Call a setState of a statefull widget from the stateless widget - flutter

Question

I have a stateless widget class that has a widget whose movements need to be tracked. I cannot keep this widget inside the stateful widgets as I don't want the state of this widget to be refreshed.
I have the following code.
import 'package:flutter/material.dart';
import 'package:control_pad/control_pad.dart';
void main() => runApp(new MyApp());
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return new MaterialApp(
home: new MyHomePage(),
);
}
}
class MyHomePage extends StatelessWidget {
#override
Widget build(BuildContext context) {
return Container(
color: Colors.white,
child: Column(
children: <Widget>[
Expanded(
child: JoystickView(
onDirectionChanged: (degree, direction) {
//Change the state here.
},
),
),
Expanded(
child: MyStateFull(),
),
],
),
);
}
}
class MyStateFull extends StatefulWidget {
#override
_MyStateFullState createState() => _MyStateFullState();
}
class _MyStateFullState extends State<MyStateFull> {
double degree = 10;
double direction = 10;
//Call this from the stateless Widget
void changedDirection(degree, direction) {
setState(() {
this.degree = degree;
this.direction = direction;
});
}
#override
Widget build(BuildContext context) {
return Container(
child: Text(
"The degree Moved is $degree and the direction is $direction",
style: TextStyle(fontSize: 25, color: Colors.black),
),
);
}
}
This code produces the following output.
I want the direction and degree values to be changed as the joystick is moved.
Thank You.

Answer 1

I tried it myself and found the solution. This can be done using streams. I will post the code just in case someone needs it in the future.
import 'package:flutter/material.dart';
import 'package:control_pad/control_pad.dart';
class MyStateLess extends StatelessWidget {
StreamController<List<double>> _controller = StreamController<List<double>>();
GlobalKey<_MyStateFullState> statefulKey = new GlobalKey<_MyStateFullState>();
#override
Widget build(BuildContext context) {
return Column(
children: <Widget>[
JoystickView(
onDirectionChanged: (degree, direction) {
List<double> temp = new List<double>();
temp.add(degree);
temp.add(direction);
_controller.add(temp);
},
),
MyStateFull(stream: _controller.stream, key: statefulKey),
],
);
}
}
class MyStateFull extends StatefulWidget {
final Stream<List<double>> stream;
MyStateFull({Key key, #required this.stream}) : super(key: key);
#override
_MyStateFullState createState() => _MyStateFullState();
}
class _MyStateFullState extends State<MyStateFull> {
double _degree = 0.0;
double _direction = 0.0;
#override
void initState() {
super.initState();
widget.stream.listen((event) {
setState(() {
_degree = event[0];
_direction = event[1];
});
});
}
#override
Widget build(BuildContext context) {
return Container(
child: Text("$_degree, $_direction"),
);
}
}