similar
/// to the previous case: the position would not have been placed out
/// of range unless it was intentional.
///
/// In addition, if the position changed and the boundaries were and
/// still are finite, then the boundary isn't enforced either, for
/// the same reason. However, if any of the boundaries were or are
/// now infinite, the boundary _is_ enforced, on the assumption that
/// infinite boundaries indicate a lazy-loading scroll view, which
/// cannot enforce boundaries while the full list has not loaded.
///
/// If the range was out of range, then the boundary is not enforced
/// even if the range is not maintained. If the range is maintained,
/// then the distance between the old position and the old boundary is
/// applied to the new boundary to obtain the new position.
///
/// If the range was in range, and the boundary is to be enforced,
/// then the new position is obtained by deferring to the other physics,
/// if any, and then clamped to the new range.
class RangeMaintainingScrollPhysics extends ScrollPhysics {
/// Creates scroll physics that maintain the scroll position in range.
const RangeMaintainingScrollPhysics({ ScrollPhysics parent }) : super(parent: parent);
......@@ -467,60 +428,18 @@ class RangeMaintainingScrollPhysics extends ScrollPhysics {
@required bool isScrolling,
@required double velocity,
}) {
bool maintainOverscroll = true;
bool enforceBoundary = true;
if (velocity != 0.0) {
// Don't try to adjust an animating position, the jumping around
// would be distracting.
maintainOverscroll = false;
enforceBoundary = false;
}
if ((oldPosition.minScrollExtent == newPosition.minScrollExtent) &&
(oldPosition.maxScrollExtent == newPosition.maxScrollExtent)) {
// If the extents haven't changed then ignore overscroll.
maintainOverscroll = false;
}
if (oldPosition.pixels != newPosition.pixels) {
// If the position has been changed already, then it might have
// been adjusted to expect new overscroll, so don't try to
// maintain the relative overscroll.
maintainOverscroll = false;
if (oldPosition.minScrollExtent.isFinite && oldPosition.maxScrollExtent.isFinite &&
newPosition.minScrollExtent.isFinite && newPosition.maxScrollExtent.isFinite) {
// In addition, if the position changed then we only enforce
// the new boundary if the previous boundary was not entirely
// finite. A common case where the position changes while one
// of the extents is infinite is a lazily-loaded list. (If the
// boundaries were finite, and the position changed, then we
// assume it was intentional.)
enforceBoundary = false;
}
}
if ((oldPosition.pixels < oldPosition.minScrollExtent) &&
(oldPosition.pixels > oldPosition.maxScrollExtent)) {
// If the old position was out of range, then we should
// not try to keep the new position in range.
enforceBoundary = false;
if (velocity != 0.0 || ((oldPosition.minScrollExtent == newPosition.minScrollExtent) && (oldPosition.maxScrollExtent == newPosition.maxScrollExtent))) {
return super.adjustPositionForNewDimensions(oldPosition: oldPosition, newPosition: newPosition, isScrolling: isScrolling, velocity: velocity);
}
if (maintainOverscroll) {
// Force the new position to be no more out of range
// than it was before, if it was overscrolled.
if (oldPosition.pixels < oldPosition.minScrollExtent) {
final double oldDelta = oldPosition.minScrollExtent - oldPosition.pixels;
return newPosition.minScrollExtent - oldDelta;
}
if (oldPosition.pixels > oldPosition.maxScrollExtent) {
final double oldDelta = oldPosition.pixels - oldPosition.maxScrollExtent;
return newPosition.maxScrollExtent + oldDelta;
}
if (oldPosition.pixels < oldPosition.minScrollExtent) {
final double oldDelta = oldPosition.minScrollExtent - oldPosition.pixels;
return newPosition.minScrollExtent - oldDelta;
}
// If we're not forcing the overscroll, defer to other physics.
double result = super.adjustPositionForNewDimensions(oldPosition: oldPosition, newPosition: newPosition, isScrolling: isScrolling, velocity: velocity);
if (enforceBoundary) {
// ...but if they put us out of range then reinforce the boundary.
