[XeTeX] Line-breaking algorithms in XeTeX

[Jonathan Kew]

Hi John,

On 27 Apr 2009, at 00:37, John Was wrote:

> Hello Jonathan
>
> I couldn't think of a way of providing a test case - I could  
> obviously show
> a PDF with the overfull rule when \looseness is -1 and without the  
> overfull
> rule (with the paragraph a line longer) when \looseness is set to 0  
> or 1,
> but that wouldn't be helpful.  The font is MinionPro, and in all  
> sizes I
> have the \spaceskip set thus:
>
> \spaceskip 0.25em plus 0.25em minus 0.075em

In general, if you want to adjust the word-spacing behavior, I'd  
recommend using the font's \fontdimen parameters (or fontspec's  
WordSpace option, for xelatex users) to control it on a per-font/size  
basis rather than setting \spaceskip, which will apply the same  
spacing to all fonts and sizes as long as it's in effect. But that's  
an aside...


> This seems to produce satisfactory results in the \hsize and  
> typesizes that
> I work with.  But it shouldn't generate this problem, I think, and  
> certainly
> not my situation (2), where the sole difference is whether there is  
> a \vfill
> \eject or \vskip between items.

I agree that the behavior you've described sounds wrong, but it's hard  
to diagnose exactly what's going on unless I can experiment with an  
example document that shows the problem. :(

I'm curious whether it is somehow related to the use of \spaceskip,  
actually, although I can't think of a specific reason why that should  
go wrong.

JK