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List:       koffice-devel
Subject:    Re: KSpread/KDE4: works, but slowly
From:       Clarence Dang <dang () kde ! org>
Date:       2006-06-14 12:39:37
Message-ID: 200606142239.40860.dang () kde ! org
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On Wednesday 14 June 2006 17:15, Tomas Mecir wrote:
> However, I noticed that it's WAY slower than the 1.5.1 version. If I
> attempt to select a range with about 30 rows and 15 columns, it's
> nearly instaneous in 1.5.1, but takes up to one second in kde4
> version. Any idea why ? Is it due to something wrong on my end, or due
> to it using some legacy stuff from Qt3 which is slow in Qt4 ?

copyBlt() and bitBlt() emulation is ridiculously slow due to QPixmap -> QImage 
-> QPixmap conversions.

QPixmap::mask() no longer returns a pointer - it recalculates the mask each 
time and if there is an alpha channel (added merely by drawing with 
QPainter), this incurs an expensive QPixmap -> QImage -> QPixmap conversion.

A QPainter opened on a QPixmap now also writes to the mask layer but only if 
XRENDER is enabled (inconsistent API, not fun).  In any case, with XRENDER, 
opening a QPainter on a QPixmap that already has a mask sometimes corrupts 
the mask.  Get around this by disabling the mask, drawing to the RGB layer 
and then putting the mask back.

Also, it is now impossible to draw a 1x1 rectangle using drawRect() with a 
QPen width of 1.
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