Re: A primer on font installation for groff (was: gropdf(1)'s 'Font installation' section is opaque to me)

[Jan Eden]

Hi Alejandro,

On 2024-04-18 20:33, G. Branden Robinson wrote:

> Hi Alex,
> 
> At 2024-04-19T00:29:37+0200, Alejandro Colomar wrote:
> > While the above is interesting, I've already read similar explanations
> > from you in related threads.  However, I still have no clue of how to
> > drop TINOR from the Linux man-pages repo and generate it from
> > something coming from a package.  :(
> 
> Well, it's tedious, which is why Peter Schaffter and others have written
> shell scripts to help with the process.
> 
> Here's a file- and program-centric overview of what's required.
> 
> 1.  You grab a modern font file from some place.  This will be a TTF or
>     OTF file.
> 
> 2.  You use FontForge or a similar tool to generate TWO files from a
>     TTF/OTF file.
> 
>     2a.  A PostScript Type 1 font in PFA and/or PFB format.  If you want
>     to embed this font in a groff-generated PostScript file, you have to
>     use PFA, because that is all grops(1) understands.  If you want to
>     embed this font in a groff-generated PDF, you can use either,
>     because gropdf(1) understands both formats.
> 
>     2b.  If you have a PFB file and need PFA, you can use groff's
>     utility pfbtops(1) to produce the latter.
> 
>     2c.  You will also have to produce an AFM file.  This stands for
>     "Adobe Font Metrics".  This describes the dimensions of the glyphs
>     in the proper font file.  The font metrics are not the font itself;
>     they merely describe it in some respects.
> 
> 3.  The formatter, troff(1), must have font metrics so that it can
>     correctly position glyphs on the page.  But GNU troff, like AT&T
>     troff before it, does not use AFM files directly for this purpose;
>     AT&T troff is older than Adobe PostScript.  Instead it uses a "font
>     description file", which includes the metrics and other information
>     important to the formatter.  The font description file is what
>     corresponds to the short, shouty *roff font names we're used to,
>     like "TR" or "S" or "CBI".
> 
> 4.  The *roff font description files must be placed where the formatter
>     can find them when it runs.  They must appear in the
>     GROFF_FONT_PATH, or the formatter must be told where to look with an
>     `-f` command-line option.
> 
> 5.  When embedding fonts in PostScript or PDF, the _output driver_
>     (grops or gropdf) must be told where to look to find them.  Each
>     driver consults a "download" file for this information.
> 
> A package manager has a few things to keep track of to ensure that the
> state of all these remains coherent.
> 
> A.  If a new "modern" (TTF/OTF) font is installed, a program to generate
>     PFA/PFB and AFM files must be run to make it available to groff.
> 
> B.  afmtodit(1) must be run to produce a groff font description file
>     from the AFM file.
> 
> C.  The font description files must be placed in groff's "font search
>     path".  In practice this means two places, one for PostScript and
>     one for PDF.
> 
> D.  The "download" files for the grops and gropdf programs must be
>     updated to list the PFA/PFB file in the correct locations.

The process is explained in detail by Walter Alejandro Iglesias on the
blog I referenced earlier[1], and he also provides a shell script
(similar to Peter's explanation and script[2]). 

[1] https://technicallywewrite.com/2023/09/16/addfonts
[2] https://www.schaffter.ca/mom/momdoc/appendices.html#fonts

- Jan

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