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

[Eli Zaretskii]

> Cc: behdad at behdad.org, harfbuzz at lists.freedesktop.org
> From: Jonathan Kew <jfkthame at gmail.com>
> Date: Sat, 11 May 2019 22:15:46 +0100
> 
> > Would wrapping in a blob the buffer returned by GetFontData be enough?
> 
> If you use GetFontData to get the complete font as a single buffer (i.e. 
> pass zero for the dwTable parameter), yes.
> 
> Alternatively, you could use hb_face_create_for_tables, with a 
> reference_table_func that uses GetFontData to read individual tables 
> when harfbuzz asks for them.

OK, thanks.  I think this is a large chunk of the solution to my
problem.

Assuming that I want to use GetFontData, what factors and aspects
should I consider when deciding whether to create a single blob with
the entire font's data or to go for the hb_face_create_for_tables
variety?

Also, does HarfBuzz support TrueType Collection (TTC) files, and if
so, does it want the data only for the currently selected font or all
of the data?