Flutter -在滑动时隐藏FAB按钮

import 'package:flutter/material.dart';

class MyPage extends StatefulWidget {
  @override
  _MyPageState createState() => _MyPageState();
}

class _MyPageState extends State<MyPage> {
  ScrollController _scrollController;
  bool _isFabVisible = true;

  @override
  void initState() {
    super.initState();
    _scrollController = ScrollController();
    _scrollController.addListener(_scrollListener);
  }

  @override
  void dispose() {
    _scrollController.dispose();
    super.dispose();
  }

  void _scrollListener() {
    if (_scrollController.position.userScrollDirection ==
        ScrollDirection.reverse) {
      setState(() {
        _isFabVisible = false;
      });
    } else if (_scrollController.position.userScrollDirection ==
        ScrollDirection.forward) {
      setState(() {
        _isFabVisible = true;
      });
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('My Page'),
      ),
      body: ListView.builder(
        controller: _scrollController,
        itemCount: 100,
        itemBuilder: (context, index) {
          return ListTile(
            title: Text('Item $index'),
          );
        },
      ),
      floatingActionButton: _isFabVisible
          ? FloatingActionButton(
              onPressed: () {
                // FAB按钮点击事件
              },
              child: Icon(Icons.add),
            )
          : null,
    );
  }
}