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RE: [css3-fonts] font selection for Unicode Variation Selector

From: Koji Ishii <kojiishi@gluesoft.co.jp>
Date: Mon, 21 Feb 2011 00:52:17 -0500
To: John Hudson <tiro@tiro.com>
CC: "www-style@w3.org" <www-style@w3.org>
Message-ID: <A592E245B36A8949BDB0A302B375FB4E0AB201D2F3@MAILR001.mail.lan>
Thank you for your response, John.

Yeah, you're right, it's tricky.

I understand what you said from technical perspective. But from authors perspective, if the author has one font for Adobe-Japan1 collection and another for Hanyo-Denshi collection[1], it means that the author must apply appropriate font for each character to render IVS correctly.

It's a little far from what authors wanted to achieve using IVS and expect to CSS font fallback mechanism, isn't it?


Regards,
Koji

[1] http://www.unicode.org/ivd/

-----Original Message-----
From: John Hudson [mailto:tiro@tiro.com] 
Sent: Monday, February 21, 2011 2:26 PM
To: Koji Ishii
Cc: www-style@w3.org
Subject: Re: [css3-fonts] font selection for Unicode Variation Selector

Koji Ishii wrote:

> When source text contains Unicode Variation Selector[1][2][3], how does that affect font choice for the code point?

> Here's an example. With the following style:
>   font-family: A B;
> and let's say both fonts contains the glyph for U+8FBA, but only font B contains VS1 of U+8FBA.

> For the source text of U+8FBA VS1, should font A be used to render it, or B?

> I assume font B, as font A does not contain the glyph the author specified and ignores VS1, but I'd appreciate clarification since Variation Selector can behave differently from the regular code point for font fallback.

It's a tricky question, because variation selector characters are default ignorable, so displaying with Font A would not be wrong from a Unicode conformance perspective: "if the variation sequence is not supported, the variation selector should be invisible and ignored."

I suspect the onus must be on authors to ensure that their font lists are in an appropriate order to support the most desirable display of the text.

JH
Received on Monday, 21 February 2011 05:52:11 GMT

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