[HarfBuzz] How to get hb_face_t and hb_font_t without Freetype?

[Eli Zaretskii]

> From: Behdad Esfahbod <behdad at behdad.org>
> Date: Sat, 11 May 2019 11:26:29 -0700
> Cc: Jonathan Kew <jfkthame at gmail.com>, 
> 	"harfbuzz at lists.freedesktop.org" <harfbuzz at lists.freedesktop.org>
> 
> Or just use hb_face_create() and hb_font_create(). 

Thanks, that's what I thought I needed to do to begin with.  However,
hb_face_create needs a 'blob' argument, and I couldn't understand how
to call hb_blob_create to get a suitable blob.  Then I looked at how
hb_ft_face_create does it, and saw that it makes a blob out of FT_Face
structure.  But I couldn't see how that blob is used by HarfBuzz, and
so couldn't decide how to call hb_blob_create in my case.

Was I asking myself the right questions?  If so, how can I find the
answers?

TIA