[HarfBuzz] an issue regarding discrepancy between Korean and Unicode standards

[Dohyun Kim]

2013/4/5 Behdad Esfahbod <behdad at behdad.org>:
> On 13-04-04 08:42 PM, Dohyun Kim wrote:
>> 2013/4/5 Behdad Esfahbod <behdad at behdad.org>:
>
> Got it.  Pushed a fix to master.
>
> Upon more testing, looks like Uniscribe always decomposes Hangul syllables to
> their jamos.  We currently don't.  Is that desirable?  In my Hangul corpus
> that's very rare (only ten cases out of millions).
>

Jamo letters are only used for medieval documents.  Oh, yes, they are
used even today for some local dialects as well.  Very rare cases
compared to modern hangul documents.  As a result, we had, and still
have, many confusions about how to implement fonts supporting Jamo.

According to Korean standard, decomposition is unnecessary and
undesirable.  According to Unicode standard, however, it is desirable
because Unicode allows combination of hangul syllable and jamo
letters. sigh.

In this confused situation, the best policy seems to be as follows:

 1. decompose hangul syllables *before* font features are applied
 2. let font do its glyph substitution
 3. compose remaining jamo glyphs to syllable *after* font features
have been applied

Regards,
--
Dohyun Kim
College of Law, Dongguk University
Seoul, Republic of Korea