Pixman Accessors

[Soeren Sandmann]

Pixman has a feature where you can set accessor functions on an image
and all pixel access will then go through those functions. It's used
exclusively for wfb.

Until now this was implemented by compiling the pixel accessors twice,
with a READ macro defined in two different ways. This is annoying for
several reasons, so instead I want to just make a copy of the image
before compositing, and then copy back afterwards.

Does anyone see a problem with this?  Performance is not a concern at
all. It was slow before and it will be slow after.

Patch here:

        http://www.daimi.au.dk/~sandmann/access-denied.patch

and git repo here:

        http://cgit.freedesktop.org/~sandmann/pixman/log/


Soren