[Qt-interest] QWidget::setCursor() and qApp->processEvents()

[Joshua Grauman]

Thanks!

This indeed did the trick, but I must admit it is a bit baffling to me. I 
didn't think the cursor was drawn by Qt, but by the OS. That's why I 
didn't think of doing a repaint although I understand how the event system 
works. Indeed, my cursor is animated and it still animates smoothly while 
I am doing my calculations while the rest of my app is completely 
unresponsive... This seems to suggest that indeed the OS is drawing the 
cursor, but then I'm still confused as to why a repaint is necessary to 
change the cursor???

Josh

> Josh:
>
>  Does some_widget_or_other->repaint() work for you?
>
>                     Atlant
>
> -----Original Message-----
> From: qt-interest-bounces at trolltech.com [mailto:qt-interest-bounces at trolltech.com] On Behalf Of Josh
> Sent: Wednesday, July 28, 2010 23:45 PM
> To: qt-interest at trolltech.com
> Subject: [Qt-interest] QWidget::setCursor() and qApp->processEvents()
>
> Hello all,
>
> Before I do some calculations in my program I want to set the cursor
> using: viewport()->setCursor(Qt::WaitCursor);
>
> However, the cursor doesn't change because of the calculations. I don't
> want to call qApp->processEvents() during the calculations because I
> actually want the ui *not* to respond while the calculations are taking
> place. So I was able to get the cursor to update BEFORE the calculations
> as follows:
>
> qApp->processEvents();
> qApp->processEvents();
> viewport()->setCursor(Qt::WaitCursor);
> for(int i=0; i<20; i++)
>   qApp->processEvents();
> do my calculations...
>
> This is obviously a hack. I needed to call processEvents 20 times for the
> cursor to update. Any less and the cursor wouldn't update before my
> calculations. I would assume that on different machines I might need
> different number of calls to processEvents(), which is undesirable. Anyone
> have any ideas on the correct way to do this?
>
> So in summary:
> How can I make sure the cursor is changed before doing my calculations
> when I don't want to call processEvents() during my calculations?
>
> Thanks!
>
> Josh
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