我有以下示例(在 iPhone X、iOS 11 上测试):
import 'package:flutter/material.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> {
@override
Widget build(BuildContext context) {
return new ListView(
children: <Widget>[
new Container(
height: 40.0,
color: Colors.blue,
),
new Container(
height: 40.0,
color: Colors.red,
),
new Container(
height: 40.0,
color: Colors.green,
),
]
);
}
}
在这种情况下,ListView 的行为与预期一致。我可以滚动到视口之外,ListView 会再次反弹(典型的 iOS 行为)。但是当我添加 ScrollController 来跟踪偏移量时,滚动的行为会发生变化:
import 'package:flutter/material.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 _controller = new ScrollController();
@override
Widget build(BuildContext context) {
return new ListView(
controller: _controller,
children: <Widget>[
new Container(
height: 40.0,
color: Colors.blue,
),
new Container(
height: 40.0,
color: Colors.red,
),
new Container(
height: 40.0,
color: Colors.green,
),
]
);
}
}
在这种情况下,无法再进行滚动。为什么当我添加 ScrollController 后,滚动就不再可能了?另外将
physics: new BouncingScrollPhysics(),
添加到 ListView 也没有帮助。
感谢您的帮助:)
要始终在
ListView
上启用滚动,您可以使用 AlwaysScrollableScrollPhysics
类包装所需的原始滚动物理。更多详细信息这里。如果您愿意,可以指定 parent
或依赖默认值。
这是添加了选项的示例:
import 'package:flutter/material.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 _controller = new ScrollController();
@override
Widget build(BuildContext context) {
return new ListView(
physics: const AlwaysScrollableScrollPhysics(), // new
controller: _controller,
children: <Widget>[
new Container(
height: 40.0,
color: Colors.blue,
),
new Container(
height: 40.0,
color: Colors.red,
),
new Container(
height: 40.0,
color: Colors.green,
),
]
);
}
}
如果你在 Flutter Web 上遇到这个问题,那么你应该用 ScrollConfiguration 包装 listview。在 ScrollConfiguration 行为参数中添加 PointerDeviceKind.mouse。 您可以查看示例。
ScrollConfiguration(
behavior: ScrollConfiguration.of(context).copyWith(dragDevices: {
PointerDeviceKind.touch,
PointerDeviceKind.mouse,
},),
child: ListView(
controller: _controller,
physics: const AlwaysScrollableScrollPhysics(),
scrollDirection: Axis.horizontal,
children: <Widget>[
for (int index = 0; index < showThumbnailList.length; index++) _thumbnail(showThumbnailList[index], index)
// showThumbnailList.map((x) => _thumbnail(x) ).toList()),
],
),
),
只需添加
AlwaysScrollableScrollPhysics
ListView(
physics: const AlwaysScrollableScrollPhysics(),
children : [...]
}
**
使用容器高度进行滚动,也可以使用 物理:AlwaysScrollableScrollPhysics(), 控制器:控制器,
**
Container(
width: 400,
child: Drawer(
child: Stack(children: [
Container(
height: MediaQuery.of(context).size.height-80,
child: ListView(
controller: controller,
padding: EdgeInsets.zero,
physics: AlwaysScrollableScrollPhysics(),
children: [
Container(
height: 300,
padding: EdgeInsets.symmetric(vertical: 20, horizontal: 10),
child: DrawerHeader(
child:Stack(children: [
Center(
child: Column(
children: [
nullCatcher(image) == "" ? Image.asset("assets/images/doctor.png",height: 90,width: 90,) : Image.network(
"$image",
height: 90,
width: 90,
),
SizedBox(width: 30,),
Text("$name",style: TextStyle(color: Colors.grey[700],fontWeight: FontWeight.bold,fontSize: 25),),
Text("$specialty",style: TextStyle(color: Colors.grey[600]),),
],
),
),
Positioned(
right: 0,bottom: 10,
child: Text("Version: 1.0.0",style: TextStyle(color: Colors.orange),))
],),
),
),
ListTile(
contentPadding: EdgeInsets.zero,
title: Container(
height: 70,
padding: EdgeInsets.symmetric(horizontal: 30),
decoration: drawerListDecoration,
child: Row(
children: [
Container(
height: 35,width: 35,
decoration: BoxDecoration(
color: Theme.of(context).accentColor,
borderRadius: BorderRadius.circular(100)
),
child: Icon(Icons.attach_file,color: Colors.white,size: 20,)),
SizedBox(width: 20,),
Text('Create Appointment'),
],
)),
onTap: () {
Navigator.pushReplacement(context, MaterialPageRoute(builder: (__)=>CreateAppointment()));
// Update the state of the app.
