[PyQt] processEvents on QlistWidget operations does nothing

[P. Mathé]

Le lundi 28 janvier 2008, Andreas Pakulat a écrit :
> On 28.01.08 12:40:36, Scott Aron Bloom wrote:
> > > Le lundi 28 janvier 2008, Scott Aron Bloom a écrit :
> > > > BTW... your issue is NOT a bug in QT... it's a bug in your understanding
> > > of how the model/view system works and refreshes the gui..
> > > You are right, it is a misunderstanding.
> > > Is is also a bug to understand that executing a QWidget.repaint()
> > > statement will immediately display the modified widget ? (I am referring
> > > to the doc that says :
> > > "Repaints the widget directly by calling paintEvent() immediately, unless
> > > updates are disabled or the widget is hidden."
> > > 
> > In my view... it should be followed with.  The painting occurs on the next execution of the event loop...
> 
> No it doesn't. The painting is done immediately, see
> src/gui/painting/qbackingstore.cpp.
> 
> However I guess addItem does something that only happens in the next run
> of the event loop.
> 
> Andreas
> 

I must admit that I start to be lost. So to try to clarify the situation I have simplified my test :
I discarded the web access, no tmer, no threading. I kept only the updating of the progressBar : the loop is as follow :

    def extraire(self):
        jours=(1, 2, 3, 4)
        self.progressBar.setValue(0)
        self.progressBar.setMaximum(4)
        for jour in jours:
            time.sleep(1)
            self.progressBar.setValue(self.progressBar.value() + 1)
            #self.log.update()
            #self.log.repaint()
            #QCoreApplication.processEvents(QEventLoop.AllEvents)
        print 'fini'

Seems to be straightforward, just for beginners ?
Now the tests :

 Case1. As is with, the three lines commented out :
		the progress bar is updated once : i.e 25% is displayed, then it jumps to 100% (probably 50%,75% and 100% displayed at once)

Case2. only "QCoreApplication.processEvents(QEventLoop.AllEvents)" uncommented :
		the progress bar is updated normally : i.e 25%, 50%, 75% and 100% are displayed in turn.

Case3. only "self.log.repaint()" uncommented :
		the progress bar is updated twice : i.e.  25% and 50% are displayed , then it jumps to 100% (probably 75% and 100% displayed at once)

Case4. only "self.log.update()" uncommented : same as Case 3.

Pierre