[compiz] slow tint when tinting the whole screen

[David Reveman]

On Mon, 2006-12-04 at 12:10 +0200, Kalle Kärkkäinen wrote:
> Hi,
> 
>    I'm running ubuntu edgy with compiz, switched from gentoo to ubuntu
> for faster updates (emerge is way slow with source builds..). So far, I
> like it.
> 
>    but that is not the issue I'm addressing now. I've noted that with
> both these machines, when I'm doing something that tints the whole
> screen to gray (like trying to logout, or using some software that
> prompts for sudo rights), it's really slow. Jagged. It seems that it's
> not vertically synced or something. 
> 
>    Other tints, like when some program has gone haywire and stopped
> responding to the system, works well (gradually and smoothly turning to
> gray). Even when maximized.
> 
>    I'm running a 1600x1200 screen with Nvidia 6600. I'd guess that this
> hardware should be able to do this smoothly. Is this at all in the
> compiz code, or is this done in some other place? (like gnome in my
> case)

Those effects are done in software. A compositing manager might make
them a bit slower. There are much more efficient ways to do those kind
of effects when a compositing manager is running and there's actually
support for this in compiz already. _NET_WM_STATE_DISPLAY_MODAL state is
set on a mapped window all other windows will be desaturated. If the
fade plugin is loaded, you'll get a nice fade to gray effect.

I once wrote a patch for gnome-session to support this and I know that
we shipped it in SLED. It's still sort of a hack so I never submitted it
upstream. Something like _NET_WM_STATE_DISPLAY_MODAL should be added to
the EWMH spec and applications like gnome-session should be modified to
use it when available.

-David