From kde-devel  Mon Dec 30 07:07:18 2002
From: Pablo de Vicente <pvicentea () wanadoo ! es>
Date: Mon, 30 Dec 2002 07:07:18 +0000
To: kde-devel
Subject: Re: How to update a QPainted qwidget?
X-MARC-Message: https://marc.info/?l=kde-devel&m=104123209730945

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El Sáb 28 Dic 2002 17:54, Arnold Krille escribió:
> On Saturday 28 December 2002 08:21, Pablo de Vicente wrote:
> >   I am writing some code in which I use QPainter to draw some axis and
> > curves on a qwidget. Now I have two basic problems:
> >  - When the axis change I try to redraw them calling update(). When doing
> > this instead of erasing the previous content of the widget and drawing
> > the new axis I only append the new ones. I have tried with repaint(true),
> > and I have also used erase() before calling update() or repaint(). But
> > none of this works.
>
> Paint your widget with the backgroundcolor first.
>
> > - if I raise a window in front of the widget where I have the curves and
> > then move the window to another place so that my widget is not covered by
> > anything the content of the qwidget disappears. That is I loose the axis
> > and curves I had previously drawn.
>
> Do you use paintEvent()?
> It should redraw you widget if the covering goes away...
>
> Arnold

 I found the probem. The problem was that paintEvent was defined for the 
parent widget and it did not automatically repaint the child widgets. So I 
changed the design of the code and I created a new object which inherits 
QWigdet so that  I can now define paintEvent only for that widget (which 
originally was a child). I was not interested in repainting the original 
parent widget.

thanks,

Pablo
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