[HarfBuzz] Selecting fonts for HarfBuzz

[Eli Zaretskii]

> Date: Fri, 7 Jun 2019 05:31:33 +0200
> From: Khaled Hosny <dr.khaled.hosny at gmail.com>
> Cc: Behdad Esfahbod <behdad at behdad.org>, harfbuzz at lists.freedesktop.org
> 
> > > HarfBuzz handles everything it understands.  It was designed, in fact, such that when combined with
> > > FreeType or other external font funcs implementation, it even "handles" font formats it does not understand. 
> > > Eg. HarfBuzz doesn't understand BDF, PCF, etc, but if you use hb-ft, you can use hb-ft for everything, and
> > > BDF, PCF etc also magically work because HarfBuzz defers to FreeType for glyph access, and simply
> > > "passes through" for the rest.  It was designed such that you can keep one shaping code path.
> > 
> > We don't currently use hb-ft on Windows.  But thanks, I think I
> > understand.
> 
> You can achieve the same by implementing font functions for the font
> formats HarfBuzz does not directly support, using e.g. GDI API to access
> glyph info in these fonts (see hb_font_funcs_set_* functions).

Thanks, I will look into this, time permitting.