The All-Singing, All-Dancing XCompMGR

Chris Ball cjb at
Thu Apr 29 18:56:29 EDT 2010


   >> First, the Frame looked awesome and animated smoothly.

   > Yes, that was interesting.  The animation was much better, no
   > longer jerky.  Probably because the motion is blurred slightly by
   > the drop shadow.  Without the drop shadow the hard outline is
   > much more obvious as it shifts position during the animation.

Yep, I like it too.  I think the reason the animation is better is
orthogonal to the drop shadow; it's because it's keeping a pixmap of
the background window to composite on top of.

   >> It appeared to be composed of four individual pieces (one on
   >> each side), which is exactly the point we hint at.

   > Yes, I like that, much easier to comprehend.  Without such a
   > hint, the frame arrival violates physics.  See screenshot of
   > frame over journal, attached.

The four-pieced frame looks like more of a bug than something we would
do intentionally to me, but I'm willing to be convinced.  I do really
like the drop shadows on areas other than the frame.

   > It also increased the speed of switching between windows.

Agreed, and this seems like the strongest reason in favor of shipping
it -- perhaps with just -n rather than -nc, to avoid the drop shadows.
We no longer see window redraws happen jerkily by clearing out a
background color rectangle and then rendering on top of it, which is
what happens in current builds when you (e.g.) switch from the home
screen to the journal.  It's a much more polished-looking experience.

I think our next steps should be to:

 * quantify the memory difference (both total and per-window) against
   not running xcompmgr.  We were already running with the composite X
   extension on, so I think the increase may be small.
 * work out whether we think the "frame pieces" drop shadow, and drop
   shadow in general, are an improvement -- we should ask the Sugar
   Design Team for their opinion on this too.

Jon N, any opinions from the openchrome end on turning on xcompmgr?

Thanks for trying this out, Nate!

- Chris.
Chris Ball   <cjb at>
One Laptop Per Child

More information about the Devel mailing list