[XeTeX] Θέμα: Re: OpenType ligatures

Alexej Kryukov anagnost at yandex.ru
Thu Nov 23 22:43:56 CET 2006

On Thursday 23 November 2006 19:23, Apostolos Syropoulos wrote:
> Ok. I do not know whether it would be possible for
> most people to write Greek, 

Well, it is possible for me :)

> so I created a simple 
> font that exhibits the problem. The letters g, a,
> and r are supposed to form a contextual ligature,
> that is they should be replaced by a single glyph if
> they are followed by a space and are preceded by a
> space.

As far as I can see, XeTeX supports contextual ligatures perfectly
well. However, in this particular case the problem is caused by 
the space character in your backtrack and lookahead: as you know,
this character is not used by TeX (and XeTeX), so that the condition 
for your contextual substitution is actually never fulfilled. 
Everything works just fine if you explicitly tell XeTeX to put 
a Unicode space before and after the problematic string, for example:

\font\x="sample:+hlig,+hist" at 12pt\x
alla \char 32 gar\char 32\ ara

I only had to correct the typo in the match pattern in your font: 
[a g r] instead of [g a r].

Alexey Kryukov <anagnost {at} yandex {dot} ru>

Moscow State University
Historical Faculty

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