[XeTeX] Line-breaking algorithms in XeTeX

[Nicolas Vaughan]

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.
>
> If someone is interested in this script. please contact me.
>
> Regards,
>
> Pander
>
> >
> >
> >
> >
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