select in flutter dart
import 'package:flutter/material.dart';
/// Usage:
/// CustomDropdown<String>(
// items: ['A', 'B', 'C'],
// onChanged: (val) => _selectedValue = val,
// center: true,
// ),
/// --> Remember: f.toString() at line 105 is @override String toString() in your class
// @override
// String toString() {
// return name;
// }
class CustomDropdown<T> extends StatefulWidget {
CustomDropdown({
Key key,
@required this.items,
@required this.onChanged,
this.onInit,
this.padding = const EdgeInsets.only(top: 10.0),
this.height = 40,
this.center = false,
this.itemText,
}) : super(key: key);
/// list item
List<T> items;
/// onChanged
void Function(T value) onChanged;
/// onInit
void Function(T value) onInit;
///padding
EdgeInsetsGeometry padding;
/// container height
double height;
/// center
bool center;
String Function(String text) itemText;
@override
_CustomDropdownState<T> createState() => _CustomDropdownState();
}
class _CustomDropdownState<T> extends State<CustomDropdown<T>> {
/// current selected value
T _selectedValue;
@override
void initState() {
super.initState();
_initValue();
}
@override
Widget build(BuildContext context) {
return _buildBody();
}
/// set default selected value when init
_initValue() {
_selectedValue = widget.items[0];
if (widget.onInit != null) widget.onInit(_selectedValue);
}
_buildBody() {
Color borderLine = Color(0xffc0c0c0);
return Padding(
padding: widget.padding,
child: Row(
mainAxisAlignment: (widget.center)
? MainAxisAlignment.center
: MainAxisAlignment.start,
children: <Widget>[
new Container(
height: widget.height,
padding: EdgeInsets.only(left: 10.0),
decoration: ShapeDecoration(
color: Colors.white,
shape: RoundedRectangleBorder(
side: BorderSide(
width: 0.8, style: BorderStyle.solid, color: borderLine),
borderRadius: BorderRadius.all(Radius.circular(5.0)),
),
),
child: new DropdownButtonHideUnderline(
child: new DropdownButton<T>(
value: _selectedValue,
onChanged: (T newValue) {
setState(() {
_selectedValue = newValue;
widget.onChanged(newValue);
});
},
items: widget.items.map((T f) {
return new DropdownMenuItem<T>(
value: f,
child: new Text(
(widget.itemText != null)
? widget.itemText(f.toString())
: f.toString(),
style: new TextStyle(color: Colors.black),
),
);
}).toList(),
),
),
),
],
),
);
}
}