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

Erik Dahlström wrote:
> On Wed, 29 Oct 2008 17:48:24 +0100, fantasai <fantasai.lists@inkedblade.net> wrote:
> 
>> Erik Dahlström wrote:
>>> On Wed, 29 Oct 2008 00:21:35 +0100, fantasai <fantasai.lists@inkedblade.net> wrote:
>>>> Doug Schepers wrote:
>>>>> fantasai wrote (on 10/28/08 7:10 PM):
>>>>>> Doug Schepers wrote:
>>>>>>> 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'.
>>>
>>>> I suggest removing the text. The first quoted sentence is very clearly wrong.
>>> Is the corresponding sentence in CSS also wrong?
>> The corresponding sentence in CSS is qualified as describing only
>> inline elements, which are effectively invisible to the bidi
>> algorithm unless 'unicode-bidi' is set.
>>
>> The same might be true of tspan elements *if* they are *never*
>> responsible for bounding the bidi algorithm's paragraph (i.e. never
>> form a "text chunk" in SVG terms). I don't know enough about SVG's
>> text model to say if that is true. But 'direction' also applies to
>> <text> elements (or should) so even if tspan elements are the
>> equivalent of CSS's inline elements, then you'd need to qualify the
>> statement to describe only them.
> 
> Thanks for the clarification. 
> 
> Yes, in SVG 1.2 Tiny a 'tspan' element can never establish a "text chunk"
> since 'tspan' lacks the 'x' and 'y' attributes that give absolute position
> adjustments for text (note that these attributes are available in SVG 1.1
> Full).
> 
> Would the following replacement text satisfy your comment:
> 
> "For the 'direction' property to have any effect on an element that does
. not by itself establish a new 'text chunk' (such as the 'tspan' element),
> the 'unicode-bidi' property's value must be 'embed' or 'bidi-override'."

I would suggest writing the parenthetical as
   (such as the 'tspan' element in SVG 1.2 Tiny)
and s/by iteself/itself/ but either way is acceptable.

Please also remove the paragraph about glyph orientation, and I will consider
my comment satisfied.

~fantasai

Received on Thursday, 30 October 2008 10:47:38 UTC