【Flutter】关于NestedScrollView滑动冲突

划重点：

TabbarView内的根组件，
不要加AutomaticKeepAliveClientMixin
不要加AutomaticKeepAliveClientMixin
不要加AutomaticKeepAliveClientMixin
重要的事情说三遍

bug背景：
先说说页面结构，整体从上到下纵向排列，最顶端是标题栏，保持固定不动，标题下面是背景图片（可被折叠收缩起来），图片下面是tabbar，tabbar下面是TabbarView（等同于Android里面的ViewPager/vue里面的swiper，tabbar和tabbarView所需的数据均需从后端获取）

排查历程：
1.首先想到的是ListView和外部NestedScrollView滑动事件冲突了，但经过一番折腾也没效果
2.新建了个小项目用来试验，简单搭了个和前面差不多的页面结构，发现竟如此丝滑，仔细比对后，就仅差一个AutomaticKeepAliveClientMixin，具体原因暂未分析，但能确定的是，和build重绘脱不开干系，demo代码如下：

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

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

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

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        colorScheme: ColorScheme.fromSeed(seedColor: Colors.deepPurple),
        useMaterial3: true,
      ),
      home: const MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  const MyHomePage({super.key, required this.title});

  final String title;

  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage>
    with SingleTickerProviderStateMixin {
  TabController? tabController;

  ValueNotifier indexNotifier = ValueNotifier(0);

  @override
  void initState() {
    super.initState();
    _fetch();
  }

  void _fetch() async {
    await Future.delayed(const Duration(seconds: 2));
    tabController = TabController(length: 11, vsync: this);
    indexNotifier.value = 100;
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        backgroundColor: Theme.of(context).colorScheme.inversePrimary,
        title: Text(widget.title),
      ),
      body: NestedScrollView(
        headerSliverBuilder: (BuildContext context, bool innerBoxIsScrolled) {
          return [
            SliverAppBar(
              titleSpacing: 0,
              pinned: true,
              floating: false,
              snap: false,
              toolbarHeight: 0,
              expandedHeight: 250,
              elevation: 0.0,
              // 移除阴影以实现透明效果
              flexibleSpace: FlexibleSpaceBar(
                // title: Text('Title'),
                background: Container(
                  width: double.infinity,
                  height: 250,
                  color: Colors.blue.withOpacity(0.5),
                ), // 半透明背景
              ),
              bottom: PreferredSize(
                preferredSize: Size.fromHeight(60),
                child: Container(
                  color: Colors.white,
                  height: 60,
                ),
              ),
            ),
          ];
        },
        body: ValueListenableBuilder(
            valueListenable: indexNotifier,
            builder: (context, itemCount, child) {
              return TabBarView(
                controller: tabController,
                children: [
                  Container(
                    child: ListView.builder(
                      itemCount: itemCount,
                      itemExtent: 50,
                      shrinkWrap: true,
                      itemBuilder: (BuildContext context, int index) {
                        return Center(
                          child: Text("${index}"),
                        );
                      },
                    ),
                  ),
                  Container(),
                  Container(),
                  Container(),
                  Container(),
                  Container(),
                  Container(),
                  Container(),
                  Container(),
                  Container(),
                  Container(),
                ],
              );
            }),
      ), // This trailing comma makes auto-formatting nicer for build methods.
    );
  }
}