[XeTeX] texlive13/harfbuzz problem with nastaleeq font

[Khaled Hosny]

On Sun, Jun 23, 2013 at 12:09:37AM +0200, Khaled Hosny wrote:
> On Sat, Jun 22, 2013 at 04:26:28PM -0400, Kamal Abdali wrote:
> > The files using a nastaleeq font (Jameel Noori Nstaleeq) which were
> > processed quite well under texlive12/xelatex/polyglossia are being typeset
> > with lots of very overfull lines under texlive13. I tried various settings
> > of the fontspec WordSpace option, \pretolerance, etc, but they didn't
> > improve the output. The same files are still typeset in TL13 very nicely
> > when I switch to a naskh font (XB Zar).
> > 
> > Attached are a source file and its pdf outputs with nastaleeq font in TL 12
> > & 13 and with naskh font in TL13. I'm sorry the files are long but shorter
> > files didn't illustrate the problem well. I'll provide links to the fonts
> > if a solution doesn't suggest itself to some expert by just looking at the
> > files here.
> 
> What happens if you omit the WordSpace option? Either way, the font is
> needed for any meaningful testing.

I actually have the font, so after a bit of testing I think the font is
working as intended. The font has a ‘ccmp’ feature for Arabic script
that maps the space glyph to a 5-units wide glyph (that is practically
the same as zero), I guess following the traditional practice of
omitting word space in Arabic calligraphy. For some reason the feature
was not applied before so the normal space was used, so it was a bug
that had desirable effect (for some people at least).

Since the font does not use ‘ccmp’ feature for anything else, it is safe
to just disable it to get the old behaviour, or you can setup things to
allow for looser interword spacing (which will not be that looser than
the old behaviour, after all).

Regards,
Khaled
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