fonts

[Colin Walters <walters@debian.org>]

So, up till now fonts in Debian were supposed to be installed via
Defoma.  Defoma has worked fairly well, but it's Debian-specific, and
very complex.

Now however we have fontconfig, which is a more generic way for
applications to find and use fonts.  Besides core components like GNOME,
KDE, and Mozilla, other applications like magicpoint are now using it as
well.  I think we should encourage this.

Defoma is not really supported by its maintainer anymore (see #180188),
and I think that we should be moving away from using Defoma, and
encouraging upstreams to support fontconfig.  They are not entirely
duplicates really; Defoma as I understand it is just kind of a trigger
mechanism, and can help non-fontconfig applications to support a variety
of fonts. 

Now, to the issue at hand: after installing a font package, fc-cache
must be rerun.  Now, we could continue to use Defoma, and I could have
fontconfig install some sort of Defoma trigger to make Defoma rerun
fc-cache.  
But given the above, I would prefer for font packages to just invoke
fc-cache directly in their postinst, and also for them to Depend on
fontconfig.

This should solve #175797.

The exact code that packages should use might look something like this:

 printf "Regenerating fonts cache..." 
 HOME=/root fc-cache -f -v 1>/var/log/fontconfig.log 2>&1 || (printf "failed; see /var/log/fontconfig.log for more information\n"; exit 1)
 printf "done.\n"

Maybe I could put this into a little shell script in the Debian
fontconfig package.

Comments?