Trouble with function called from a GUI callback fonction

I use GUIDE to make an interface.

I obtain some callbacks in wich I want to use another function as follow:

function CallbackFunction(hObject, eventdata, handles) 
...
myFunction(hObject, eventdata, handles);
...
guidata(hObject, handles); 

end % function   

fucntion myFunction(hObject, eventdata, handles)
...
handles.Var=

guidata(hObject, handles); 

end % fonction

But this seems to cause me many problems. I seem to miss something.

I just want to write a function that is called from a callback function and that can change handles variables?

Answer 1

[Geoff Hayes]

Claude - look closely at the order in which handles is updated. The

 function CallbackFunction(hObject, eventdata, handles)

is called passing in the latest (at the time) version of handles. This parameter (along with the other two) are passed in to your function

 function myFunction(hObject, eventdata, handles)

where the code updates the handles object and then saves it using

 guidata(hObject, handles);

But then we return back to your CallbackFunction and maybe do something, and then calls

 guidata(hObject, handles);

But which version of handles is this? This is the copy that was passed into this function when CallbackFunction was called. It is not the updated version from your call to myFunction since myFunction does not return the updated handles structure, and your code probably doesn't refresh handles (after this call to myFunction) with

 handles = guidata(hObject);

So you can do at least two different things - return the updated handles structure from myFunction by changing its signature to

 function [handles] = myFunction(hObject, eventdata, handles);

and so your code would become something like

 function CallbackFunction(hObject, eventdata, handles) 
 ...
 handles = myFunction(hObject, eventdata, handles);
 ...
 guidata(hObject, handles);   % in case you've updated handles again
 end % function

Or you can refresh your local copy as

 function CallbackFunction(hObject, eventdata, handles) 
 ...
 myFunction(hObject, eventdata, handles);
 handles = guidata(hObject);
 ...
 guidata(hObject, handles);   % in case you've updated handles again
 end % function

Hopefully, one of the above solutions will work for you!