Michael Everson wrote:
> At 09:41 -0600 2002-07-02, John H. Jenkins wrote:
>
> >Alas, but that's technically impossible. Both OT and AAT (I'm not
> >sure about Graphite) require that single characters map to single
> >glyphs, which are then processed.
I am confused by this statement; perhaps some expert in fonts can help me
checking my understanding.
The OpenType specs published on the Adobe site states that table GSUB has a
subtable to handle ligatures ("LookupType 4: Ligature Substitution
Subtable": http://partners.adobe.com/asn/developer/opentype/gsub.html#LSF1).
It says that "A Ligature Substitution (LigatureSubst) subtable identifies
ligature substitutions where a single glyph replaces multiple glyphs"
(multiple *glyphs*, not multiple characters).
OK: literally speaking, it is true that OT maps single characters to single
glyphs, but then it maps multiple glyphs to ligature glyphs, so what's the
difference?
I mean: isn't this two-step mapping:
code point -> glyph ID
component glyph ID's -> ligature glyph ID
functionally equivalent to an hypothetical one-step mapping?
component code points -> ligature glyph ID
Am I missing something?
_ Marco
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