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Don't attempt to draw invisible overflow indicator (#12534)

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If the flex is empty, there's no space in which to draw the overflow indicator,
so we shouldn't bother trying to draw it.

Fixes #12532
This commit is contained in:
Adam Barth 2017-10-17 11:17:08 -07:00 committed by GitHub
parent 3d7a4eed44
commit a13320253c
4 changed files with 60 additions and 10 deletions
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4
packages/flutter/lib/src/rendering/flex.dart
View File

@ -971,6 +971,10 @@ class RenderFlex extends RenderBox with ContainerRenderObjectMixin<RenderBox, Fl
return; return;
} }
// There's no point in drawing the children if we're empty.
if (size.isEmpty)
return;
// We have overflow. Clip it. // We have overflow. Clip it.
context.pushClipRect(needsCompositing, offset, Offset.zero & size, defaultPaint); context.pushClipRect(needsCompositing, offset, Offset.zero & size, defaultPaint);

56
packages/flutter/test/rendering/flex_overflow_test.dart Normal file
View File

@ -0,0 +1,56 @@
// Copyright 2017 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
import 'package:flutter_test/flutter_test.dart';
import 'package:flutter/widgets.dart';
import 'mock_canvas.dart';
void main() {
testWidgets('Flex overflow indicator', (WidgetTester tester) async {
await tester.pumpWidget(
new Center(
child: new Column(
children: <Widget>[
const SizedBox(width: 200.0, height: 200.0),
],
),
),
);
expect(find.byType(Column), isNot(paints..rect()));
await tester.pumpWidget(
new Center(
child: new SizedBox(
height: 100.0,
child: new Column(
children: <Widget>[
const SizedBox(width: 200.0, height: 200.0),
],
),
),
),
);
expect(tester.takeException(), isNotNull);
expect(find.byType(Column), paints..rect());
await tester.pumpWidget(
new Center(
child: new SizedBox(
height: 0.0,
child: new Column(
children: <Widget>[
const SizedBox(width: 200.0, height: 200.0),
],
),
),
),
);
expect(find.byType(Column), isNot(paints..rect()));
});
}

4
packages/flutter/test/widgets/column_test.dart
View File

@ -384,8 +384,6 @@ void main() {
) )
)); ));
expect(tester.takeException(), contains('overflowed'));
final RenderBox renderBox = tester.renderObject(find.byKey(childKey)); final RenderBox renderBox = tester.renderObject(find.byKey(childKey));
expect(renderBox.size.width, equals(0.0)); expect(renderBox.size.width, equals(0.0));
expect(renderBox.size.height, equals(100.0)); expect(renderBox.size.height, equals(100.0));
@ -779,8 +777,6 @@ void main() {
) )
)); ));
expect(tester.takeException(), contains('overflowed'));
final RenderBox renderBox = tester.renderObject(find.byKey(childKey)); final RenderBox renderBox = tester.renderObject(find.byKey(childKey));
expect(renderBox.size.width, equals(0.0)); expect(renderBox.size.width, equals(0.0));
expect(renderBox.size.height, equals(100.0)); expect(renderBox.size.height, equals(100.0));

6
packages/flutter/test/widgets/row_test.dart
View File

@ -302,8 +302,6 @@ void main() {
), ),
)); ));
expect(tester.takeException(), contains('overflowed'));
final RenderBox renderBox = tester.renderObject(find.byKey(childKey)); final RenderBox renderBox = tester.renderObject(find.byKey(childKey));
expect(renderBox.size.width, equals(100.0)); expect(renderBox.size.width, equals(100.0));
expect(renderBox.size.height, equals(0.0)); expect(renderBox.size.height, equals(0.0));
@ -727,8 +725,6 @@ void main() {
), ),
)); ));
expect(tester.takeException(), contains('overflowed'));
final RenderBox renderBox = tester.renderObject(find.byKey(childKey)); final RenderBox renderBox = tester.renderObject(find.byKey(childKey));
expect(renderBox.size.width, equals(100.0)); expect(renderBox.size.width, equals(100.0));
expect(renderBox.size.height, equals(0.0)); expect(renderBox.size.height, equals(0.0));
@ -1152,8 +1148,6 @@ void main() {
), ),
)); ));
expect(tester.takeException(), contains('overflowed'));
final RenderBox renderBox = tester.renderObject(find.byKey(childKey)); final RenderBox renderBox = tester.renderObject(find.byKey(childKey));
expect(renderBox.size.width, equals(100.0)); expect(renderBox.size.width, equals(100.0));
expect(renderBox.size.height, equals(0.0)); expect(renderBox.size.height, equals(0.0));