Flutter relative position of elements inside container - flutter

Question

I have the following slightly modified standart app, in which
the button and the result are put in a container.
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> {
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(widget.title),
),
body: Center(
child: containerWidget()
),
);
}
}
class containerWidget extends StatefulWidget {
#override
_containerWidgetState createState() => _containerWidgetState();
}
class _containerWidgetState extends State<containerWidget> {
int _counter = 0;
void _incrementCounter() {
setState(() {
_counter++;
});
}
#override
Widget build(BuildContext context) {
return Container(
color: Colors.red,
height : 300,
width : 300,
child:
Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Text(
'You have pushed the button this many times:',
),
Text(
'$_counter',
style: Theme.of(context).textTheme.headline4,
),
FloatingActionButton(
onPressed: _incrementCounter,
tooltip: 'Increment',
child: Icon(Icons.add),
),
],
),
);
}
}
In a first step, I would like to get the width and size of the screen to set the relative position of the container widget within the screen.
In a second step, I would like to modify the position of the Button within the Container widget, that means either
by getting the absolute position of the container to set the absolute position of the button w.r.t the screen size
or
by setting the relative position of the button inside the container
Positioned(left: 30.0,
top: 50.0,
child: Container(
width: 100.0,
height: 80.0,
decoration: new BoxDecoration(color: Colors.red),
child: ...

Answer 1

For the height and width of the screen you can check ou this answer :
Flutter screen size
if you'd like to move the button relative to the parent Container, you can wrap the container with a Stack widget, and set the container and button as its children(meaning you have to move the button outside the container), then simply wrap the button with a Positioned widget and use arguments right : , left : , top : , bottom : , to control the button's position with respect to the container
//for example, this means the container is 30px to the left and 50px from the top
Positioned(left: 30.0,
top: 50.0,
child: Container()),