Flutter web - How to listen on open Drawer state and close it
Solution 1
Here is the Solution.
You're Code is enough. Just a few changes to your code
Wrap this
Scaffold.of(context).openEndDrawer();
inWidgetsBinding.instance.addPostFrameCallback((_) { Scaffold.of(context).openEndDrawer(); //No Error ///The Error was coming, As you're trying to build a widget when it is ///rebuilding widget Tree due to the change in the width of the browser. ///Wrapping it inside ensures that the code will run after the build. });
Don't Use
setState(() {});
Use 520 instead of 500
Reason
The error was coming, As you're trying to build a widget when it is rebuilding Widget Tree due to the change in the width of the browser. Wrapping this
Scaffold.of(context).openEndDrawer();
insideWidgetsBinding.instance.addPostFrameCallback((_) {});
ensures that the code will run after the widget get's build.
Here's Updated Code
class HomePage extends StatelessWidget {
@override
Widget build(BuildContext context) {
final size = MediaQuery.of(context).size.width;
print(size);
return Scaffold(
drawer: Drawer(),
body: CustomNavBar(
screenSize: size,
),
);
}
}
class CustomNavBar extends StatefulWidget {
final double screenSize;
const CustomNavBar({
Key key,
this.screenSize,
}) : super(key: key);
@override
_CustomNavBarState createState() => _CustomNavBarState();
}
class _CustomNavBarState extends State<CustomNavBar> {
@override
Widget build(BuildContext context) {
if (Scaffold.of(context).isDrawerOpen && widget.screenSize > 520) {
print("Drawer is Opened");
WidgetsBinding.instance.addPostFrameCallback((_) {
Scaffold.of(context).openEndDrawer(); //No Error
///The error was coming, As you're trying to build a widget when it is
///rebuilding widget Tree due to the change in the width of the browser.
///Wrapping it inside ensure that the code will run after the build.
});
// Don't call setState((){}); Not Required;
// as every time you change the width it rebuilds all the widget again
// setState(() {});
}
return widget.screenSize > 520
? Container(color: Colors.red) //desktop screen
: Center(
//mobile screen
child: IconButton(
icon: Icon(Icons.menu),
onPressed: () => Scaffold.of(context).openDrawer(),
),
);
}
}
The error was
The following assertion was thrown while notifying status listeners for
AnimationController:
setState() or markNeedsBuild() called during build.
This Scaffold widget cannot be marked as needing to build because the framework is
already in the
process of building widgets. A widget can be marked as needing to be built during
the build phase
only if one of its ancestors is currently building. This exception is allowed
because the framework
builds parent widgets before children, which means a dirty descendant will always be
built.
Otherwise, the framework might not visit this widget during this build phase.
The widget on which setState() or markNeedsBuild() was called was:
Scaffold
The widget which was currently being built when the offending call was made was:
CustomNavBar
Tip
Use the Layout Builder for Responsive UI.
@override
Widget build(BuildContext context) {
return LayoutBuilder(
builder: (context, constraints) {
if (constraints.maxWidth > 800) {
return XScreen();
} else if (constraints.maxWidth < 1200 && constraints.maxWidth > 800) {
return Yscreen()?? ZScreen();
} else {
return XScreen()?? ZScreeen();
}
},
);
}
Solution 2
You shouldn't have to close the drawer manually. Why not just get rid of the drawer when the screen width is less than 500?
class SampleDrawer extends StatelessWidget {
final GlobalKey<ScaffoldState> k = GlobalKey();
@override
Widget build(BuildContext context) {
// new
final size = MediaQuery.of(context).size.width;
if (k.currentState.isDrawerOpen && size < 500) {
Navigator.pop(context); // close drawer
}
return Scaffold(
key: k,
drawer: size > 500 ? Drawer() : null,
body: CustomNavBar(),
);
}
}
class CustomNavBar extends StatelessWidget {
@override
Widget build(BuildContext context) {
final size = MediaQuery.of(context).size.width;
return size > 500
? Container(color: Colors.red) //desktop screen
: Center( //mobile screen
child: IconButton(
icon: Icon(Icons.menu),
onPressed: () => Scaffold.of(context).openDrawer(),
),
);
}
}
The Scaffold will be rebuilt whenever the width of the device changes, and the drawer will automatically be omitted if the width is less than 500.
Raine Dale Holgado
BS in Computer Engineering, graduated from Silliman University. Interested in Web/Mobile development and Dart/Flutter. Love to explore new technology.
Updated on December 24, 2022Comments
-
Raine Dale Holgado over 1 year
Im working on flutter responsive web UI. And I want to close the opened drawer on a specific screen width for mobile and desktop screen width, so if I stretch my browser, the drawer should close.
For example I opened the drawer (screen width less than 500)
And when the screen width is greater than 500, I want the opened drawer to automatically close.
Note: When the Drawer is opened. I have a code already that checked the screen width that show a button menu drawer or not. But basically, when the user open the drawer then suddenly stretch the browser the drawer should closed.
Code below. Thanks for the help
class HomePage extends StatelessWidget { @override Widget build(BuildContext context) { final size = MediaQuery.of(context).size.width; return Scaffold( drawer: Drawer(), body: CustomNavBar(screenSize: size), ); } } class CustomNavBar extends StatefulWidget { final double screenSize; const CustomNavBar({Key key, this.screenSize}) : super(key: key); @override _CustomNavBarState createState() => _CustomNavBarState(); } class _CustomNavBarState extends State<CustomNavBar> { @override Widget build(BuildContext context) { if (Scaffold.of(context).isDrawerOpen && widget.screenSize > 500) { print("Drawer is Opened"); Scaffold.of(context).openEndDrawer(); //animation error setState(() {}); } return widget.screenSize > 500 ? Container(color: Colors.red) //desktop screen : Center( //mobile screen child: IconButton( icon: Icon(Icons.menu), onPressed: () => Scaffold.of(context).openDrawer(), ), ); } }
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Raine Dale Holgado over 3 yearstried that before but when the drawer is currently opened and making it to null it throws widget error
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Ganesh Tiwari over 3 yearsThis solution works for me on my machine you should give it a try ;)
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Raine Dale Holgado over 3 years@GaneshTiwari, that only work on managing the drawer. But my question is the Opened Drawer. Try opening the drawer then suddenly stretch it, use that code again.. It will cause some animation errors.. I need help on managing the Opened Drawer.
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Raine Dale Holgado over 3 yearsThanks that solved the problem. just a follow up question , i can also use this WidgetsBinding.instance.addPostFrameCallback((_) {}); on initstate right?..
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DIVYANSHU SAHU over 3 yearsYes you can I usually use WidgetsBinding.instance.addPostFrameCallback((_) {}); on InitState.
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uanirudhx over 3 years@Reign please try my new code. I have edited the answer.