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Fixes some widgets(ListView.builder, GridView.builder etc.) state-lose issue (#100547)

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xubaolin 2022-03-25 09:27:08 +08:00 committed by GitHub
parent c920ac2bc4
commit 31191dd29a
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10 changed files with 275 additions and 10 deletions
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10
packages/flutter/lib/src/widgets/animated_list.dart
View File

@ -339,6 +339,7 @@ class SliverAnimatedList extends StatefulWidget {
const SliverAnimatedList({
Key? key,
required this.itemBuilder,
this.findChildIndexCallback,
this.initialItemCount = 0,
}) : assert(itemBuilder != null),
assert(initialItemCount != null && initialItemCount >= 0),
@ -359,6 +360,9 @@ class SliverAnimatedList extends StatefulWidget {
/// [SliverAnimatedListState.removeItem] removes an item immediately.
final AnimatedListItemBuilder itemBuilder;
/// {@macro flutter.widgets.SliverChildBuilderDelegate.findChildIndexCallback}
final ChildIndexGetter? findChildIndexCallback;
/// {@macro flutter.widgets.animatedList.initialItemCount}
final int initialItemCount;
@ -507,7 +511,11 @@ class SliverAnimatedListState extends State<SliverAnimatedList> with TickerProvi
}
SliverChildDelegate _createDelegate() {
return SliverChildBuilderDelegate(_itemBuilder, childCount: _itemsCount);
return SliverChildBuilderDelegate(
_itemBuilder,
childCount: _itemsCount,
findChildIndexCallback: widget.findChildIndexCallback,
);
}
/// Insert an item at [index] and start an animation that will be passed to

18
packages/flutter/lib/src/widgets/page_view.dart
View File

@ -665,9 +665,14 @@ class PageView extends StatefulWidget {
/// [itemBuilder] will be called only with indices greater than or equal to
/// zero and less than [itemCount].
///
/// [PageView.builder] by default does not support child reordering. If
/// you are planning to change child order at a later time, consider using
/// [PageView] or [PageView.custom].
/// {@template flutter.widgets.PageView.findChildIndexCallback}
/// The [findChildIndexCallback] corresponds to the
/// [SliverChildBuilderDelegate.findChildIndexCallback] property. If null,
/// a child widget may not map to its existing [RenderObject] when the order
/// of children returned from the children builder changes.
/// This may result in state-loss. This callback needs to be implemented if
/// the order of the children may change at a later time.
/// {@endtemplate}
///
/// {@macro flutter.widgets.PageView.allowImplicitScrolling}
PageView.builder({
@ -679,6 +684,7 @@ class PageView extends StatefulWidget {
this.pageSnapping = true,
this.onPageChanged,
required IndexedWidgetBuilder itemBuilder,
ChildIndexGetter? findChildIndexCallback,
int? itemCount,
this.dragStartBehavior = DragStartBehavior.start,
this.allowImplicitScrolling = false,
@ -689,7 +695,11 @@ class PageView extends StatefulWidget {
}) : assert(allowImplicitScrolling != null),
assert(clipBehavior != null),
controller = controller ?? _defaultPageController,
childrenDelegate = SliverChildBuilderDelegate(itemBuilder, childCount: itemCount),
childrenDelegate = SliverChildBuilderDelegate(
itemBuilder,
findChildIndexCallback: findChildIndexCallback,
childCount: itemCount,
),
super(key: key);
/// Creates a scrollable list that works page by page with a custom child

5
packages/flutter/lib/src/widgets/reorderable_list.dart
View File

@ -430,6 +430,7 @@ class SliverReorderableList extends StatefulWidget {
const SliverReorderableList({
Key? key,
required this.itemBuilder,
this.findChildIndexCallback,
required this.itemCount,
required this.onReorder,
this.onReorderStart,
@ -447,6 +448,9 @@ class SliverReorderableList extends StatefulWidget {
/// {@macro flutter.widgets.reorderable_list.itemBuilder}
final IndexedWidgetBuilder itemBuilder;
/// {@macro flutter.widgets.SliverChildBuilderDelegate.findChildIndexCallback}
final ChildIndexGetter? findChildIndexCallback;
/// {@macro flutter.widgets.reorderable_list.itemCount}
final int itemCount;
@ -908,6 +912,7 @@ class SliverReorderableListState extends State<SliverReorderableList> with Ticke
// by a zero height SizedBox, so that the gap can move around. To make the
// list extent stable we add a dummy entry to the end.
childCount: widget.itemCount + (_dragInfo != null ? 1 : 0),
findChildIndexCallback: widget.findChildIndexCallback,
);
if (widget.itemExtent != null) {
return SliverFixedExtentList(

