On Wed, 2019-03-06 at 15:52 +1100, Graeme Gill wrote: > Adam Jackson wrote: > > > X kinda has three mechanisms for this. The first one, that nobody > > really uses, is setting the colormap for a DirectColor visual. > > Actually this is something I check and set to linear before > calibration & profiling in the ArgyllCMS tools.
Yeah, I was corrected about this on IRC as well. Apparently DirectColor really is a thing people use. > > The second, which games typically use, is setting per-channel gamma > > (implicitly for the whole screen) as single floating-point values with > > the xf86vidmode extension. > > Typically this is too crude a control for color management use. > My assumption (which could be wrong) is that this is overridden > by the per-crtc LUT. Technically I think what happens is the vidmode gamma is applied to RANDR's "compat" output, which is chosen by some handwavey heuristic. > > All of these are effectively the program specifying its transformation > > to what it hopes is linear in device space. The sample server happens > > to implement all three as global state, but that's an implementation > > detail. It would be straightforward to give each Xwayland client the > > illusion of complete control if we wanted. > > For the purposes of setting the display global color calibration state, > then this is not desirable. Sure, but one would not expect to control the display's global calibration state from an X client in this model, for broadly the same reasons that RANDR under Xwayland is read-only. The wayland server owns that state, the Xwayland server is simply a very demanding wayland client. - ajax _______________________________________________ wayland-devel mailing list wayland-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/wayland-devel
