Ternary operator not updating alert dialog UI in Flutter-CodePudding

I have an alert dialog that contains a Camera Preview from the camera package, and after I take a picture, I want the alert dialog to instead show a loading screen. I was hoping to accomplish this by using a ternary operator in the dialog. Below is the dialog I call when I press a button, where isCalculating is a bool that is originally set to false, _initializeControllerFuture initializes the camera, Loading() is the loading screen, and Stack() has the Camera Preview as well as some other things.

cameraDialog(context) async {
    await showDialog(
      barrierDismissible: false,
      context: context,
      builder: (_) => AlertDialog(
        insetPadding: EdgeInsets.all(5.0),
        contentPadding: EdgeInsets.all(3.0),
        content: FutureBuilder<void>(
          future: _initializeControllerFuture,
          builder: (context, snapshot) {
            if (snapshot.connectionState == ConnectionState.done) {
              return isCalculating
                  ? Loading()
                  : Stack(

In the cameraDialog I have a button that takes a picture, sets the bool isCalculating to true, runs some other code, and sets the bool isCalculating back to false. During this time I want the alert dialog to update its UI and show the Loading() widget. Below is the on pressed event for the button in the cameraDialog:

onPressed: () async {
                  originalFile = await controller.takePicture();
                  setState(() {
                    isCalculating = true;
                  });
                  ... other code is run here ...
                  Navigator.of(context).pop();
                  setState(() {
                    isCalculating = false;
                  });
                },

CodePudding user response：

As you can see cameraDialog is a function which is triggered by also a function like onPress or onTap . When you call setState its really call Widget build(BuildContext context) method and rebuilt the widget tree but it never handle the state of a function or inside a function's content. So calling setState where you use it has no usefulness. So what you can do? you can create a StatefullWidget ex- MyAlertDialog and show it like

onTap: ()=> showDialog(context: context, builder: (ctx) => MyAlertDialog()),

and inside MyAlertDialog you can handle your state just like you did here.