Flutter实现多主题的六种方法

Posted 2022-03-15 大前端之旅

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首先我们不用任何状态管理pckage

​main.dart​

import package:flutter/material.dart;
import package:flutter_themes_demo/themes.dart;

void main() 
  runApp(MyApp());


class MyApp extends StatefulWidget 
  MyApp(Key key) : super(key: key);

  @override
  _MyAppState createState() => _MyAppState();


class _MyAppState extends State<MyApp> 
  @override
  void initState() 
    super.initState();
    currentTheme.addListener(() 
      setState(() );
    );
  

  @override
  Widget build(BuildContext context) 
    return MaterialApp(
      home: MyHomePage(title: Flutter Theme Demo),
      title: Flutter Theme Demo,
      theme: CustomTheme.lightTheme,
      darkTheme: CustomTheme.darkTheme,
      themeMode: currentTheme.currentTheme,
    );
  


class MyHomePage extends StatefulWidget 
  MyHomePage(Key key, this.title) : super(key: key);
  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();


class _MyHomePageState extends State<MyHomePage> 
  @override
  Widget build(BuildContext context) 
    final theme = Theme.of(context);

    return Scaffold(
      appBar: AppBar(
        title: Text(
          widget.title,
          style: TextStyle(
            color: theme.accentColor,
          ),
        ),
        actions: [
          IconButton(
            icon: const Icon(Icons.brightness_4_rounded),
            onPressed: () 
              currentTheme.toggleTheme();
            ,
          ),
        ],
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Text(
              Fluter Themes Demo,
            ),
          ],
        ),
      ),
    );
  

​themes.dart​

import package:flutter/material.dart;

CustomTheme currentTheme = CustomTheme();

class CustomTheme with ChangeNotifier 
  static bool _isDarkTheme = false;
  ThemeMode get currentTheme => _isDarkTheme ? ThemeMode.dark : ThemeMode.light;

  void toggleTheme() 
    _isDarkTheme = !_isDarkTheme;
    notifyListeners();
  

  static ThemeData get lightTheme 
    return ThemeData(
      primaryColor: Colors.lightBlue,
      accentColor: Colors.white,
      backgroundColor: Colors.white,
      scaffoldBackgroundColor: Colors.white,
      textTheme: TextTheme(
        headline1: TextStyle(color: Colors.black),
        headline2: TextStyle(color: Colors.black),
        bodyText1: TextStyle(color: Colors.black),
        bodyText2: TextStyle(color: Colors.black),
      ),
    );
  

  static ThemeData get darkTheme 
    return ThemeData(
      primaryColor: Colors.black,
      accentColor: Colors.red,
      backgroundColor: Colors.grey,
      scaffoldBackgroundColor: Colors.grey,
      textTheme: TextTheme(
        headline1: TextStyle(color: Colors.white),
        headline2: TextStyle(color: Colors.white),
        bodyText1: TextStyle(color: Colors.white),
        bodyText2: TextStyle(color: Colors.white),
      ),
    );
  

第二种方式 provider

先看我们的代码结构

main.dart

import package:flutter/material.dart;
import package:flutter/services.dart;
import package:provider/provider.dart;
import package:theme_example/page/home_page.dart;
import package:theme_example/provider/theme_provider.dart;

Future main() async 
  WidgetsFlutterBinding.ensureInitialized();
  await SystemChrome.setPreferredOrientations([
    DeviceOrientation.portraitUp,
    DeviceOrientation.portraitDown,
  ]);

  runApp(MyApp());


class MyApp extends StatelessWidget 
  static const String title = Light & Dark Theme;

  @override
  Widget build(BuildContext context) => ChangeNotifierProvider(
        create: (context) => ThemeProvider(),
        builder: (context, _) 
          final themeProvider = Provider.of<ThemeProvider>(context);

          return MaterialApp(
            title: title,
            themeMode: themeProvider.themeMode,
            theme: MyThemes.lightTheme,
            darkTheme: MyThemes.darkTheme,
            home: HomePage(),
          );
        ,
      );

provider文件夹

​theme_provider.dart​

import package:flutter/material.dart;
import package:flutter/scheduler.dart;

class ThemeProvider extends ChangeNotifier 
  ThemeMode themeMode = ThemeMode.system;

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