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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