Dicee - simple app to learn Stateful Flutter widgets

dicee_main.dart

import 'dart:math';
import 'package:flutter/material.dart';

void main() {
  return runApp(
    MaterialApp(
      home: Scaffold(
        backgroundColor: Colors.red,
        appBar: AppBar(
          backgroundColor: Colors.red,
          title: Text('Dicee'),
        ),
        body: DicePage(),
      ),
    ),
  );
}

class DicePage extends StatefulWidget {
  @override
  _DicePageState createState() => _DicePageState();
}

class _DicePageState extends State<DicePage> {
  int leftDiceNum = Random().nextInt(6) + 1;
  int rightDiceNum = Random().nextInt(6) + 1;

  void stateUpdate() {
    setState(() {
      leftDiceNum = Random().nextInt(6) + 1;
      rightDiceNum = Random().nextInt(6) + 1;
    });
  }

  @override
  Widget build(BuildContext context) {
    return Center(
      child: Column(
        children: <Widget>[
          Spacer(
            flex: 2,
          ),
          Row(
            children: <Widget>[
              Spacer(
                flex: 2,
              ),
              Expanded(
                flex: 4,
                child: FlatButton(
                  onPressed: stateUpdate,
                  child: Image.asset('images/dice$leftDiceNum.png'),
                ),
              ),
              Spacer(),
              Expanded(
                flex: 4,
                child: FlatButton(
                  onPressed: stateUpdate,
                  child: Image.asset('images/dice$rightDiceNum.png'),
                ),
              ),
              Spacer(
                flex: 2,
              ),
            ],
          ),
          Spacer(
            flex: 1,
          ),
          Row(
            children: <Widget>[
              Spacer(
                flex: 2,
              ),
              Expanded(
                flex: 4,
                child: FlatButton(
                  onPressed: stateUpdate,
                  child: Image.asset('images/dice$leftDiceNum.png'),
                ),
              ),
              Spacer(),
              Expanded(
                flex: 4,
                child: FlatButton(
                  onPressed: stateUpdate,
                  child: Image.asset('images/dice$rightDiceNum.png'),
                ),
              ),
              Spacer(
                flex: 2,
              ),
            ],
          ),
          Spacer(
            flex: 2,
          ),
        ],
      ),
    );
  }
}

pubspec.yaml

name: flutterfirstapp
description: Dicee - simple app to learn Stateful Flutter widgets
version: 1.0.0+1

environment:
  sdk: ">=2.7.0 <3.0.0"

dependencies:
  flutter:
    sdk: flutter
  cupertino_icons: ^0.1.3

dev_dependencies:
  flutter_test:
    sdk: flutter

# For information on the generic Dart part of this file, see the
# following page: https://dart.dev/tools/pub/pubspec

# The following section is specific to Flutter.
flutter:

  # The following line ensures that the Material Icons font is
  # included with your application, so that you can use the icons in
  # the material Icons class.
  uses-material-design: true

  # To add assets to your application, add an assets section, like this:
  assets:
    - images/

  # An image asset can refer to one or more resolution-specific "variants", see
  # https://flutter.dev/assets-and-images/#resolution-aware.

  # For details regarding adding assets from package dependencies, see
  # https://flutter.dev/assets-and-images/#from-packages

  fonts:
  - family: Pacifico
    fonts:
     - asset: fonts/Pacifico-Regular.ttf

  - family: SourceSansPro
    fonts:
      - asset: fonts/Source_Sans_Pro/SourceSansPro-Regular.ttf

  # For details regarding fonts from package dependencies,
  # see https://flutter.dev/custom-fonts/#from-packages