Re: Composition [was Re: gnome-session proposal]

[Christian Kirbach <christian kirbach googlemail com>]

On Thu, 26 Jun 2008 16:02:24 -0600, Iain * <iaingnome gmail com> wrote:

> On Thu, Jun 26, 2008 at 10:49 PM, Patryk Zawadzki <patrys pld-linux org>  
> wrote:
>
> > Nah, one thing about a compositor is that it keeps off-screen copies
> > of all the windows so it does not have to invalidate regions when the
> > stacking order changes.

Agreed. Refocusing would only enforce a redraw once; if you move one  
window gently
across another full-screen window in the background the effect multipies.
It will trigger loads of redraws resulting in flicker and/or partially  
drawn windows.
Most visible on slow CPU machines.


> To be totally honest, I've never really thought of that as being all
> that important.

In my opinion eliminating the need for extra redraws is the greatest  
benefit
a compositor has for the user. It really smoothens the desktop experience.


> I don't think I've ever thought "You know, I wish that window would
> redraw faster" when I've restacked it

Maybe not when restacking, but move windows on top of other, widget-packed
windows (rhythmbox comes to my mind). Try moving at different speeds
on a computer with a slow CPU (500 Mhz). I bet you will see.

> If a compositor just kept off screen copies of windows, and didn't
> have live previews etc etc, would you honestly use it?

Definitely. In fact I turned off all bling like previews and use only the  
basic
shrink and fade away minimise effect. Smooth and easy on the eyes.


Regards

--
Christian Kirbach
Christian Kirbach googlemail com