Re: Printing

[Eli Zaretskii <eliz@gnu.org>]

> From: Richard M Stallman <rms@gnu.org>
> CC: cmr.pent@gmail.com, emacs-devel@gnu.org
> Date: Sun, 29 Mar 2009 21:17:07 -0400
> 
>     It works fine out of the box for ASCII and Latin-1 characters.
>     Outside that area, ps-print needs non-trivial setup.
> 
> What setup does it need?

See the commentary at the beginning of ps-mule.el.

> Why is it needed?

Because ps-print needs to know how to send non-ASCII characters to the
printer.  Characters from scripts that the printer supports directly
can be sent verbatim (encoded by a suitable coding-system).  Other
characters need to be downloaded into the printer before we can use
them.

> If the user invokes it without doing this setup,
> does it warn the user it won't work?

If some of the characters in the region you print don't have a
corresponding entry in ps-mule-font-info-database, it says something
vague about "some characters will not be printed".  If all of them
have entries, but the entries do not correctly reflect what the
printer can or cannot do, you get bad printout with no warning at all.

One way to fix this would be to update our default for
ps-mule-font-info-database so that it handles Unicode -- assuming that
modern PostScript printers indeed support large subranges of the
Unicode codespace.  I'm not an expert on printing, so I wouldn't know
if this is possible.