[comp.text.tex] Output routine challenge/question

drstrip@intvax.UUCP (David R. Strip) (01/11/91)

(This was originally intended to be sent to David Solomon who wrote a
great 3 part series on output routines, but his mailer doesn't seem to 
want to talk to my mailer. Are you there at dxs@mx.csun.edu, finger puts
you there, but the mailer refuses to accept mail for you.)

Suppose you wanted a page format with two columns, and with
a window in the two columns in the center of the page. (This layout
is frequently used in the Atlantic monthly) For ease of discussion,
let's assume that the window is 1/3 the height of the columns, is equal
to col width + col spacing, and is centered inthe page.

Presumably the way to do this is to write an output routine that sets
\hsize and \vsize to the various required sizes, generates the 6 necessary
pieces (top , middle, bottom of each col.) then assembles the whole thing.

What I don't understand is how to make the changes in \hsize work as 
desired, since \hsize is based on  when the paragraph ends, and here
we need to reset it possibly in mid-paragraph, possibly after the paragrahp
has been added to the  main vertical list (MVL)
I guess you need to take apart the MVL, but
I am not clear on how you do that, and force the paragraphs to be reset,
with possibly new line breaks?

Any hints?

Thanks
strip
drstrip@cs.sandia.gov