[HarfBuzz] List OpenType features

[Adam Twardoch (List)]

> On 18 Nov 2015, at 13:40, Nikolay Sivov <bunglehead at gmail.com> wrote:
> 
> On 18.11.2015 15:27, Edu García wrote:
>> Thank you!
>> 
>> That's the one I suspected. However, as its second parameter, it wants a
>> "hb_tag_t table_tag". What is that table tag, and how do I get it?
> 
> There's only two possible tags you can use in this case - HB_OT_TAG_GSUB and HB_OT_TAG_GPOS.

Yes, giving HB_OT_TAG_GSUB will get you the list of substitution features in the font and HB_OT_TAG_GPOS will give you the list of positioning features. GSUB features are always applied before GPOS features. It's possible that the same feature is defined in both tables, then the GSUB portion of the feature will be applied first, GPOS later. 

A.