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
初学者也可以试试。
class Visibility extends StatefulWidget {
@override
_VisibilityState createState() => _VisibilityState();
}
class _VisibilityState extends State<Visibility> {
bool a = true;
String mText = "Press to hide";
@override
Widget build(BuildContext context) {
return new MaterialApp(
title: "Visibility",
home: new Scaffold(
body: new Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
new RaisedButton(
onPressed: _visibilitymethod, child: new Text(mText),),
a == true ? new Container(
width: 300.0,
height: 300.0,
color: Colors.red,
) : new Container(),
],
)
),
);
}
void _visibilitymethod() {
setState(() {
if (a) {
a = false;
mText = "Press to show";
} else {
a = true;
mText = "Press to hide";
}
});
}
}
其他回答
Flutter现在包含一个可见性小部件，您可以使用它来显示/隐藏小部件。小部件还可以通过更改替换来在两个小部件之间切换。
这个小部件可以实现任何可见、不可见、消失等状态。
Visibility(
visible: true //Default is true,
child: Text('Ndini uya uya'),
//maintainSize: bool. When true this is equivalent to invisible;
//replacement: Widget. Defaults to Sizedbox.shrink, 0x0
),
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;
});
},)
],
)
bool _visible = false;
void _toggle() {
setState(() {
_visible = !_visible;
});
}
onPressed: _toggle,
Visibility(
visible:_visible,
child: new Container(
child: new Container(
padding: EdgeInsets.fromLTRB(15.0, 0.0, 15.0, 10.0),
child: new Material(
elevation: 10.0,
borderRadius: BorderRadius.circular(25.0),
child: new ListTile(
leading: new Icon(Icons.search),
title: new TextField(
controller: controller,
decoration: new InputDecoration(
hintText: 'Search for brands and products', border: InputBorder.none,),
onChanged: onSearchTextChanged,
),
trailing: new IconButton(icon: new Icon(Icons.cancel), onPressed: () {
controller.clear();
onSearchTextChanged('');
},),
),
),
),
),
),
更新
Flutter现在有一个可见性小部件。要实现您自己的解决方案，请从下面的代码开始。
自己做一个小部件。
显示/隐藏
class ShowWhen extends StatelessWidget {
final Widget child;
final bool condition;
ShowWhen({this.child, this.condition});
@override
Widget build(BuildContext context) {
return Opacity(opacity: this.condition ? 1.0 : 0.0, child: this.child);
}
}
显示/删除
class RenderWhen extends StatelessWidget {
final Widget child;
final bool condition;
RenderWhen({this.child, this.show});
@override
Widget build(BuildContext context) {
return this.condition ? this.child : Container();
}
}
顺便问一下，有没有人对上面的小部件有更好的名字?
更多的阅读
关于如何制作可见性小部件的文章。
初学者也可以试试。
class Visibility extends StatefulWidget {
@override
_VisibilityState createState() => _VisibilityState();
}
class _VisibilityState extends State<Visibility> {
bool a = true;
String mText = "Press to hide";
@override
Widget build(BuildContext context) {
return new MaterialApp(
title: "Visibility",
home: new Scaffold(
body: new Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
new RaisedButton(
onPressed: _visibilitymethod, child: new Text(mText),),
a == true ? new Container(
width: 300.0,
height: 300.0,
color: Colors.red,
) : new Container(),
],
)
),
);
}
void _visibilitymethod() {
setState(() {
if (a) {
a = false;
mText = "Press to show";
} else {
a = true;
mText = "Press to hide";
}
});
}
}
