[Xcb] Drawing a 32-bit bitmap quickly

Adam Langley agl at imperialviolet.org
Fri Nov 14 17:26:35 PST 2008

I have an application which would like to draw a 32-bit bitmap (ARGB,
pre-multiplied alpha) using shared memory where possible.

I can happily paint a 24-bit shared memory segment with XCB (the root
window is 24-bits deep). However, even though there is a 32-bit visual
and 32-bits is a supported depth for the screen, I cannot create a
32-bit deep window. I always get a BadMatch error no matter which
combination of arguments I try. The XLib programming manual suggests
that child windows don't have to be the same depth as their parents.
Is that true?

If it so, how should I go about it? Can I use the Xrender extension?



Adam Langley agl at imperialviolet.org http://www.imperialviolet.org

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