processEvents() and threads

**jogeshwarakundi** · 19th February 2009, 09:40

hi correct me if i am wrong, but i understand that your problem is:

int main(void)
{
QApplication app;
//animation code
heavyProcessingFunc();
app.exec();
}

calling processEvents() with a timer started in main also does not give timer call back.
the timer of qt also works with the eventloop so till you do an app.exec() the event loop is not started and hence you wont get timercall backs.
if you are not allowed to change the heayProcessingFunc() you should definitely move it into another thread. or else i dont think we can figure out a way to do the animation smoothly!!!
but then the problem in interesting and a neat final solution would be a nice thing to see...

cheers!

**talk2amulya** · 19th February 2009, 09:49

well, i cant move the heavy processing code to another thread cuz there are lots of gui calls in it..and a thread cant have gui calls..i think this problem can only be solved if i get to process events of main thread from another thread..for which i couldnt find an api..any other pointers?

**jogeshwarakundi** · 19th February 2009, 09:56

Originally Posted by talk2amulya

well, i cant move the heavy processing code to another thread cuz there are lots of gui calls in it..and a thread cant have gui calls..i think this problem can only be solved if i get to process events of main thread from another thread..for which i couldnt find an api..any other pointers?

does this heavy processing function call the GUI elements directly? would it not be possible to, in some way, decouple the function and the GUI elements?
because, if it is not the case, we have a simple issue of a function which takes a lot of time being invoked in a thread! and obviously the thread does nothing but execute the function for a long time!!!

**talk2amulya** · 19th February 2009, 10:14

THATS the reason why i was trying to call processEvents() from another thread, thinking it would solve my problem..but evidently it doesnt save my life..

**^NyAw^** · 19th February 2009, 12:05

Hi,

Can you try to add "processEvents" calls into the process function? If you have a loop, you can add it to be called every loop iteration, ...

**talk2amulya** · 19th February 2009, 12:28

well, i mentioned it before also..i have tried that and that does work..although the loading icon animates intermittently..but it definitely moves..but i've been asked to find "another" way of doing it..and now i m coming to the conclusion that perhaps it cant be done in any other way, if i m not missing anything that QT provides and i m not aware of or u guys are not aware of...

**jogeshwarakundi** · 19th February 2009, 12:35

this had to be! managerial decisions on how the code should execute

(not meant against anyone, but I have had a fair share of these kind of things myself!!!)...
but may be there is no way this can be achieved, unless ofcourse there is some obscure hard-to-find feature somewhere hidden in qt!!!