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Add convenience constructors for SliverList (#116605)

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* init

* lint

* add the other two slivers

* fix lint

* add test for sliverlist.separated

* add3 more

* fix lint and tests

* remove trailing spaces

* remove trailing spaces 2

* fix lint

* fix lint again
This commit is contained in:
Tae Hyung Kim 2023-01-03 14:33:55 -08:00 committed by GitHub
parent bd69ef70ae
commit a7942e80d4
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4 changed files with 705 additions and 1 deletions
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289
packages/flutter/lib/src/widgets/sliver.dart
View File

@ -3,6 +3,7 @@
// found in the LICENSE file.
import 'dart:collection' show HashMap, SplayTreeMap;
import 'dart:math' as math;
import 'package:flutter/foundation.dart';
import 'package:flutter/rendering.dart';
@ -1035,6 +1036,184 @@ class SliverList extends SliverMultiBoxAdaptorWidget {
required super.delegate,
});
/// A sliver that places multiple box children in a linear array along the main
/// axis.
///
/// This constructor is appropriate for sliver lists with a large (or
/// infinite) number of children because the builder is called only for those
/// children that are actually visible.
///
/// Providing a non-null `itemCount` improves the ability of the [SliverGrid]
/// to estimate the maximum scroll extent.
///
/// `itemBuilder` will be called only with indices greater than or equal to
/// zero and less than `itemCount`.
///
/// {@macro flutter.widgets.ListView.builder.itemBuilder}
///
/// {@macro flutter.widgets.PageView.findChildIndexCallback}
///
/// The `addAutomaticKeepAlives` argument corresponds to the
/// [SliverChildBuilderDelegate.addAutomaticKeepAlives] property. The
/// `addRepaintBoundaries` argument corresponds to the
/// [SliverChildBuilderDelegate.addRepaintBoundaries] property. The
/// `addSemanticIndexes` argument corresponds to the
/// [SliverChildBuilderDelegate.addSemanticIndexes] property.
///
/// {@tool snippet}
/// This example, which would be inserted into a [CustomScrollView.slivers]
/// list, shows an infinite number of items in varying shades of blue:
///
/// ```dart
/// SliverList.builder(
/// itemBuilder: (BuildContext context, int index) {
/// return Container(
/// alignment: Alignment.center,
/// color: Colors.lightBlue[100 * (index % 9)],
/// child: Text('list item $index'),
/// );
/// },
/// )
/// ```
/// {@end-tool}
SliverList.builder({
super.key,
required NullableIndexedWidgetBuilder itemBuilder,
ChildIndexGetter? findChildIndexCallback,
int? itemCount,
bool addAutomaticKeepAlives = true,
bool addRepaintBoundaries = true,
bool addSemanticIndexes = true,
}) : super(delegate: SliverChildBuilderDelegate(
itemBuilder,
findChildIndexCallback: findChildIndexCallback,
childCount: itemCount,
addAutomaticKeepAlives: addAutomaticKeepAlives,
addRepaintBoundaries: addRepaintBoundaries,
addSemanticIndexes: addSemanticIndexes,
));
/// A sliver that places multiple box children, separated by box widgets, in a linear array along the main
/// axis.
///
/// This constructor is appropriate for sliver lists with a large (or
/// infinite) number of children because the builder is called only for those
/// children that are actually visible.
///
/// Providing a non-null `itemCount` improves the ability of the [SliverGrid]
/// to estimate the maximum scroll extent.
///
/// `itemBuilder` will be called only with indices greater than or equal to
/// zero and less than `itemCount`.
///
/// {@macro flutter.widgets.ListView.builder.itemBuilder}
///
/// {@macro flutter.widgets.PageView.findChildIndexCallback}
///
///
/// The `separatorBuilder` is similar to `itemBuilder`, except it is the widget