16
packages/flutter/lib/src/widgets/scroll_view.dart
View File

@ -1126,6 +1126,8 @@ class ListView extends BoxScrollView {
/// efficient, however, is to create the instances on demand using this
/// constructor's `itemBuilder` callback.
///
/// {@macro flutter.widgets.PageView.findChildIndexCallback}
///
/// The `addAutomaticKeepAlives` argument corresponds to the
/// [SliverChildBuilderDelegate.addAutomaticKeepAlives] property. The
/// `addRepaintBoundaries` argument corresponds to the
@ -1133,10 +1135,6 @@ class ListView extends BoxScrollView {
/// `addSemanticIndexes` argument corresponds to the
/// [SliverChildBuilderDelegate.addSemanticIndexes] property. None may be
/// null.
///
/// [ListView.builder] by default does not support child reordering. If
/// you are planning to change child order at a later time, consider using
/// [ListView] or [ListView.custom].
ListView.builder({
Key? key,
Axis scrollDirection = Axis.vertical,
@ -1149,6 +1147,7 @@ class ListView extends BoxScrollView {
this.itemExtent,
this.prototypeItem,
required IndexedWidgetBuilder itemBuilder,
ChildIndexGetter? findChildIndexCallback,
int? itemCount,
bool addAutomaticKeepAlives = true,
bool addRepaintBoundaries = true,
@ -1167,6 +1166,7 @@ class ListView extends BoxScrollView {
),
childrenDelegate = SliverChildBuilderDelegate(
itemBuilder,
findChildIndexCallback: findChildIndexCallback,
childCount: itemCount,
addAutomaticKeepAlives: addAutomaticKeepAlives,
addRepaintBoundaries: addRepaintBoundaries,
@ -1211,6 +1211,8 @@ class ListView extends BoxScrollView {
/// view's children are created in advance, or all at once when the [ListView]
/// itself is created, it is more efficient to use the [ListView] constructor.
///
/// {@macro flutter.widgets.PageView.findChildIndexCallback}
///
/// {@tool snippet}
///
/// This example shows how to create [ListView] whose [ListTile] list items
@ -1246,6 +1248,7 @@ class ListView extends BoxScrollView {
bool shrinkWrap = false,
EdgeInsetsGeometry? padding,
required IndexedWidgetBuilder itemBuilder,
ChildIndexGetter? findChildIndexCallback,
required IndexedWidgetBuilder separatorBuilder,
required int itemCount,
bool addAutomaticKeepAlives = true,
@ -1278,6 +1281,7 @@ class ListView extends BoxScrollView {
}
return widget;
},
findChildIndexCallback: findChildIndexCallback,
childCount: _computeActualChildCount(itemCount),
addAutomaticKeepAlives: addAutomaticKeepAlives,
addRepaintBoundaries: addRepaintBoundaries,
@ -1797,6 +1801,8 @@ class GridView extends BoxScrollView {
/// `itemBuilder` will be called only with indices greater than or equal to
/// zero and less than `itemCount`.
///
/// {@macro flutter.widgets.PageView.findChildIndexCallback}
///
/// The [gridDelegate] argument must not be null.
///
/// The `addAutomaticKeepAlives` argument corresponds to the
@ -1815,6 +1821,7 @@ class GridView extends BoxScrollView {
EdgeInsetsGeometry? padding,
required this.gridDelegate,
required IndexedWidgetBuilder itemBuilder,
ChildIndexGetter? findChildIndexCallback,
int? itemCount,
bool addAutomaticKeepAlives = true,
bool addRepaintBoundaries = true,
@ -1828,6 +1835,7 @@ class GridView extends BoxScrollView {
}) : assert(gridDelegate != null),
childrenDelegate = SliverChildBuilderDelegate(
itemBuilder,
findChildIndexCallback: findChildIndexCallback,
childCount: itemCount,
addAutomaticKeepAlives: addAutomaticKeepAlives,
addRepaintBoundaries: addRepaintBoundaries,