result = result.clamp(newPosition.minScrollExtent, newPosition.maxScrollExtent) as double;
if (oldPosition.pixels > oldPosition.maxScrollExtent) {
final double oldDelta = oldPosition.pixels - oldPosition.maxScrollExtent;
return newPosition.maxScrollExtent + oldDelta;
}
return result;
return newPosition.pixels.clamp(newPosition.minScrollExtent, newPosition.maxScrollExtent) as double;
}
}
......
packages/flutter/lib/src/widgets/scroll_position.dart
View file @ 32ee0084
......@@ -226,7 +226,7 @@ abstract class ScrollPosition extends ViewportOffset with ScrollMetrics {
/// If there is any overscroll, it is reported using [didOverscrollBy].
double setPixels(double newPixels) {
assert(_pixels != null);
assert(SchedulerBinding.instance.schedulerPhase != SchedulerPhase.persistentCallbacks, 'A scrollable\'s position should not change during the build, layout, and paint phases, otherwise the rendering will be confused.');
assert(SchedulerBinding.instance.schedulerPhase.index <= SchedulerPhase.transientCallbacks.index);
if (newPixels != pixels) {
final double overscroll = applyBoundaryConditions(newPixels);
assert(() {
......@@ -471,37 +471,27 @@ abstract class ScrollPosition extends ViewportOffset with ScrollMetrics {
return true;
}
bool _pendingDimensions = false;
ScrollMetrics _lastMetrics;
@override
bool applyContentDimensions(double minScrollExtent, double maxScrollExtent) {
assert(minScrollExtent != null);
assert(maxScrollExtent != null);
assert(haveDimensions == (_lastMetrics != null));
if (!nearEqual(_minScrollExtent, minScrollExtent, Tolerance.defaultTolerance.distance) ||
!nearEqual(_maxScrollExtent, maxScrollExtent, Tolerance.defaultTolerance.distance) ||
_didChangeViewportDimensionOrReceiveCorrection) {
assert(minScrollExtent != null);
assert(maxScrollExtent != null);
assert(minScrollExtent <= maxScrollExtent);
final ScrollMetrics oldPosition = haveDimensions ? copyWith() : null;
_minScrollExtent = minScrollExtent;
_maxScrollExtent = maxScrollExtent;
final ScrollMetrics currentMetrics = haveDimensions ? copyWith() : null;
final ScrollMetrics newPosition = haveDimensions ? copyWith() : null;
_didChangeViewportDimensionOrReceiveCorrection = false;
_pendingDimensions = true;
if (haveDimensions && !correctForNewDimensions(_lastMetrics, currentMetrics)) {
if (haveDimensions && !correctForNewDimensions(oldPosition, newPosition))
return false;
}
_haveDimensions = true;
}
assert(haveDimensions);
if (_pendingDimensions) {
applyNewDimensions();
_pendingDimensions = false;
}
assert(!_didChangeViewportDimensionOrReceiveCorrection, 'Use correctForNewDimensions() (and return true) to change the scroll offset during applyContentDimensions().');
_lastMetrics = copyWith();
return true;
}
......@@ -556,7 +546,6 @@ abstract class ScrollPosition extends ViewportOffset with ScrollMetrics {
@mustCallSuper
void applyNewDimensions() {
assert(pixels != null);
assert(_pendingDimensions);
activity.applyNewDimensions();
_updateSemanticActions(); // will potentially request a semantics update.
