Flutter: possible to detect when a drawer is open?

Question

Is it possible to detect when a Drawer is open so that we can run some routine to update its content?

A typical use case I have would be to display the number of fol

Answer 1

Detecting & Running Functions When Drawer Is Opened / Closed

• Run initState() when open drawer by any action.
• Run dispose() when close drawer by any action.

class MyDrawer extends StatefulWidget {
    @override
    _MyDrawerState createState() => _MyDrawerState();
}

class _MyDrawerState extends State {

    @override
    void initState() {
        super.initState();
        print("open");
    }

    @override
    void dispose() {
        print("close");
        super.dispose();
    }

    @override
    Widget build(BuildContext context) {
        return Drawer(
            child: Column(
                children: [
                    Text("test1"),
                    Text("test2"),
                    Text("test3"),
                ],
            ),
        );
    }
}

State Management Considerations

If you are altering state with these functions to rebuild drawer items, you may encounter the error: Unhandled Exception: setState() or markNeedsBuild() called during build.

This can be handled by using the following two functions in initState() source

Option 1

WidgetsBinding.instance.addPostFrameCallback((_){
  // Add Your Code here.
});

Option 2

SchedulerBinding.instance.addPostFrameCallback((_) {
  // add your code here.
});

Full Example of Option 1

@override
void initState() {
    super.initState();
    WidgetsBinding.instance.addPostFrameCallback((_) {
        // Your Code Here
    });
}