/// that gets placed between itemBuilder(context, index) and itemBuilder(context, index + 1).
///
/// The `addAutomaticKeepAlives` argument corresponds to the
/// [SliverChildBuilderDelegate.addAutomaticKeepAlives] property. The
/// `addRepaintBoundaries` argument corresponds to the
/// [SliverChildBuilderDelegate.addRepaintBoundaries] property. The
/// `addSemanticIndexes` argument corresponds to the
/// [SliverChildBuilderDelegate.addSemanticIndexes] property.
/// {@tool snippet}
///
/// This example shows how to create a [SliverList] whose [Container] items
/// are separated by [Divider]s.
///
/// ```dart
/// SliverList.separated(
/// itemBuilder: (BuildContext context, int index) {
/// return Container(
/// alignment: Alignment.center,
/// color: Colors.lightBlue[100 * (index % 9)],
/// child: Text('list item $index'),
/// );
/// },
/// separatorBuilder: (BuildContext context, int index) => const Divider(),
/// )
/// ```
/// {@end-tool}
SliverList.separated({
super.key,
required NullableIndexedWidgetBuilder itemBuilder,
ChildIndexGetter? findChildIndexCallback,
required NullableIndexedWidgetBuilder separatorBuilder,
int? itemCount,
bool addAutomaticKeepAlives = true,
bool addRepaintBoundaries = true,
bool addSemanticIndexes = true,
}) : assert(itemBuilder != null),
assert(separatorBuilder != null),
super(delegate: SliverChildBuilderDelegate(
(BuildContext context, int index) {
final int itemIndex = index ~/ 2;
final Widget? widget;
if (index.isEven) {
widget = itemBuilder(context, itemIndex);
} else {
widget = separatorBuilder(context, itemIndex);
assert(() {
if (widget == null) {
throw FlutterError('separatorBuilder cannot return null.');
}
return true;
}());
}
return widget;
},
findChildIndexCallback: findChildIndexCallback,
childCount: itemCount == null ? null : math.max(0, itemCount * 2 - 1),
addAutomaticKeepAlives: addAutomaticKeepAlives,
addRepaintBoundaries: addRepaintBoundaries,
addSemanticIndexes: addSemanticIndexes,
semanticIndexCallback: (Widget _, int index) {
return index.isEven ? index ~/ 2 : null;
},
));
/// A sliver that places multiple box children in a linear array along the main
/// axis.
///
/// This constructor uses a list of [Widget]s to build the sliver.
///
/// The `addAutomaticKeepAlives` argument corresponds to the
/// [SliverChildBuilderDelegate.addAutomaticKeepAlives] property. The
/// `addRepaintBoundaries` argument corresponds to the
/// [SliverChildBuilderDelegate.addRepaintBoundaries] property. The
/// `addSemanticIndexes` argument corresponds to the
/// [SliverChildBuilderDelegate.addSemanticIndexes] property.
///
/// {@tool snippet}
/// This example, which would be inserted into a [CustomScrollView.slivers]
/// list, shows an infinite number of items in varying shades of blue:
///
/// ```dart
/// SliverList.list(
/// children: const <Widget>[
/// Text('Hello'),
/// Text('World!'),
/// ],
/// );
/// ```
/// {@end-tool}
SliverList.list({
super.key,
required List<Widget> children,
bool addAutomaticKeepAlives = true,
bool addRepaintBoundaries = true,
bool addSemanticIndexes = true,
}) : super(delegate: SliverChildListDelegate(
children,
addAutomaticKeepAlives: addAutomaticKeepAlives,
addRepaintBoundaries: addRepaintBoundaries,
addSemanticIndexes: addSemanticIndexes,
));
@override
SliverMultiBoxAdaptorElement createElement() => SliverMultiBoxAdaptorElement(this, replaceMovedChildren: true);
@ -1098,6 +1277,116 @@ class SliverFixedExtentList extends SliverMultiBoxAdaptorWidget {
required this.itemExtent,
});
/// A sliver that places multiple box children in a linear array along the main
/// axis.
///
/// [SliverFixedExtentList] places its children in a linear array along the main
/// axis starting at offset zero and without gaps. Each child is forced to have
