如何在颤抖中将一个有状态的小部件的状态从另一个状态更改为? [英] how to change the state of one statefulwidget from another in flutter?
问题描述
我有一个有状态的小部件，有条件地在堆栈中渲染两个孩子，我想更改第三个孩子的出借条件.有什么主意吗?
I have a stateful widget which is conditionally rendering two childs inside stack, and i want to change the condition of the rending from a third child . any idea ?
父代码:
class MapPage extends StatelessWidget {
@override
Widget build(BuildContext context) {
return Scaffold(
body:Body()
);
}
}
class Body extends StatefulWidget {
final String showScreen;
const Body({
Key key,
this.showScreen="post",
}) : super(key:key);
@override
_BodyState createState() => _BodyState();
}
class _BodyState extends State<Body> {
Widget _conditionedWidget(){
if(this.widget.showScreen=="map"){
return MapScreen();
}else if(this.widget.showScreen == "post"){
return PostScreen();
}
}
@override
Widget build(BuildContext context) {
return Stack(
children: <Widget>[
DrawerScreen(),
_conditionedWidget(),
],
);
}
}
子代码
class DrawerScreen extends StatefulWidget {
@override
_DrawerScreenState createState() => _DrawerScreenState();
}
class _DrawerScreenState extends State<DrawerScreen> {
@override
Widget build(BuildContext context) {
return Container(
color:kPrimaryColor,
padding:EdgeInsets.only(top:70),
child:Column(
children: <Widget>[
Row(
children: <Widget>[
SizedBox(width:20.0),
CircleAvatar(),
SizedBox(width:10.0),
Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: <Widget>[
Text('Biswas Sampad',style:TextStyle(
color:Colors.white,
fontWeight: FontWeight.bold,
fontSize: 20.0,
)),
Text('@biswassampad',style:TextStyle(
color:Colors.grey[200],
fontSize: 15.0,
))
],
)
],
),
Container(
padding: EdgeInsets.symmetric(horizontal: 20,vertical:20),
margin: EdgeInsets.symmetric(vertical:30),
child: Column(
children: <Widget>[
MenuButton(icon:Icons.style, name:'Explore',action:(){
print('showing maop');
}),
MenuButton(icon:Icons.tag_faces, name:'Profile',action:(){
print('showing profile');
}),
MenuButton(icon:Icons.people, name:'People',action:(){
print('showing People');
}),
MenuButton(icon:Icons.speaker_notes, name:'Messages',action:(){
print('showing messages');
}),
MenuButton(icon:Icons.notifications, name:'Notifications',action:(){
print('showing Notifications');
}),
MenuButton(icon:Icons.satellite,name:'Settings',action:(){
print('showing settings');
})
],
),
),
LogoutSection()
],
)
);
}
}
所以基本上我想从DrawerScreen> MenuButton> action更改父窗口小部件的showScreen值?
So basically i want to change the showScreen value of the parent widget from DrawerScreen>MenuButton>action ?
任何想法怎么做！预先感谢.
any idea how to do it !! Thanks in advance.
推荐答案
您可以在"DrawerScreen"窗口中使用 Function .这样的小部件:
You can use the Function in "DrawerScreen" widget like this :
将此代码写到类的标题中:
write this code into the header of the class :
final Function onChangeState = Function();
DrawerScreen({@rquired onChangeState});
并在MenuButton中调用 onChangeState 函数，如下所示:
and in MenuButton call onChangeState function , like this:
MenuButton(icon:Icons.satellite,name:'Settings',action:(){
widget.onChangeState("Settings");
})
并将 Body 小部件中的旧代码更改为:
and change old code in Body widget to :
@override
Widget build(BuildContext context) {
return Stack(
children: <Widget>[
DrawerScreen(onChangeState : (newState){
setState(){
this.widget.showScreen = newState;
};
}),
_conditionedWidget(),
],
);
}
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