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Old 05-09-10, 02:55 PM   #1
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Join Date: Mar 2006
Posts: 23
Exclamation non anti-aliased font drawing is slow


In this thread I thought kde rendering was slow because of some problems related to Qt and NVidia.

Maybe it is still the case, but I just found that the problem is more precisely due to my font rendering setup: since I don't like anti-aliased fonts, I always disable AA for font size between 8 and 15, and that's what is causing the problem: disabling AA!
=> if I re-enable AA, everything renders fast, and there is nearly no difference between -graphicssystem raster.

Is it a known issue?
Is there a way to have fast rendering with non anti-aliased fonts?

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cyrion is offline   Reply With Quote
Old 05-09-10, 04:12 PM   #2
Join Date: Oct 2009
Posts: 7
Default Re: non anti-aliased font drawing is slow

Yes your are right, nvidias driver is quite slow in many 2d rendering situations. I'm very glad some one else complains about the well known and old old old non-antiased-fonts problem.

Everyone who want's to test: open a folder in detailed view with dolphin (anti-aliased fonts) and do some window resizing, then switch to a non-antialiased font.config and do the same. The slowness should be obvious. Or use gtkperf to get values.

__________________________________________________ __________________________
PLEASE spend some time to fix the old 2d bugs or do some performance improvement there, and after that you can play with the fancy stuff (vdpau etc.)!!
__________________________________________________ __________________________

And again the tip who don't like anti-aliased fonts: a mixed anti-aliased and non-anti-aliased font environment is also possible. For me tahoma non-anti-aliased (gui elements) and the rest aliased fonts do a very good job. See the man pages.

example of exception in fonts.conf for Tahoma
<match target="font">
<test name="family">
<edit mode="assign" name="antialias">
TaintedKernel is offline   Reply With Quote
Old 05-10-10, 06:11 AM   #3
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Default Re: non anti-aliased font drawing is slow

I did the experiment with Dolphin with and without AA fonts (Tahoma) and didn't notice a difference (slow as always).
When resizing the Dolphin window the redrawing occurs with about 200ms of delay between frames (which is very slow). This happens regardless of AA.
When kwin effects are enabled, kwin CPU usage skyrockets, and with effects disabled Xorg does the same.
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Old 05-10-10, 09:29 AM   #4
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Default Re: non anti-aliased font drawing is slow

@all I'm not sure thay this problem is due only to nvidia since gtk apps runs smoothly, with or without AA enabled.

Or maybe Qt is accelerating font rendering by using some advanced X-related extensions that nvidia don't support, and that gtk does not use? This could explain why using qt raster engine is faster with non-AA...

So, for now I'm sticking with using -graphicssystem raster.

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