import 'package:flutter/material.dart';
void main() {
runApp(MyApp());
}
final darkNotifier = ValueNotifier<bool>(false);
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return ValueListenableBuilder<bool>(
valueListenable: darkNotifier,
builder: (BuildContext context, bool isDark, Widget? child) {
return MaterialApp(
title: 'Flutter Demo',
themeMode: isDark ? ThemeMode.dark : ThemeMode.light,
theme: ThemeData(primaryColor: Colors.blue),
darkTheme: ThemeData.dark(),
home: MyHomePage(
title: 'Homepage',
),
);
});
}
}
class MyHomePage extends StatefulWidget {
MyHomePage({Key? key, required this.title}) : super(key: key);
final String title;
@override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
@override
void dispose() {
darkNotifier.dispose();
super.dispose();
}
@override
Widget build(BuildContext context) {
bool isDark = darkNotifier.value;
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:',
),
Text(
_darkNotifier.value ? 'DarkMode' : 'LightMode',
style: Theme.of(context).textTheme.headline4,
),
],
),
),
floatingActionButton: FloatingActionButton(
onPressed: () {
isDark = !isDark;
darkNotifier.value = isDark;
},
tooltip: 'Increment',
child: Icon(isDark ? Icons.wb_sunny_outlined : Icons.bubble_chart),
),
);
}
}