# [XeTeX] Line-breaking algorithms in XeTeX

Diederick C. Niehorster diederick at niehorster.eu
Mon Apr 27 11:26:40 CEST 2009

Hi Pander,

Although I have no direct need for your script, I could see it being
very useful. Maybe it should be posted on CTAN (possibly after going
through a quick internal review round here), if you are okay with
that.

Best,
Diederick

On Mon, Apr 27, 2009 at 3:50 PM, Nicolas Vaughan <nivaca at gmail.com> wrote:
> Hi Pander,
> I am interested in your script.
> Best,
> Nicolas Vaughan
>
>
> On Mon, Apr 27, 2009 at 2:33 AM, Pander <pander at users.sourceforge.net>
> wrote:
>>
>> John Was wrote:
>> > Dear All
>> >
>> > Since starting to use (plain) XeTeX I've noticed something strange with
>> > the paragraphing/line-breaking mechanism which has never happened during
>> > the ten years or so during which I have used traditional TeX.  It is
>> > cropping up in the fourth issue of a periodical that I have set with
>> > XeTeX, so I'm pretty sure that it's not a random fluke.
>> >
>> > (1) I sometimes get an overfull rule (i.e. rectangular box) at the
>> > right-hand side which will disappear when I either (a) attach the word
>> > causing the problem to the next word with ~, forcing it over (I
>> > sometimes have to put the word in an \hbox{} as well); or (b) when I
>> > increase the line-count by giving \looseness1 for the paragraph.  In the
>> > past, plain TeX would always make such decisions for itself and never
>> > generate an overfull rule when it could find a way to justify the
>> > paragraph without doing so.  This happens most frequently in the reviews
>> > section of the periodical, where  \looseness is set to -1 by default to
>> > save as much space as possible:  but until I started to use XeTeX, it
>> > was always the case that if the paragraph could not lose a line, then
>> > the negative looseness was ignored and the paragraph was set
>> > successfully with normal looseness  (i.e. \looseness = 0).  It was never
>> > (I think) the case that a tight looseness which generated an overfull
>> > box would get through and need manual intervention from me.  So has
>> > something altered in the way XeTeX is handling the line-breaks, giving
>> > priority to the looseness command even at the expense of generating an
>> > overfull rule, and even when zero looseness would cause that error to
>> > disappear?
>> >
>> > (2) This is even more puzzling (and more of an nuisance).  For the
>> > purpose of sending contributors proofs of their reviews I start each
>> > review on a new page so that they don't also receive the tops and tails
>> > of adjacent reviews, but while initially typesetting I have the reviews
>> > running on consecutively, as they will do in the final published
>> > version.  There is a switch at the end of each review which generates a
>> > \vfill \eject when \ifseparatereviews is true, otherwise it just
>> > produces a \vskip: there is no other difference.  Yet I sometimes get
>> > overfull rules showing up (at random points) when the reviews are
>> > separated out, even though the same paragraph typeset without error
>> > while the reviews were set to run on continuously.  The problem almost
>> > (but not entirely) disappears if I double the \hfuzz when the
>> > \ifseparatereviews switch is true, but that is no more than a quick fix
>> > to prevent authors receiving proofs with worrying blobs at the
>> > right-hand side.  This seems incomprehensible, but as it has happened
>> > with four out of four periodical issues I can't be imagining it - and
>> > the commands are precisely the same as the ones I used when the
>> > periodical was typeset using traditional plain TeX, with no new
>> > parameters such as alteration to \spaceskip or anything else that might
>> > cause this to happen.
>> >
>> > (1) and (2) seem likely to be part of the same problem (though not
>> > necessarily so).  Any ideas, or at least insight into what XeTeX is
>> > doing that old plain TeX didn't?
>> >
>> > Thanks
>> >
>> >
>> > John
>>
>> Hi all,
>>
>> Slightly related is something I have made. Sometimes you have some
>> freedom of choice in font and in the dimensions of the margins of the
>> work you are about to make. Each selection will have a different amount
>> of:
>> - Overfull
>> - Underfull
>> - hyphenation exceptions
>>
>> I have made a python script that, via exhaustive enumeration, will find
>> the optimum settings for a minimum amount of occurrences of the list
>> above. Using those optimal settings could be a smarter starting point
>> for fixing widows, orphans and hyphenation exceptions.
>>
>>
>> Regards,
>>
>> Pander
>>
>> >
>> >
>> >
>> >
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