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Fix clipping for SliverLists (#18410)

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Michael Goderbauer 2018-06-15 10:11:40 -07:00 committed by GitHub
parent 409007827b
commit 6ab3abfbc3
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GPG Key ID: 4AEE18F83AFDEB23
3 changed files with 118 additions and 2 deletions
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5
packages/flutter/lib/src/rendering/sliver_fixed_extent_list.dart
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@ -248,13 +248,16 @@ abstract class RenderSliverFixedExtentBoxAdaptor extends RenderSliverMultiBoxAda
to: trailingScrollOffset,
);
final double targetEndScrollOffsetForPaint = constraints.scrollOffset + constraints.remainingPaintExtent;
final int targetLastIndexForPaint = targetEndScrollOffsetForPaint.isFinite ?
getMaxChildIndexForScrollOffset(targetEndScrollOffsetForPaint, itemExtent) : null;
geometry = new SliverGeometry(
scrollExtent: estimatedMaxScrollOffset,
paintExtent: paintExtent,
cacheExtent: cacheExtent,
maxPaintExtent: estimatedMaxScrollOffset,
// Conservative to avoid flickering away the clip during scroll.
hasVisualOverflow: (targetLastIndex != null && lastIndex >= targetLastIndex)
hasVisualOverflow: (targetLastIndexForPaint != null && lastIndex >= targetLastIndexForPaint)
|| constraints.scrollOffset > 0.0,
);

3
packages/flutter/lib/src/rendering/sliver_list.dart
View File

@ -274,13 +274,14 @@ class RenderSliverList extends RenderSliverMultiBoxAdaptor {
from: childScrollOffset(firstChild),
to: endScrollOffset,
);
final double targetEndScrollOffsetForPaint = constraints.scrollOffset + constraints.remainingPaintExtent;
geometry = new SliverGeometry(
scrollExtent: estimatedMaxScrollOffset,
paintExtent: paintExtent,
cacheExtent: cacheExtent,
maxPaintExtent: estimatedMaxScrollOffset,
// Conservative to avoid flickering away the clip during scroll.
hasVisualOverflow: endScrollOffset > targetEndScrollOffset || constraints.scrollOffset > 0.0,
hasVisualOverflow: endScrollOffset > targetEndScrollOffsetForPaint || constraints.scrollOffset > 0.0,
);
// We may have started the layout while scrolled to the end, which would not

112
packages/flutter/test/widgets/list_view_test.dart
View File

@ -5,6 +5,8 @@
import 'package:flutter_test/flutter_test.dart';
import 'package:flutter/widgets.dart';
import '../rendering/mock_canvas.dart';
class TestSliverChildListDelegate extends SliverChildListDelegate {
TestSliverChildListDelegate(List<Widget> children) : super(children);
@ -293,4 +295,114 @@ void main() {
// Leave left/right padding as is for children.
expect(innerMediaQueryPadding, const EdgeInsets.symmetric(horizontal: 30.0));
});
testWidgets('ListView clips if overflow is smaller than cacheExtent', (WidgetTester tester) async {
// Regression test for https://github.com/flutter/flutter/issues/17426.
await tester.pumpWidget(
new Directionality(
textDirection: TextDirection.ltr,
child: new Center(
child: new Container(
height: 200.0,
child: new ListView(
cacheExtent: 500.0,
children: <Widget>[
new Container(
height: 90.0,
),
new Container(
height: 110.0,
),
new Container(
height: 80.0,
),
],
),
),
),
),
);
expect(find.byType(Viewport), paints..clipRect());
});
testWidgets('ListView does not clips if no overflow', (WidgetTester tester) async {
await tester.pumpWidget(
new Directionality(
textDirection: TextDirection.ltr,
child: new Center(
child: new Container(
height: 200.0,
child: new ListView(
cacheExtent: 500.0,
children: <Widget>[
new Container(
height: 100.0,
),
],
),
),
),
),
);
expect(find.byType(Viewport), isNot(paints..clipRect()));
});
testWidgets('ListView (fixed extent) clips if overflow is smaller than cacheExtent', (WidgetTester tester) async {
// Regression test for https://github.com/flutter/flutter/issues/17426.
await tester.pumpWidget(
new Directionality(
textDirection: TextDirection.ltr,
child: new Center(
child: new Container(
height: 200.0,
child: new ListView(
itemExtent: 100.0,
cacheExtent: 500.0,
children: <Widget>[
new Container(
height: 100.0,
),
new Container(
height: 100.0,
),
new Container(
height: 100.0,
),
],
),
),
),
),
);
expect(find.byType(Viewport), paints..clipRect());
});
testWidgets('ListView (fixed extent) does not clips if no overflow', (WidgetTester tester) async {
await tester.pumpWidget(
new Directionality(
textDirection: TextDirection.ltr,
child: new Center(
child: new Container(
height: 200.0,
child: new ListView(
itemExtent: 100.0,
cacheExtent: 500.0,
children: <Widget>[
new Container(
height: 100.0,
),
],
),
),
),
),
);
expect(find.byType(Viewport), isNot(paints..clipRect()));
});
}