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List:       xfree-render
Subject:    Re: [Render] pre-allocated colors (a patch)
From:       Olivier Chapuis <olivier.chapuis () free ! fr>
Date:       2002-09-13 11:11:04
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On Thu, Sep 05, 2002 at 03:20:33PM -0700, Keith Packard wrote:
> 
> Around 22 o'clock on Sep 5, Olivier Chapuis wrote:
> 
> > After some times I discover that it is the XRender extension which does
> > that and I take a look at the code: xc/programs/Xserver/render/miindex.c.
> > There is something strange in the code: too many colors are allocated with
> > a PseudoColor visual class, only the color cube is used but some greys are
> > also allocated (in depth 8, 28/21 colors "lost"). Attached to this message
> > a patch which fixes this.
> 
> The intent is that there be more resolution along the grey axis for AA 
> text; a 4x4x4 (or 6x6x6) cube gives too few gray entries.  The RGB->pixel
> conversion table should identify gray values and pick the nearer extra 
> gray values rather than other entries in the cube.
> 
> I just realized now that the RGB->pixel uses a 32x32x32 table to do the 
> conversion; it might be better to allocate gray values exactly aligned 
> with those instead of some random ramp.  Perhaps 16 gray values in addition
> to the 4x4x4 cube would be a better solution.
>

Ok. Maybe I should read the code before submitting a patch... In
general I do that.
I was a bit obsessed by my dithering formulae which work only with
cubes or gray table (and 32 approx. may break the dithering). Sorry.

What about XRender and Dithering?

Thanks, Olivier
 
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