How to add decoration DropdownButton in Flutter - flutter

Question

I have a dropdown button as you can see below.
child: DropdownButton<String>(
value: dropDownValue,
icon: Icon(Icons.keyboard_arrow_down),
iconSize: 15,
elevation: 16,
style: TextStyle(color: Colors.grey),
underline: Container(
decoration: ShapeDecoration(
shape: RoundedRectangleBorder(
side: BorderSide(width: 1.0, style: BorderStyle.solid),
borderRadius: BorderRadius.all(Radius.circular(5.0)),
),
),
),
onChanged: (String newValue) {
setState(() {
dropDownValue = newValue;
});
},
items: [dropDownValue,...snapshot.data.data]
.map<DropdownMenuItem<String>>((String value) {
return DropdownMenuItem<String>(
value: value,
child: Text(value.name),
);
}).toList(),
),
I want to shape it like in the image by using decoration in Container, but i can't shape it the way i want
But right now this is the image I have. How do I add an edge to my dropdown button? Is there a known way for this?

Answer 1

You can copy paste run full code below
You can use DropdownButtonFormField with InputDecoration set fillColor and hintText
code snippet
DropdownButtonFormField(
decoration: InputDecoration(
border: OutlineInputBorder(
borderRadius: const BorderRadius.all(
const Radius.circular(30.0),
),
),
filled: true,
hintStyle: TextStyle(color: Colors.grey[800]),
hintText: "Name",
fillColor: Colors.blue[200]),
value: dropDownValue,
working demo
full code
import 'package:flutter/material.dart';
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
visualDensity: VisualDensity.adaptivePlatformDensity,
),
home: MyHomePage(title: 'Flutter Demo Home Page'),
);
}
}
class MyHomePage extends StatefulWidget {
MyHomePage({Key key, this.title}) : super(key: key);
final String title;
#override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
int _counter = 0;
String dropDownValue;
List<String> cityList = [
'Ajman',
'Al Ain',
'Dubai',
'Fujairah',
'Ras Al Khaimah',
'Sharjah',
'Umm Al Quwain'
];
void _incrementCounter() {
setState(() {
_counter++;
});
}
#override
void initState() {
//setFilters();
super.initState();
}
setFilters() {
setState(() {
dropDownValue = cityList[2];
});
}
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(widget.title),
),
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
DropdownButtonFormField(
decoration: InputDecoration(
border: OutlineInputBorder(
borderRadius: const BorderRadius.all(
const Radius.circular(30.0),
),
),
filled: true,
hintStyle: TextStyle(color: Colors.grey[800]),
hintText: "Name",
fillColor: Colors.blue[200]),
value: dropDownValue,
onChanged: (String Value) {
setState(() {
dropDownValue = Value;
});
},
items: cityList
.map((cityTitle) => DropdownMenuItem(
value: cityTitle, child: Text("$cityTitle")))
.toList(),
),
],
),
),
floatingActionButton: FloatingActionButton(
onPressed: _incrementCounter,
tooltip: 'Increment',
child: Icon(Icons.add),
),
);
}
}

Answer 2

You can just wrap your DropdownButton widget into DecoratedBox :
return DecoratedBox(
decoration: ShapeDecoration(
color: Colors.cyan,
shape: RoundedRectangleBorder(
side: BorderSide(width: 1.0, style: BorderStyle.solid, color: Colors.cyan),
borderRadius: BorderRadius.all(Radius.circular(25.0)),
),
),
child: Padding(
padding: const EdgeInsets.symmetric(horizontal: 40.0, vertical: 0.0),
child: DropdownButton<String>(
value: dropdownValue,
icon: Icon(null),
elevation: 16,
onChanged: (String newValue) {
setState(() {
dropdownValue = newValue;
});
},
underline: SizedBox(),
items: <String>['City', 'Country', 'State']
.map<DropdownMenuItem<String>>((String value) {
return DropdownMenuItem<String>(
value: value,
child: Text(value),
);
}).toList(),
),
),
);
Output :