[Xquartz-dev] Xcomposite extension in XQuartz

[John D. Duncan, III]

Hello all. I was wondering if there is any word on the status of getting 
the COMPOSITE extension built into XQuartz? I personally use a bunch of 
UNIX-y GUI programs and dockapps (some of them quite old). I've found 
that, when doing graphically intensive actions (such as quickly 
scrolling in a unicode-rxvt term, forwarding my SSH session to XQuartz 
to write LaTeX/use eclipse from our campus workstation computers/submit 
moodle assignments in firefox), that there is quite a good deal of 
graphical sluggishness. CPU use does not spike much, so I am assuming 
that this is a flaw of the X server rendering itself (or perhaps the OS 
X drivers?).

I have somewhat superficial knowledge of the COMPOSITE extension, but I 
was under the impression that X11 compositors (such as compton) get 
around this issue by using open-gl/randr rendering as their graphical 
back-end (among many other hacks).

It seems that programs which do use open-gl rendering are unaffected by 
the sluggishness caused by my dockapss (glxgears, for example).

I was also under the impression that most modern UNIX-y Desktop 
Environments (such as Gnome, KDE, etc.) come with compositors built in 
(for eye-candy such as v-synch, drop shadows, smooth scrolling, etc.).

It seems like adding COMPOSITE extension support could potentially bring 
over users from other operating systems (especially with the wonderful 
pkg-src development from Jonathan Perkin at joyent) that could further 
help re-vitalize the OS X open-source community.

I know that, normally, to enable the composite extension in X11 you 
would just add:

Section "Extensions"
     Option         "Composite" "Enable"
EndSection

to your xorg.conf file. As we know, XQuartz uses a different system 
where all of the X server extensions are always started on launch 
(xrandr, etc.)

Am I missing something, or is XQuartz still being built without the 
COMPOSITE extension enabled? I remember reading archives from the past 
that explained how builds would fail while trying to compile with 
COMPOSITE support [1]. That was years ago, and I thought there was a 
modern XQuartz branch that supported the extension..[0]

Here are some (bad examples) of the issue that I am talking about:
http://cs.gettysburg.edu/~duncjo01/XQuartz.webm
http://cs.gettysburg.edu/~duncjo01/XQuartz-glx.webm

Notice how, especially in the second screencast, extreme scrolling in 
the urxvt buffer causes the dockapps to hang, while the glxgears program 
chugs along at a smooth 60fps. I was hoping that enabling the COMPOSITE 
extension and using a compositor such as compton could alleviate such 
issues in the future.

Let me apologize in advanced if I have interpreted this issue completely 
incorrectly; I am no X11 expert.

[0]: 
https://lists.macosforge.org/pipermail/xquartz-changes/2011-May/001054.html

[1]: http://lists.apple.com/archives/x11-users/2011/Feb/msg00013.html

- John D.