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RE: Alignment of paragraphs with unicode-bidi: plaintext

From: Ryosuke Niwa <rniwa@webkit.org>
Date: Tue, 6 Dec 2011 10:25:36 -0800
Message-ID: <CABNRm61JfgmHgJZALcAfvqJy-=SFXxhbJ7SrcvjjDpuDNJqFnA@mail.gmail.com>
To: CE Whitehead <cewcathar@hotmail.com>
Cc: smontagu@smontagu.org, public-i18n-bidi@w3.org, www-style@w3.org, matial@il.ibm.com, aharon@google.com
On Dec 6, 2011 10:18 AM, "CE Whitehead" <cewcathar@hotmail.com> wrote:
>
>
>
>
> ________________________________
> From: aharon@google.com
> Date: Tue, 6 Dec 2011 09:38:59 +0200
> To: matial@il.ibm.com
> CC: public-i18n-bidi@w3.org; smontagu@smontagu.org; www-style@w3.org
>
> Subject: Re: Alignment of paragraphs with unicode-bidi: plaintext
>
> https://bugs.webkit.org/show_bug.cgi?id=71194 has been filed about this
on WebKit, and there seems to be a consensus that unicode-bidi:plaintext
would work better if it affected alignment (when text-align/text-align-last
is start or end). There are two possible ways to proceed:
>
> - Change WebKit's behavior as proposed.
> - Wait for a change in the spec - or at least a sign that such a change
is coming.
>
> Fantasai, any guidance?
>
> Aharon
>
> Hmm Aharon, maybe alignment should work off the text/current paragraph's
direction only when the paragraph has at least around 100 bytes (64, or
maybe 128) or something of substance . . . to make direction worth
determining.
> (Just a thought.)

That'll makethe algorithm needlessly complicated, not to mention its
behavior will be hard to determine and will have a surprising side-effects.
eg What happens if you initially had 101 characters and then removed 2?

> Best,
>
> --C. E. Whitehead
> cewcathar@hotmail.com
>
>
> On Mon, Oct 31, 2011 at 5:52 PM, Aharon (Vladimir) Lanin <
aharon@google.com> wrote:
>>
>> Sounds good.
>>
>> Fantasai, do you think it can be specified that way in Writing Modes
level 3?
>>
>> Levi, how difficult would it be to implement in WebKit?
>>
>> Aharon
>>
>>
>> On Mon, Oct 31, 2011 at 2:35 AM, Matitiahu Allouche <matial@il.ibm.com>
wrote:
>>>
>>> My opinion, for what it's worth, is that plaintext paragraphs should be
aligned in sync with paragraph direction for "text-align:start", opposite
to paragraph direction for "text-align:end", to absolute right or left for
"text-align:right" and "text-align:left" respectively.
>>> "text-align:center" should not be a problem.
>>> "text-align:justify" should not be a problem for lines down to the last
one in the paragraph. The last one should be handled like for
"text-align:start".
>>>
>>> The advantage of this proposal is that it provides more readability for
common cases when most paragraphs follow the same direction and span at
least a few lines.
>>> For special cases when there are very short paragraphs with alternate
directions, the author can specify "text-align:right" or "text-align:left",
so we get the advantages of both solutions (Gecko and Chrome).
>>>
>>> Shalom (Regards),  Mati
>>>       Bidi Architect
>>>       Globalization Center Of Competency - Bidirectional Scripts
>>>       IBM Israel
>>>       Mobile: +972 52 2554160
>>>
>>>
>>>
>>>
>>> From:        "Aharon (Vladimir) Lanin" <aharon@google.com>
>>> To:        Simon Montagu <smontagu@smontagu.org>
>>> Cc:        public-i18n-bidi@w3.org, "www-style@w3.org" <www-style@w3.org>

>>> Date:        31/10/2011 00:27
>>> Subject:        Re: Alignment of paragraphs with unicode-bidi:
plaintext
>>> ________________________________
>>>
>>>
>>>
>>> I can see arguments for either approach being better. On the one hand,
text is more readable aligned to its own start side. On the other hand,
 paragraphs with alternating alignment, especially when many are less than
half a line long, can look "jagged", and in extreme cases can result in the
user not even noticing the paragraphs aligned to the minority side.
>>>
>>> Furthermore, we would need to specify how allowing plaintext to base
alignment on paragraph direction would play with text-align. Is it supposed
to be limited to "text-align:start" and "text-align:end"?
>>>
>>> I would very much like to hear what people think about this.
>>>
>>> Aharon
>>>
>>>
>>>
>>> On Sun, Oct 30, 2011 at 1:28 PM, Simon Montagu <smontagu@smontagu.org>
wrote:
>>> As far as I can see, there is no explicit specification in CSS Writing
Modes Module Level 3 of what effect "unicode-bidi: plaintext" should have
on the default alignment of paragraphs.
>>>
>>> When implementing "unicode-bidi: plaintext" for Gecko, I took it for
granted that each paragraph in the element would determine its
directionality by the heuristic in the UBA, and then determine the start of
the line box depending on the directionality of the paragraph.
>>>
>>> I just noticed that recent versions of Chrome behave differently:
directionality is determined for each paragraph separately, but alignment
is determined by the first paragraph in the element, and all subsequent
paragraphs get the same alignment.
>>>
>>> As I said, there doesn't seem to be anything in the spec to say which
approach is correct. I think the behaviour in Gecko is more intuitive and
useful, but then I would, wouldn't I? Either way, it is probably worth
adding something to the spec to make it explicit.
>>>
>>>
>>>
>>
>
Received on Tuesday, 6 December 2011 18:26:05 GMT

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