问题
I am currently building app where I need to use Nested Routing keeping one screen same and routing on different one. I want to when that second route is popped so that I can change value of expanded to fill whole screen. Gist in Github. Here is code sample:
import 'package:flutter/material.dart';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
// This widget is the root of your application.
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: Scaffold(body: MyHomePage()),
);
}
}
class MyHomePage extends StatefulWidget {
MyHomePage({Key key}) : super(key: key);
@override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> with RouteAware {
bool rightPanelIsShown;
Widget child;
final GlobalKey<NavigatorState> navigatorKey = GlobalKey();
final RouteObserver<PageRoute> _routeObserver = RouteObserver<PageRoute>();
@override
void initState() {
super.initState();
setState(() {
rightPanelIsShown = false;
child = Container();
});
}
@override
void didChangeDependencies() {
super.didChangeDependencies();
_routeObserver.subscribe(this, ModalRoute.of(context));
setState(() {
child = Container();
});
}
@override
void didPop() {
super.didPop();
print('popped');
setState(() {
rightPanelIsShown = false;
});
}
@override
void dispose() {
print("dis");
_routeObserver.unsubscribe(this);
super.dispose();
}
@override
Widget build(BuildContext context) {
return Container(
color: Colors.white,
child: Row(
children: <Widget>[
Expanded(
flex: 1,
child: Center(
child: FlatButton(
color: Colors.blue,
onPressed: () => setState(() {
rightPanelIsShown = !rightPanelIsShown;
child = Page1();
}),
child: Text(
'Open Right Panel',
style: TextStyle(color: Colors.white, fontSize: 25.0),
),
),
),
),
rightPanelIsShown
? Expanded(
flex: 1,
child: Navigator(
onGenerateRoute: (route) => MaterialPageRoute(
builder: (context) => child,
),
),
)
: Container(),
],
),
);
}
}
class Page1 extends StatelessWidget {
const Page1({Key key}) : super(key: key);
@override
Widget build(BuildContext context) {
return Container(
child: Column(
children: <Widget>[
Text(
'Page1',
style: TextStyle(
fontSize: 30.0,
),
),
_buildGoToButton(context),
_buildBackbutton(context)
],
),
);
}
FlatButton _buildGoToButton(BuildContext context) {
return FlatButton(
color: Colors.green,
onPressed: () {
Navigator.push(
context,
MaterialPageRoute(
builder: (_) => Page2(),
),
);
},
child: Text(
'Go To Page 2',
style: TextStyle(fontSize: 21.0),
),
);
}
FlatButton _buildBackbutton(BuildContext context) {
return FlatButton(
color: Colors.red,
onPressed: () {
Navigator.pop(context);
},
child: Text(
'Close',
style: TextStyle(fontSize: 21.0),
),
);
}
}
class Page2 extends StatelessWidget {
const Page2({Key key}) : super(key: key);
@override
Widget build(BuildContext context) {
return Container(
child: Column(
children: <Widget>[
Text(
'Page2',
style: TextStyle(
fontSize: 30.0,
),
),
_buildBackButton(context)
],
),
);
}
FlatButton _buildBackButton(BuildContext context) {
return FlatButton(
color: Colors.red,
onPressed: () {
Navigator.pop(context);
},
child: Text(
'Close',
style: TextStyle(fontSize: 21.0),
),
);
}
}
Screencast of built upto
When click on close on right panel Page1 it should also change state of parent. Thanks,
Update
Working with help of João Soares
import 'package:flutter/material.dart';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
// This widget is the root of your application.
