Flutter扩展ThemeData，添加颜色等

import 'package:flutter/material.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    // 扩展ThemeData
    ThemeData myTheme = ThemeData.from(
      ThemeData.light().copyWith(
        primaryColor: Colors.blue, // 添加新的颜色属性
        accentColor: Colors.green,
      ),
    );

    return MaterialApp(
      theme: myTheme, // 使用扩展后的ThemeData
      home: HomePage(),
    );
  }
}

class HomePage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('My App'),
      ),
      body: Container(
        color: Theme.of(context).primaryColor, // 使用主题中的颜色
        child: Center(
          child: Text(
            'Hello, World!',
            style: Theme.of(context).textTheme.headline4, // 使用主题中的字体样式
          ),
        ),
      ),
    );
  }
}