[mythtv-users] OT: How to calculate displaysize

Michael T. Dean mtdean at thirdcontact.com
Fri Sep 2 16:20:17 UTC 2005


Brian C. Huffman wrote:

>Ok...so I found that my display is running at 75dpi (bad for fonts).  However,
>the howto up on mythtv.info is very vague:
>
>http://www.mythtv.info/moin.cgi/DisplaySize
>
>Does anyone have advice to give on how to accurately determine and specify your
>displaysize in xorg.conf?
>  
>
1) You can start X with a command-line option:
startx -- -dpi 100

(won't work if you need different horizontal and vertical DPI).

2) You can calculate the appropriate "DisplaySize" based on the 
resolution you're using:

Given 1 inch = 25.4millimeters
DisplaySize is specified in millimeters
You're using a resolution of X x Y:

DisplaySize should be set to the truncated integer value (note, you have 
to do the math yourself, don't specify the equation in your X 
configuration file):

DisplaySize: ((X / 100) * 25.4) ((Y / 100) * 25.4)

So, for 1024x768:

1024 / 100 = 10.24 * 25.4 = 260.096 = 260
768 / 100 = 7.68 * 25.4 = 195.5072 = 195

DisplaySize  260 195

Some round instead of truncating.  I've found that truncating gives best 
results...

HTH.

Mike


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