Pass variables from callbacks to custom functions in a GUI

I created a gui with two buttons that allow you to load the stl files and record the mesh on axes. I wanted to create a custom function to be called every time the changes to the mesh are displayed in order to refresh the display. I'm having trouble passing the loaded data to the function, when I run it I get the error message:

"Object must be a figure or one of its child objects"

Can anyone tell me what am I wrong? Thank you!

This is the callbacks of the button:

        function OpenSTLfileButtonPushed(app, event)
            
            [file, pathToFile] = uigetfile({'*.*','All Files'},'Select .STL File');

            [f,v,N] = stlread(strcat(pathToFile,file));

            v_min_x = min(v(:,1));
            v_min_y = min(v(:,2));
            v_min_z = min(v(:,3));

            v(:,1) = v(:,1) - v_min_x;
            v(:,2) = v(:,2) - v_min_y;
            v(:,3) = v(:,3) - v_min_z;
            
            [f2,v2] = remove_duplicate_vertex(f,v);
            
            edgeUnici = UniqueEdgeSearch(f2);
            
            
            handles.f2 = f2;
            handles.v2 = v2;
            guidata(app, handles);
            
            refresh(app, handles);

        end

And and this is the custom function:

         function refresh(app,handles)
                        
            disp("ciao");
                        
            f2 = handles.f2;
            v2 = handles.v2;
            
            stlPlotGUI(v2,f2,'C','k',app.UIAxes);
            
            hold(app.UIAxes, 'on' );
            
         end

[Adam]

Which line is giving the error? And what is stlPlotGUI? Is it one of your functions?

[Gabriele Rossi]

yes, stlPlotGUI is one of my function. This is a error message:

Error using guidata (line 87)
Object must be a figure or one of its child objects.

Error in Applicazione/OpenSTLfileButtonPushed (line 67)
            guidata(app, handles);
 
Error using matlab.ui.control.internal.controller.ComponentController/executeUserCallback (line 335)
Error while evaluating Button PrivateButtonPushedFcn.

Answer 1

[Rik]

I'm going to assume the error occurs at this line

guidata(app, handles);

You are mixing a GUIDE-style GUI syntax with an AppDesigner GUI. The guidata function stores data with a figure, which you don't really need when using AppDesigner. You can store your data in the app properties, or use the handle to your uifigure as the first input to guidata.

[Gabriele Rossi]

Could you give me an example of syntax to use in my case?

[Adam]

app.f2 = f2;
app.v2 = v2;

Then add a properties block to your app (there is a button somewhere up in the top left I think to do this, I haven't used it for a while so can't remember) that should look something like this:

properties( access = private )
    f2;
    v2;
end

[Gabriele Rossi]

Perfect, thanks for the help. Thank you!