flutter -使用provider全局更改字体大小

dependencies:
  flutter:
    sdk: flutter
  provider: ^6.0.0

import 'package:flutter/material.dart';
import 'package:provider/provider.dart';

class FontSizeModel extends ChangeNotifier {
  double _fontSize = 16.0;

  double get fontSize => _fontSize;

  set fontSize(double size) {
    _fontSize = size;
    notifyListeners();
  }
}

void main() {
  runApp(
    ChangeNotifierProvider(
      create: (context) => FontSizeModel(),
      child: MyApp(),
    ),
  );
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        // 根据字体大小状态类中的值设置全局字体大小
        textTheme: Theme.of(context).textTheme.apply(fontSizeFactor: Provider.of<FontSizeModel>(context).fontSize),
      ),
      home: HomePage(),
    );
  }
}

class HomePage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Home'),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            Text(
              'Hello, World!',
              style: TextStyle(fontSize: 20.0),
            ),
            Consumer<FontSizeModel>(
              builder: (context, fontSizeModel, child) {
                return Slider(
                  value: fontSizeModel.fontSize,
                  min: 10.0,
                  max: 30.0,
                  onChanged: (value) {
                    fontSizeModel.fontSize = value;
                  },
                );
              },
            ),
          ],
        ),
      ),
    );
  }
}