Wow, that works like a charm! Thank you, Max!
It's also a very insightful example of how to use and inject Lua code in the
TeX output routine. Do you mind if I add it to the wiki? (Probably under
"Wrapping".)
Many thanks again!
Benjamin
> On Jun 24, 2022, at 01:44, Max Chernoff <mse...@telus.net> wrote:
>
>> I've been confronted with the following 'intriguing' formatting requirement
>> for a document:
>
> "Intriguing" is definitely right here. I suspect these guidelines were made
> for typewriters and haven't been updated since.
>
>> to limit the number of glyphs per line to 112.
>
> 112 characters per line sounds much too long anyways.
>
> From "The Elements of Typographic Style":
> > Anything from 45 to 75 characters is widely regarded as a satisfactory
> > length of line for a single-column page set in a serifed text face
> > in a text size. The 66-character line (counting both letters and
> > spaces) is widely regarded as ideal. For multiple-column work, a
> > better average is 40 to 50 characters.
> >
> > If the type is well set and printed, lines of 85 or 90 characters
> > will pose no problem in discontinuous texts, such as bibliographies,
> > or, with generous leading, in footnotes. But even with generous
> > leading, a line that averages more than 75 or so characters is likely
> > to be too long for continuous reading.
>
> If you use something like
>
> \setuplayout[width=80\averagecharwidth]
>
> then your lines will for sure have fewer than 112 characters and will
> probably be more readable too.
>
>> I'm nevertheless curious if there is a Lua/TeX solution to this "problem"?
>
> Option 1: Use a monospaced font. Then 112 characters per line <=> page width
> = 112em.
>
> Option 2: A hacky Lua solution
>
> \startluacode
> local max_length = 112
>
> local glyph_id = node.id "glyph"
> local disc_id = node.id "disc"
> local glue_id = node.id "glue"
>
> function userdata.limiter(head)
> language.hyphenate(head)
>
> local chars = 0
> local width = 0
> local n = head
> while n do
> if n.id == glyph_id or n.id == glue_id then
> chars = chars + 1
> width = width + n.width - (n.shrink or 0)
> end
>
> if chars >= max_length or width > tex.hsize then
> local back_chars = 0
> local end_disc = nil
>
> while n do
> if n.id == glue_id then
> local penalty = node.new "penalty"
> penalty.penalty = -10000
> node.insertbefore(head, n, penalty)
> break
> end
>
> if not end_disc and n.id == disc_id then
> end_disc = n
> end
>
> if end_disc and back_chars >= 5 then
> end_disc.penalty = -10000
> break
> end
>
> if n.id == glyph_id then
> back_chars = back_chars + 1
> end
>
> n = n.prev
> end
>
> width = 0
> chars = 0
> end
>
> n = n.next
> end
>
> return head
> end
>
> nodes.tasks.appendaction(
> "processors",
> "before",
> "userdata.limiter"
> )
> \stopluacode
>
> \setuppapersize[landscape,letter]
> \showframe
>
> \starttext
> \setupalign[flushleft]
>
> \setupbodyfont[14pt]
> \samplefile{knuth}
>
> \setupbodyfont[12pt]
> \samplefile{knuth}
>
> \setupbodyfont[10pt]
> \samplefile{knuth}
>
> \page
> \setupalign[normal]
>
> \setupbodyfont[14pt]
> \samplefile{knuth}
>
> \setupbodyfont[12pt]
> \samplefile{knuth}
>
> \setupbodyfont[10pt]
> \samplefile{knuth}
> \stoptext
>
> This code will ensure that no line ever exceeds "max_length" characters. It
> uses a greedy algorithm instead of the standard TeX algorithm for line
> breaking, but it still produces mostly decent results.
>
> -- Max
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