Dropdown default minimumSize when maximumSize is null returns a width of 0 #170970
Description
Steps to reproduce
- Create a Dropdown widget without minimum or maximum width (let it expand to the parent size)
- open the dropdown and see the items not be expanded to the same size the Dropdown, it should be the same size that the anchor parent
The problem is in dropdown_menu.dart line 969:
if (widget.width != null) {
effectiveMenuStyle = effectiveMenuStyle.copyWith(
minimumSize: MaterialStateProperty.resolveWith<Size?>((Set<MaterialState> states) {
final double? effectiveMaximumWidth =
effectiveMenuStyle!.maximumSize?.resolve(states)?.width;
return Size(math.min(widget.width!, effectiveMaximumWidth ?? 0.0), 0.0);
}),
);
} else if (anchorWidth != null) {
effectiveMenuStyle = effectiveMenuStyle.copyWith(
minimumSize: MaterialStateProperty.resolveWith<Size?>((Set<MaterialState> states) {
final double? effectiveMaximumWidth =
effectiveMenuStyle!.maximumSize?.resolve(states)?.width;
return Size(math.min(anchorWidth, effectiveMaximumWidth ?? 0.0), 0.0);
}),
);
}
When a maximum size is not being applied in the theme or directly in the widget this instructions return a minumim size of Size(0.0, 0.0) because when using math.min of effectiveMaximumWidth (and this is null) ?? 0.0 will always be <= anchorWidth or widget.width.
Instead when effectiveMaximumWidth is null this should use the size of the anchor or the one given in width:
Size(math.min(anchorWidth, effectiveMaximumWidth ?? anchorWidth)
Size(math.min(widget.width!, effectiveMaximumWidth ?? widget.width)
Expected results
This was the result prior 3.32
Actual results
Code sample
Code sample
import 'package:flutter/material.dart';
void main() {
runApp(const MainApp());
}
class MainApp extends StatelessWidget {
const MainApp({super.key});
@override
Widget build(BuildContext context) {
return MaterialApp(
theme: ThemeData.light().copyWith(
dropdownMenuTheme: DropdownMenuThemeData(
textStyle: const TextStyle(fontSize: 14),
inputDecorationTheme: const InputDecorationTheme(
border: UnderlineInputBorder(),
),
menuStyle: MenuStyle(
shape: const WidgetStatePropertyAll(
RoundedRectangleBorder(
borderRadius: BorderRadius.all(Radius.circular(8)),
),
),
/// This is the only way to make it expand to the same size the
/// parent dropdown (if there is no constraint of the anchro to the parent)
/// but shouldn't be a requirement
maximumSize: const WidgetStatePropertyAll(Size.infinite),
padding: const WidgetStatePropertyAll(EdgeInsets.zero),
visualDensity: const VisualDensity(vertical: -2),
side: WidgetStatePropertyAll(
BorderSide(color: Colors.grey.shade200),
),
backgroundColor: WidgetStateColor.fromMap({
WidgetState.disabled: Colors.grey.shade400,
WidgetState.selected: Colors.purple.shade600,
WidgetState.any: Colors.white,
}),
),
),
),
home: const Scaffold(
body: SafeArea(minimum: EdgeInsets.all(16), child: DropdownExample()),
),
);
}
}
enum Gender { male, female }
class DropdownExample extends StatelessWidget {
const DropdownExample({super.key});
@override
Widget build(BuildContext context) {
return DropdownMenu(
dropdownMenuEntries: const [
DropdownMenuEntry(value: Gender.female, label: 'Female'),
DropdownMenuEntry(value: Gender.male, label: 'Male'),
],
enableSearch: false,
expandedInsets: EdgeInsets.zero,
hintText: 'Select an option',
selectedTrailingIcon: const Icon(Icons.keyboard_arrow_up, size: 16),
trailingIcon: const Icon(Icons.keyboard_arrow_down, size: 16),
);
}
}Screenshots or Video
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