import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatefulWidget {
  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage>
    with SingleTickerProviderStateMixin {
  TabController _tabController;
  ScrollController _scrollViewController;

  @override
  void initState() {
    super.initState();
    _tabController = TabController(vsync: this, length: 2);
    _scrollViewController = ScrollController(initialScrollOffset: 0.0);
  }

  @override
  void dispose() {
    _tabController.dispose();
    _scrollViewController.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: NestedScrollView(
        controller: _scrollViewController,
        headerSliverBuilder: (BuildContext context, bool boxIsScrolled) {
          return <Widget>[
            SliverAppBar(
              expandedHeight: 300.0,
              title: Text('Tab Controller Example'),
              pinned: true,
              floating: true,
              forceElevated: boxIsScrolled,
            )
          ];
        },
        body: PageOne(),
      ),
    );
  }
}

class PageOne extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return ListView.builder(
      itemExtent: 250.0,
      itemBuilder: (context, index) => Container(
            padding: EdgeInsets.all(10.0),
            child: Material(
              elevation: 4.0,
              borderRadius: BorderRadius.circular(5.0),
              color: index % 2 == 0 ? Colors.cyan : Colors.deepOrange,
              child: Center(
                child: Text(index.toString()),
              ),
            ),
          ),
    );
  }
}