}
......
packages/flutter/lib/src/widgets/scrollable.dart
View file @ 32ee0084
......@@ -694,7 +694,7 @@ class ScrollableState extends State<Scrollable> with TickerProviderStateMixin, R
key: _scrollSemanticsKey,
child: result,
position: position,
allowImplicitScrolling: _physics.allowImplicitScrolling,
allowImplicitScrolling: widget?.physics?.allowImplicitScrolling ?? _physics.allowImplicitScrolling,
semanticChildCount: widget.semanticChildCount,
);
}
......@@ -706,7 +706,6 @@ class ScrollableState extends State<Scrollable> with TickerProviderStateMixin, R
void debugFillProperties(DiagnosticPropertiesBuilder properties) {
super.debugFillProperties(properties);
properties.add(DiagnosticsProperty<ScrollPosition>('position', position));
properties.add(DiagnosticsProperty<ScrollPhysics>('effective physics', _physics));
}
@override
......@@ -974,7 +973,7 @@ class ScrollAction extends Action<ScrollIntent> {
assert(state.position.viewportDimension != null);
assert(state.position.maxScrollExtent != null);
assert(state.position.minScrollExtent != null);
assert(state._physics == null || state._physics.shouldAcceptUserOffset(state.position));
assert(state.widget.physics == null || state.widget.physics.shouldAcceptUserOffset(state.position));
if (state.widget.incrementCalculator != null) {
return state.widget.incrementCalculator(
ScrollIncrementDetails(
......@@ -1063,7 +1062,7 @@ class ScrollAction extends Action<ScrollIntent> {
assert(state.position.minScrollExtent != null);
// Don't do anything if the user isn't allowed to scroll.
if (state._physics != null && !state._physics.shouldAcceptUserOffset(state.position)) {
if (state.widget.physics != null && !state.widget.physics.shouldAcceptUserOffset(state.position)) {
return;
}
final double increment = _getIncrement(state, intent);
......
packages/flutter/test/widgets/range_maintaining_scroll_physics_test.dart
View file @ 32ee0084
......@@ -219,45 +219,4 @@ void main() {
expect(position.maxScrollExtent, 100.0);
expect(position.pixels, 0.0);
});
testWidgets('expanding page views', (WidgetTester tester) async {
await tester.pumpWidget(Padding(padding: const EdgeInsets.only(right: 200.0), child: TabBarDemo()));
await tester.tap(find.text('bike'));
await tester.pump();
await tester.pump(const Duration(seconds: 1));
final Rect bike1 = tester.getRect(find.byIcon(Icons.directions_bike));
await tester.pumpWidget(Padding(padding: EdgeInsets.zero, child: TabBarDemo()));
final Rect bike2 = tester.getRect(find.byIcon(Icons.directions_bike));
expect(bike2.center, bike1.shift(const Offset(100.0, 0.0)).center);
});
}
class TabBarDemo extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
home: DefaultTabController(
length: 3,
child: Scaffold(
appBar: AppBar(
bottom: const TabBar(
tabs: <Widget>[
Tab(text: 'car'),
Tab(text: 'transit'),
Tab(text: 'bike'),
],
),
title: const Text('Tabs Demo'),
),
body: const TabBarView(
children: <Widget>[
Icon(Icons.directions_car),
Icon(Icons.directions_transit),
Icon(Icons.directions_bike),
],
),
),
),
);
}
}
\ No newline at end of file
packages/flutter/test/widgets/scroll_activity_test.dart deleted 100644 → 0
View file @ 360023e2
// 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.
// @dart = 2.8
import 'package:flutter/material.dart';
import 'package:flutter/scheduler.dart';
import 'package:flutter_test/flutter_test.dart';
List<Widget> children(int n) {
return List<Widget>.generate(n, (int i) {
return Container(height: 100.0, child: Text('$i'));
});
}
void main() {
testWidgets('Scrolling with list view changes', (WidgetTester tester) async {
final ScrollController controller = ScrollController();
await tester.pumpWidget(MaterialApp(home: ListView(children: children(30), controller: controller)));
final double thirty = controller.position.maxScrollExtent;
controller.jumpTo(thirty);
await tester.pump();
controller.jumpTo(thirty + 100.0); // past the end
await tester.pump();
await tester.pumpWidget(MaterialApp(home: ListView(children: children(31), controller: controller)));
expect(controller.position.pixels, thirty + 200.0); // same distance past the end
expect(await tester.pumpAndSettle(), 7); // now it goes ballistic...
