How to stop while loop in one buttons's callback function from another button's callback function in Gui?

I have a while loop in one button's callback function which creates a webcam object and takes a snapshot. The other button clears the camera object, closes the GUI and opens another GUI but because the while loop is still running in the first button's callback function I get an error saying that the camera object is deleted so cannot take snapshot. How can I remove this error? Possibly stop the first button callback's while loop when the second button is pressed. I am deleting the camera object because the second GUI needs to create a new camera object of the same webcam so I have to delete it in the first GUI.

Answer 1

[Geoff Hayes]

Momin - you can use exit the while loop by using a flag that is set in the second push button callback. For example,

 function pushbutton1_Callback(hObject, eventdata, handles)
 handles.cameraCleared = 0;
 guidata(hObject,handles);
 % do something
 while true
     handles = guidata(hObject); % refresh the handles data
     if handles.cameraCleared
         break;
     end
     % else the camera object still exists so keep doing your stuff
     pause(0.001); % need a pause so that this function is interruptible
 end

In the second pushbutton callback, we set this flag because we have cleared the camera object.

 function pushbutton2_Callback(hObject, eventdata, handles)
 handles.cameraCleared = 1;
 %etc.

In the first callback, we need to refresh the handles structure. If we don't, then we will always be using the local (old) copy of handles that we started with.

Try the above and see what happens! (This code assumes that you are using GUIDE to develop your GUIs.)

[Dang Le Minh]

Thank you so much. It works. Even though it does increase the time operation for the function but it is okay.