Re: river detection

[Ed L Cashin <ecashin@coe.uga.edu>]

Hans Hagen <pragma@wxs.nl> writes:

> At 11:58 AM 1/10/01 -0500, Ed L Cashin wrote:
> 
> >But you could just do a TeX macro that expands to a kind of matrix
> >like this:
> >
> >           (5, 6) (11, 15) (35, 40)
> >           (7, 9) (11, 15) (26, 30)
> >           (2, 4) (11, 14) (24, 26)
> >
> >(there's a river at position eleven).
> 
> Eh ... when tex typesets a paragraph, all input is already converted to
> lists and macro expansion is gone. So, bbox info should come from the list
> to dvi pass [or maybe from within the paragraph builder]. Keep in mind that
> f i e t s [bicycle] is not just 5 chars, but becomes fi e t s and that at
> some point the hyphenation engine pops in too. No way to hyphenate
> \hbox{f}\hbox{i}...\hbox{s}.

I don't know what you mean by "the list to dvi pass".

Within the paragraph builder, though, I'm thinking that there's a time
when TeX tries a certain paragraph configuration.  At that time, you
have information about where the horizontal glue between hboxes begins
and ends.  That's the information that I was talking about in my
example.  With "I   w u v   fi e t s", TeX knows that there's a good
bit of horizontal glue after the "v" box and before the "fi" box.  It
knows the leftmost and rightmost position of that glue, right?

I was thinking that the river badness can be calculated at that time,
but are you saying that it can't be calculated at that time by a macro
because all the macro expansion is not going on at that time?

-- 
--Ed Cashin                     PGP public key:
  ecashin@coe.uga.edu           http://www.coe.uga.edu/~ecashin/pgp/