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: Scaffold(body: MyHomePage()),
);
}
}
class MyHomePage extends StatefulWidget {
MyHomePage({Key key}) : super(key: key);
@override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> with RouteAware {
bool rightPanelIsShown;
Widget child;
final GlobalKey<NavigatorState> navigatorKey = GlobalKey();
final RouteObserver<PageRoute> _routeObserver = RouteObserver<PageRoute>();
@override
void initState() {
super.initState();
setState(() {
rightPanelIsShown = false;
child = Container();
});
}
@override
void didChangeDependencies() {
super.didChangeDependencies();
_routeObserver.subscribe(this, ModalRoute.of(context));
setState(() {
child = Container();
});
}
@override
void didPop() {
super.didPop();
print('popped');
setState(() {
rightPanelIsShown = false;
});
}
@override
void dispose() {
print("dis");
_routeObserver.unsubscribe(this);
super.dispose();
}
@override
Widget build(BuildContext context) {
return Container(
color: Colors.white,
child: Row(
children: <Widget>[
Expanded(
flex: 1,
child: Center(
child: Column(
children: <Widget>[
FlatButton(
color: Colors.blue,
onPressed: () => setState(() {
rightPanelIsShown = !rightPanelIsShown;
child = Page1(
callback: onPop,
);
}),
child: Text(
'Open Right Panel 1',
style: TextStyle(color: Colors.white, fontSize: 25.0),
),
),
FlatButton(
color: Colors.blue,
onPressed: () => setState(() {
rightPanelIsShown = !rightPanelIsShown;
child = Page3(
callback: onPop,
);
}),
child: Text(
'Open Right Panel 2',
style: TextStyle(color: Colors.white, fontSize: 25.0),
),
),
],
),
),
),
rightPanelIsShown
? Expanded(
flex: 1,
child: PanelView(
child: child,
),
)
: Container(),
],
),
);
}
onPop(value) {
print("popped");
setState(() {
rightPanelIsShown = false;
});
}
}
class PanelView extends StatefulWidget {
final Widget child;
PanelView({Key key, this.child}) : super(key: key);
@override
_PanelViewState createState() => _PanelViewState();
}
class _PanelViewState extends State<PanelView> {
@override
Widget build(BuildContext context) {
return Navigator(
onGenerateRoute: (route) {
return MaterialPageRoute(builder: (context) {
return Container(
child: widget.child,
);
});
},
);
}
}
class Page1 extends StatelessWidget {
final Function callback;
const Page1({Key key, this.callback}) : super(key: key);
@override
Widget build(BuildContext context) {
return Container(
child: Column(
children: <Widget>[
Text(
'Page1',
style: TextStyle(
fontSize: 30.0,
),
),
_buildGoToButton(context),
_buildBackbutton(context)
],
),
);
}
FlatButton _buildGoToButton(BuildContext context) {
return FlatButton(
color: Colors.green,
onPressed: () {
Navigator.push(
context,
MaterialPageRoute(
builder: (_) => Page2(),
),
);
},
child: Text(
'Go To Page 2',
style: TextStyle(fontSize: 21.0),
),
);
}
FlatButton _buildBackbutton(BuildContext context) {
return FlatButton(
color: Colors.red,
onPressed: () {
callback('hello');
Navigator.of(context).pop();
},
child: Text(
'Close',
style: TextStyle(fontSize: 21.0),
),
);
}
}
class Page2 extends StatelessWidget {
const Page2({Key key}) : super(key: key);
@override
Widget build(BuildContext context) {
return Container(
child: Column(
children: <Widget>[
Text(
'Page2',
style: TextStyle(
fontSize: 30.0,
),
),
_buildBakButton(context)
],
),
);
}
FlatButton _buildBakButton(BuildContext context) {
return FlatButton(
color: Colors.red,
onPressed: () {
Navigator.pop(context);
},
child: Text(
'Close',
style: TextStyle(fontSize: 21.0),
),
);
}
}
class Page3 extends StatelessWidget {
final Function callback;
const Page3({Key key, this.callback}) : super(key: key);
@override
Widget build(BuildContext context) {
return Container(
child: Column(
children: <Widget>[
Text(
'Page2',
style: TextStyle(
fontSize: 30.0,
),
),
_buildBakButton(context)
],
),
);
}
FlatButton _buildBakButton(BuildContext context) {
return FlatButton(
color: Colors.red,
onPressed: () {
callback('page3');
Navigator.pop(context);
},
child: Text(
'Close',
style: TextStyle(fontSize: 21.0),
),
);
}
}
If there is better solution where I don't have to pass callback to every child widget of PanelView like if have 2 buttons in left panel and it determines which widget will be shown in right panel where button child determines child widget setting it in state.
回答1:
If you are writing all your code in the same class, you can just call a function from your main class inside the Navigator:
Widget
Navigator(
onGenerateRoute: (route) => MaterialPageRoute(
builder: (context) {
return Container(
color: Colors.orange,
child: RaisedButton(
child: Text('Close panel'),
onPressed: () {
panelClosed("I'm sending data back");
Navigator.of(context).pop();
}
)
);
}
),
),
Method
void panelClosed(data){
print("Panel closed");
setState(() {
message = data;
});
}
If instead you want your Navigator in a separate class, then you just need to pass down the function you want to call from the parent class to the child class like this:
Widget in parent class
Expanded(
flex: 1,
child: PanelView(callBack: panelClosed,)
)
Method
void panelClosed(data){
print("Panel closed");
setState(() {
message = data;
});
}
The class with the navigator
class PanelView extends StatefulWidget {
final Function callBack;
PanelView({this.callBack});
@override
_PanelViewState createState() => _PanelViewState();
}
class _PanelViewState extends State<PanelView> {
@override
Widget build(BuildContext context) {
return Navigator(
onGenerateRoute: (route) {
return MaterialPageRoute(
builder: (context) {
return Container(
color: Colors.orange,
child: Column(
children: <Widget>[
Text('panel 2'),
RaisedButton(
child: Text('Close'),
onPressed: () {
widget.callBack('send any data here');
Navigator.of(context).pop();
}
),
],
),
);
},
);
},
);
}
}
来源：https://stackoverflow.com/questions/59660086/how-to-know-pop-event-happened-inside-nested-widget-in-flutter