Introduce Theme extensions #98033
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| // Copyright 2014 The Flutter Authors. All rights reserved. | ||
| // Use of this source code is governed by a BSD-style license that can be | ||
| // found in the LICENSE file. | ||
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| // Flutter code sample for ThemeExtension | ||
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| import 'package:flutter/material.dart'; | ||
| import 'package:flutter/scheduler.dart'; | ||
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| @immutable | ||
| class MyColors extends ThemeExtension<MyColors> { | ||
| const MyColors({ | ||
| required this.blue, | ||
| required this.red, | ||
| }); | ||
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| final Color? blue; | ||
| final Color? red; | ||
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| @override | ||
| MyColors copyWith({Color? red, Color? blue}) { | ||
| return MyColors( | ||
| blue: blue ?? this.blue, | ||
| red: red ?? this.red, | ||
| ); | ||
| } | ||
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| @override | ||
| MyColors lerp(ThemeExtension<MyColors>? other, double t) { | ||
| if (other is! MyColors) { | ||
| return this; | ||
| } | ||
| return MyColors( | ||
| blue: Color.lerp(blue, other.blue, t), | ||
| red: Color.lerp(red, other.red, t), | ||
| ); | ||
| } | ||
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| // Optional | ||
| @override | ||
| String toString() => 'MyColors(blue: $blue, red: $red)'; | ||
| } | ||
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| void main() { | ||
| // Slow down time to see lerping. | ||
| timeDilation = 5.0; | ||
| runApp(const MyApp()); | ||
| } | ||
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| class MyApp extends StatefulWidget { | ||
| const MyApp({Key? key}) : super(key: key); | ||
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| static const String _title = 'Flutter Code Sample'; | ||
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| @override | ||
| State<MyApp> createState() => _MyAppState(); | ||
| } | ||
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| class _MyAppState extends State<MyApp> { | ||
| bool isLightTheme = true; | ||
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| void toggleTheme() { | ||
| setState(() => isLightTheme = !isLightTheme); | ||
| } | ||
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| @override | ||
| Widget build(BuildContext context) { | ||
| return MaterialApp( | ||
| title: MyApp._title, | ||
| theme: ThemeData.light().copyWith( | ||
| extensions: <ThemeExtension<dynamic>>{ | ||
| const MyColors( | ||
| blue: Color(0xFF1E88E5), | ||
| red: Color(0xFFE53935), | ||
| ), | ||
| }, | ||
| ), | ||
| darkTheme: ThemeData.dark().copyWith( | ||
| extensions: <ThemeExtension<dynamic>>{ | ||
| const MyColors( | ||
| blue: Color(0xFF90CAF9), | ||
| red: Color(0xFFEF9A9A), | ||
| ), | ||
| }, | ||
| ), | ||
| themeMode: isLightTheme ? ThemeMode.light : ThemeMode.dark, | ||
| home: Home( | ||
| isLightTheme: isLightTheme, | ||
| toggleTheme: toggleTheme, | ||
| ), | ||
| ); | ||
| } | ||
| } | ||
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| class Home extends StatelessWidget { | ||
| const Home({ | ||
| Key? key, | ||
| required this.isLightTheme, | ||
| required this.toggleTheme, | ||
| }) : super(key: key); | ||
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| final bool isLightTheme; | ||
| final void Function() toggleTheme; | ||
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| @override | ||
| Widget build(BuildContext context) { | ||
| final MyColors myColors = Theme.of(context).extension<MyColors>()!; | ||
| return Material( | ||
| child: Center( | ||
| child: Row( | ||
| mainAxisAlignment: MainAxisAlignment.center, | ||
| children: <Widget>[ | ||
| Container(width: 100, height: 100, color: myColors.blue), | ||
| const SizedBox(width: 10), | ||
| Container(width: 100, height: 100, color: myColors.red), | ||
| const SizedBox(width: 50), | ||
| IconButton( | ||
| icon: Icon(isLightTheme ? Icons.nightlight : Icons.wb_sunny), | ||
| onPressed: toggleTheme, | ||
| ), | ||
| ], | ||
| ) | ||
| ), | ||
| ); | ||
| } | ||
| } | ||
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NICE, thanks for including darkTheme in the example.