[HarfBuzz] Beginner question: What are cluster levels?

[Graham Douglas]

On 04/01/2016 17:06, Behdad Esfahbod wrote:
> Hi Jamie and Deepak,
>
> I'll try to get a detailed reply to this thread tomorrow.
>
> Cheers,
> behdad
>
> <snip>
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Hi Behdad

I too am interested in this. In particular, suppose you have a shaped
glyph,
---such as an Arabic ligature--- I'd like to know if it is possible to
determine
the set of (unshaped) input characters (glyphs) from which the ligature was
constructed. I'm not doing hit testing, just PDF generation (via LuaTeX
--- and libraqm).
I just want typeset things like this:

LIGATURE <--- ...+U2+U1

where Ui are the constituent unshaped Arabic glyphs
which have been combined to create the LIGATURE.

Cheers
Graham