flutter width based on text flutter code example

Example: flutter set text width

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatefulWidget {
  @override
  MyAppState createState() {
    return new MyAppState();
  }
}

class MyAppState extends State {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: SafeArea(
          child: Center(
            child: Container(
              color: Colors.blue,
              width: 300.0,
              height: 200.0,
              child: FittedBox(
                fit: BoxFit.contain,
                child: Text("Whee"),
              ),
            ),
          ),
        ),
      ),
    );
  }
}