Re: ZWL, ZWNL no difference?

From: John Jenkins (jenkins@apple.com)
Date: Thu Dec 30 1999 - 13:25:47 EST


on 12/30/99 8:36 AM, John Cowan at jcowan@reutershealth.com wrote:

> "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.
>

Fonts don't have such lists, nor does ATSUI (at least). And they're not
filtered out before the character-glyph mapping -- and I'm pretty sure that
current OT systems are the same.

To work, you'd need to have:

f + i -->
f + SHY + i -->
(f + ZWL + i ) -->
(f + SHY + ZWL + i ) -->
(f + ZWL + SHY + i ) -->

All explicitly in your list of potential ligatures in your font.

=====
John H. Jenkins
jenkins@apple.com
tseng@blueneptune.com
http://www.blueneptune.com/~tseng



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