[RFC wayland-protocols] Color management protocol

[Pekka Paalanen]

On Tue, 20 Dec 2016 15:17:31 +1100
Graeme Gill <graeme2 at argyllcms.com> wrote:

> Pekka Paalanen wrote:
> >> Since Wayland doesn't currently implement any color management support,
> >> I'm not following how it can be a step backwards.  
> > 
> > It is step towards "clients are in control and the compositor does not
> > know what is happening". That is, a step towards X11 design and away
> > from Wayland design principles.  
> 
> It depends on what you mean by "control". Wayland can't operate
> without applications providing the content, and color is part of
> content.

When I was talking about configuration, your reply talks about content
delivery. We are continuously talking past each other. I talk about one
thing, you deliberately interpret me talking about the other thing, so
that you can make me look silly. I'm tired of correcting that in every
turn.

Clients control what they send to the compositor: that is content
delivery.

Configuration controls compositor's global settings, like CRTC CLUT
values.

This difference is fundamental to any kind of Wayland protocol design.
And it is DIFFERENT from X11 on purpose.

> >> Wayland is useless unless there is a way to manage it. Which means
> >> that it should have channels for administrative tools to configure it.  
> > 
> > Indeed: Administrative tools. These are part of the compositor or the
> > desktop environment distribution. They have the privileges to configure
> > the compositor.  
> 
> And how are management functions that can't reasonably be contained
> in the compositor handled then ?
> A compositor is _not_ going to come with display color calibration
> and profiling functionality - it's too complex and specialized.
> The user will insist on being able to choosing such tools anyway.

Why would you not let compositors use the CMS libraries people have
developed?

Or are all today's CMS implementations so intimitely written to the X11
model that they simply cannot work at all? That would be very sad, but
also something that requires work on them, not only on Wayland and
compositors.

Maybe the CMS implementations should be primarily used by the
compositors rather than applications then.

> > However, in this thread we are talking about arbitrary applications,
> > not administrative tools.  
> 
> There is no difference, apart from any privilege needed.

This is where we disagree, and that prevents us from making any
progress.


Thanks,
pq
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