Re: ZWL, ZWNL no difference?

From: John Cowan (jcowan@reutershealth.com)
Date: Thu Dec 30 1999 - 11:35:56 EST


"Mark E. Davis" wrote:

> A. If we have an existing font, with existing ligature glyph mappings,
> then
> - changing the font for ZWNL support means mapping it to the empty glyph.
> - changing the font for ZWL support means mapping it to the empty glyph,
> plus adding all the new triple ligature mappings.

Not necessarily. The font probably has some notion of "ligature-ignorables"
which may appear between the characters of a ligature without breaking it up,
such as SHY. (Or are those filtered out before the font rendering stage?)
If so, ZWL could be added to that list.

> B. If we have an existing font, without existing ligature glyph mappings,
> then
> - changing the font for ZWNL support means mapping it to the empty glyph.
> - changing the font for ZWL support means mapping it to the empty glyph,
> plus adding all the new triple ligature mappings.

I'm confused. If there are no existing ligature glyphs, then surely no new
mappings are needed except for ZWL and ZWNL themselves.
 
> C. If we have a font with multiple levels of ligature glyph mapping
> support, [...]
> - changing the font for ZWNL support means mapping it to the empty glyph.
> - changing the font for ZWL support means mapping it to the empty glyph,
> plus adding all the new triple ligature mappings to every level, e.g.
> ending up with:

The same solution as in case A works here.

> Of course, this is only the font support. Every other process: searching,
> sorting, etc. needs to be modified.

These processes definitely already have a notion of ignorables, so the
modification is just an extension.

-- 

Schlingt dreifach einen Kreis vom dies! || John Cowan <jcowan@reutershealth.com> Schliesst euer Aug vor heiliger Schau, || http://www.reutershealth.com Denn er genoss vom Honig-Tau, || http://www.ccil.org/~cowan Und trank die Milch vom Paradies. -- Coleridge (tr. Politzer)



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