在Android中，每个单独的View子类都有一个setVisibility()方法，允许你修改View对象的可见性
有3个设置可见性的选项:
可见:在布局中显示视图 不可见:隐藏视图，但留下一个空白，相当于视图在可见时所占据的空白 消失:隐藏视图，并将其完全从布局中移除。就好像它的高和宽都是0dp
对于Flutter中的小部件，是否有与上述相同的东西?
快速参考: https://developer.android.com/reference/android/view/View.html#attr_android:visibility
当前回答
与问题协作，并展示一个用空Container()替换它的示例。
下面是一个例子:
import "package:flutter/material.dart";
void main() {
runApp(new ControlleApp());
}
class ControlleApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return new MaterialApp(
title: "My App",
home: new HomePage(),
);
}
}
class HomePage extends StatefulWidget {
@override
HomePageState createState() => new HomePageState();
}
class HomePageState extends State<HomePage> {
bool visibilityTag = false;
bool visibilityObs = false;
void _changed(bool visibility, String field) {
setState(() {
if (field == "tag"){
visibilityTag = visibility;
}
if (field == "obs"){
visibilityObs = visibility;
}
});
}
@override
Widget build(BuildContext context){
return new Scaffold(
appBar: new AppBar(backgroundColor: new Color(0xFF26C6DA)),
body: new ListView(
children: <Widget>[
new Container(
margin: new EdgeInsets.all(20.0),
child: new FlutterLogo(size: 100.0, colors: Colors.blue),
),
new Container(
margin: new EdgeInsets.only(left: 16.0, right: 16.0),
child: new Column(
children: <Widget>[
visibilityObs ? new Row(
crossAxisAlignment: CrossAxisAlignment.end,
children: <Widget>[
new Expanded(
flex: 11,
child: new TextField(
maxLines: 1,
style: Theme.of(context).textTheme.title,
decoration: new InputDecoration(
labelText: "Observation",
isDense: true
),
),
),
new Expanded(
flex: 1,
child: new IconButton(
color: Colors.grey[400],
icon: const Icon(Icons.cancel, size: 22.0,),
onPressed: () {
_changed(false, "obs");
},
),
),
],
) : new Container(),
visibilityTag ? new Row(
crossAxisAlignment: CrossAxisAlignment.end,
children: <Widget>[
new Expanded(
flex: 11,
child: new TextField(
maxLines: 1,
style: Theme.of(context).textTheme.title,
decoration: new InputDecoration(
labelText: "Tags",
isDense: true
),
),
),
new Expanded(
flex: 1,
child: new IconButton(
color: Colors.grey[400],
icon: const Icon(Icons.cancel, size: 22.0,),
onPressed: () {
_changed(false, "tag");
},
),
),
],
) : new Container(),
],
)
),
new Row(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
new InkWell(
onTap: () {
visibilityObs ? null : _changed(true, "obs");
},
child: new Container(
margin: new EdgeInsets.only(top: 16.0),
child: new Column(
children: <Widget>[
new Icon(Icons.comment, color: visibilityObs ? Colors.grey[400] : Colors.grey[600]),
new Container(
margin: const EdgeInsets.only(top: 8.0),
child: new Text(
"Observation",
style: new TextStyle(
fontSize: 12.0,
fontWeight: FontWeight.w400,
color: visibilityObs ? Colors.grey[400] : Colors.grey[600],
),
),
),
],
),
)
),
new SizedBox(width: 24.0),
new InkWell(
onTap: () {
visibilityTag ? null : _changed(true, "tag");
},
child: new Container(
margin: new EdgeInsets.only(top: 16.0),
child: new Column(
children: <Widget>[
new Icon(Icons.local_offer, color: visibilityTag ? Colors.grey[400] : Colors.grey[600]),
new Container(
margin: const EdgeInsets.only(top: 8.0),
child: new Text(
"Tags",
style: new TextStyle(
fontSize: 12.0,
fontWeight: FontWeight.w400,
color: visibilityTag ? Colors.grey[400] : Colors.grey[600],
),
),
),
],
),
)
),
],
)
],
)
);
}
}
其他回答
在flutter 1.5和Dart 2.3中，对于可视性消失，您可以在集合中使用if语句设置可见性，而不必使用容器。
e.g
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Text('This is text one'),
if (_isVisible) Text('can be hidden or shown'), // no dummy container/ternary needed
Text('This is another text'),
RaisedButton(child: Text('show/hide'), onPressed: (){
setState(() {
_isVisible = !_isVisible;
});
},)
],
)
尝试Offstage小部件
如果属性off - stage:true则不占用物理空间且不可见，
如果属性offstage:false它将占用物理空间而可见
Offstage(
offstage: true,
child: Text("Visible"),
),
你可以在你的代码中用一个叫做(Visibility)的新小部件封装任何小部件，这是你想让它不可见的小部件最左边的黄色灯
例如:假设你想让一行不可见:
Click in the lamp and choose (Wrap with widget) Rename the widget to Visibility Add the visible property and set it to false The Child of the newly created widget (Visibility Widget) is the Widget that you want it to be invisible Visibility( visible: false, child: Row( crossAxisAlignment: CrossAxisAlignment.start, children: <Widget>[ SizedBox( width: 10, ), Text("Search", style: TextStyle(fontSize: 20 ),), ], ), ),
我希望它能在将来帮助到别人
class VisibilityExample extends StatefulWidget {
const VisibilityExample({Key? key}) : super(key: key);
