Qt-interest Archive, September 2007
Re: QProgressDialog
Message 1 in thread
André Somers wrote:
QThread was exactly what I needed,
thanks,
Marie
> Marie-Christine Vallet wrote:
>
>
>> Hi,
>> I wanted to do a progress dialog for which the progress bar would
>> advance with time and then reset it to zero and start again while my
>> operation was in progress (a bit like the Qt::BusyCursor).
>>
>> When I use the code below, the progress dialog only appears after my
>> operation is over and is therefore not very useful. Is this a normal
>> behavior? If it is how can I show the progress dialog before. I tried
>> using pd->show(); the only problem is that my progress bar does not
>> move until after the my operation is over.
>> /lists.trolltech.com/qt-interest/
>>
> Yes, this is normal. The problem is that Qt doesn't get the time to process
> any events in your "long operations" part of the code. It needs that time
> in order to paint your dialog, update the statusbar within and even to
> process the timer. There are several ways to achieve that. The easiest way
> would be to stick a qApp->processEvents() at regular intervals in your long
> operation. Another way is to divide the long operation in chunks, and use
> timers to process them sequentially. Once you get this working, it works
> better (in my experience) than the processEvents method, but it's messy to
> make. The last (and maybe best) option is to use a QThread to do your long
> operation, so the GUI stays responsive without any tricks. I'd go with that
> option I think. It's not that hard to achieve, especially if your operation
> is relatively self-contained.
>
> Regards,
>
> André
>
>
>
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