8
packages/flutter/lib/src/widgets/sliver.dart
View File

@ -194,6 +194,10 @@ abstract class SliverChildDelegate {
/// This will be called during `performRebuild` in [SliverMultiBoxAdaptorElement]
/// to check if a child has moved to a different position. It should return the
/// index of the child element with associated key, null if not found.
///
/// If not provided, a child widget may not map to its existing [RenderObject]
/// when the order of children returned from the children builder changes.
/// This may result in state-loss.
int? findIndexByKey(Key key) => null;
@override
@ -429,14 +433,16 @@ class SliverChildBuilderDelegate extends SliverChildDelegate {
/// Defaults to providing an index for each widget.
final SemanticIndexCallback semanticIndexCallback;
/// {@template flutter.widgets.SliverChildBuilderDelegate.findChildIndexCallback}
/// Called to find the new index of a child based on its key in case of reordering.
///
/// If not provided, a child widget may not map to its existing [RenderObject]
/// when the order in which children are returned from [builder] changes.
/// when the order of children returned from the children builder changes.
/// This may result in state-loss.
///
/// This callback should take an input [Key], and it should return the
/// index of the child element with that associated key, or null if not found.
/// {@endtemplate}
final ChildIndexGetter? findChildIndexCallback;
@override

40
packages/flutter/test/widgets/animated_list_test.dart
View File

@ -7,6 +7,46 @@ import 'package:flutter/widgets.dart';
import 'package:flutter_test/flutter_test.dart';
void main() {
// Regression test for https://github.com/flutter/flutter/issues/100451
testWidgets('SliverAnimatedList.builder respects findChildIndexCallback', (WidgetTester tester) async {
bool finderCalled = false;
int itemCount = 7;
late StateSetter stateSetter;
await tester.pumpWidget(
Directionality(
textDirection: TextDirection.ltr,
child: StatefulBuilder(
builder: (BuildContext context, StateSetter setState) {
stateSetter = setState;
return CustomScrollView(
slivers: <Widget>[
SliverAnimatedList(
initialItemCount: itemCount,
itemBuilder: (BuildContext context, int index, Animation<double> animation) => Container(
key: Key('$index'),
height: 2000.0,
),
findChildIndexCallback: (Key key) {
finderCalled = true;
return null;
},
),
],
);
},
),
)
);
expect(finderCalled, false);
// Trigger update.
stateSetter(() => itemCount = 77);
await tester.pump();
expect(finderCalled, true);
});
testWidgets('AnimatedList', (WidgetTester tester) async {
Widget builder(BuildContext context, int index, Animation<double> animation) {
return SizedBox(

39
packages/flutter/test/widgets/grid_view_test.dart
View File

@ -12,6 +12,45 @@ import '../rendering/rendering_tester.dart' show TestClipPaintingContext;
import 'states.dart';
void main() {
// Regression test for https://github.com/flutter/flutter/issues/100451
testWidgets('GridView.builder respects findChildIndexCallback', (WidgetTester tester) async {
bool finderCalled = false;
int itemCount = 7;
late StateSetter stateSetter;
await tester.pumpWidget(
Directionality(
textDirection: TextDirection.ltr,
child: StatefulBuilder(
builder: (BuildContext context, StateSetter setState) {
stateSetter = setState;
return GridView.builder(
itemCount: itemCount,
itemBuilder: (BuildContext _, int index) => Container(
key: Key('$index'),
height: 2000.0,
),
findChildIndexCallback: (Key key) {
finderCalled = true;
return null;
},
gridDelegate: const SliverGridDelegateWithFixedCrossAxisCount(
crossAxisCount: 4,
),
);
},
),
)
);
expect(finderCalled, false);
// Trigger update.
stateSetter(() => itemCount = 77);
await tester.pump();
expect(finderCalled, true);
});
testWidgets('Empty GridView', (WidgetTester tester) async {
await tester.pumpWidget(
Directionality(

