[HarfBuzz] Reading a GSUB subtable

[Behdad Esfahbod]

Hi Owen,

I had to look up SMuFL.  I see it's been around since 2013.  I never heard
about it and don't think anyone I know has either.  I browsed the
specification and found it bizarre when it comes to its relationship with
OpenType.  But that's out of scope of your project.

Given that SMuFL hardcodes what the alternates are anyway, I suggest you
just use a hardcoded list and don't look into GSUB.  If you still want to,
we don't have that API in HarfBuzz yet, but we can converge to adding it
quickly I think.  Here's the issue to follow:

  https://github.com/harfbuzz/harfbuzz/issues/673

Cheers,
behdad

On Mon, Jun 15, 2020 at 2:52 PM Owen Lamb <owendlamb at gmail.com> wrote:

> Hello,
>
> I tried sending this once, but it apparently went to moderator approval
> because I wasn't a member of the list. It's been a few days without
> response, so I decided to sign up for the list and try again. Hopefully
> it'll make it through this time! My original message is as follows:
>
> I'm working on a GSoC project for the LilyPond music engraving program,
> changing the music notation font standard to SMuFL, which ideally supports
> OpenType features, i.e. ligatures and stylistic alternates. For the most
> part, we've been using the FreeType library, but since FT doesn't support
> OT features, I've begun to look elsewhere. HarfBuzz seems like a good
> choice, as we already use Pango elsewhere in the program, so we already
> have a dependency on it.
>
> However, I'm having trouble navigating the documentation, in particular
> how to read the GSUB table's entire 'salt' lookup subtable at once (and
> others, as needed), as an easy-to-use format, e.g. std::map. Is there a way
> to take a font face loaded through FT and extract feature subtables from it
> in this way?
>
> Thanks in advance,
> Owen Lamb
> _______________________________________________
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>


-- 
behdad
http://behdad.org/
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