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Don't crash if Slider is given an empty range. (#10133)

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Instead just disable the slider.

Fixes https://github.com/flutter/flutter/issues/10055
This commit is contained in:
Ian Hickson 2017-05-16 19:35:01 -07:00 committed by GitHub
parent 6ffcadfa38
commit 940473e5d6
2 changed files with 42 additions and 4 deletions
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16
packages/flutter/lib/src/material/slider.dart
View file

@ -31,6 +31,9 @@ import 'typography.dart';
/// that use a slider will listen for the [onChanged] callback and rebuild the
/// slider with a new [value] to update the visual appearance of the slider.
///
/// The slider will be disabled if [onChanged] is null or if the range given by
/// [min]..[max] is empty (i.e. if [min] is equal to [max]).
///
/// Requires one of its ancestors to be a [Material] widget.
///
/// See also:
@ -61,6 +64,7 @@ class Slider extends StatefulWidget {
}) : assert(value != null),
assert(min != null),
assert(max != null),
assert(min <= max),
assert(value >= min && value <= max),
assert(divisions == null || divisions > 0),
assert(thumbOpenAtMin != null),
@ -101,12 +105,16 @@ class Slider extends StatefulWidget {
/// The minimum value the user can select.
///
/// Defaults to 0.0.
/// Defaults to 0.0. Must be less than or equal to [max].
///
/// If the [max] is equal to the [min], then the slider is disabled.
final double min;
/// The maximum value the user can select.
///
/// Defaults to 1.0.
/// Defaults to 1.0. Must be greater than or equal to [min].
///
/// If the [max] is equal to the [min], then the slider is disabled.
final double max;
/// The number of discrete divisions.
@ -162,13 +170,13 @@ class _SliderState extends State<Slider> with TickerProviderStateMixin {
assert(debugCheckHasMaterial(context));
final ThemeData theme = Theme.of(context);
return new _SliderRenderObjectWidget(
value: (widget.value - widget.min) / (widget.max - widget.min),
value: widget.max > widget.min ? (widget.value - widget.min) / (widget.max - widget.min) : 0.0,
divisions: widget.divisions,
label: widget.label,
activeColor: widget.activeColor ?? theme.accentColor,
thumbOpenAtMin: widget.thumbOpenAtMin,
textTheme: theme.accentTextTheme,
onChanged: widget.onChanged != null ? _handleChanged : null,
onChanged: (widget.onChanged != null) && (widget.max > widget.min) ? _handleChanged : null,
vsync: this,
);
}

30
packages/flutter/test/material/slider_test.dart
View file

@ -85,6 +85,36 @@ void main() {
expect(SchedulerBinding.instance.transientCallbackCount, equals(0));
});
testWidgets('Slider can be given zero values',
(WidgetTester tester) async {
final List<double> log = <double>[];
await tester.pumpWidget(new Material(
child: new Slider(
value: 0.0,
min: 0.0,
max: 1.0,
onChanged: (double newValue) { log.add(newValue); },
),
));
await tester.tap(find.byType(Slider));
expect(log, <double>[0.5]);
log.clear();
await tester.pumpWidget(new Material(
child: new Slider(
value: 0.0,
min: 0.0,
max: 0.0,
onChanged: (double newValue) { log.add(newValue); },
),
));
await tester.tap(find.byType(Slider));
expect(log, <double>[]);
log.clear();
});
testWidgets('Slider can draw an open thumb at min',
(WidgetTester tester) async {
Widget buildApp(bool thumbOpenAtMin) {