What is X server DPI used for?

[Nifty Hat Mitch]

On Tue, Jul 06, 2004 at 12:01:49AM -0400, Kevin Flynn wrote:
> Hello,
> 

> I recently learned that my X server (stock xorg-x11-6.7.0-2 from
> FC2) is running at 75x75 DPI while my LCD display (SXGA+ with
> 1400x1050 pixels, and 12x9 inches physical size) apparently has a
> resolution of about 116 DPI.  So I tried with restarting X with -dpi
> 116, but I don't really notice any differences.  In fact, I tried
> setting it across a broad range of values and still saw no apparent
> differences.  What does the X server use the DPI parameter for?
> Does it matter if X is using a different DPI than the native
> resolution of my display?  Will my fonts be screwed up or something?


There are numerous ways of measuring fonts. In the end they are
rendered to a height based on the apparent dot per inch aspect of the
screen.

One interaction is the selection of pre rendered fonts.
  ..../X11/fonts/75dpi/...
  ..../X11/fonts/100dpi/...

I see in /etc/X11/Xresources

  ! Fix the Xft dpi to 96; this prevents tiny fonts
  ! or HUGE fonts depending on the screen size.
  Xft.dpi: 96

This tells me that you might change things with a line
in your $HOME/.Xresources file like:

  Xft.dpi: 116

If you like the fonts leave things!  When attempting to match fonts to
various displays some ugly results are possible.  Keep good notes so
you can undo or redo this class of changes.

If you understand how to get a virtual terminal you might touch
/etc/X11/Xresources but global files should be kept as original as
possible.  A badly configured display can be hard to fix.


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