/// the [itemExtent] in the main axis and the
/// [SliverConstraints.crossAxisExtent] in the cross axis.
///
/// This constructor is appropriate for sliver lists with a large (or
/// infinite) number of children whose extent is already determined.
///
/// Providing a non-null `itemCount` improves the ability of the [SliverGrid]
/// to estimate the maximum scroll extent.
///
/// `itemBuilder` will be called only with indices greater than or equal to
/// zero and less than `itemCount`.
///
/// {@macro flutter.widgets.ListView.builder.itemBuilder}
///
/// The `itemExtent` argument is the extent of each item.
///
/// {@macro flutter.widgets.PageView.findChildIndexCallback}
///
/// The `addAutomaticKeepAlives` argument corresponds to the
/// [SliverChildBuilderDelegate.addAutomaticKeepAlives] property. The
/// `addRepaintBoundaries` argument corresponds to the
/// [SliverChildBuilderDelegate.addRepaintBoundaries] property. The
/// `addSemanticIndexes` argument corresponds to the
/// [SliverChildBuilderDelegate.addSemanticIndexes] property.
/// {@tool snippet}
///
/// This example, which would be inserted into a [CustomScrollView.slivers]
/// list, shows an infinite number of items in varying shades of blue:
///
/// ```dart
/// SliverFixedExtentList.builder(
/// itemExtent: 50.0,
/// itemBuilder: (BuildContext context, int index) {
/// return Container(
/// alignment: Alignment.center,
/// color: Colors.lightBlue[100 * (index % 9)],
/// child: Text('list item $index'),
/// );
/// },
/// )
/// ```
/// {@end-tool}
SliverFixedExtentList.builder({
super.key,
required NullableIndexedWidgetBuilder itemBuilder,
required this.itemExtent,
ChildIndexGetter? findChildIndexCallback,
int? itemCount,
bool addAutomaticKeepAlives = true,
bool addRepaintBoundaries = true,
bool addSemanticIndexes = true,
}) : super(delegate: SliverChildBuilderDelegate(
itemBuilder,
findChildIndexCallback: findChildIndexCallback,
childCount: itemCount,
addAutomaticKeepAlives: addAutomaticKeepAlives,
addRepaintBoundaries: addRepaintBoundaries,
addSemanticIndexes: addSemanticIndexes,
));
/// A sliver that places multiple box children in a linear array along the main
/// axis.
///
/// [SliverFixedExtentList] places its children in a linear array along the main
/// axis starting at offset zero and without gaps. Each child is forced to have
/// the [itemExtent] in the main axis and the
/// [SliverConstraints.crossAxisExtent] in the cross axis.
///
/// This constructor uses a list of [Widget]s to build the sliver.
///
/// The `addAutomaticKeepAlives` argument corresponds to the
/// [SliverChildBuilderDelegate.addAutomaticKeepAlives] property. The
/// `addRepaintBoundaries` argument corresponds to the
/// [SliverChildBuilderDelegate.addRepaintBoundaries] property. The
/// `addSemanticIndexes` argument corresponds to the
/// [SliverChildBuilderDelegate.addSemanticIndexes] property.
///
/// {@tool snippet}
/// This example, which would be inserted into a [CustomScrollView.slivers]
/// list, shows an infinite number of items in varying shades of blue:
///
/// ```dart
/// SliverFixedExtentList.list(
/// itemExtent: 50.0,
/// children: const <Widget>[
/// Text('Hello'),
/// Text('World!'),
/// ],
/// );
/// ```
/// {@end-tool}
SliverFixedExtentList.list({
super.key,
required List<Widget> children,
required this.itemExtent,
bool addAutomaticKeepAlives = true,
bool addRepaintBoundaries = true,
bool addSemanticIndexes = true,
}) : super(delegate: SliverChildListDelegate(
children,
addAutomaticKeepAlives: addAutomaticKeepAlives,
addRepaintBoundaries: addRepaintBoundaries,
addSemanticIndexes: addSemanticIndexes,
));
/// The extent the children are forced to have in the main axis.
final double itemExtent;

