From kde-freeqt  Tue Oct 20 09:36:31 1998
From: Jo Dillon <emily () thelonious ! new ! ox ! ac ! uk>
Date: Tue, 20 Oct 1998 09:36:31 +0000
To: kde-freeqt
Subject: Re: [freeqt] Fix on filling
X-MARC-Message: https://marc.info/?l=kde-freeqt&m=90887791325035

Olivier Galibert (galibert@pobox.com) spake thusly:
> On Mon, Oct 19, 1998 at 09:25:19PM +0200, Lokh wrote:
> > I see a problem with the new brush drawing scheme though.
> > To redraw the background of the scrollbar I need to draw the
> > background and then the density bitmap. The result is a more
> > or less visible flicker (hard to see with style windows but
> > obvious with the next one).
> 
> You  can't see it  easily with the windows  style because of the magic
> fourth line:
>   virtual harmony_style_implementation *instantiate(QObject *obj) {
>     harmony_windows_QScrollBar *i = new harmony_windows_QScrollBar;
>     QScrollBar *qsb = static_cast<QScrollBar *>(obj);
>     qsb->setDoubleBuffer(true);  <----
>     i->update_values(qsb);
>     return i;
>   }

  Hmm. I tend to stick double-buffers in normal class constructors. Probably
the best way to handle it would be a config file setting allowing the
advanced user to decide which widgets he wants double-buffered :)
 
> 
> 
> > The best thing i was thinking about was to use OpaqueStipple, which
> > allow you to do the 2 operations at the same time _if_ the background
> > color is correctly set (it was not the case before your modifications).
> 
> While  I do agree with  you,  I saw no way   to choose said background
> while keeping with Qt's qpainter interface.
> 
>   OG.
> 

-- 
	Jo

Harmony - the project to create an LGPL Qt clone
http://harmony.ruhr.de