ARGB off the off-screen

[sshachar at t2.technion.ac.il]

Quoting Daniel Stone <daniel at fooishbar.org>:

> wfb allows you to define custom access methods to read and write pixels,
> so you can store anything with an arbitrary pixmap.

That's great - but since I can't seem to find anything about wfb, even in this
list's archive, where can I learn more? (And as Michel noted one way I can
control all CPU frambuffer access is by making PrepareAccess fail and providing
Upload/Download hooks. Or are you talking about something different?)
 
> Current videos either have an overlay that is scanned out straight from
> the buffer, or as a 3D texture.
 
Ok, but in order for an overlay to integrate well with say a window manager it
can't be a simple direct read from a rectangular buffer. Some areas are covered
by other objects, some may cover translucently or be covered by translucent
objects etc') - how are these cases handeled then?