expect(controller.position.pixels, thirty + 100.0); // and ends up at the end
});
testWidgets('Ability to keep a PageView at the end manually (issue 62209)', (WidgetTester tester) async {
await tester.pumpWidget(const MaterialApp(home: PageView62209()));
expect(find.text('Page 1'), findsOneWidget);
expect(find.text('Page 100'), findsNothing);
await tester.drag(find.byType(PageView62209), const Offset(-800.0, 0.0));
await tester.pump();
expect(find.text('Page 1'), findsNothing);
expect(find.text('Page 2'), findsOneWidget);
expect(find.text('Page 100'), findsNothing);
await tester.drag(find.byType(PageView62209), const Offset(-800.0, 0.0));
await tester.pump();
expect(find.text('Page 1'), findsNothing);
expect(find.text('Page 3'), findsOneWidget);
expect(find.text('Page 100'), findsNothing);
await tester.drag(find.byType(PageView62209), const Offset(-800.0, 0.0));
await tester.pump();
expect(find.text('Page 1'), findsNothing);
expect(find.text('Page 4'), findsOneWidget);
expect(find.text('Page 100'), findsNothing);
await tester.drag(find.byType(PageView62209), const Offset(-800.0, 0.0));
await tester.pump();
expect(find.text('Page 1'), findsNothing);
expect(find.text('Page 5'), findsOneWidget);
expect(find.text('Page 100'), findsNothing);
await tester.drag(find.byType(PageView62209), const Offset(-800.0, 0.0));
await tester.pump();
expect(find.text('Page 1'), findsNothing);
expect(find.text('Page 5'), findsNothing);
expect(find.text('Page 100'), findsOneWidget);
await tester.tap(find.byType(FlatButton)); // 6
await tester.pump();
expect(find.text('Page 1'), findsNothing);
expect(find.text('Page 6'), findsNothing);
expect(find.text('Page 5'), findsNothing);
expect(find.text('Page 100'), findsOneWidget);
await tester.tap(find.byType(FlatButton)); // 7
await tester.pump();
expect(find.text('Page 1'), findsNothing);
expect(find.text('Page 6'), findsNothing);
expect(find.text('Page 7'), findsNothing);
expect(find.text('Page 5'), findsNothing);
expect(find.text('Page 100'), findsOneWidget);
await tester.drag(find.byType(PageView62209), const Offset(800.0, 0.0));
await tester.pump();
expect(find.text('Page 1'), findsNothing);
expect(find.text('Page 5'), findsOneWidget);
expect(find.text('Page 100'), findsNothing);
await tester.drag(find.byType(PageView62209), const Offset(800.0, 0.0));
await tester.pump();
expect(find.text('Page 1'), findsNothing);
expect(find.text('Page 4'), findsOneWidget);
expect(find.text('Page 5'), findsNothing);
expect(find.text('Page 100'), findsNothing);
await tester.tap(find.byType(FlatButton)); // 8
await tester.pump();
expect(find.text('Page 1'), findsNothing);
expect(find.text('Page 8'), findsNothing);
expect(find.text('Page 4'), findsOneWidget);
expect(find.text('Page 5'), findsNothing);
expect(find.text('Page 100'), findsNothing);
await tester.drag(find.byType(PageView62209), const Offset(800.0, 0.0));
await tester.pump();
expect(find.text('Page 3'), findsOneWidget);
await tester.drag(find.byType(PageView62209), const Offset(800.0, 0.0));
await tester.pump();
expect(find.text('Page 2'), findsOneWidget);
await tester.drag(find.byType(PageView62209), const Offset(800.0, 0.0));
await tester.pump();
expect(find.text('Page 6'), findsOneWidget);
await tester.drag(find.byType(PageView62209), const Offset(800.0, 0.0));
await tester.pump();
expect(find.text('Page 7'), findsOneWidget);
await tester.drag(find.byType(PageView62209), const Offset(800.0, 0.0));
await tester.pump();
