[arch-general] xdpyinfo displays wrong "dimension" values

[Ralf Mardorf]

Hi,

I followed https://wiki.archlinux.org/index.php/Xorg#Display_size_and_DPI .
I measured the screen size of the LCD and the CRT manually and in
addition I calculated the screen size of the LCD. FWIW manual measuring
provided the same result as the calculation.

This is my xorg.conf

[rocketmouse at archlinux ~]$ cat /etc/X11/xorg.conf
Section "Monitor"
    Identifier  "HDMI2"
    DisplaySize  526 296
    Option      "PreferredMode" "1920x1080"
    Option      "Primary" "true"
EndSection

Section "Monitor"
    Identifier   "VGA1"
    DisplaySize  367 278
    Modeline    "1024x768" 65.00 1024 1048 1184 1344 768 771 777 806
    Option       "PreferredMode" "1024x768"
    Option       "RightOf" "HDMI2"
EndSection

Section "Device"
	Identifier  "Card0"
        Driver      "intel"
        #Driver     "vesa"
EndSection

Section "ServerFlags"
    Option "BlankTime" "0"
    Option "StandbyTime" "0"
    Option "SuspendTime" "0"
    Option "OffTime" "0"
EndSection

For my session I added a few modes using xrandr:

[rocketmouse at archlinux ~]$ xrandr
Screen 0: minimum 8 x 8, current 1920 x 1080, maximum 32767 x 32767
HDMI1 disconnected primary (normal left inverted right x axis y axis)
HDMI2 connected 1920x1080+0+0 (normal left inverted right x axis y axis) 530mm x 300mm
   1920x1080     60.00*+  50.00    59.94  
   1920x1080i    60.00    50.00    59.94  
   1680x1050     59.88  
   1600x900      60.00  
   1280x1024     60.02  
   1280x800      59.91  
   1280x720      60.00    50.00    59.94  
   1024x768      60.00  
   800x600       60.32  
   720x576       50.00  
   720x576i      50.00  
   720x480       60.00    59.94  
   720x480i      60.00    59.94  
   640x480       60.00    59.94  
   720x400       70.08  
VGA1 connected (normal left inverted right x axis y axis)
   1024x768      60.00 +  60.00  
   800x600       60.32    56.25  
   848x480       60.00  
   640x480       59.94  
   1152x864_90hz_xdh_default  90.00  
   1440x960_86hz_xdh_music-1  86.00  
   1368x768_90hz_xdh_music-2  90.00  
   1024x768_60hz_xdh_no-risk  60.00  
VIRTUAL1 disconnected (normal left inverted right x axis y axis)

[rocketmouse at archlinux ~]$ xdpyinfo | grep "screen" -A2 # HDMI LCD on and VGA CRT off
default screen number:    0
number of screens:    1

screen #0:
  dimensions:    1920x1080 pixels (506x285 millimeters)
  resolution:    96x96 dots per inch
[rocketmouse at archlinux ~]$ xdpyinfo | grep "screen" -A2 # HDMI LCD off and VGA CRT 1024x768
default screen number:    0
number of screens:    1

screen #0:
  dimensions:    1024x768 pixels (269x201 millimeters)
  resolution:    97x97 dots per inch
[rocketmouse at archlinux ~]$ xdpyinfo | grep "screen" -A2 # HDMI LCD off and VGA CRT 1152x864
default screen number:    0
number of screens:    1

screen #0:
  dimensions:    1152x864 pixels (301x226 millimeters)
  resolution:    97x97 dots per inch

Is this a bug or do I misunderstand something?

Regards,
Ralf