[Groff] Font Composition

[jon arbuckle]

Dear list,

       I have been groff-ing for some time now, and have been
primarily interested in the mom macro package.  However, I have
some questions to ask about groff font structure for PostScript
output.

1) The UnderlinePosition and UnderlineThickness values from the
   afm files are discarded by afmtodit.  There is nothing
   corresponding to the in the groff devps font files.  How is
   groff then expected to provide proper underlining to text?

2) Can groff `compose' fonts, so to say?  Many fonts are supplied
   with permissive licences that permit redistribution but not
   modification.  If one wants to use such fonts in `expert'
   mode, one has to *purchase* costly expert versions of these
   fonts.  I propose that we create the new `expert' versions of
   these fonts as libre-software, modulo the characters already
   present in the gratis fonts.  That is, PostScript fonts that
   contain *only* the ligatures ff, ffi, ffl for a widely
   available gratis font, say Luxi Serif or Georgia.  Also,
   separate fonts can be created which have optical small caps,
   old-style figures etc.  If we have these fonts, is there any
   way to set up a font-file so that groff mainly uses
   characters from the regular font, and switches to another
   font (which will be intentionally visually compatible with
   the main font) when it needs ffi, or small caps, or old-style
   figures?  Thus we can `compose' a `virtual' font that is a
   super-set of the gratis and libre fonts.  This will be
   compatible with the licence agreements of the gratis fonts
   (as we are not *modifying* them), as well as ameliorate the
   need to purchase `expert' fonts.  Is this possible?  If not,
   can the groff-developers kindly consider this?

3) Another type of composition may be useful.  As opposed to the
   `design-time' composition discussed in the previous point,
   this is `run-time' composition.  This involves providing
   groff with a certain set of instructions that cause it to
   render *every* character of a font in a slightly different
   way, keeping the metrics the same, or differing in a
   systematic way.  In effect, the additional instructions will
   be drawing primitives, but should be made general to permit,
   for example, overprinting.  This technique can be utilised to
   effect using only that most expressive of mediums---
   PostScript, but can be used to wonderful effect for
   generating special effects such as strikethrough, underline,
   and pseudo-boldify/italicise reliably, and without any of the
   trickery macro-packages must employ to get around to it.  It
   can also be creatively used for many more effects.

       Will the knowledgeable people please consider?

       Thanking you all,
                                                Yours sincerely.

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