103
packages/flutter/lib/src/widgets/sliver_prototype_extent_list.dart
View File

@ -40,6 +40,109 @@ class SliverPrototypeExtentList extends SliverMultiBoxAdaptorWidget {
required this.prototypeItem,
}) : assert(prototypeItem != null);
/// A sliver that places its box children in a linear array and constrains them
/// to have the same extent as a prototype item along the main axis.
///
/// This constructor is appropriate for sliver lists with a large (or
/// infinite) number of children whose extent is already determined.
///
/// Providing a non-null `itemCount` improves the ability of the [SliverGrid]
/// to estimate the maximum scroll extent.
///
/// `itemBuilder` will be called only with indices greater than or equal to
/// zero and less than `itemCount`.
///
/// {@macro flutter.widgets.ListView.builder.itemBuilder}
///
/// The `prototypeItem` argument is used to determine the extent of each item.
///
/// {@macro flutter.widgets.PageView.findChildIndexCallback}
///
/// The `addAutomaticKeepAlives` argument corresponds to the
/// [SliverChildBuilderDelegate.addAutomaticKeepAlives] property. The
/// `addRepaintBoundaries` argument corresponds to the
/// [SliverChildBuilderDelegate.addRepaintBoundaries] property. The
/// `addSemanticIndexes` argument corresponds to the
/// [SliverChildBuilderDelegate.addSemanticIndexes] property.
///
/// {@tool snippet}
/// This example, which would be inserted into a [CustomScrollView.slivers]
/// list, shows an infinite number of items in varying shades of blue:
///
/// ```dart
/// SliverPrototypeExtentList.builder(
/// prototypeItem: Container(
/// alignment: Alignment.center,
/// child: const Text('list item prototype'),
/// ),
/// itemBuilder: (BuildContext context, int index) {
/// return Container(
/// alignment: Alignment.center,
/// color: Colors.lightBlue[100 * (index % 9)],
/// child: Text('list item $index'),
/// );
/// },
/// )
/// ```
/// {@end-tool}
SliverPrototypeExtentList.builder({
super.key,
required NullableIndexedWidgetBuilder itemBuilder,
required this.prototypeItem,
ChildIndexGetter? findChildIndexCallback,
int? itemCount,
bool addAutomaticKeepAlives = true,
bool addRepaintBoundaries = true,
bool addSemanticIndexes = true,
}) : super(delegate: SliverChildBuilderDelegate(
itemBuilder,
findChildIndexCallback: findChildIndexCallback,
childCount: itemCount,
addAutomaticKeepAlives: addAutomaticKeepAlives,
addRepaintBoundaries: addRepaintBoundaries,
addSemanticIndexes: addSemanticIndexes,
));
/// A sliver that places multiple box children in a linear array along the main
/// axis.
///
/// This constructor uses a list of [Widget]s to build the sliver.
///
/// The `addAutomaticKeepAlives` argument corresponds to the
/// [SliverChildBuilderDelegate.addAutomaticKeepAlives] property. The
/// `addRepaintBoundaries` argument corresponds to the
/// [SliverChildBuilderDelegate.addRepaintBoundaries] property. The
/// `addSemanticIndexes` argument corresponds to the
/// [SliverChildBuilderDelegate.addSemanticIndexes] property.
///
/// {@tool snippet}
/// This example, which would be inserted into a [CustomScrollView.slivers]
/// list, shows an infinite number of items in varying shades of blue:
///
/// ```dart
/// SliverPrototypeExtentList.list(
/// prototypeItem: const Text('Hello'),
/// children: const <Widget>[
/// Text('Hello'),
/// Text('World!'),
/// ],
/// );
/// ```
/// {@end-tool}
SliverPrototypeExtentList.list({
super.key,
required List<Widget> children,
required this.prototypeItem,
bool addAutomaticKeepAlives = true,
bool addRepaintBoundaries = true,
bool addSemanticIndexes = true,
}) : super(delegate: SliverChildListDelegate(
children,
addAutomaticKeepAlives: addAutomaticKeepAlives,
addRepaintBoundaries: addRepaintBoundaries,
addSemanticIndexes: addSemanticIndexes,
));
/// Defines the main axis extent of all of this sliver's children.
///
/// The [prototypeItem] is laid out before the rest of the sliver's children

56
packages/flutter/test/widgets/sliver_prototype_item_extent_test.dart
View File

