颤动2:在ThemeData中存储渐变

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      theme: ThemeData(
        // 在ThemeData中存储线性渐变
        appBarTheme: AppBarTheme(
          backgroundColor: Colors.blue,
          elevation: 0,
          gradient: LinearGradient(
            begin: Alignment.topLeft,
            end: Alignment.bottomRight,
            colors: [Colors.blue, Colors.green],
          ),
        ),
      ),
      home: Scaffold(
        appBar: AppBar(
          title: Text('Gradient Demo'),
        ),
        body: Container(
          // 使用渐变背景
          decoration: BoxDecoration(
            gradient: Theme.of(context).appBarTheme.gradient,
          ),
          child: Center(
            child: Text(
              'Hello World',
              style: TextStyle(
                color: Colors.white,
                fontSize: 24,
              ),
            ),
          ),
        ),
      ),
    );
  }
}