[luatex] tex.linebreak - overfull hbox

Michal Hoftich michal.h21 at gmail.com
Fri Dec 5 13:55:45 CET 2014

Hi Patrick,

have you seen https://github.com/michal-h21/linebreaking/blob/master/linebreaker.lua
? I think I tried exactly what you want (plus river detection, which
doesn't work really well). Regarding your question, every `hlist` node
has `glue_sign` and `glue_set` attributes, I tested for overfull boxes

function linebreaker.par_badness(head)
local n = 0
for line in node.traverse_id(0, head) do
print(get_text(line.head), line.glue_order, line.glue_sign, line.glue_set)
-- glue_sign: > 0 = normal, 1 = stretch, 2 = shrink
-- we count only shrink, but stretch may result in overfull box as well
-- I just don't know how to detect which value of glue_set means error
if line.glue_sign == 2 and line.glue_set >= 1 then n = n + 1 end
return n

I think I've found these vales by experimenting, I couldn't find exact
meaning of `glue_set`. So this function just count number of overfull
boxes in the paragraph.


2014-12-05 13:30 GMT+01:00 Patrick Gundlach <patrick at gundla.ch>:
> Hello,
> I believe I have asked this question before (sorry). When I call tex.linebreak(): is there a way to find out if a "overfull hbox" message occurred (without parsing the log file)?
> I want to reformat a paragraph until no line sticks over the right margin by increasing some parameters such as emergencystretch. I can now look at the result and call node.dimensions for every line, but I am looking for an easier (and cheaper) way.
> Patrick

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