[cairo] How to switch/port backends?

[Erdem U. Altinyurt]

Hi all,
I wanted to test new backends like drm, vg and gallium. Is there a
tutorial for how to convert one backend to another? Specially looking
for add those backends to cairogears and see difference between them.
http://cgit.freedesktop.org/~anholt/cairogears

It's weird that xrender works slower than ımage backend at my computer
at cariogears. Does it due compositing (compiz) or my drivers (fglrx)
fault? Thanks.
Regards,
Erdem