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RE: [CSS3-text] text-underline-position and superscript

From: Koji Ishii <kojiishi@gluesoft.co.jp>
Date: Sun, 26 Dec 2010 09:22:52 -0500
To: Ambrose LI <ambrose.li@gmail.com>
CC: "Belov, Charles" <Charles.Belov@sfmta.com>, "www-style@w3.org" <www-style@w3.org>
Message-ID: <A592E245B36A8949BDB0A302B375FB4E0AA8B1C054@MAILR001.mail.lan>
Thank you for your summary. Yes, the way you organized issues matches to what I think they should be.

For issue #1, it's generalized as "underlining to text that contains multiple different properties (fonts, super/sub, etc.)", and I agree that it should be handled better. Actually it does in the current CSS3 text spec[1]. Can you please review it and see if the problem still exists?

For issue #2, I still see the issue is the same one as Kenny brought up[2]. I'm not against the idea, I actually would like it happen, I'm just saying the issue is different from #1. I was actually hoping to write up something once I've got responses to [2] and we all have got consensus, but it didn't happen unfortunately. If you could go back to the thread and continue the discussions, that'd be helpful to make it happen.

[1] http://dev.w3.org/csswg/css3-text/#line-decoration
[2] http://lists.w3.org/Archives/Public/www-style/2010Dec/0117.html


Regards,
Koji

-----Original Message-----
From: Ambrose LI [mailto:ambrose.li@gmail.com] 
Sent: Sunday, December 26, 2010 11:00 PM
To: Koji Ishii
Cc: Belov, Charles; www-style@w3.org
Subject: Re: [CSS3-text] text-underline-position and superscript

Sorry for following up on myself again. I'll blame it being early morning, but let me reorganize myself a bit and restate how the two ideas are related:

==================================================

There are two generalized principles common to Charles' and my ideas, and the two general principles are that:

1. We need some way to specify that, in some situations, no matter what the glyph-specific underline position is, we want to keep a constant underline position for some logical grouping of characters.

(1a) For superscript/subscripts: underlines don't move up/down due to the super/subscripting

(1b) For Chinese: underlines don't move up/down when there are Latin or other non-CJK characters in the sequence

2. As a corollary of the above, we need some way to specify that underlines are always visually disjoint if they are semantically marked up as separate.

(2a) For superscripts/subscripts: The logical markup is provided by SUP or SUB and we make it clear that we want the underlines to move up/down along with the super/subscript

(2b) For Chinese: The logical markup is provided by U and we make it clear that the two adjacent underlines should never run into each other

(2c) The Chinese use case could also potentially be useful for non-Chinese situations

What Charles proposed are ways to specify how the constant underline position in #1 should be determined, and to specify how a non-constant underline position in #2 can be explicitly specified for superscripts and subscripts. Perhaps there can be ways to get rid of the proposed keywords, but his proposal is a good analysis (without considering the requirements for the Chinese typography) of what we will need to deal with when we need the browser to figure out a constant position for the underlining.

Charles did not explicitly specify a use case for "pixel positioning", but I suggested it as a possible fix for incorrect underline position in Chinese. The above also shows that the counter-proposal of correcting the underline positions in CJK fonts (which still should be corrected, since this affects also word processors) alone will not be a complete fix to the Chinese problem. Personally, I envision "pixel positioning" to be usable as a workaround for both problem #1, and problem #2 when we are dealing specifically with superscripts and subscripts; it may not be a perfect solution but this could be what Charles had in mind, *especially* if you don't want the proposed additional keywords.

--
cheers,
-ambrose

does anyone know how to fix Snow Leopard? it broke input method switching and is causing many typing mistakes and is very annoying
Received on Sunday, 26 December 2010 14:26:15 GMT

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