Sub-pixel positioning

Roger Larsson roger.larsson at
Wed Mar 17 02:04:05 CET 2004

On Wednesday 17 March 2004 00.17, Adrian Page wrote:
> On Tuesday 16 March 2004 8:02 pm, Roger Larsson wrote:
> > > Using valgrind to profile KisToolBrush::mouseMove() with a pipe brush,
> > > about 80-90% of the time is spent in computeDab(), and around 10% in
> > > compositeCopy() and compositeOver(). The compositing code also has
> > > plenty of room for improvement, part of which would be using
> > > premultiplied alpha for the RGBA buffers. We can also replace division
> > > by shifts and optimise for each channel depth we support.
> >
> > Yea but how much time is spent in X because of what Krita does?
> > (I had 60%...)
> >
> > Please try with my patch (for brushes).
> I tried your patch, but on my system the lag it introduces makes it feel
> worse. Perhaps that's why I don't get as much time spent in X when
> profiling, as for me, X is less of a bottleneck?

Now I remember, I did see less of the problem after I upgraded memory
(and did remove some of my old stuff)

But you can try with another kis_notify_limit like 10
(then it will be updated at at least 100 Hz - about what your monitor does)

[make it global - then you can play around with different values in the 

How does your system look like?
* CPU				
* Memory
* Videoboard (and X server)
* Painting device

Mine is: Pentium3 933MHz, 512MB, MX 440SE (Nvidia / XFree depending on),
 Wacom Intous 2 (hmm. it has more pressure levels than most so I guess I might
 be getting bigger patterns)


Roger Larsson

More information about the kimageshop mailing list