[TOC] ## theme 從 Flutter 3.16 版本開始， Material 3 是 Flutter 的默認主題。 **設置主題** ``` MaterialApp( title: appName, theme: ThemeData( useMaterial3: true, // Define the default brightness and colors. colorScheme: ColorScheme.fromSeed( seedColor: Colors.purple, // ··· brightness: Brightness.dark, ), // Define the default `TextTheme`. Use this to specify the default // text styling for headlines, titles, bodies of text, and more. textTheme: TextTheme( displayLarge: const TextStyle( fontSize: 72, fontWeight: FontWeight.bold, ), // ··· titleLarge: GoogleFonts.oswald( fontSize: 30, fontStyle: FontStyle.italic, ), bodyMedium: GoogleFonts.merriweather(), displaySmall: GoogleFonts.pacifico(), ), ), home: const MyHomePage( title: appName, ), ); ``` 大部分`ThemeData`實例會設置以下兩個屬性。它們會影響大部分樣式屬性。 1. [`colorScheme`](https://api.flutter-io.cn/flutter/material/ThemeData/colorScheme.html)定義了顏色。 2. [`textTheme`](https://api.flutter-io.cn/flutter/material/ThemeData/textTheme.html)定義了文字樣式。 **應用指定的主題** ``` Container( padding: const EdgeInsets.symmetric( horizontal: 12, vertical: 12, ), color: Theme.of(context).colorScheme.primary, child: Text( 'Text with a background color', // ··· style: Theme.of(context).textTheme.displaySmall ), ), ``` **繼承樣式** ``` ```