[HarfBuzz] hangul shaper patches

[Jonathan Kew]

On 22/1/14 12:53, Behdad Esfahbod wrote:
> Thanks Jonathan.  I've merged these.
>
> A few points:
>
> /* Same order as the feature array below */
> enum {
>    NONE,
>
>    LJMO,
>    VJMO,
>    TJMO,
>
>    FIRST_HANGUL_FEATURE = LJMO,
>    HANGUL_FEATURE_COUNT = TJMO + 1
> };
>
> Do you really need the NONE?  I don't see where / how that's used.

The NONE isn't explicitly used, but is there as a placeholder for the 
zero value, so that we can tell whether info.hangul_shaping_feature() 
has actually been set on a glyph at all.

>
> I just want to note that by applying the jamo features only to one character
> at a time, we disallow contextual rules,

Is this true? I thought we ignored the mask when matching context, and 
only used it for the actual input string.

> but I guess that's what Uniscribe
> does also?

malgun.ttf has lookups that include backtrack and/or lookahead in some 
of its *jmo features. I haven't yet explicitly traced to see them to see 
what matches where, but the fact that we match uniscribe on the entire 
wikipedia wordlist suggests we're probably OK.

JK