expect(find.text('Page 8'), findsOneWidget);
await tester.drag(find.byType(PageView62209), const Offset(800.0, 0.0));
await tester.pump();
expect(find.text('Page 1'), findsOneWidget);
await tester.tap(find.byType(FlatButton)); // 9
await tester.pump();
expect(find.text('Page 1'), findsOneWidget);
expect(find.text('Page 9'), findsNothing);
await tester.drag(find.byType(PageView62209), const Offset(-800.0, 0.0));
await tester.pump();
expect(find.text('Page 9'), findsOneWidget);
});
}
class PageView62209 extends StatefulWidget {
const PageView62209();
@override
_PageView62209State createState() => _PageView62209State();
}
class _PageView62209State extends State<PageView62209> {
int _nextPageNum = 1;
final List<Carousel62209Page> _pages = <Carousel62209Page>[];
@override
void initState() {
super.initState();
for (int i = 0; i < 5; i++) {
_pages.add(Carousel62209Page(
key: Key('$_nextPageNum'),
number: _nextPageNum++,
));
}
_pages.add(const Carousel62209Page(number: 100));
}
@override
Widget build(BuildContext context) {
return Scaffold(
body: Column(
children: <Widget>[
Expanded(child: Carousel62209(pages: _pages)),
FlatButton(
child: const Text('ADD PAGE'),
onPressed: () {
setState(() {
_pages.insert(
1,
Carousel62209Page(
key: Key('$_nextPageNum'),
number: _nextPageNum++,
),
);
});
},
)
],
),
);
}
}
class Carousel62209Page extends StatelessWidget {
const Carousel62209Page({this.number, Key key}) : super(key: key);
final int number;
@override
Widget build(BuildContext context) {
return Center(child: Text('Page $number'));
}
}
class Carousel62209 extends StatefulWidget {
const Carousel62209({Key key, this.pages}) : super(key: key);
final List<Carousel62209Page> pages;
@override
_Carousel62209State createState() => _Carousel62209State();
}
class _Carousel62209State extends State<Carousel62209> {
// page variables
PageController _pageController;
int _currentPage = 0;
// controls updates outside of user interaction
List<Carousel62209Page> _pages;
bool _jumpingToPage = false;
@override
void initState() {
super.initState();
_pages = widget.pages.toList();
_pageController = PageController(initialPage: 0, keepPage: false);
}
@override
void didUpdateWidget(Carousel62209 oldWidget) {
super.didUpdateWidget(oldWidget);
if (!_jumpingToPage) {
int newPage = -1;
for (int i = 0; i < widget.pages.length; i++) {
if (widget.pages[i].number == _pages[_currentPage].number) {
newPage = i;
}
}
if (newPage == _currentPage) {
_pages = widget.pages.toList();
} else {
_jumpingToPage = true;
SchedulerBinding.instance.addPostFrameCallback((_) {
if (mounted) {
setState(() {
_pages = widget.pages.toList();
_currentPage = newPage;
_pageController.jumpToPage(_currentPage);
SchedulerBinding.instance.addPostFrameCallback((_) {
_jumpingToPage = false;
});
});
}
});
}
}
}
@override
void dispose() {
_pageController.dispose();
super.dispose();
}
bool _handleScrollNotification(ScrollNotification notification) {
if (notification is ScrollUpdateNotification) {
final int page = _pageController.page.round();
if (!_jumpingToPage && _currentPage != page) {
_currentPage = page;
}
}
return true;
}
@override
Widget build(BuildContext context) {
return NotificationListener<ScrollNotification>(
onNotification: _handleScrollNotification,
child: PageView.builder(
controller: _pageController,
itemCount: _pages.length,
itemBuilder: (BuildContext context, int index) {
return _pages[index];
},
),
);
}
}
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