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RE: Need to clarify the effects of bidi paragraph breaks

From: CE Whitehead <cewcathar@hotmail.com>
Date: Thu, 16 Dec 2010 14:30:15 -0500
Message-ID: <SNT142-w23E793B9FBE67B1E767EEFB3150@phx.gbl>
To: <mohiem@eg.ibm.com>, <aharon@google.com>
CC: <fantasai.lists@inkedblade.net>, <public-i18n-bidi@w3.org>, <public-i18n-bidi-request@w3.org>, <www-style@w3.org>


+ 1 on this
OR NOT TO BE?
(with rtl characters)
should be displayed as RTL even though on a new line.  (And it is in my ie8 browser, so I am confused; the only trouble comes in notepad with the punctuation I think . . . and does not seem to  )



itehead
cewcathar@hotmail.com 
 


 

> To: aharon@google.com
> CC: fantasai.lists@inkedblade.net; public-i18n-bidi@w3.org; public-i18n-bidi-request@w3.org; www-style@w3.org
> From: MOHIEM@eg.ibm.com
> Date: Thu, 16 Dec 2010 12:51:39 +0200
> Subject: Re: Need to clarify the effects of bidi paragraph breaks
> 
> I support the proposal of not allowing <br> to break the inherited
> directionality as Aharon highlighted in the example below:
> "OR NOT TO BE?"
> In my opinion the above should be displayed as RTL.
> 
> 
> Thanks And Best regards,
> Mohamed Mohie , PMP®
> ________________________________________________
> GCoC BIDI ,
> Advisory Software Engineer, Project Manager, M.Sc.
> Cairo Technology Development Center (CTDC) - CMMI L5
> IBM Egypt
> 
> 
> 
> From: "Aharon (Vladimir) Lanin" <aharon@google.com>
> To: W3C style mailing list <www-style@w3.org>, fantasai
> <fantasai.lists@inkedblade.net>, "public-i18n-bidi@w3.org"
> <public-i18n-bidi@w3.org>
> Date: 16/12/2010 12:13 Õ
> Subject: Need to clarify the effects of bidi paragraph breaks
> Sent by: public-i18n-bidi-request@w3.org
> 
> 
> 
> Currently, the CSS Writing Modes Module Level 3 spec on text direction
> states:
> 
> "User agents that support bidirectional text must apply the Unicode
> bidirectional algorithm to every sequence of inline boxes uninterrupted by
> a forced (bidi class B) line break or block boundary. This sequence forms
> the "paragraph" unit in the bidirectional algorithm. The paragraph
> embedding level is set according to the value of the ‘direction’ property
> of the containing block rather than by the heuristic given in steps P2 and
> P3 of the Unicode algorithm."
> 
> Further down in the same major section, the definition of
> unicode-bidi:plaintext states:
> 
> "For the purposes of the Unicode bidirectional algorithm, the base
> directionality of each "paragraph" for which the element is the containing
> block element is determined not by the element's computed ‘direction’ as
> usual, but by following rules P1, P2, and P3 of the Unicode bidirectional
> algorithm."
> 
> I think that these parts of the spec needs to be tweaked in several
> respects:
> 
> 1. There is no reason to mention rule P1 when describing how
> unicode-bidi:plaintext affects the base directionality of each paragraph.
> P1 deals with how the text is split up into paragraphs, not with the
> direction of each paragraph, and applies to all content, regardless
> of unicode-bidi:plaintext.
> 
> 2. I think it would improve clarity to mention the unicode-bidi:plaintext
> exception when first describing how the paragraph embedding level is set
> (first quote above). Thus, the last sentence of the first quote should
> read:
> 
> "The paragraph embedding level is set according to the value of the
> ‘direction’ property of the containing block, unless the containing block
> element has unicode-bidi:plaintext, in which case it is set according to
> the heuristic given in steps P2 and P3 of the Unicode algorithm."
> 
> 3. We must probably explicitly define the effect of a paragraph break (i.e.
> a block boundary or bidi class B line break, which in HTML5 includes <br>)
> when the path from the containing block element to the paragraph break
> includes elements with a unicode-bidi value other than "normal". For
> example, what happens when we have (as usual, uppercase English is used
> instead of RTL characters) :
> 
> <div dir=ltr>
> <span dir=rtl>
> TO BE<br>
> OR NOT TO BE?
> </span>
> -- hamlet, in rtl translation.
> </div>
> 
> Should the "OR NOT TO BE?" be displayed in rtl ("?EB OT TON RO") or in ltr
> ("EB OT TON RO?")?
> 
> While it seems obvious that it should be displayed in RTL because it is
> part of a <span dir=rtl>, that is not the result if we simply translate the
> above into Unicode bidi formatting characters, i.e.
> 
> [RLE]TO BE
> OR NOT TO BE?[PDF] -- hamlet, in rtl translation.
> 
> The overall direction of both paragraphs is ltr (P2 and P3 are overridden),
> and since the paragraph break resets all embedding levels, the [PDF] is
> orphaned, and the question mark winds up to the right of "EB OT TON RO".
> 
> I believe that the correct approach to take is to treat the second bidi
> paragraph (i.e. "TO BE ... translation.") the same as:
> 
> <div dir=ltr>
> <span dir=rtl>
> OR NOT TO BE?
> </span>
> -- hamlet, in rtl translation.
> </div>
> 
> In other words, while the paragraph's overall level should be set according
> to the value of the ‘direction’ property of the containing block (ltr), it
> should be opened by repeating the embeddings or overrides introduced by the
> elements between the paragraph break and the containing block - in our
> example, the equivalent of an RLE (which is then matched by the </span>'s
> PDF equivalent).
> 
> This is similar to the CSS specs for anonymous block boxes, i.e:
> 
> "When an inline box contains a block box, the inline box (and its inline
> ancestors within the same line box) are broken around the block. The line
> boxes before the break and after the break are enclosed in anonymous boxes,
> and the block box becomes a sibling of those anonymous boxes. When such an
> inline box is affected by relative positioning, the relative positioning
> also affects the block box."
> 
> "The properties of anonymous boxes are inherited from the enclosing
> non-anonymous box".
> 
> Does a line break does result in anonymous boxes? If not, we certainly need
> something in the Writing Modes spec. Actually, it would be good to have it
> either anyway, just to clarify things.
> 
> 4. When the path from the containing block element to the paragraph break
> includes an element with unicode-bidi:isolate, there is no reason to go
> back all the way to the containing block element to get the new paragraph's
> base direction and the embeddings to be reconstituted at its start. Instead
> of referring to the containing block element, the spec should be referring
> to the closest unicode-bidi:isolate ancestor or containing block element,
> whichever is closer.
> 
> Aharon
 		 	   		  
Received on Thursday, 16 December 2010 19:30:50 GMT

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