[NTG-context] Count (and limit) glyphs per line?

[Hans Hagen]

On 6/24/2022 5:15 AM, Benjamin Buchmuller via ntg-context wrote:
> Dear list,
> 
> I've been confronted with the following 'intriguing' formatting requirement for a document:
> 
> "
> • Type density:  Must be no more than 15 characters per linear inch (including characters and spaces).
> • Line spacing: Must be no more than six lines per vertical inch.
> "
> 
> While the line spacing resolves in ConTeXt to
> 
> \setupinterlinespace[line=\dimexpr(1in / 6)]
> 
> I was wondering if one can limit "type density" as the number of glyphs per inch in TeX too? I thought, it is more convenient to rephrase this request (for a 7 in textwidth) to limit the number of glyphs per line to 112. (Font must be sans or serif, of course ...)
> 
> I've tried
> 
> \setuplayout[width=112\averagecharwidth]
> 
> which, however, results in ~120–130 characters and spaces per line. Pragmatically, I'm narrowing the text width to empirically match the requirement, but I'm nevertheless curious if there is a Lua/TeX solution to this "problem"?
Just assume the worst case and take the narrowest character:

\showframe

\setupbodyfont[modern] % we need to set the font

\normalexpanded {
     \setuplayout
        [textwidth=\the\dimexpr112\fontcharwd\font`.\relax]
}

\starttext
     \input tufte
\stoptext



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