X Video extension PutImage func

[A B]

Hello,
     I'm novice in X System.

     I read i830_video.c in xf86-video-intel 2.12.0, and have several
questions about X Video extension.

1.  The prototype of PutImage() seems to be a complete "overlay" way.
     I have been quite confusing after read
http://en.wikipedia.org/wiki/X_video_extension#The_role_of_window_manager_support_and_compositing
, which mentions compositing vs overlay.
     Is it possible to composite/stack/etc. with current X Video extension?

2.  In i830_video.c, it seems that the only difference between "textured"
and "overlay" methods is PutImage func ptr.
     So why both of them is necessary?

3.  I have no knowledge of Intel GMA hardware, and didn't understand
i830_video.c well.
     One quick question is that, in the "textured" PutImage(), what is the
render target? Where is the code setting that render target?

yours,
Jim Liu
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.x.org/archives/xorg-devel/attachments/20100809/57846951/attachment.htm>