[cairo] recent additions to glitz

[David Reveman]

Glitz (0.1.2) should now handle simultaneous transform and repeat of
surfaces correctly. We should get this working correctly with libpixman
and xrender as well.

Another addition to glitz is the "polygon opacity" feature. This feature
allows you to set the opacity level of the source surface when
compositing trapezoids and triangles. Cairo's OpenGL backend now uses
this for efficient translucent surface pattern rendering.

I think the "polygon opacity" feature could easily be added to libpixmap
and xrender as well. I can try to add this to libpixman if you find it
useful.

Here's a cairo OpenGL screenshot showing pattern transform, repeat and
translucency (no intermediate surfaces were used when rendering):

http://www.cs.umu.se/~c99drn/pics/cairo-translucent-transformed-repeating-surface-pattern.png

 
-David