Revert "Fix excessive rebuilds of DSS (#69724)" (#71459)
This reverts commit 16dce765775da51416f119a21fc88a8de9ee5fd3.
diff --git a/packages/flutter/lib/src/widgets/draggable_scrollable_sheet.dart b/packages/flutter/lib/src/widgets/draggable_scrollable_sheet.dart
index 9303c98..dac3c02 100644
--- a/packages/flutter/lib/src/widgets/draggable_scrollable_sheet.dart
+++ b/packages/flutter/lib/src/widgets/draggable_scrollable_sheet.dart
@@ -288,17 +288,17 @@
class _DraggableScrollableSheetState extends State<DraggableScrollableSheet> {
late _DraggableScrollableSheetScrollController _scrollController;
late _DraggableSheetExtent _extent;
- // The child only gets rebuilt when dependencies or the widget change.
- // Otherwise, excessive rebuilds of the child are triggered every time the
- // scroll extent changes, which is very expensive and does not provide any
- // helpful information to the child. If the child needs to rebuild whenever
- // the scroll position changes, they can always subscribe to it.
- Widget? _child;
@override
void initState() {
super.initState();
- _updateExtent();
+ _extent = _DraggableSheetExtent(
+ minExtent: widget.minChildSize,
+ maxExtent: widget.maxChildSize,
+ initialExtent: widget.initialChildSize,
+ listener: _setExtent,
+ );
+ _scrollController = _DraggableScrollableSheetScrollController(extent: _extent);
}
@override
@@ -317,33 +317,13 @@
}
_extent._currentExtent.value = _extent.initialExtent;
}
- _child = widget.builder(context, _scrollController);
- }
-
- @override
- void didUpdateWidget(DraggableScrollableSheet oldWidget) {
- super.didUpdateWidget(oldWidget);
- _updateExtent();
- // Call this unconditionally - the closure may not change even though it
- // refers to things outside of its identity, e.g. a tearoff from state that
- // has an `if (stateVariable)`.
- _child = widget.builder(context, _scrollController);
- }
-
- void _updateExtent() {
- _extent = _DraggableSheetExtent(
- minExtent: widget.minChildSize,
- maxExtent: widget.maxChildSize,
- initialExtent: widget.initialChildSize,
- listener: _setExtent,
- );
- _scrollController = _DraggableScrollableSheetScrollController(extent: _extent);
}
void _setExtent() {
setState(() {
// _extent has been updated when this is called.
});
+
}
@override
@@ -353,7 +333,7 @@
_extent.availablePixels = widget.maxChildSize * constraints.biggest.height;
final Widget sheet = FractionallySizedBox(
heightFactor: _extent.currentExtent,
- child: _child,
+ child: widget.builder(context, _scrollController),
alignment: Alignment.bottomCenter,
);
return widget.expand ? SizedBox.expand(child: sheet) : sheet;
@@ -364,7 +344,6 @@
@override
void dispose() {
_scrollController.dispose();
- _child = null;
super.dispose();
}
}
diff --git a/packages/flutter/test/widgets/draggable_scrollable_sheet_test.dart b/packages/flutter/test/widgets/draggable_scrollable_sheet_test.dart
index 9e1fcc4..f39d4e2 100644
--- a/packages/flutter/test/widgets/draggable_scrollable_sheet_test.dart
+++ b/packages/flutter/test/widgets/draggable_scrollable_sheet_test.dart
@@ -309,149 +309,4 @@
expect(notificationTypes, types);
});
}
-
- testWidgets('Builder is not called excessively', (WidgetTester tester) async {
- int buildCount = 0;
- await tester.pumpWidget(Directionality(
- textDirection: TextDirection.ltr,
- child: Stack(
- children: <Widget>[
- DraggableScrollableSheet(
- builder: (BuildContext context, ScrollController scrollController) {
