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Re: position of baseline relative to em square

From: Chris Lilley <chris@w3.org>
Date: Wed, 01 Dec 1999 11:20:12 +0100
Message-ID: <3844F65C.2DD925AF@w3.org>
To: Nick Nussbaum <nickn@seanet.com>
CC: www-font@w3.org, Todd Fahrner <fahrner@pobox.com>


Nick Nussbaum wrote:
> 
> Neither is correct.
> The baseline is a function of the script. Han and Math center character
> center the baseline and the em square would be correct. Latin fonts use an
> assymmetric baseline. Since some fonts support multiple scripts, the safest
> thing would be to provide a font property with a value for each script. This
> is why there's a BASE table in Truetype Open, although default values can be
> calculated for older formats based on the script.

Yes, that is what the four 'baseline' font descriptors are for in CSS2
@font-face

> Note that characters actually are aligned optically to the baseline. See
> http://www.microsoft.com/typography/developers/fdsspec/default.htm
> for a nice discussion of some of the complexities.
> If you had to choose one, it would be better to use Em Square rather than
> Bounding box. Bounding box means that two fonts of the same typeface  with
> different character sets might  align differently because one had Uppercase
> accents.

Yes.

--
Chris
Received on Wednesday, 1 December 1999 05:20:18 GMT

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