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Re: [SVGMobile12] Lack of BIDI 'direction' (ISSUE-2058)

From: Erik Dahlström <ed@opera.com>
Date: Wed, 29 Oct 2008 11:17:49 +0100
To: fantasai <fantasai.lists@inkedblade.net>, "Doug Schepers" <schepers@w3.org>
Cc: www-style@w3.org, public-i18n-core@w3.org, www-svg <www-svg@w3.org>
Message-ID: <op.ujr6vz09gqiacl@gnorps.linkoping.osa>

On Wed, 29 Oct 2008 00:21:35 +0100, fantasai <fantasai.lists@inkedblade.net> wrote:

>
> Doug Schepers wrote:
>> Hi, fantasai-
>>
>> fantasai wrote (on 10/28/08 7:10 PM):
>>> Doug Schepers wrote:
>>>> fantasai wrote (on 9/17/08 7:51 PM):
>>>>> I therefore strongly recommend that SVG Tiny include the 'direction'
>>>>> property.
>>>> Thanks for your suggestion.  We agree with you and the I18N WG, and have
>>>> added both 'direction' and 'unicode-bidi' properties. [1]
>>>>
>>>> http://dev.w3.org/SVG/profiles/1.2T/publish/text.html#DirectionProperty
>>>   # For the 'direction' property to have any effect, the 'unicode-bidi'
>>>   # property's value must be embed or bidi-override.
>>>
>>> This is false. As I explained before, the 'direction' property alone has an
>>> effect when set at the paragraph level ("paragraph" being the unit of text
>>> the bidi algorithm operates on).

I'm guessing this wording was the SVG translation of the following sentence in CSS:
"For the 'direction' property to have any effect on inline-level elements, the 'unicode-bidi' property's value must be 'embed' or 'override'."

So the question then becomes: what is an "inline-level element" in terms of svg?

I'm thinking that this might be the 'tspan' element, since that cannot start a text content block by itself. The 'tspan' element always needs to be enclosed in a 'text content block element'. 

>>>   # The 'direction' property applies only to glyphs oriented perpendicular
>>>   # to the inline-progression-direction, which includes the usual case of
>>>   # horizontally-oriented Latin or Arabic text and the case of narrow-cell
>>>   # Latin or Arabic characters rotated 90 degrees clockwise relative to a
>>>   # top-to-bottom inline-progression-direction.
>>>
>>> This doesn't make any sense. The 'direction' property does not apply to
>>> glyphs, it applies to text runs. (Although when combined with
>>> "bidi-override" it does also apply to characters.)
>>
>> As I understand it, the wording for 'direction' and 'unicode-bidi' comes
>> directly from SVG 1.1, and has been around for a while.  However, it's
>> possible that there was an error (or ambiguity) in that spec.  If you
>> could propose alternative wording, and if the I18N WG concurs with you,
>> the SVG WG will almost certainly make the suggested change (though I'd
>> have to check with them first, of course).
>
> I suggest removing the text. The first quoted sentence is very clearly wrong.

Is the corresponding sentence in CSS also wrong?

> The second quoted sentence is most likely referring to the effects of the
> glyph-orientation properties, which are not included in SVG 1.2 Tiny, and
> which are very poorly defined in SVG 1.1.

I agree that this sentence seems both incorrect and unnecessary in SVG 1.2 Tiny.

Cheers
/Erik

-- 
Erik Dahlstrom, Core Technology Developer, Opera Software
Co-Chair, W3C SVG Working Group
Personal blog: http://my.opera.com/macdev_ed
Received on Wednesday, 29 October 2008 10:16:36 GMT

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