[HarfBuzz] unbreaking mixed-up khmer fonts

[Behdad Esfahbod]

On 12-11-19 07:58 AM, Jonathan Kew wrote:
> Hi Behdad,
> 
> Hope you've had a good weekend - thanks for all the good work last week.
> 
> One thing has come up: it seems we've broken things for some widely-used Khmer
> fonts. E.g. the font "hanuman.ttf" used on http://khmer.rfa.org/. This font
> has a 'liga' feature, but nevertheless relies on going through the indic
> shaper; it duplicates many of its lookups from 'abvs', etc., into 'liga' and
> 'clig', but it does not use these features to do the pre-base vowel or
> subjoined consonants.
> 
> The result is that it fails when shaped using the generic shaper, but works ok
> if we use the indic shaper with 'liga' disabled (because the features it puts
> in liga are just references to the lookups that are also in abvs etc, so
> ignoring liga is fine).
> 
> And so I think we need to revert the Khmer part of
> 981748cb2e9b48b77177b19ec1f972cab7afda89 (but keep the Myanmar part), and rely
> only on 6b389ddc3623d042ded4731f4d62dc354002fdd0 to deal with the pre-base
> duplication that we were seeing with fonts like Kh-Battambang. Remind me if
> there's something else that would break?

I think we were seeing Kh-Battang and family fail to do prebase reordering
because they don't have a pref features.  We started adding the hardcoded-Ra
support back for 'pref' stuff, but gave up since that was ugly.

What do you think we should do now?

b

> JK

-- 
behdad
http://behdad.org/