[Openicc] Suggested update to "ICC Profiles in X Specification 0.4"

[Graeme Gill]

Richard Hughes wrote:

> So, with Wayland none of these will work. Even with XWayland one
> applications root window is not accessible by another application (by
> design).

It makes XWayland support useless for color critical users then.
(I gather even XRANDR is broken in XWayland, since it is read only).

> Whilst I agree that the current specification is super
> unclear I don't think adding more root window atoms or output
> properties when Linux is very much transitioning to another
> incompatible display framework is useful.

I'm not suggesting adding any more atoms, merely clarifying
the existing usage, since an inconsistency has been reported.

As for Wayland, I'm struggling to locate documentation of Wayland's color
management support - if any. There certainly doesn't appear to be anything
in the place I'd expect to find it - the Wayland client doco. or protocol
specifications. Pointers welcome.

[ My understanding of your color management implementation based on colord is that
  it is a systems specific workaround for the lack of Wayland protocol color management
  support, not a general Wayland solution that all implementations could use. ]

Bottom line - without good backwards compatibility with X11 and/or good native
color management support, color critical users simply won't be able to transition
to Wayland.

I'm guessing that if an appropriate Wayland protocol was added (as an extension ?),
then it would be possible to implement it using colord for Gnome systems, and
also fix XWayland so that existing X11 applications will work (i.e. emulate
root window _ICC_PROFILE setting/getting, XRANDR property getting/setting,
CRTC lookup table getting/setting etc).

Graeme Gill.