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[ttml2] rubyAlign withBase

From: r12a via GitHub <sysbot+gh@w3.org>
Date: Thu, 16 Feb 2017 17:26:02 +0000
To: public-tt@w3.org
Message-ID: <issues.opened-208190394-1487265960-sysbot+gh@w3.org>
r12a has just created a new issue for https://github.com/w3c/ttml2:

== rubyAlign withBase ==
10.2.34 tts:rubyAlign
https://www.w3.org/TR/2016/WD-ttml2-20161117/#style-attribute-rubyAlign

> If the value of this attribute is withBase, then, if NR and NB are 
equal, the ith glyph area descendant of IR is center aligned 
(horizontally or vertically) with the ith glyph area descendant of IB;
 otherwise (the number of ruby and base glyph areas are not equal), 
the semantics of center apply.

For a discussion of what constitutes a glyph area descendant see 
https://github.com/w3c/ttml2/issues/236

I can't really understand the use case for this value. I'm assuming 
that the mapping of ruby text to base text should normally be achieved
 using markup, since that's where the semantics happen.  I'm finding 
it hard to imagine a situation where NR and NB are likely to be equal 
other than the cases where you have one of each eg. 亜(あ)麻(ま)仁(に), much
 less when you'd want the ruby text and base text to be aligned with 
the each other.  

I think this could encourage authors to use poor markup, such as 
亜麻仁(あまに) rather than 亜(あ)麻(ま)仁(に) , which would cause problems for 
line breaking. It could also produce some false positives.

And if NR and NB are equal in some text, given that this is the 
default for auto, i think it might produce surprises, since it would 
produce a different alignment on those cases, whether you intend that 
or not.

Please view or discuss this issue at 
https://github.com/w3c/ttml2/issues/248 using your GitHub account
Received on Thursday, 16 February 2017 17:26:09 UTC

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