在flutter中有没有一个完全动态的标高和背景颜色的AppBar？

import 'package:flutter/material.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: CustomScrollView(
          slivers: <Widget>[
            SliverAppBar(
              expandedHeight: 200, // 设置AppBar的最大高度
              flexibleSpace: FlexibleSpaceBar(
                background: Container(
                  decoration: BoxDecoration(
                    gradient: LinearGradient(
                      colors: [Colors.blue, Colors.green], // 设置渐变背景颜色
                      begin: Alignment.topLeft,
                      end: Alignment.bottomRight,
                    ),
                  ),
                ),
              ),
            ),
            SliverList(
              delegate: SliverChildBuilderDelegate(
                (BuildContext context, int index) {
                  return ListTile(
                    title: Text('Item $index'),
                  );
                },
                childCount: 100,
              ),
            ),
          ],
        ),
      ),
    );
  }
}