// ...
},
),
ListTile(
contentPadding: EdgeInsets.zero,
title: Container(
height: 70,
padding: EdgeInsets.symmetric(horizontal: 30),
decoration: drawerListDecoration,
child: Row(
children: [
Container(
height: 35,width: 35,
decoration: BoxDecoration(
color: Theme.of(context).accentColor,
borderRadius: BorderRadius.circular(100)
),
child: Icon(Icons.attach_file,color: Colors.white,size: 20,)),
SizedBox(width: 20,),
Text('Appointment / Prescription List'),
],
)),
onTap: () {
Navigator.pushReplacement(context, MaterialPageRoute(builder: (__)=>AppointmentList()));
// Navigator.pop(context);
},
),
Container(
height: 70,
padding: EdgeInsets.symmetric(horizontal: 30 ),
color: Colors.grey[200],
child: Row(
children: [
Container(
height: 35,width: 35,
decoration: BoxDecoration(
color: Theme.of(context).accentColor,
borderRadius: BorderRadius.circular(100)
),
child: Icon(Icons.attach_file,color: Colors.white,size: 20,)),
SizedBox(width: 20,),
Text("Clinical Options:",style: TextStyle(fontWeight: FontWeight.bold,color: Colors.grey[600]),),
],
),
),
ListTile(
contentPadding: EdgeInsets.zero,
title: Container(
height: childHeight,
padding: EdgeInsets.only(left: childPaddeing),
// decoration: drawerListDecoration,
child: Row(
children: [
lineDesign(),
SizedBox(width: 20,),
Text('Chief Complain'),
],
)),
onTap: () {
Navigator.pushReplacement(context, MaterialPageRoute(builder: (__)=>AppointmentList()));
// Navigator.pop(context);
},
),
ListTile(
contentPadding: EdgeInsets.zero,
title: Container(
height: 50,
padding: EdgeInsets.symmetric(horizontal: 45),
decoration: drawerListDecoration,
child: Row(
children: [
lineDesign(),
SizedBox(width: 20,),
Text('On Examination'),
],
)),
onTap: () {
Navigator.pushReplacement(context, MaterialPageRoute(builder: (__)=>AppointmentList()));
// Navigator.pop(context);
},
),
ListTile(
contentPadding: EdgeInsets.zero,
title: Container(
height: 70,
padding: EdgeInsets.symmetric(horizontal: 30),
decoration: drawerListDecoration,
child: Row(
children: [
Container(
height: 35,width: 35,
decoration: BoxDecoration(
color: Theme.of(context).accentColor,
borderRadius: BorderRadius.circular(100)
),
child: Icon(Icons.attach_file,color: Colors.white,size: 20,)),
SizedBox(width: 20,),
Text('Examination Category'),
],
)),
onTap: () {
Navigator.pushReplacement(context, MaterialPageRoute(builder: (__)=>AppointmentList()));
// Navigator.pop(context);
},
),
ListTile(
contentPadding: EdgeInsets.zero,
title: Container(
height: 70,
padding: EdgeInsets.symmetric(horizontal: 30),
decoration: drawerListDecoration,
child: Row(
children: [
Container(
height: 35,width: 35,
decoration: BoxDecoration(
color: Theme.of(context).accentColor,
borderRadius: BorderRadius.circular(100)
),
child: Icon(Icons.attach_file,color: Colors.white,size: 20,)),
SizedBox(width: 20,),
Text('Diagnosis'),
],
)),
onTap: () {
Navigator.pushReplacement(context, MaterialPageRoute(builder: (__)=>AppointmentList()));
