Re: [Groff] space width

[Werner LEMBERG]

>> Letter-spacing is bad in general.
>
> I find this statement a bit too broad, especially in the context of
> groff, whose only means of justifying lines presently is through the
> expansion of wordspace, often with ghastly results.

Well, even if it is the only possible solution in groff,
letter-spacing is still bad in general.

> Have a look at the first page of pdf output of typesetting.mom in
> the mom examples files.  Admittedly, the example given shows
> letterspacing used in a rag context, but it's very hard not to agree
> that the "massaged" passage using very small amounts of
> letterspacing (expanded and reduced) is typographically superior to
> the unmassaged version.

What you demonstrate is something *completely* different.  You are
using letter-spacing to change a property of the font Times-Roman,
namely its extremely tight spacing, quite suitable for narrow
newspaper columns but rather awkward for long lines.  This is *not*
related to the letter-spacing used for improving the grayness of
paragraphs while justifying them.

No question that your use of letter-spacing is fully qualified.
However, a better solution might be the creation of an additional set
of groff font files for Times Roman that multiply the glyph widths and
kerning values by a certain factor.

>> A better solution is font expansion, as implemented e.g. in
>> pdflatex.  Unfortunately, MM fonts have been abandoned...
>
> In which case, one has to ask: is justification through wordspacing
> alone, as is the case with groff now, a superior solution to
> implementing word-and letter-spacing?

Oh, my rant was quite general.  Of course there isn't a better
solution currently in groff to what you provide.

>> Given today's memory abundance and the high velocity of CPUs, the
>> ideal route would be to implement a document-wide algorithm for
>> typesetting a document (in contrast to TeX's page-wide approach).
>
> Completely agree.  The Holy Grail of typesetting.  Do you think it
> will ever come to be?

I think a lot of professional systems (this is, proprietary stuff
available for astronomical prices) for serious typesetting already
have that, especially if combined with GUIs for visual manipulation.
Unfortunately, no TeX or troff variant provides it.  However, Lout
(https://savannah.nongnu.org/projects/lout) comes with that feature:

  Optimal paragraph breaking and automatic hyphenation were copied
  from Donald E. Knuth’s TEX system, and the optimal paragraph
  breaking algorithm was applied to the problem of producing optimal
  page breaks.

I've never used Lout, so I can't comment further.  You might also read

  http://tex.stackexchange.com/questions/114292/why-no-vertical-mode-knuth-plass

for more information.


    Werner