Qt-interest Archive, July 2007
Is it necessary to delete allocated QCustomEvent object manually????
Message 1 in thread
hi,
I am sending the event in a thread for painting widget in a slot, like
QCustomEvent *e=new QCustomEvent(10000);
QApplication::postEvent(fm,&e);
As i am not deleting e (deallocating memory of e), because when i use
delete e
in a custom event slot,it will give me segmentation fault....
Now i am not deleting e, and its working ok without any problem....
But as i am creating object of QCustomEvent, in a thread everytime when i
paint widget.... can u tell me plz...will it give me problem in a future as i
am not deallocating memory....
Thanks and Regards,
Niranjan.
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Message 2 in thread
Hi,
IIRC, according to the docs you MUST NOT delete QEvent-Objects because the
event-handling subsystem will take ownership and asure that processed
events will be deleted.
Regards,
Malte
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Message 3 in thread
On Jul 16, 2007, at 8:12 AM, Niranjan wrote:
> hi,
>
>
>
> I am sending the event in a thread for painting widget in a slot, like
>
> QCustomEvent *e=new QCustomEvent(10000);
> QApplication::postEvent(fm,&e);
>
> As i am not deleting e (deallocating memory of e), because when i use
>
> delete e
>
> in a custom event slot,it will give me segmentation fault....
>
> Now i am not deleting e, and its working ok without any problem....
>
> But as i am creating object of QCustomEvent, in a thread everytime
> when i
> paint widget.... can u tell me plz...will it give me problem in a
> future as i
> am not deallocating memory....
>
>
> Thanks and Regards,
> Niranjan.
According to the documentation, posted events are "taken over" and
deleted after processing.
see:
http://doc.trolltech.com/4.3/qcoreapplication.html#postEvent
or
http://doc.trolltech.com/3.3/qapplication.html#postEvent
depending on what version of Qt you are using (i'm guesing that it's
Qt 3 becouse of "QCustomEvent" class
"The event must be allocated on the heap since the post event queue
will take ownership of the event and delete it once it has been posted."
Also you have error in your code snippet
QCustomEvent *e = new QCustomEvent(10000);
QApplication::postEvent(fm, e);
or it should be:
QCustomEvent e(10000);
QApplication::sendEvent(fm, &e);
It depends if you want to wait for event being processed, or if you
want to queue it.
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