Flutter: Calling SetState() from another class

Question

I am trying to make a simple image that appears or disappears when a button is pushed. This button resides in a separate class to the image, so in Flutter this creates a m

Answer 1

It simple, you need to send your SinglePlayMode::toggleCoin function as callback to dropDownMenu class.

class dropDownMenu extends StatefulWidget {  
        final _callback; // callback reference holder
                                   //you will pass the callback here in constructor
    dropDownMenu( {@required void toggleCoinCallback() } ) :
       _callback = toggleCoinCallback;
        @override
      _dropDownMenuState createState() => _dropDownMenuState();
    }

    class _dropDownMenuState extends State<dropDownMenu> {
      @override
      Widget build(BuildContext context) {
        return Stack(
          children: <Widget> [
            Column(
              mainAxisAlignment: MainAxisAlignment.end,
              children: <Widget>[
                Container(
                  child: Opacity(
                    opacity: 0.0,
                    child: FloatingActionButton(
                      heroTag: null,
                      onPressed:  (){
                        widget?._callback(); // callback calling
                      },
                    ),
                  ),
              );
           }
      }

Then when you create a dropDownMenu class instance in your SinglePlayerMode class you will do

    dropDownMenu(
       toggleCoinCallback: toogleCoin,
    );