Hide button on scroll

main.dart

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

const Color darkBlue = Color.fromARGB(255, 18, 32, 47);

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      theme: ThemeData.dark().copyWith(
        scaffoldBackgroundColor: darkBlue,
      ),
      debugShowCheckedModeBanner: false,
      home: AppView2(),
    );
  }
}

class LogoHidingScrollView extends StatefulWidget {
  const LogoHidingScrollView({
    Key? key,
  }) : super(key: key);

  _LogoHidingScrollViewState createState() => _LogoHidingScrollViewState();
}

class _LogoHidingScrollViewState extends State<LogoHidingScrollView> {
  final ScrollController _scrollController = ScrollController();
  bool _isVisible = true;

  void initState() {
    _isVisible = true;
    _scrollController.addListener(() {
      if (_scrollController.position.userScrollDirection ==
          ScrollDirection.reverse) {
        if (_isVisible == true) {
          /* only set when the previous state is false
             * Less widget rebuilds
             */
          print("**** $_isVisible up"); //Move IO away from setState
          setState(() {
            _isVisible = false;
          });
        }
      } else {
        if (_scrollController.position.userScrollDirection ==
            ScrollDirection.forward) {
          if (_isVisible == false) {
            setState(() {
              _isVisible = true;
            });
          }
        }
      }
    });
    super.initState();
  }

  Widget build(BuildContext context) {
    return SizedBox(
      height: 500,
      child: Stack(
        children: [
          CustomScrollView(
            controller: _scrollController,
            scrollDirection: Axis.horizontal,
            shrinkWrap: true,
            slivers: <Widget>[
              SliverPadding(
                padding: const EdgeInsets.all(20.0),
                sliver: SliverList(
                  delegate: SliverChildListDelegate(
                    <Widget>[
                      FlutterLogo(
                        size: 600,
                      )
                    ],
                  ),
                ),
              ),
            ],
          ),
          Visibility(
            visible: _isVisible,
            child: Align(
              alignment: Alignment.centerRight,
              child: FloatingActionButton(
                  child: const Icon(Icons.arrow_forward_ios), onPressed: () {}),
            ),
          )
        ],
      ),
    );
  }
}

class AppView2 extends StatefulWidget {
  const AppView2({
    Key? key,
  }) : super(key: key);

  @override
  _AppViewState createState() => _AppViewState();
}

class _AppViewState extends State<AppView2> {
  late ScrollController _hideButtonController;
  bool _isVisible = true;

  @override
  void initState() {
    _isVisible = true;
    _hideButtonController = ScrollController();
    _hideButtonController.addListener(() {
      if (_hideButtonController.positions
          .any((pos) => pos.userScrollDirection == ScrollDirection.reverse)) {
        if (_isVisible == true) {
          /* only set when the previous state is false
             * Less widget rebuilds
             */
          print("**** $_isVisible up"); //Move IO away from setState
          setState(() {
            _isVisible = false;
          });
        }
      } else {
        if (_hideButtonController.positions
            .any((pos) => pos.userScrollDirection == ScrollDirection.forward)) {
          if (_isVisible == false) {
            setState(() {
              _isVisible = true;
            });
          }
        }
      }
    });
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    return SafeArea(
        child: Scaffold(
            appBar: AppBar(
              title: Text("Example app bar"),
            ),
            body: CustomScrollView(slivers: <Widget>[
              SliverList(
                delegate: SliverChildBuilderDelegate(
                    (BuildContext context, int index) {
                  return const LogoHidingScrollView();
                }, childCount: 10),
              )
            ])));
  }
}