Gimp had the only cheap effective, backward compatible solution:
There was a setting that showed a ruler in the screen, you could scale it to match a ruler you were holding against the screen.
It disappeared after a while...
There was a setting that showed a ruler in the screen, you could scale it to match a ruler you were holding against the screen.
It disappeared after a while...
$ xdpyinfo | grep -A 2 '^screen #'
screen #0:
dimensions: 1920x1080 pixels (483x272 millimeters)
resolution: 101x101 dots per inch
$
Option "DPI" "96 x 96"
i read a little more on the link you provided... and the closest to the gimp old way of doing that is putting the width and height of the viable area of the monitor in mm. think that might work rather well if it's correctly implemented.