Flutter 入门与实战：设置 App 的主色调与字体

import 'package:flutter/material.dart';
 
void main() => runApp(MyApp());
 
class MyApp extends StatelessWidget {
  // 设置应用的主题样式
  final ThemeData theme = ThemeData(
    primarySwatch: Colors.blue, // 设置主色调为蓝色
    visualDensity: VisualDensity.adaptivePlatformDensity,
  );
 
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: theme, // 应用主题
      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> {
  int _counter = 0;
 
  void _incrementCounter() {
    setState(() {
      _counter++;
    });
  }
 
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Text(
              'You have pushed the button this many times:',
              style: Theme.of(context).textTheme.headline6, // 使用主题中的字体样式
            ),
            Text(
              '$_counter',
              style: Theme.of(context).textTheme.headline4, // 使用主题中的字体样式
            ),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _incrementCounter,
        tooltip: 'Increment',
        child: Icon(Icons.add),
      ), // This trailing comma makes auto-formatting nicer for build methods.
    );
  }
}

这段代码继续上一节的内容，展示了如何在Flutter应用中设置主色调和使用主题中定义的字体样式。通过ThemeData我们定义了主色调和字体样式，并在Text组件中使用Theme.of(context)来应用这些样式。这是学习如何在Flutter应用中统一设计样式的一个很好的例子。