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Re: [css-writing-modes-3] central baseline of text with 'text-orientation: upright'

From: Gérard Talbot <www-style@gtalbot.org>
Date: Fri, 29 Aug 2014 22:47:59 -0400
To: Koji Ishii <kojiishi@gluesoft.co.jp>, fantasai <fantasai.lists@inkedblade.net>
Cc: W3C www-style mailing list <www-style@w3.org>
Message-ID: <b8cbbce531540e191ea7f6a4ce4b046c@gtalbot.org>
Le 2014-08-27 23:43, Gérard Talbot a écrit :
> Hello,
> 
> "
> In vertical writing mode, the central baseline is used as the dominant
> baseline when text-orientation is mixed or upright.
> "
> http://www.w3.org/TR/css-writing-modes-3/#text-baselines
> 
> I do not understand how and why there can be a central baseline for
> text with 'text-orientation' set to 'upright'. How can this be?
> 
> This image
> 
> http://www.w3.org/TR/css-writing-modes-3/text-orientation-up.png
> 
> of vertical text in 2 line boxes has text-orientation set to upright.
> 
> Now, how can the baseline-alignment of glyphs be using the central
> baseline here?
> 
> Gérard

I may have stumbled on a possible explanation:

"
Ideographic (cl-19), hiragana (cl-15) and katakana (cl-16) characters 
are the same size, and have square character frames of equal dimensions.
"
2.1.2 Kanji, Hiragana and Katakana
http://www.w3.org/TR/jlreq/#kanji_hiragana_and_katakana

"
Ideographic (cl-19), hiragana (cl-15) and katakana (cl-16) characters 
for Japanese composition have basically been designed to have a square 
character frame from the letterpress printing era on.
"
2.3.1 Directional Factors in Japanese Composition
http://www.w3.org/TR/jlreq/#directional_factors_in_japanese_composition


If this is the case, then a central baseline can be determined for text 
with 'text-orientation' set to 'upright' but is this feature (characters 
designed to have a square character frame) also the case for other 
vertical scripts?

Gérard
Received on Saturday, 30 August 2014 02:48:30 UTC

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