Flutter - Radio Animation is not showing up on showDialog - dart

Question

I'm trying to create a Radio in a showDialog, however the animation that occurs on Radio does not appear in showDialog.
For example: when tapped in foo2 nothing happens, and when you exit in showDialog and go back to it, foo2 is selected.
Below is the code and a gif showing what is happening:
import "package:flutter/material.dart";
void main() {
runApp(new ControlleApp());
}
class ControlleApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return new MaterialApp(
title: "My App",
home: new HomePage(),
);
}
}
class HomePage extends StatefulWidget {
#override
HomePageState createState() => new HomePageState();
}
enum _RadioGroup {
foo1,
foo2
}
class HomePageState extends State<HomePage> {
_RadioGroup _itemType = _RadioGroup.foo1;
void changeItemType(_RadioGroup type) {
setState(() {
_itemType = type;
});
}
void showDemoDialog<T>({ BuildContext context, Widget child }) {
showDialog<T>(
context: context,
child: child,
);
}
#override
Widget build(BuildContext context){
return new Scaffold(
appBar: new AppBar(backgroundColor: new Color(0xFF26C6DA)),
body: new Container(
child: new Row(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
new InkWell(
onTap: (){
showDemoDialog<String>(
context: context,
child: new SimpleDialog(
title: const Text("show"),
children: <Widget>[
new Row(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
new Radio<_RadioGroup>(
groupValue: _itemType,
value: _RadioGroup.foo1,
onChanged: changeItemType
),
const Text("foo1"),
new Radio<_RadioGroup>(
groupValue: _itemType,
value: _RadioGroup.foo2,
onChanged: changeItemType
),
const Text("foo2"),
],
)
],
)
);
},
child: new Container(
margin: new EdgeInsets.only(top: 16.0, bottom: 8.0),
child: new Text("Show"),
),
)
],
),
)
);
}
}

Answer 1

Remember that components are immutable.
When you call showDialog, the content of that dialog won't change even if HomePage does.
The solution is easy. You need to refactor a bit your code to something like :
showDialog(
context: context,
builder: (context) => MyForm()
)
and instead of changing the state of HomePage, you instead change the state of MyForm.
example :
class Test extends StatelessWidget {
void onSubmit(String result) {
print(result);
}
#override
Widget build(BuildContext context) {
return Scaffold(
body: Center(
child: RaisedButton(
onPressed: () => showDialog(context: context, builder: (context) => MyForm(onSubmit: onSubmit)),
child: Text("dialog"),
),
),
);
}
}
typedef void MyFormCallback(String result);
class MyForm extends StatefulWidget {
final MyFormCallback onSubmit;
MyForm({this.onSubmit});
#override
_MyFormState createState() => _MyFormState();
}
class _MyFormState extends State<MyForm> {
String value = "foo";
#override
Widget build(BuildContext context) {
return SimpleDialog(
title: Text("My form"),
children: <Widget>[
Radio(
groupValue: value,
onChanged: (value) => setState(() => this.value = value),
value: "foo",
),
Radio(
groupValue: value,
onChanged: (value) => setState(() => this.value = value),
value: "bar",
),
FlatButton(
onPressed: () {
Navigator.pop(context);
widget.onSubmit(value);
},
child: new Text("submit"),
)
],
);
}
}