Re: line breaking hints?

[Taco Hoekwater <taco@elvenkind.com>]

Santy, Michael wrote:
> Hello,
> 
> I'm looking for a way to give ConTeXt's line breaking algorithm a
> hint on where it is allowed to break a line.  For example, I want
> ConTeXt to break lines, if necessary, when it encounters '//' in a
> string.  I don't want to force a line break there, but if context
> needs to break the line, I want it to be after a "//".

I've been trying various things, but so far I have failed to find
a general solution to do this.

Normally you would say something like "\penalty-100" to hint that
some place is a good place to break a line, but such a hint is never
exclusive: TeX will happily use breakpoints elsewhere if those appear
to be better to the line breaking algorithm.

That's why you would need something like:

   \def\\{\hskip0pt plus .5\hsize \penalty-100 \hskip0pt plus -.5\hsize}

to make the break more attractive. The downside is that this actually
works by based on the 'break width' of the line, and because it will
not prevent other breaks, the break above will always be taken if the
current to-be-broken line is half-full or more already (so a line
that may actually fit on one line can be broken in two).

Anyway, as you don't mind ragged right typesetting, this should work
more or less:

   \def\specialpar#1%
     {\begingroup
      \rightskip=0pt plus \hsize
      \linepenalty100
      \clubpenalty0\widowpenalty0
      \hyphenpenalty10000\exhyphenpenalty10000
      \def\\{\penalty-50}%
      #1\endgraf
      \endgroup}

   \specialpar{HE QUICK BROWN FOX JUMPED OVER THE LAZY DOG//\\ NOW IS THE
    TIME FOR ALL GOOD MEN TO COME TO THE AID OF THEIR COUNTRY.}

Note I've added a special macro \\, instead of attemping to automate
breaking after //.

This 'solution' is far from perfect, but the problem is simply hard.

Best wishes,
Taco

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