@ -3,7 +3,6 @@
// found in the LICENSE file.
import 'package:flutter/material.dart';
import 'package:flutter/widgets.dart';
import 'package:flutter_test/flutter_test.dart';
class TestItem extends StatelessWidget {
@ -41,6 +40,61 @@ Widget buildFrame({ int? count, double? width, double? height, Axis? scrollDirec
}
void main() {
testWidgets('SliverPrototypeExtentList.builder test', (WidgetTester tester) async {
await tester.pumpWidget(
MaterialApp(
home: Scaffold(
body: CustomScrollView(
slivers: <Widget>[
SliverPrototypeExtentList.builder(
itemBuilder: (BuildContext context, int index) => TestItem(item: index),
prototypeItem: const TestItem(item: -1, height: 100.0),
itemCount: 20,
),
],
),
),
),
);
// The viewport is 600 pixels high, lazily created items are 100 pixels high.
for (int i = 0; i < 6; i += 1) {
final Finder item = find.widgetWithText(Container, 'Item $i');
expect(item, findsOneWidget);
expect(tester.getTopLeft(item).dy, i * 100.0);
expect(tester.getSize(item).height, 100.0);
}
for (int i = 7; i < 20; i += 1) {
expect(find.text('Item $i'), findsNothing);
}
});
testWidgets('SliverPrototypeExtentList.builder test', (WidgetTester tester) async {
await tester.pumpWidget(
MaterialApp(
home: Scaffold(
body: CustomScrollView(
slivers: <Widget>[
SliverPrototypeExtentList.list(
prototypeItem: const TestItem(item: -1, height: 100.0),
children: <int>[0, 1, 2, 3, 4, 5, 6, 7].map((int index) => TestItem(item: index)).toList(),
),
],
),
),
),
);
// The viewport is 600 pixels high, lazily created items are 100 pixels high.
for (int i = 0; i < 6; i += 1) {
final Finder item = find.widgetWithText(Container, 'Item $i');
expect(item, findsOneWidget);
expect(tester.getTopLeft(item).dy, i * 100.0);
expect(tester.getSize(item).height, 100.0);
}
expect(find.text('Item 7'), findsNothing);
});
testWidgets('SliverPrototypeExtentList vertical scrolling basics', (WidgetTester tester) async {
await tester.pumpWidget(buildFrame(count: 20, height: 100.0));

