[HarfBuzz] Choosing "dev2" vs "deva" OT script for shaping

[Behdad Esfahbod]

On 15-05-06 03:33 PM, Adam Twardoch (List) wrote:
> If a font includes both a "dev2" and a "deva" implementation for Devanagari OT shaping, is there an API-compliant way to choose one over the other? 

Not right now.

I can extend the BCP 47 extension to also choose the script system if it's
available.  Eg, a language setting of "x-hbotdeva" will choose "deva" whereas
"x-hbotdev2" will choose "dev2".  This works for script tags that have four
letters (ie, not 'lao ', 'yi  ', 'nko ', and 'vai ').

We would only recognize the three-letter ones as language system tag.

This will be useful for choosing 'math' script as well.

Jonathan, do you have anything against this?

b