@override
_VisibilityExampleState createState() => _VisibilityExampleState();
}
class _VisibilityExampleState extends State<VisibilityExample> {
bool visible = false;
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: const Text('Lines'),
),
body: Container(
color: Colors.black87,
child: Stack(alignment: Alignment.bottomCenter, children: [
ListView(
shrinkWrap: true,
children: [
Container(
height: 200,
),
InkWell(
onTap: () {},
onHover: (value) {
print(value);
setState(() {
visible = !visible;
});
},
child: Visibility(
maintainSize: true,
maintainAnimation: true,
maintainState: true,
visible: visible,
child: Row(
mainAxisAlignment: MainAxisAlignment.center,
children: [
IconButton(
color: Colors.white54,
icon: const Icon(
Icons.arrow_left_outlined,
),
onPressed: () {},
),
const SizedBox(
width: 5,
),
IconButton(
color: Colors.white54,
icon: const Icon(
Icons.add_circle_outlined,
),
onPressed: () {},
),
const SizedBox(
width: 5,
),
IconButton(
color: Colors.white54,
icon: const Icon(
Icons.remove_circle,
),
onPressed: () {},
),
const SizedBox(
width: 5,
),
IconButton(
color: Colors.white54,
icon: const Icon(
Icons.arrow_right_outlined,
),
onPressed: () {},
),
const SizedBox(
width: 5,
),
IconButton(
color: Colors.white54,
icon: const Icon(Icons.replay_circle_filled_outlined),
onPressed: () {},
),
],
),
),
),
],
),
]),
),
);
}
}
与问题协作，并展示一个用空Container()替换它的示例。
下面是一个例子:
import "package:flutter/material.dart";
void main() {
runApp(new ControlleApp());
}
class ControlleApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return new MaterialApp(
title: "My App",
home: new HomePage(),
);
}
}
class HomePage extends StatefulWidget {
@override
HomePageState createState() => new HomePageState();
}
class HomePageState extends State<HomePage> {
bool visibilityTag = false;
bool visibilityObs = false;
void _changed(bool visibility, String field) {
setState(() {
if (field == "tag"){
visibilityTag = visibility;
}
if (field == "obs"){
visibilityObs = visibility;
}
});
}
@override
Widget build(BuildContext context){
return new Scaffold(
appBar: new AppBar(backgroundColor: new Color(0xFF26C6DA)),
body: new ListView(
children: <Widget>[
new Container(
margin: new EdgeInsets.all(20.0),
child: new FlutterLogo(size: 100.0, colors: Colors.blue),
),
new Container(
margin: new EdgeInsets.only(left: 16.0, right: 16.0),
child: new Column(
children: <Widget>[
visibilityObs ? new Row(
crossAxisAlignment: CrossAxisAlignment.end,
children: <Widget>[
new Expanded(
flex: 11,
child: new TextField(
maxLines: 1,
style: Theme.of(context).textTheme.title,
decoration: new InputDecoration(
labelText: "Observation",
isDense: true
),
),
),
new Expanded(
flex: 1,
child: new IconButton(
color: Colors.grey[400],
icon: const Icon(Icons.cancel, size: 22.0,),
onPressed: () {
_changed(false, "obs");
},
),
),
],
) : new Container(),
visibilityTag ? new Row(
crossAxisAlignment: CrossAxisAlignment.end,
children: <Widget>[
new Expanded(
flex: 11,
child: new TextField(
maxLines: 1,
style: Theme.of(context).textTheme.title,
decoration: new InputDecoration(
labelText: "Tags",
isDense: true
),
),
),
new Expanded(
flex: 1,
child: new IconButton(
color: Colors.grey[400],
icon: const Icon(Icons.cancel, size: 22.0,),
onPressed: () {
_changed(false, "tag");
},
),
),
],
) : new Container(),
],
)
),
new Row(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
new InkWell(
onTap: () {
visibilityObs ? null : _changed(true, "obs");
},
child: new Container(
margin: new EdgeInsets.only(top: 16.0),
child: new Column(
children: <Widget>[
new Icon(Icons.comment, color: visibilityObs ? Colors.grey[400] : Colors.grey[600]),
new Container(
margin: const EdgeInsets.only(top: 8.0),
child: new Text(
"Observation",
style: new TextStyle(
fontSize: 12.0,
fontWeight: FontWeight.w400,
color: visibilityObs ? Colors.grey[400] : Colors.grey[600],
),
),
),
],
),
)
),
new SizedBox(width: 24.0),
new InkWell(
onTap: () {
visibilityTag ? null : _changed(true, "tag");
},
child: new Container(
margin: new EdgeInsets.only(top: 16.0),
child: new Column(
children: <Widget>[
new Icon(Icons.local_offer, color: visibilityTag ? Colors.grey[400] : Colors.grey[600]),
new Container(
margin: const EdgeInsets.only(top: 8.0),
child: new Text(
"Tags",
style: new TextStyle(
fontSize: 12.0,
fontWeight: FontWeight.w400,
color: visibilityTag ? Colors.grey[400] : Colors.grey[600],
),
),
),
],
),
)
),
],
)
],
)
);
}
}