258
packages/flutter/test/widgets/slivers_test.dart
View File

@ -992,6 +992,264 @@ void main() {
expect(secondTapped, 1);
});
testWidgets('SliverList.builder can build children', (WidgetTester tester) async {
int firstTapped = 0;
int secondTapped = 0;
final Key key = UniqueKey();
await tester.pumpWidget(MaterialApp(
home: Scaffold(
key: key,
body: CustomScrollView(
slivers: <Widget>[
SliverList.builder(
itemCount: 2,
itemBuilder: (BuildContext context, int index) {
return Material(
color: index.isEven ? Colors.yellow : Colors.red,
child: InkWell(
onTap: () {
index.isEven ? firstTapped++ : secondTapped++;
},
child: Text('Index $index'),
),
);
},
),
],
),
),
));
// Verify correct hit testing
await tester.tap(find.text('Index 0'));
expect(firstTapped, 1);
expect(secondTapped, 0);
firstTapped = 0;
await tester.tap(find.text('Index 1'));
expect(firstTapped, 0);
expect(secondTapped, 1);
});
testWidgets('SliverList.builder can build children', (WidgetTester tester) async {
int firstTapped = 0;
int secondTapped = 0;
final Key key = UniqueKey();
await tester.pumpWidget(MaterialApp(
home: Scaffold(
key: key,
body: CustomScrollView(
slivers: <Widget>[
SliverList.builder(
itemCount: 2,
itemBuilder: (BuildContext context, int index) {
return Material(
color: index.isEven ? Colors.yellow : Colors.red,
child: InkWell(
onTap: () {
index.isEven ? firstTapped++ : secondTapped++;
},
child: Text('Index $index'),
),
);
},
),
],
),
),
));
// Verify correct hit testing
await tester.tap(find.text('Index 0'));
expect(firstTapped, 1);
expect(secondTapped, 0);
firstTapped = 0;
await tester.tap(find.text('Index 1'));
expect(firstTapped, 0);
expect(secondTapped, 1);
});
testWidgets('SliverList.separated can build children', (WidgetTester tester) async {
int firstTapped = 0;
int secondTapped = 0;
final Key key = UniqueKey();
await tester.pumpWidget(MaterialApp(
home: Scaffold(
key: key,
body: CustomScrollView(
slivers: <Widget>[
SliverList.separated(
itemCount: 2,
itemBuilder: (BuildContext context, int index) {
return Material(
color: index.isEven ? Colors.yellow : Colors.red,
child: InkWell(
onTap: () {
index.isEven ? firstTapped++ : secondTapped++;
},
child: Text('Index $index'),
),
);
},
separatorBuilder: (BuildContext context, int index) => Text('Separator $index'),
),
],
),
),
));
// Verify correct hit testing
await tester.tap(find.text('Index 0'));
expect(firstTapped, 1);
expect(secondTapped, 0);
firstTapped = 0;
await tester.tap(find.text('Index 1'));
expect(firstTapped, 0);
expect(secondTapped, 1);
});
testWidgets('SliverList.separated has correct number of children', (WidgetTester tester) async {
final Key key = UniqueKey();
await tester.pumpWidget(MaterialApp(
home: Scaffold(
key: key,
body: CustomScrollView(
slivers: <Widget>[
SliverList.separated(
itemCount: 2,
itemBuilder: (BuildContext context, int index) => const Text('item'),
separatorBuilder: (BuildContext context, int index) => const Text('separator'),
),
],
),
),
));
expect(find.text('item'), findsNWidgets(2));
expect(find.text('separator'), findsNWidgets(1));
});
testWidgets('SliverList.list can build children', (WidgetTester tester) async {
int firstTapped = 0;
int secondTapped = 0;
final Key key = UniqueKey();
await tester.pumpWidget(MaterialApp(
home: Scaffold(
key: key,
body: CustomScrollView(
slivers: <Widget>[
SliverList.list(
children: <Widget>[
Material(
color: Colors.yellow,
child: InkWell(
onTap: () => firstTapped++,
child: const Text('Index 0'),
),
),
Material(
color: Colors.red,
child: InkWell(
onTap: () => secondTapped++,
child: const Text('Index 1'),
),
),
],
),
],
),
),
));
// Verify correct hit testing
await tester.tap(find.text('Index 0'));
expect(firstTapped, 1);
expect(secondTapped, 0);
firstTapped = 0;
await tester.tap(find.text('Index 1'));
expect(firstTapped, 0);
expect(secondTapped, 1);
});
testWidgets('SliverFixedExtentList.builder can build children', (WidgetTester tester) async {
int firstTapped = 0;
int secondTapped = 0;
final Key key = UniqueKey();
await tester.pumpWidget(MaterialApp(
home: Scaffold(
key: key,
body: CustomScrollView(
slivers: <Widget>[
SliverFixedExtentList.builder(
itemCount: 2,
itemExtent: 100,
itemBuilder: (BuildContext context, int index) {
return Material(
color: index.isEven ? Colors.yellow : Colors.red,
child: InkWell(
onTap: () {
index.isEven ? firstTapped++ : secondTapped++;
},
child: Text('Index $index'),
),
);
},
),
],
),
),
));
// Verify correct hit testing
await tester.tap(find.text('Index 0'));
expect(firstTapped, 1);
expect(secondTapped, 0);
firstTapped = 0;
await tester.tap(find.text('Index 1'));
expect(firstTapped, 0);
expect(secondTapped, 1);
});
testWidgets('SliverList.list can build children', (WidgetTester tester) async {
int firstTapped = 0;
int secondTapped = 0;
final Key key = UniqueKey();
await tester.pumpWidget(MaterialApp(
home: Scaffold(
key: key,
body: CustomScrollView(
slivers: <Widget>[
SliverFixedExtentList.list(
itemExtent: 100,
children: <Widget>[
Material(
color: Colors.yellow,
child: InkWell(
onTap: () => firstTapped++,
child: const Text('Index 0'),
),
),
Material(
color: Colors.red,
child: InkWell(
onTap: () => secondTapped++,
child: const Text('Index 1'),
),
),
],
),
],
),
),
));
// Verify correct hit testing
await tester.tap(find.text('Index 0'));
expect(firstTapped, 1);
expect(secondTapped, 0);
firstTapped = 0;
await tester.tap(find.text('Index 1'));
expect(firstTapped, 0);
expect(secondTapped, 1);
});
testWidgets('SliverGrid.builder can build children', (WidgetTester tester) async {
int firstTapped = 0;
int secondTapped = 0;