I've been do a lot of reading about how to properly use the "handles" variable and how to interact with the master copy through guidata(hObject). My first question is when to use it. For instance, I have a callback function.
function resetButton_Callback(hObject, eventdata, handles)
Do I need to call handles=guidata(hObject) right away or is it safe to assume that at the instant the callback occurs, the difference in time between what would be in "handles" through the function call would be identical to what would be through "guidata(hObject)"?
But what I haven't been able to understand properly is say I have a timer function for my GUI and updates the handles ever 0.1 second. How do I work with the handles then?
function Gui_OpeningFcn(hObject, eventdata, handles, varargin)
handles.count = 0;
handles.timerData = timer('TimerFcn',{@timerFunction,hObject},'StartDelay',1,'ExecutionMode','fixedRate','BusyMode','drop','Period',0.1);
guidata(hObject,handles);
end
function timerFunction(hObect,eventdata,theGUI)
handles = guidata(theGUI);
handles.count = handles.count + 1;
disp(handles.count);
guidata(theGUI,handles);
end
function resetButton_Callback(hObject, eventdata, handles)
handles.count = 0;
guidata(hObject,handles);
end
When I click the resetButton, the count never resets. However, if I do the following, I can see the count updating inside the callback. So I know it's getting the latest handles. It's just not taking the new handles back to the timer. The timer function is always overwriting the handles.
function resetButton_Callback(hObject, eventdata, handles)
disp(handles.count)
handles.count = 0;
guidata(hObject,handles);
end
If I remove the guidata(theGUI,handles) from the timer, the timer never updates. And if I have the resetButton set a value to count, the data is changed.
function timerFunction(hObect,eventdata,theGUI)
handles = guidata(theGUI);
handles.count = handles.count + 1;
disp(handles.count);
end
function resetButton_Callback(hObject, eventdata, handles)
handles.count = 10;
guidata(hObject,handles);
end
Initially count = 1, after button is pressed count = 11. It proves the handles are being overwritten by the timer.
Is the answer to stop and start the timer when updating the handles in a callback? EDIT: That kinda worked. If I hit the button once, it doesn't reset. But if I hit the button twice, fast, it works. I suppose I need to wait for the timer to properly stop. There seems to be some timing/function blocking issues here with the callback.
function resetButton_Callback(hObject, eventdata, handles)
disp(handles.count)
handles.count = 0;
stop(handles.timerData);
guidata(hObject,handles);
start(handles.timerData);
end
