Fix SliverMainAxisGroup scrollOffsetCorrection (#174369)
Fixes : [#174368](https://github.com/flutter/flutter/issues/174368)
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diff --git a/packages/flutter/lib/src/rendering/sliver_group.dart b/packages/flutter/lib/src/rendering/sliver_group.dart
index 75774aa..ae3b28c 100644
--- a/packages/flutter/lib/src/rendering/sliver_group.dart
+++ b/packages/flutter/lib/src/rendering/sliver_group.dart
@@ -326,7 +326,17 @@
),
parentUsesSize: true,
);
+
final SliverGeometry childLayoutGeometry = child.geometry!;
+
+ final double? scrollOffsetCorrection = childLayoutGeometry.scrollOffsetCorrection;
+ if (scrollOffsetCorrection != null) {
+ geometry = SliverGeometry(scrollOffsetCorrection: scrollOffsetCorrection);
+ return;
+ }
+
+ assert(childLayoutGeometry.debugAssertIsValid());
+
final double childPaintOffset = layoutOffset + childLayoutGeometry.paintOrigin;
final SliverPhysicalParentData childParentData =
child.parentData! as SliverPhysicalParentData;
diff --git a/packages/flutter/test/widgets/sliver_main_axis_group_test.dart b/packages/flutter/test/widgets/sliver_main_axis_group_test.dart
index 3367d0c..41c6cb0 100644
--- a/packages/flutter/test/widgets/sliver_main_axis_group_test.dart
+++ b/packages/flutter/test/widgets/sliver_main_axis_group_test.dart
@@ -1331,6 +1331,104 @@
expectedLocalPosition: const Offset(15, 5),
);
});
+ testWidgets(
+ 'With SliverList can handle inaccurate scroll offset due to changes in children list',
+ (WidgetTester tester) async {
+ bool skip = true;
+ Widget buildItem(BuildContext context, int index) {
+ return !skip || index.isEven
+ ? Card(
+ child: ListTile(title: Text('item$index', style: const TextStyle(fontSize: 80))),
+ )
+ : Container();
+ }
+
+ await tester.pumpWidget(
+ MaterialApp(
+ theme: ThemeData(useMaterial3: false),
+ home: Scaffold(
+ body: CustomScrollView(
+ slivers: <Widget>[
+ SliverMainAxisGroup(
+ slivers: <Widget>[
+ SliverList(delegate: SliverChildBuilderDelegate(buildItem, childCount: 30)),
+ ],
+ ),
+ ],
+ ),
+ ),
+ ),
+ );
+ // Only even items 0~12 are on the screen.
+ for (int index = 0; index <= 12; index++) {
+ expect(find.text('item$index'), index.isEven ? findsOneWidget : findsNothing);
+ }
+ expect(find.text('item12'), findsOneWidget);
+ expect(find.text('item14'), findsNothing);
+
+ await tester.drag(find.byType(CustomScrollView), const Offset(0.0, -750.0));
+ await tester.pump();
+ // Only even items 16~28 are on the screen.
+ expect(find.text('item15'), findsNothing);
+ expect(find.text('item16'), findsOneWidget);
+ expect(find.text('item28'), findsOneWidget);
+
+ skip = false;
+ await tester.pumpWidget(
+ MaterialApp(
+ home: Scaffold(
+ body: CustomScrollView(
+ slivers: <Widget>[
+ SliverMainAxisGroup(
+ slivers: <Widget>[
+ SliverList(delegate: SliverChildBuilderDelegate(buildItem, childCount: 30)),
+ ],
+ ),
+ ],
+ ),
+ ),
+ ),
+ );
+
+ // Only items 12~19 are on the screen.
+ expect(find.text('item11'), findsNothing);
+ expect(find.text('item12'), findsOneWidget);
+ expect(find.text('item19'), findsOneWidget);
+ expect(find.text('item20'), findsNothing);
+
+ await tester.drag(find.byType(CustomScrollView), const Offset(0.0, 250.0));
+ await tester.pump();
+
+ // Only items 10~16 are on the screen.
+ expect(find.text('item9'), findsNothing);
+ expect(find.text('item10'), findsOneWidget);
+ expect(find.text('item16'), findsOneWidget);
+ expect(find.text('item17'), findsNothing);
+
+ // The inaccurate scroll offset should reach zero at this point
+ await tester.drag(find.byType(CustomScrollView), const Offset(0.0, 250.0));
+ await tester.pump();
+
+ // Only items 7~13 are on the screen.
+ expect(find.text('item6'), findsNothing);
+ expect(find.text('item7'), findsOneWidget);
+ expect(find.text('item13'), findsOneWidget);
+ expect(find.text('item14'), findsNothing);
+
+ // It will be corrected as we scroll, so we have to drag multiple times.
+ await tester.drag(find.byType(CustomScrollView), const Offset(0.0, 250.0));
+ await tester.pump();
+ await tester.drag(find.byType(CustomScrollView), const Offset(0.0, 250.0));
+ await tester.pump();
+ await tester.drag(find.byType(CustomScrollView), const Offset(0.0, 250.0));
+ await tester.pump();
+
+ // Only items 0~6 are on the screen.
+ expect(find.text('item0'), findsOneWidget);
+ expect(find.text('item6'), findsOneWidget);
+ expect(find.text('item7'), findsNothing);
+ },
+ );
}
Widget _buildSliverList({
