Question

当用户上下滚动时，我需要在Flutter中实现BottomNavigationBar的隐藏/显示功能。请，如果您知道该怎么做，或者有一个示例，并且可以分享，我将非常感谢您的帮助！

Here is the link of my question there in github

我想要的例子

Answer 1

此代码用于按动画隐藏滚动

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

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      home: WorkoutDetailsPage(Workout()),
    );
  }
}

class Exercise {
  String name;
  Exercise({@required name}) {
    this.name = name;
  }
}

class Workout {
  String name = "my name";
}

class WorkoutDetailsPage extends StatefulWidget {
  Workout _workout = Workout();

  WorkoutDetailsPage(this._workout);

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


class _WorkoutDetailsPageState extends State<WorkoutDetailsPage> {
  final List<Exercise> exercises = [
    Exercise(name: "Push Ups"),
    Exercise(name: "Bench press"),
    Exercise(name: "Pull ups"),
    Exercise(name: "Press ups"),
    Exercise(name: "Crunches"),
    Exercise(name: "Sit ups"),
    Exercise(name: "BIceps curl"),
    Exercise(name: "Something else"),
    Exercise(name: "Push Ups"),
    Exercise(name: "Bench press"),
    Exercise(name: "Pull ups"),
    Exercise(name: "Press ups"),
    Exercise(name: "Crunches"),
    Exercise(name: "Sit ups"),
    Exercise(name: "BIceps curl"),
    Exercise(name: "Something else"),
    Exercise(name: "Push Ups"),
    Exercise(name: "Bench press"),
    Exercise(name: "Pull ups"),
    Exercise(name: "Press ups"),
    Exercise(name: "Crunches"),
    Exercise(name: "Sit ups"),
    Exercise(name: "BIceps curl"),
    Exercise(name: "Something else"),
    Exercise(name: "Push Ups"),
    Exercise(name: "Bench press"),
    Exercise(name: "Pull ups"),
    Exercise(name: "Press ups"),
    Exercise(name: "Crunches"),
    Exercise(name: "Sit ups"),
    Exercise(name: "BIceps curl"),
    Exercise(name: "Something else"),
    Exercise(name: "Push Ups"),
    Exercise(name: "Bench press"),
    Exercise(name: "Pull ups"),
    Exercise(name: "Press ups"),
    Exercise(name: "Crunches"),
    Exercise(name: "Sit ups"),
    Exercise(name: "BIceps curl"),
    Exercise(name: "Something else"),
  ];

  ScrollController _hideButtonController;

  bool _isVisible = true;
  @override
  void initState() {
    super.initState();
    _isVisible = true;
    _hideButtonController = new ScrollController();
    _hideButtonController.addListener(() {
      print("listener");
      if (_hideButtonController.position.userScrollDirection ==
          ScrollDirection.reverse) {
        setState(() {
          _isVisible = false;
          print("**** $_isVisible up");
        });
      }
      if (_hideButtonController.position.userScrollDirection ==
          ScrollDirection.forward) {
        setState(() {
          _isVisible = true;
          print("**** $_isVisible down");
        });
      }
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      floatingActionButtonAnimator: FloatingActionButtonAnimator.scaling,
      floatingActionButtonLocation: FloatingActionButtonLocation.centerDocked,
      floatingActionButton: _isVisible
          ? FloatingActionButton(
              backgroundColor: Colors.blue,
              elevation: 12,
              onPressed: () {},
            )
          : null,
      bottomNavigationBar: AnimatedContainer(
        duration: Duration(milliseconds: 200),
        height: _isVisible ? 60 : 0.0,
        child: BottomAppBar(
          elevation: 8,
          shape: CircularNotchedRectangle(),
          color: Colors.blue,
          child: Container(
            height: 60,
            child: Row(
              children: <Widget>[Text("data")],
            ),
          ),
        ),
      ),
      body: CustomScrollView(
        controller: _hideButtonController,
        slivers: <Widget>[
          SliverAppBar(
            expandedHeight: 150,
            pinned: true,
            floating: true,
            snap: true,
            flexibleSpace: FlexibleSpaceBar(
              title: Text(widget._workout.name),
            ),
          ),
          SliverList(
            delegate: SliverChildBuilderDelegate(buildSliverListItem,
                childCount: exercises.length),
          ),
        ],
      ),
    );
  }

  Widget buildSliverListItem(BuildContext context, int index) {
    return Center(
      child: ListTile(
        title: Text(exercises[index].name),
      ),
    );
  }
}

还是您https://medium.com/nonstopio/hide-or-show-app-bar-and-bottom-navigation-bar-while-scrolling-in-flutter-3994f78e52c0

滚动时如何隐藏BottomNavigationBar-Flutter

1 个答案: