[RFC wayland-protocols] Add the color-management protocol

[Carsten Haitzler (The Rasterman)]

On Wed, 21 Dec 2016 09:56:05 +0000 Daniel Stone <daniel at fooishbar.org> said:

> Hi,
> 
> On 21 December 2016 at 00:36, Carsten Haitzler <raster at rasterman.com> wrote:
> > On Tue, 20 Dec 2016 16:46:07 +0000 Daniel Stone <daniel at fooishbar.org> said:
> >> On 19 December 2016 at 02:08, Carsten Haitzler <raster at rasterman.com>
> >> wrote:
> >> > so... here is my question - shouldn't the colorspace be tired to a
> >> > buffer? not a surface? yes. i know. the surface "displays" the buffer...
> >> > but the colorspace is intrinsic to the buffer content... right?
> >>
> >> Conceptually, buffer is a good shout, but buffers are hidden from you
> >> in EGL. Given that people will want to do (at least vaguely)
> >> colour-correct GL rendering, that makes surface rather than bufer the
> >> right choice.
> >
> > i actually meant wl_buffer which is really the abstraction on top of these
> > buffers... ?
> 
> No, I mean that client rendering looks like this in EGL:
> egl_dpy = eglGetPlatformDisplay(...);
> egl_cfg = eglChooseConfig(egl_dpy, ...);
> egl_surf = eglCreateWindowSurface(egl_dpy, egl_cfg, ...);
> egl_ctx = eglCreateContext(egl_dpy, egl_cfg, ...);
> (bool) eglMakeCurrent(egl_dpy, egl_surf, egl_surf, egl_ctx);
> {
>     (void) gl*();
>     (bool) eglSwapBuffers();
> }

oh yeah. i was not thinking if client is using egl and eglswapbuffers is hiding
everything. i was thinking clients explicitly sending buffers.

> At no point does an EGL client ever come into contact with the
> wl_buffers produced by EGL. They are utterly opaque, and hidden inside
> the EGL implementation. This means that, in order to get
> colour-correct rendering through EGL, you either have to have it
> attached to the surface (which the client can see and control), or you
> have to grow EGL API for the entire breadth of colour management. This
> is a lot of the reason why we have things like opaque region attached
> to the surface, with the commit latched, rather than buffers.
> 
> Cheers,
> Daniel
> 


-- 
------------- Codito, ergo sum - "I code, therefore I am" --------------
The Rasterman (Carsten Haitzler)    raster at rasterman.com