我在正文和底部导航栏中有一个博客文章列表。我想在帖子列表向下滚动时用向下滑动动画隐藏底部导航栏，并在向上滚动时用向上滑动动画显示。怎么做？
最佳答案
此解决方案只是解决此问题的方法。 可能会有一些不利的变化。
import 'package:flutter/material.dart';
import 'package:flutter/rendering.dart';
void main() {
runApp(new MyApp());
}
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return new MaterialApp(
title: 'Flutter Demo',
theme: new ThemeData(
primarySwatch: Colors.blue,
),
home: new MyHomePage(title: 'Flutter Demo Home Page'),
);
}
}
class MyHomePage extends StatefulWidget {
MyHomePage({Key key, this.title}) : super(key: key);
final String title;
@override
_MyHomePageState createState() => new _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
ScrollController _hideButtonController;
var _isVisible;
@override
initState() {
super.initState();
_isVisible = true;
_hideButtonController = new ScrollController();
_hideButtonController.addListener(() {
if (_hideButtonController.position.userScrollDirection ==
ScrollDirection.reverse) {
if(_isVisible)
setState(() {
_isVisible = false;
print("**** $_isVisible up");
});
}
if (_hideButtonController.position.userScrollDirection ==
ScrollDirection.forward) {
if(!_isVisible)
setState(() {
_isVisible = true;
print("**** $_isVisible down");
});
}
});
}
@override
Widget build(BuildContext context) {
return new Scaffold(
appBar: new AppBar(
title: new Text(widget.title),
),
body: new Center(
child: new CustomScrollView(
controller: _hideButtonController,
shrinkWrap: true,
slivers: <Widget>[
new SliverPadding(
padding: const EdgeInsets.all(20.0),
sliver: new SliverList(
delegate: new SliverChildListDelegate(
<Widget>[
const Text('I\'m dedicating every day to you'),
const Text('Domestic life was never quite my style'),
const Text('When you smile, you knock me out, I fall apart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('I realize I am crazy'),
],
),
),
),
],
)),
bottomNavigationBar: AnimatedContainer(
duration: Duration(milliseconds: 500),
height: _isVisible ? 60.0 : 0.0,
child: _isVisible
? new BottomNavigationBar(
type: BottomNavigationBarType.fixed,
items: [
new BottomNavigationBarItem(
icon: Icon(Icons.home),
title: Text('Home'),
),
new BottomNavigationBarItem(
icon: Icon(Icons.card_giftcard),
title: Text('Offers'),
),
new BottomNavigationBarItem(
icon: Icon(Icons.account_box),
title: Text('Account'),
),
],
currentIndex: 0,
)
: Container(
color: Colors.white,
width: MediaQuery.of(context).size.width,
),
),
);
}
}
你也可以使用 sliver bar :-
import 'package:flutter/material.dart';
import 'package:flutter/rendering.dart';
void main() {
runApp(new MyApp());
}
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return new MaterialApp(
title: 'Flutter Demo',
theme: new ThemeData(
primarySwatch: Colors.blue,
),
home: new MyHomePage(title: 'Flutter Demo Home Page'),
);
}
}
class MyHomePage extends StatefulWidget {
MyHomePage({Key key, this.title}) : super(key: key);
final String title;
@override
_MyHomePageState createState() => new _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
ScrollController _hideButtonController;
var _isVisible;
@override
initState() {
super.initState();
_isVisible = true;
_hideButtonController = new ScrollController();
_hideButtonController.addListener(() {
if (_hideButtonController.position.userScrollDirection ==
ScrollDirection.reverse) {
setState(() {
_isVisible = false;
print("**** $_isVisible up");
});
}
if (_hideButtonController.position.userScrollDirection ==
ScrollDirection.forward) {
setState(() {
_isVisible = true;
print("**** $_isVisible down");
});
}
});
}
final GlobalKey<ScaffoldState> scaffoldKey = GlobalKey<ScaffoldState>();
TextEditingController searchController = new TextEditingController();
@override
Widget build(BuildContext context) {
return Scaffold(
backgroundColor: Colors.white,
resizeToAvoidBottomPadding: true,
drawer: Container(),
key: scaffoldKey,
body: NestedScrollView(
controller: _hideButtonController,
headerSliverBuilder: (BuildContext context, bool innerBoxIsScrolled) {
return <Widget>[
SliverAppBar(
title: Container(
child: Card(
elevation: 3.0,
margin: EdgeInsets.only(top: 10.0),
shape: RoundedRectangleBorder(
borderRadius: BorderRadius.all(Radius.circular(2.0))),
child: Padding(
padding: EdgeInsets.symmetric(horizontal: 15.0),
child: Row(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
children: <Widget>[
GestureDetector(
child: Icon(
Icons.sort,
color: Colors.black54,
),
onTap: () {
scaffoldKey.currentState.openDrawer();
},
),
SizedBox(
width: 10.0,
),
Expanded(
child: TextField(
controller: searchController,
decoration: InputDecoration(
border: InputBorder.none,
hintText: "What are you looking for?"),
),
),
GestureDetector(
onTap: () {
searchController.clear();
},
child: Icon(
Icons.clear,
color: Colors.black54,
),
),
],
),
),
),
),
elevation: 10.0,
automaticallyImplyLeading: false,
expandedHeight: 70,
floating: true,
snap: true,
)
];
},
body: new ListView(
children: <Widget>[
const Text('I\'m dedicating every day to you'),
const Text('Domestic life was never quite my style'),
const Text('When you smile, you knock me out, I fall apart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('I realize I am crazy'),
const Text('I\'m dedicating every day to you'),
const Text('Domestic life was never quite my style'),
const Text('When you smile, you knock me out, I fall apart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('And I thought I was so smart'),
const Text('I realize I am crazy'),
],
),
),
bottomNavigationBar: AnimatedContainer(
duration: Duration(seconds: 1),
height: _isVisible ? 60.0 : 0.0,
child: _isVisible
? AnimatedContainer(
duration: Duration(milliseconds: 200),
height: _isVisible ? 60.0 : 0.0,
child: _isVisible
? new BottomNavigationBar(
type: BottomNavigationBarType.fixed,
items: [
new BottomNavigationBarItem(
icon: Icon(Icons.home),
title: Text('Home'),
),
new BottomNavigationBarItem(
icon: Icon(Icons.card_giftcard),
title: Text('Offers'),
),
new BottomNavigationBarItem(
icon: Icon(Icons.account_box),
title: Text('Account'),
),
],
currentIndex: 0,
)
: Container(
color: Colors.white,
width: MediaQuery.of(context).size.width,
),
)
: Container(
color: Theme.of(context).primaryColor,
width: MediaQuery.of(context).size.width,
),
),
// _isVisible
// ? bottomNavigationBar()
// : Container(
// height: 0.0,
// width: MediaQuery.of(context).size.width,
// ),
);
}
}
请评论您对此代码的看法，以便我们改进此代码。
这是取自这个答案:- Flutter - Hiding FloatingActionButton
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