ธีม: ThemeData, Material 3 และโหมดมืด

import 'package:flutter/material.dart';

void main() {
  runApp(const ShopApp());
}

class ShopApp extends StatelessWidget {
  const ShopApp({super.key});

  @override
  Widget build(BuildContext context) {
    const seed = Colors.teal;
    return MaterialApp(
      theme: ThemeData(
        colorScheme: ColorScheme.fromSeed(
          seedColor: seed,
        ),
      ),
      darkTheme: ThemeData(
        colorScheme: ColorScheme.fromSeed(
          seedColor: seed,
          brightness: Brightness.dark,
        ),
      ),
      themeMode: ThemeMode.system,
      home: Scaffold(
        appBar: AppBar(title: const Text('Shop')),
        body: const Center(child: Text('Welcome')),
      ),
    );
  }
}

import 'package:flutter/material.dart';

class PriceTag extends StatelessWidget {
  const PriceTag({super.key, required this.price});

  final double price;

  @override
  Widget build(BuildContext context) {
    final colors = Theme.of(context).colorScheme;
    final text = Theme.of(context).textTheme;
    return Container(
      padding: const EdgeInsets.symmetric(
        horizontal: 12,
        vertical: 6,
      ),
      decoration: BoxDecoration(
        color: colors.primaryContainer,
        borderRadius: BorderRadius.circular(8),
      ),
      child: Text(
        '$price €',
        style: text.titleMedium?.copyWith(
          color: colors.onPrimaryContainer,
        ),
      ),
    );
  }
}

import 'package:flutter/material.dart';

final ThemeData appTheme = ThemeData(
  colorScheme: ColorScheme.fromSeed(
    seedColor: Colors.teal,
  ),
  appBarTheme: const AppBarTheme(
    centerTitle: true,
    elevation: 0,
  ),
  filledButtonTheme: FilledButtonThemeData(
    style: FilledButton.styleFrom(
      padding: const EdgeInsets.symmetric(
        horizontal: 24,
        vertical: 12,
      ),
    ),
  ),
);