73
packages/flutter/test/widgets/list_view_test.dart
View File

@ -76,6 +76,79 @@ class _StatefulListViewState extends State<_StatefulListView> {
}
void main() {
// Regression test for https://github.com/flutter/flutter/issues/100451
testWidgets('ListView.builder respects findChildIndexCallback', (WidgetTester tester) async {
bool finderCalled = false;
int itemCount = 7;
late StateSetter stateSetter;
await tester.pumpWidget(
Directionality(
textDirection: TextDirection.ltr,
child: StatefulBuilder(
builder: (BuildContext context, StateSetter setState) {
stateSetter = setState;
return ListView.builder(
itemCount: itemCount,
itemBuilder: (BuildContext _, int index) => Container(
key: Key('$index'),
height: 2000.0,
),
findChildIndexCallback: (Key key) {
finderCalled = true;
return null;
},
);
},
),
)
);
expect(finderCalled, false);
// Trigger update.
stateSetter(() => itemCount = 77);
await tester.pump();
expect(finderCalled, true);
});
// Regression test for https://github.com/flutter/flutter/issues/100451
testWidgets('ListView.separator respects findChildIndexCallback', (WidgetTester tester) async {
bool finderCalled = false;
int itemCount = 7;
late StateSetter stateSetter;
await tester.pumpWidget(
Directionality(
textDirection: TextDirection.ltr,
child: StatefulBuilder(
builder: (BuildContext context, StateSetter setState) {
stateSetter = setState;
return ListView.separated(
itemCount: itemCount,
itemBuilder: (BuildContext _, int index) => Container(
key: Key('$index'),
height: 2000.0,
),
findChildIndexCallback: (Key key) {
finderCalled = true;
return null;
},
separatorBuilder: (BuildContext _, int __) => const Divider(),
);
},
),
)
);
expect(finderCalled, false);
// Trigger update.
stateSetter(() => itemCount = 77);
await tester.pump();
expect(finderCalled, true);
});
testWidgets('ListView default control', (WidgetTester tester) async {
await tester.pumpWidget(
Directionality(

36
packages/flutter/test/widgets/page_view_test.dart
View File

@ -12,6 +12,42 @@ import 'semantics_tester.dart';
import 'states.dart';
void main() {
// Regression test for https://github.com/flutter/flutter/issues/100451
testWidgets('PageView.builder respects findChildIndexCallback', (WidgetTester tester) async {
bool finderCalled = false;
int itemCount = 7;
late StateSetter stateSetter;
await tester.pumpWidget(
Directionality(
textDirection: TextDirection.ltr,
child: StatefulBuilder(
builder: (BuildContext context, StateSetter setState) {
stateSetter = setState;
return PageView.builder(
itemCount: itemCount,
itemBuilder: (BuildContext _, int index) => Container(
key: Key('$index'),
height: 2000.0,
),
findChildIndexCallback: (Key key) {
finderCalled = true;
return null;
},
);
},
),
)
);
expect(finderCalled, false);
// Trigger update.
stateSetter(() => itemCount = 77);
await tester.pump();
expect(finderCalled, true);
});
testWidgets('PageView resize from zero-size viewport should not lose state', (WidgetTester tester) async {
// Regression test for https://github.com/flutter/flutter/issues/88956
final PageController controller = PageController(

40
packages/flutter/test/widgets/reorderable_list_test.dart
View File

@ -7,6 +7,46 @@ import 'package:flutter/material.dart';
import 'package:flutter_test/flutter_test.dart';
void main() {
// Regression test for https://github.com/flutter/flutter/issues/100451
testWidgets('SliverReorderableList.builder respects findChildIndexCallback', (WidgetTester tester) async {
bool finderCalled = false;
int itemCount = 7;
late StateSetter stateSetter;
await tester.pumpWidget(
MaterialApp(
home: StatefulBuilder(
builder: (BuildContext context, StateSetter setState) {
stateSetter = setState;
return CustomScrollView(
slivers: <Widget>[
SliverReorderableList(
itemCount: itemCount,
itemBuilder: (BuildContext _, int index) => Container(
key: Key('$index'),
height: 2000.0,
),
findChildIndexCallback: (Key key) {
finderCalled = true;
return null;
},
onReorder: (int oldIndex, int newIndex) { },
),
],
);
},
),
)
);
expect(finderCalled, false);
// Trigger update.
stateSetter(() => itemCount = 77);
await tester.pump();
expect(finderCalled, true);
});
// Regression test for https://github.com/flutter/flutter/issues/88191
testWidgets('Do not crash when dragging with two fingers simultaneously', (WidgetTester tester) async {
final List<int> items = List<int>.generate(3, (int index) => index);