[cairo] Pixel packing mismatch on XRender glyph rendering

Carl Worth cworth at cworth.org
Wed Jun 6 18:43:44 PDT 2007


On Wed, 6 Jun 2007 12:11:50 -0500, "Matt Hoosier" wrote:
> I tried to trace this by inserting some breakpoints on
> XRenderCompositeText{8,16,32}, and was surprised to see that
> XRenderCompositeText8 is the variety which gets called on the client
> side, rather than XRenderCompositeText16 to match the 565 pixel

I don't think the 8, 16, and 32 here mean what you think they do.

> Does anybody have a guess about why the glyph surfaces would be chosen
> in a different image depth than the regular images?

Presumably you're getting glyph surfaces that have alpha for
antialiasing. Your X server's RGB565 visual doesn't have any room for
alpha, so cairo is choosing an ARGB32 visual instead.

You might have better luck if you turn off the antialiased fonts,
(though, obviously they won't look nearly as nice).

Also, I believe Daniel Amelang recently submitted a patch to improve
the 8888 over 565 rendering for the X server, right Daniel?

-Carl
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