Screen fading, logout dialog banding

[Sitsofe Wheeler]

On Mon, 2006-05-08 at 12:57 +0200, Frank Schoep wrote:

> After closely watching the effects of gksudo, lock-screen and logout it seems 
> that all three are using different code to achieve the same effect. Of all 
> three my personal preference is the lock-screen one, it's real smooth and 
> does not exhibit banding. I'm not sure if the screensaver selection affects 
> the lock-screen fade, I've got some OpenGL fireworks set up as screensaver.
>
> Are there reasons for the different implementations in each of the components 
> I listed? It would be great if the logout fade could be rewritten to be at 
> least as good as gksudo, so the (8-bit?) color banding is gone.

The screen lock one can play gamma tricks because it is doing the whole
screen (i.e. no part of the screen needs to be visible during or after
the fade.

> I'm not sure about this, but is there a possibility of introducing a shared 
> library which offers a solid base of fullscreen operations like fading? It 
> could be set up to provide technical superior implementations if available on 
> the X server (backing store / composite / OpenGL)?

An OpenGL fade should be faster and smoother with the only catch being
that grabbing the screen into a GL surface is relatively slow unless you
can get the entire screen via composite (i.e. you are running on XGL).
In fact on XGL it might already be a GL surface... As for a library I
don't see why one couldn't be made but who is going to do the work of
actually writing it?

> I wanted to file a bug report against the logout dialog, but couldn't 
> determine in which package it lives. Is it worth filing a bug for this and 
> which package should I choose?

If https://launchpad.net/distros/ubuntu/+source/gnome-session/+bug/40314
is anything to go by gnome-session