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Fix dropdown buttons menus being clipped by the edge of the screen (#12059)

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Fix dropdown buttons menus being clipped by the edge of the screen
This commit is contained in:
Collin Jackson 2017-09-15 16:59:51 -07:00 committed by GitHub
parent e163a81560
commit d62832b91a
2 changed files with 39 additions and 4 deletions
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8
packages/flutter/lib/src/material/dropdown.dart
View File

@ -203,7 +203,9 @@ class _DropdownMenuRouteLayout<T> extends SingleChildLayoutDelegate {
// with which to dismiss the menu.
// -- https://material.google.com/components/menus.html#menus-simple-menus
final double maxHeight = math.max(0.0, constraints.maxHeight - 2 * _kMenuItemHeight);
final double width = buttonRect.width + 8.0;
// The width of a menu should be at most the view width. This ensures that
// the menu does not extend past the left and right edges of the screen.
final double width = math.min(constraints.maxWidth, buttonRect.width + 8.0);
return new BoxConstraints(
minWidth: width,
maxWidth: width,
@ -225,9 +227,7 @@ class _DropdownMenuRouteLayout<T> extends SingleChildLayoutDelegate {
}
return true;
});
final double width = buttonRect.width + 8.0;
return new Offset(buttonRect.left.clamp(0.0, size.width - width), menuTop);
return new Offset(buttonRect.left.clamp(0.0, size.width - childSize.width), menuTop);
}
@override

35
packages/flutter/test/material/dropdown_test.dart
View File

@ -164,6 +164,41 @@ void main() {
expect(value, equals('two'));
});
testWidgets('Dropdown in ListView', (WidgetTester tester) async {
// Regression test for https://github.com/flutter/flutter/issues/12053
// Positions a DropdownButton at the left and right edges of the screen,
// forcing it to be sized down to the viewport width
final String value = 'foo';
final UniqueKey itemKey = new UniqueKey();
await tester.pumpWidget(
new MaterialApp(
home: new Material(
child: new ListView(
children: <Widget>[
new DropdownButton<String>(
value: value,
items: <DropdownMenuItem<String>>[
new DropdownMenuItem<String>(
key: itemKey,
value: value,
child: new Text(value),
),
],
onChanged: (_) {},
),
],
),
),
),
);
await tester.tap(find.text(value));
await tester.pump();
final List<RenderBox> itemBoxes = tester.renderObjectList(find.byKey(itemKey)).toList();
expect(itemBoxes[0].localToGlobal(Offset.zero).dx, equals(0.0));
expect(itemBoxes[1].localToGlobal(Offset.zero).dx, equals(16.0));
expect(itemBoxes[1].size.width, equals(800.0 - 16.0 * 2));
});
testWidgets('Dropdown screen edges', (WidgetTester tester) async {
int value = 4;
final List<DropdownMenuItem<int>> items = <DropdownMenuItem<int>>[];