RE: [SVGMobile12] Lack of BIDI 'direction'

At 06:41 08/10/11, Phillips, Addison wrote:
>Hello Chris,
>
>Thanks for this note. A few comments.
>
>> 
>> That is correct. Thank you for pointing out this omission. SVG 1.1
>> has
>> a direction property, as does SVG Basic 1.1. SVG Tiny 1.1 did not
>> have
>> it, because the text element could not have a tspan child element
>> in
>> Tiny 1.1 and thus adittional levels of embedding were not possible.
>
>Additional levels of embedding were, in fact, possible, since most 
>embedding levels come from character properties. The lack of 'tspan' meant 
>that no additional overriding markup was possible.
>
>> 
>> > This is a problem because the Unicode bidirectional algorithm
>> needs a
>> > base direction for each "paragraph" that it operates on. For
>> plain text
>> > it guesses based on the first character in the text, but this is
>> not
>> > always accurate.
>> 
>> Yes, if the initial character is directionally weak, or neutral, it
>> will not give the expected results and must be overidden.
>
>The first character might even be strongly opposed to the base direction of 
>the overall paragraph. A paragraph might start, for example, with a word in 
>Arabic script, even though the sentence is in English. That does not mean 
>the whole paragraph should have a base direction of RTL for layout purposes.

I concur with Addison. If there was a version of SVG that
did not allow direction because it thought it could rely on
the implicit setting of the base directionality in the Unicode
bidi algorithm, then I'd call this at least an oversight.
[Of course, that was everybody's oversight, and we may have to
live with some of its consequences.]

The Unicode bidi algorithm comes with this implicit setting
because if there is no other way to get a base directionality,
that's may be the least bad setting. But it doesn't mean that
technology that has a chance to provide an explicit setting
possibility shouldn't do so.

Regards,     Martin.

>> The SVG WG has discussed your recommendation and agrees with it. In
>> response you your last call feedback, SVG Tiny 1.2 will re-instate
>> both the 'direction' and the 'unicode-bidi' properties from SVG 1.1.
>
>Thanks. I18N Core supports Fantasai's comment. I suspect the WG will concur 
>with the resolution at our next teleconference (Wednesday)
>
>Addison
>
>
>Addison Phillips
>Globalization Architect -- Lab126
>Chair -- W3C Internationalization Core WG
>
>Internationalization is not a feature.
>It is an architecture.


#-#-#  Martin J. Du"rst, Assoc. Professor, Aoyama Gakuin University
#-#-#  http://www.sw.it.aoyama.ac.jp       mailto:duerst@it.aoyama.ac.jp

Received on Tuesday, 14 October 2008 06:29:18 UTC