Re: (long) Re: Chromatic font research

From: Doug Ewell (dewell@adelphia.net)
Date: Sat Jun 29 2002 - 11:20:23 EDT


William Overington <WOverington at ngo dot globalnet dot co dot uk>
wrote:

> My point in citing The Respectfully Experiment in the recent post is
> that even though the reasons for not including any more ligatures in
> Unicode may have seemed totally reasonable at the time that that
> decision was made, the idea of James Kass that the glyphs for
> ligatures in an OpenType font could also be accessed directly does
> add new evidence to the situation. In the light of this new evidence,
> I am wondering whether the decision not to encode any new ligatures
> in regular Unicode could possibly be looked at again.

So the "new evidence" is that a precomposed glyph can be used both (a)
directly, to render a single Unicode code point, and (b) indirectly, to
render a combining sequence? There's nothing new there, William.

Font designers regularly include a glyph for U+FB01 LATIN SMALL LIGATURE
FI. It has always been known, and obvious, that a user could access
this glyph directly by encoding U+FB01. With the advent of OpenType and
a smart-enough rendering system, the user could alternatively encode the
sequence U+0066 U+200D U+0069 (f ZWJ i) and get the same glyph. (Or, as
John Jenkins points out, if you have a Mac you can see this glyph simply
by encoding "fi," without the need for the ZWJ hint.)

This isn't limited to ligatures, either. Font designers also regularly
include a glyph for U+00E1 LATIN SMALL LETTER A WITH ACUTE. You can
either encode U+00E1 directly and see the glyph, or you can encode
U+0061 U+0301 (a ) and get the same glyph. This doesn't even require
OpenType, just non-spacing glyphs.

What is so different about doing this with a ct ligature, encoded
provisionally in the PUA, compared to doing it with the fi ligature or
the a-with-acute that have been in Unicode at least since version 1.1?
Where is the new scientific discovery?

> My intended meaning was that both types of ligation (precomposed and
> ZWJ) could be in the same font.

Of course they can.

> Also, it is not a matter of overturning a decision, it is a matter of
> the decision being modified in the light of the new evidence, namely
> that both methods may be used simultaneously in an OpenType font.

Without worrying about the distinction between "overturning" and
"modifying" a decision, the fact remains that there is nothing new about
this "new evidence." Every OpenType font designer knows it.

-Doug Ewell
 Fullerton, California



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