> Both X and Wayland request information from display. If that information is available there they can read it. Both. Or do you thing that Wayland is reading the mind of display creators, while Xorg can't do that? ;-)
Yep. Try that trick with Xrandr on legacy NVidia drivers (hint: it doesn't work).
Of course, your app can also read display EDIDs and parse them. Through the X protocol! But that kinda says that you should probably stop doing it.
> Run `xrandr --verbose` and see "Subpixel" there.
>cyberax@whale2:~$ xrandr --verbose
> SZ: Pixels Physical Refresh
>*0 1024 x 768 ( 260mm x 195mm ) *60
>Current rotation - normal
>Current reflection - none
>Rotations possible - normal
>Reflections possible - none
>Setting size to 0, rotation to normal
>Setting reflection on neither axis