[cairo] ARGB surface for A8

[Chris Wilson]

On Sun, 5 Dec 2010 04:08:15 -0800, L A <l.thee.a at gmail.com> wrote:
> My hardware does not seem to like the A8 format. I have noticed that
> clips and paths use this format in cairo. I was thinking of either
> changing CAIRO_CONTENT_ALPHAs to CAIRO_CONTENT_COLOR_ALPHA or to
> allocate ARGB surfaces when the pixel format is CAIRO_FORMAT_A8 and
> set the surface pixman_format as ARGB. Do you see any problems with
> these? If you do, can you offer alternatives?

You impose huge inefficiencies into the common path for mask calculations
(and will require rewriting almost all of that code).

Perform the a8 to a8r8g8b8 conversion when downloading to the hardware.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre