Questions about XPresent

[Po Lu]

Keith Packard <keithp at keithp.com> writes:

> I got started creating a 'semi-automatic compositing' design where the
> compositing manager could tell the X server "Hey, just composite this
> window to the screen in the 'obvious' way and don't bother me with the
> details".

Wouldn't that just be RedirectWindow with automatic updates, except
without using CopyArea when the depths are the same and the window is
not opaque, instead using CompositePicture with PictOpOver synchronized
with vblank?

I think it would have to composite the contents of windows underneath
too in some cases.  There would also have to be a way for clients using
visuals with an alpha channels to tell the X server which parts of their
windows are opaque, similar to _NET_WM_OPAQUE_REGION in the wm-spec.

That sounds surprisingly simple, as long you only "automatically
composite" windows whose clip lists are the same as their bounds.