[HarfBuzz] Fwd: ZWNJ is being ignored

[Khaled Hosny]

On Wed, May 01, 2013 at 02:30:43PM +0100, Jonathan Kew wrote:
> On 1/5/13 13:57, Georg Duffner wrote:
> >Am 2013-05-01 11:30, schrieb Jonathan Kew:
> 
> >>Presumably, the way to handle this as a font developer is to explicitly
> >>handle the ZWNJ, by adding something like
> >>
> >>   sub f' zwnj f by f;
> > >
> >>ahead of the existing rule. That should in effect block the "ligature"
> >>when ZWNJ is present, if I'm understanding correctly.
> >
> >It wouldn’t change anything, as zwnj is ignored in contextual chaining
> >lookups.
> 
> Are you sure - have you tried this approach? AIUI, if zwnj is
> explicitly present in the lookahead context, it should be matched,
> and hence that rule would prevent the following rule (without the
> zwnj) being applied.

IIRC, HarfBuzz converts ZWNJ into space glyph at some point, a while ago
I wanted to do a contextual positioning involving ZWNJ and it worked
only when I used space in the context.

Regards,
Khaled