1 | initial version |
In Flutter, a checkbox can be applied to a dropdown menu item by creating a custom dropdown menu item widget that includes a checkbox. Here's an example:
class CheckboxDropdownMenuItem<T> extends DropdownMenuItem<T> {
final bool checked;
final ValueChanged<bool> onChanged;
CheckboxDropdownMenuItem({
Key key,
@required T value,
@required Widget child,
this.checked = false,
this.onChanged,
}) : super(key: key, value: value, child: child);
@override
Widget build(BuildContext context) {
return Row(
children: <Widget>[
Checkbox(
value: checked,
onChanged: onChanged,
),
Expanded(
child: child,
),
],
);
}
}
Then, you can use this custom dropdown menu item widget wherever you would use a regular dropdown menu item, like this:
DropdownButton(
value: selectedValue,
items: [
CheckboxDropdownMenuItem(
value: 'option1',
child: Text('Option 1'),
checked: selectedValues.contains('option1'),
onChanged: (value) {
if (value) {
setState(() {
selectedValues.add('option1');
});
} else {
setState(() {
selectedValues.remove('option1');
});
}
},
),
// more items here
],
onChanged: (value) {
setState(() {
selectedValue = value;
});
},
)
In this example, we're using a list of selected values to keep track of which options have been checked. When the checkbox changes, we update this list and re-render the dropdown menu item.