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Re: I18N-ISSUE-145: text-transform: full-width explanation [CSS3-text-prep]

From: Richard Ishida <ishida@w3.org>
Date: Thu, 22 May 2014 12:10:46 +0100
Message-ID: <537DDB36.3040704@w3.org>
To: Koji Ishii <kojiishi@gluesoft.co.jp>, Internationalization Core Working Group WG <public-i18n-core@w3.org>
Thanks for the explanation, Koji. I think I understand now. Iiuc, a 
codepoint such as U+0041 is converted to a full-width character because 
the application knows that there is a character (U+FF21) with a <wide> 
decomposition to U+0041.  (I assume there is never a situation where 
more than one fullwidth character decomposes to the same non-fullwidth 
character - which would set up an ambiguity.)

RI


On 16/12/2011 15:23, Koji Ishii wrote:
> Thank you for the review. If you look at UnicodeData.txt[1], decomposition mappings look like this:
>
> FF21 FULLWIDTH LATIN CAPITAL LETTER A <wide> 0041
> FF61 HALFWIDTH IDEOGRAPHIC FULL STOP <narrow> 3002
>
> So, the "text-transform: full-width" should transform:
> U+0041 -> U+FF21
> U+FF61 -> U+3002
>
> The decomposition tag naming looks like opposite from my intuition, but the current text describes the correct behavior, doesn't it?
>
> [1] http://www.unicode.org/Public/UNIDATA/UnicodeData.txt
>
> Regards,
> Koji
>
> -----Original Message-----
> From: Internationalization Core Working Group Issue Tracker [mailto:sysbot+tracker@w3.org]
> Sent: Friday, December 16, 2011 7:08 PM
> To: public-i18n-core@w3.org
> Subject: I18N-ISSUE-145: text-transform: full-width explanation [CSS3-text-prep]
>
>
> I18N-ISSUE-145: text-transform: full-width explanation [CSS3-text-prep]
>
> http://www.w3.org/International/track/issues/145
>
> Raised by: Richard Ishida
> On product: CSS3-text-prep
>
> 2.1. Transforming Text: the ‘text-transform’ property http://dev.w3.org/csswg/css3-text/#text-transform
>
> "The definition of fullwidth and halfwidth forms can be found on the Unicode consortium web site at [UAX11]. The mapping to fullwidth form is defined by taking code points with the <wide> or the <narrow> tag in their Decomposition_Mapping in [UAX44]. For the <narrow> tag, the mapping is from the code point to the decomposition (minus <narrow> tag), and for the <wide> tag, the mapping is from the decomposition (minus the <wide> tag) back to the original code point."
>
> I don't understand this. If you map to decomposition mappings the characters are no longer full-width, right? How can your example abbr:lang(ja) { text-transform: full-width;  convert the ASCII characters in abbreviations in Japanese to their fullwidth variants so that they lay out and line break like ideographs?
>
>
>
>
Received on Thursday, 22 May 2014 11:11:27 UTC

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