// Navigator.pop(context);
},
),
ListTile(
contentPadding: EdgeInsets.zero,
title: Container(
height: 70,
padding: EdgeInsets.symmetric(horizontal: 30),
decoration: drawerListDecoration,
child: Row(
children: [
Container(
height: 35,width: 35,
decoration: BoxDecoration(
color: Theme.of(context).accentColor,
borderRadius: BorderRadius.circular(100)
),
child: Icon(Icons.attach_file,color: Colors.white,size: 20,)),
SizedBox(width: 20,),
Text('Investigations'),
],
)),
onTap: () {
Navigator.pushReplacement(context, MaterialPageRoute(builder: (__)=>AppointmentList()));
// Navigator.pop(context);
},
),
],
),
),
Positioned(
bottom: 0,
left: 0,
right: 0,
child: ButtonTheme(
child: RaisedButton(
color: Colors.red[900],
onPressed: (){
if(blocState is LogoutInLoading){}else logoutAlert(blocContext);
},
child: Container(
height: 70,
child:blocState is LogoutInLoading ? Container( height: 20,width: 20,margin: EdgeInsets.symmetric(vertical: 25), child: CircularProgressIndicator(valueColor: AlwaysStoppedAnimation(Colors.white),),) : Row(
mainAxisAlignment: MainAxisAlignment.center,
children: [
Text("Sign Out",style: TextStyle(color: Colors.white,fontWeight: FontWeight.bold,fontSize: 25),),
SizedBox(width: 20,),
Icon(Icons.logout,color: Colors.white,)
],
),
),
),
)
)
],),
),
);
在我的例子中,我只是向父容器添加了指定的高度,就像这样
sizedBox(
height:300
child: child: ListView.builder(
controller: _controller,
physics: const AlwaysScrollableScrollPhysics(),
shrinkWrap: true,
itemCount: news.length,
itemBuilder: (context, index) {
//container
}
)
我认为这个解决方案没有 CustomScrollView 会更好。只需使用NotificationListener 来包装ListView 即可。
Widget noti = new NotificationListener(
child:listView,
onNotification: (ScrollNotification note){
print(note.metrics.pixels.toInt());
},
);
我测试过,弹跳有效
我找到了一个解决方案,如何使用内容高度小于视口的列表来跟踪偏移量。在
NotificationListener
方法中将 CustomScrollView
与 build()
一起使用,如下所示:
import 'package:flutter/material.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 _controller = new ScrollController();
@override
Widget build(BuildContext context) {
return new NotificationListener(
onNotification: _handleScrollPosition,
child: new CustomScrollView(
slivers: [
new SliverList(
delegate: new SliverChildListDelegate([
new Container(
height: 40.0,
color: Colors.blue,
),
new Container(
height: 40.0,
color: Colors.red,
),
new Container(
height: 40.0,
color: Colors.green,
),
])
)
]
)
);
}
bool _handleScrollPosition(ScrollNotification notification) {
print(notification.metrics.pixels);
return true;
}
}
只要没有仅
ScrollController
(或“更好”(更优雅))解决方案的解决方案,我就会接受这个答案。
在 macOS 中
class MyCustomScrollBehavior extends MaterialScrollBehavior {
// Override behavior methods and getters like dragDevices
@override
Set<PointerDeviceKind> get dragDevices => {
PointerDeviceKind.touch,
PointerDeviceKind.mouse,
// etc.
};
}
// Set ScrollBehavior for an entire application.
MaterialApp(
scrollBehavior: MyCustomScrollBehavior(),
// ...
);