flutter - 一键切换黑暗模式

如果某个具体的Widget不希望直接使用全局的Theme，而希望自己来定义，只需要在Widget的父节点包裹一下Theme即可.

在新的页面的Scaffold外，包裹了一个Theme，并且设置data为一个新的ThemeData.

class HYSecondPage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Theme(
      data: ThemeData(),
      child: Scaffold(
      ),
    );
  }
}

完整代码:

class _MyHomePageState extends State<MyHomePage> {
  int _counter = 0;

  void _incrementCounter() {
    setState(() {
     
      _counter++;
    });
  }

  var themechange = ThemeData.light();

  @override
  Widget build(BuildContext context) {
   
    return Theme(
      data:themechange,
      child: Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: Column(
         
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            FlatButton(
          child: Text("theme", 
                  style: TextStyle(color: Colors.black)

                  ),
                
                  onPressed: () {
                 
                    (themechange == ThemeData.dark())?(themechange = ThemeData.light()):(themechange = ThemeData.dark());

                    setState(() {
                      
                    });
                  },
), 
            Text(
              'You have pushed the button this many times:',
            ),
            Text(
              '$_counter',
              style: Theme.of(context).textTheme.headline4,
            ),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _incrementCounter,
        tooltip: 'Increment',
        child: Icon(Icons.add),
      ), 
    ),
    );
  }
}