- buildCount += 1;
- return Container(
- color: const Color(0xFFABCDEF),
- child: ListView.builder(
- controller: scrollController,
- itemExtent: 100,
- itemCount: 100,
- itemBuilder: (BuildContext context, int index) => Text('Item $index'),
- ),
- );
- },
- ),
- ],
- ),
- ));
- expect(buildCount, 1);
- await tester.flingFrom(const Offset(0, 325), const Offset(0, -325), 200);
- expect(buildCount, 1);
- await tester.pumpAndSettle();
- expect(buildCount, 1);
- });
-
- testWidgets('Builder is called if widget updates', (WidgetTester tester) async {
- int buildCount = 0;
- final GlobalKey key = GlobalKey();
- await tester.pumpWidget(Directionality(
- textDirection: TextDirection.ltr,
- child: Stack(
- children: <Widget>[
- DraggableScrollableSheet(
- key: key,
- builder: (BuildContext context, ScrollController scrollController) {
- buildCount += 1;
- return Container(
- color: const Color(0xFFABCDEF),
- child: ListView.builder(
- controller: scrollController,
- itemExtent: 100,
- itemCount: 100,
- itemBuilder: (BuildContext context, int index) => Text('Item $index'),
- ),
- );
- },
- ),
- ],
- ),
- ));
- expect(buildCount, 1);
- expect(find.text('Item 1'), findsOneWidget);
-
- await tester.pumpWidget(Directionality(
- textDirection: TextDirection.ltr,
- child: Stack(
- children: <Widget>[
- DraggableScrollableSheet(
- key: key,
- builder: (BuildContext context, ScrollController scrollController) {
- buildCount += 1;
- return Container(
- color: const Color(0xFFFEDCBA),
- child: ListView.builder(
- controller: scrollController,
- itemExtent: 50,
- itemCount: 100,
- itemBuilder: (BuildContext context, int index) => Text('New Item $index'),
- ),
- );
- },
- ),
- ],
- ),
- ));
- expect(buildCount, 2);
- expect(find.text('Item 1'), findsNothing);
- expect(find.text('New Item 1'), findsOneWidget);
- });
-
- testWidgets('Changes to min/max/initial child size are respected', (WidgetTester tester) async {
- final GlobalKey key = GlobalKey();
- final Key childKey = UniqueKey();
- await tester.pumpWidget(Directionality(
- textDirection: TextDirection.ltr,
- child: Stack(
- children: <Widget>[
- DraggableScrollableSheet(
- key: key,
- minChildSize: .25,
- maxChildSize: 1.0,
- initialChildSize: .5,
- builder: (BuildContext context, ScrollController scrollController) {
- return Container(
- key: childKey,
- color: const Color(0xFFABCDEF),
- child: ListView.builder(
- controller: scrollController,
- itemExtent: 100,
- itemCount: 100,
- itemBuilder: (BuildContext context, int index) => Text('Item $index'),
- ),
- );
- },
- ),
- ],
- ),
- ));
- expect(find.text('Item 1'), findsOneWidget);
- expect(tester.getRect(find.byKey(childKey)), const Rect.fromLTRB(0, 300, 800, 600));
-
- await tester.pumpWidget(Directionality(
- textDirection: TextDirection.ltr,
- child: Stack(
- children: <Widget>[
- DraggableScrollableSheet(
- key: key,
- minChildSize: .5,
- maxChildSize: .75,
- initialChildSize: .6,
- builder: (BuildContext context, ScrollController scrollController) {
- return Container(
- key: childKey,
- color: const Color(0xFFFEDCBA),
- child: ListView.builder(
- controller: scrollController,
- itemExtent: 50,
- itemCount: 100,
- itemBuilder: (BuildContext context, int index) => Text('New Item $index'),
- ),
- );
- },
- ),
- ],
- ),
- ));
- expect(find.text('New Item 1'), findsOneWidget);
- expect(tester.getRect(find.byKey(childKey)), const Rect.fromLTRB(0, 240, 800, 600));
- });
}
