MATLAB: Stop/Delete Timer Issues While Closing GUI

closing guitimer

Hi,
I use a timer to update an axes in a GUI. I want to handle the case in which the user closes the window while the timer is still running, i.e., the axes still beeing updated.
The Problem:
However, every so often the execution time of the TimerFcn is longer than the timers period (depending on the pc's performance). This can cause an error when closing the GUI while the timer is still running.
    Error while evaluating TimerFcn for timer 'timer-1'
    Bad handle
FYI, I use
    T = timerfind;
    if ~isempty(T)
        stop(T)
        delete(T)
    end
in the figure's delete function. Apparently, the TimerFcn is still being called after the execution of the figure's delete function. Hence, within my TimerFcn an error occurs during a call to
    cla(myaxes),
for cla expects a valid figure handle (though the GUI's figure has just been deleted).
All in all, it seems that the execution time being larger than the timer period is causing this. Of course I could reduce the timer period, but this is not desirable. I figured out a workaround by using a try-catch phrase within the TimerFcn, however it's not a proper solution.
Question:
Is there any way to force the TimerFcn to stop and somehow flush its executin queue/event buffer, regardless of its current state? Any thoughts about solving this issue are very welcome!
Thank you in advance!
Hannes

Best Answer

Here's my function. I call it in the figMainWindow_CloseRequestFcn() function which gets called when the user tried to close the GUI by any means. To make double sure, I also call in in the callback for a push button I have labeled "Exit", btnExit_Callback(). It looks pretty similar to yours, perhaps a little more robust. I never have any problem with it but I have my timer running at 20 calls per second to monitor a switch on a light booth.
%----------------------------------------------------------------------------
function StopTimer(handles)
try
  fprintf('Entering StopTimer...\n');
  listOfTimers = timerfindall % List all timers, just for info.
  % Get handle to the one timer that we should have.
  if isempty(listOfTimers)
    % Exit if there is no timer to turn off.
    fprintf('There are no timers to turn off. Leaving StopTimer().\n');
    return;
  end
  handleToTimer = getappdata(handles.figMainWindow, 'timerObj');
  % Stop that timer.
  stop(handleToTimer);
  % Delete all timers from memory.
  listOfTimers = timerfindall
  if ~isempty(listOfTimers)
    delete(listOfTimers(:));
  end
  fprintf('Left StopTimer and turned off all timers.\n');
catch ME
  errorMessage = sprintf('Error in StopTimer().\nThe error reported by MATLAB is:\n\n%s', ME.message);
  fprintf('%s\n', errorMessage);
  WarnUser(errorMessage);
end
return; % from btnStopTimer_Callback
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