[HarfBuzz] HarfBuzz shaping of R2L text

[Richard Wordingham]

On Mon, 03 Jun 2019 05:34:13 +0300
Eli Zaretskii <eliz at gnu.org> wrote:

> > Date: Sun, 2 Jun 2019 20:29:15 +0100
> > From: Richard Wordingham <richard.wordingham at ntlworld.com>
> > Cc: harfbuzz at lists.freedesktop.org
> > 
> > On Sun, 02 Jun 2019 21:01:35 +0300
> > Eli Zaretskii <eliz at gnu.org> wrote:
> >   
> > > The version of HarfBuzz I built on Windows and am using with
> > > Emacs has Graphite support, so I reckon I don't have to worry
> > > about picking up a Graphite shaper?  
> > 
> > It depends what you want to do with the shaper.  If you want to
> > study what it does in the way of sequencing the glyphs, you need to
> > ensure you use the shaper you want to study!  The order the glyphs
> > are presented to the renderer may be very different between using a
> > Graphite shaper and using the HarfBuzz OpenType shaper.  For one
> > thing, swapping glyphs round is easy in Graphite and complicated in
> > OpenType.  
> 
> I don't think I understand what you mean by "Graphite shaper".  I'm
> using just HarfBuzz (which has Graphite capabilities); no other shaper
> is involved.

As far as I am aware, HarfBuzz does not interpret Graphite font
tables.  It uses a Graphite library from SIL to apply the font
definition to the character stream.  That library provides the
"Graphite shaper".

Richard.