[Openicc] Linux CM ideology, was: meta data in test chart

[Richard Hughes]

On 28 January 2011 07:36, Kai-Uwe Behrmann <ku.b at gmx.de> wrote:
> During a discussion with Jim Gettys, he stated the right place would be the
> compositing window manager. So I stopped any effort in bringing CM into Xorg
> itself. Now I continue with CompICC and libXcm to help in enabling other
> compositing window mangagers.

This is the same conclusion I came to last year. You can't access the
3D engine in Xorg, and without a 3D engine, color conversion is two
orders of magnitude too slow. I would make one small change tho.
Dealing with bare compositing managers like compiz means you have a
huge 2D array of pixels to deal with, and have to track "regions" of
pixels manually and calculate things like the intersection and other
grotty details.

My idea was to put the pixel conversion higher up in the window
manager itself, in my case mutter, and use GLSL shaders attached to
contexts themselves and allow GL and the WM to do all the heavy
lifting for things like intersections and windows being dragged about.
My code had actors opt-out of the color conversion, so it was quite
possible to have the toolbar not CM, and the main content CM aware. It
also meant the applications themselves didn't need to know what output
they were on, and things like that.

If anyone is interested, I can push my mutter tree onto github. I
spent quite a bit of time getting the 3D texture support in clutter,
but now I think most distros are shipping a 3D texture enabled clutter
by default.

As large gamut display devices become more and more "mainstream" I
think this kind of thing is going to be more and more important.

Richard.