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Re: Alignment of paragraphs with unicode-bidi: plaintext [css3-text] [css3-writing-modes]

From: Aharon (Vladimir) Lanin <aharon@google.com>
Date: Sun, 29 Apr 2012 15:57:48 +0300
Message-ID: <CA+FsOYbwc=U_MCPfZjd7St6e1b12TEiZ5ZU9O8nofrhOYKbE5A@mail.gmail.com>
To: fantasai <fantasai.lists@inkedblade.net>
Cc: public-i18n-bidi@w3.org, "www-style@w3.org" <www-style@w3.org>
> If you feel it's important to drop "inline", I'll raise an issue with the
CSSWG.
> But I think it's better to keep it, as there is also a block direction to
consider.

I think that "inline base direction" is a fine name for a line box
property. I just did not want the spec to refer to the "inline base
direction" of a bidi paragraph, and it no longer does, so everything is
fine.

> Ok, I've made edits to that effect and pushed them here:
> http://dev.w3.org/csswg/css3-**text/#bidi-linebox<http://dev.w3.org/csswg/css3-text/#bidi-linebox>

Pretty close, just a few minor editing remarks:

> The start and end edges of a line box are determined by the inline
base direction
> of the line box. In most cases, this is given by its containing
block's computed
> ‘direction’. However if the containing block has ‘unicode-bidi: plaintext’
> [CSS3-WRITING-MODES], the inline base direction must be determined by the

inline base direction -> inline base direction of a line box

> bidi paragraphs to which it belongs: that is, the bidi paragraph that is
immediately

paragraphs -> paragraph

> contained by the line box's containing block and for which the line box
holds content.
> An empty line box (i.e. one that contains no atomic inlines or characters
other than
> the line-breaking character, if any), takes its inline base direction
from the previous

"preceding" is arguably better than "previous", but this is not important

> line box (if any), or, if this is the first line box in the containing
block, then from the
> ‘direction’ property of the containing block.

> It's kindof a long complicated section. I'm wondering if there's a better
place to put it...

I don't think it's too bad.

A few more editorial contents:

> EXAMPLE 8
> In the following example, every other line is right-aligned:
> <pre style="unicode-bidi: plaintext">

Perhaps the style should include text-align:start for clarity, since there
is no telling what is being inherited.

> EXAMPLE 9
> <para style="direction: rtl; unicode-bidi:plaintext">

Does this need display:block for clarity?

> <quote style="unicode-bidi:plaintext">שלום!</quote>", he said.

Does the <quote> need display:inline for clarity?

> [...]
> line box displays belongs

remove "displays"

>  the <quote>‘s bidi-isolated

>From the > to the end of the paragraph, the styling is incorrect.

On Thu, Apr 26, 2012 at 2:34 AM, fantasai <fantasai.lists@inkedblade.net>wrote:

> On 04/15/2012 06:34 AM, Aharon (Vladimir) Lanin wrote:
>
>>  Ok, I have
>>>     An element immediately contains a bidi paragraph if the element
>>> itself,
>>>     but none of its descendants, is a block container or bidi-isolating
>>>     inline that contains the entire bidi paragraph.
>>>
>>
>> It is not immediately obvious that the "that contains the entire bidi
>> paragraph"
>> clause applies to both the "block container" and "bidi-isolating inline"
>> cases.
>> It may be a little clearer if it is phrased as:
>>
>> An element immediately contains a bidi paragraph if the element itself,
>> but
>> none of its descendants, both contains the entire bidi paragraph and is
>> either
>> a block container or bidi-isolating inline.
>>
>
> Ok, fixed.
>
>
>  > I am not sure why you use the term "inline base direction"
>>> > (of a bidi paragraph) instead of just "base direction".
>>>
>>
>>   See http://dev.w3.org/csswg/css3-**writing-modes/#text-flow<http://dev.w3.org/csswg/css3-writing-modes/#text-flow>
>>>  It's to contrast it with the block flow direction.
>>>
>>
>> Writing Modes defines inline base direction as a property of a writing
>> mode (along with block flow direction). The definition
>> being proposed for Text, on the other hand, is talking about a property
>> of a bidi paragraph. An "inline base direction"
>> property has never been defined for paragraphs. What UAX #9 does define
>> for paragraphs is "paragraph embedding level" and then
>> "paragraph direction [...] in some contexts [...] also known as the base
>> direction".
>>
>
> I think it's reasonable to conclude that the "inline base direction" in CSS
> and the "base direction" in UAX9 are the same thing.
>
> If you feel it's important to drop "inline", I'll raise an issue with the
> CSSWG.
> But I think it's better to keep it, as there is also a block direction to
> consider.
>
>
>  Writing Modes itself, when talking about
>> a property of a paragraph, uses the terms "paragraph embedding level" and
>> "base directionality", but not "inline base direction".
>>
>
> The use of "paragraph embedding level" is explicitly hooking into the
> terminology used in UAX9, so that can't change. I've looked over the
> other cases and tried to make them consistent, though; older versions
> of the draft used "base directionality" in place of "inline base
> direction".
>
>   In fact, perhaps Text should actually give a precise definition of a
>> line box's inline base direction
>> (as we have been discussing here), and then simply say that "the start
>> and end edges of a line box are relative to the line
>> box's inline base direction".
>> ...
>>
>> I think I have a much better idea here: instead of deriving it from the
>> previous bidi paragraph (which is actually
>> ill-defined), derive it from the preceding line box (in the same
>> containing block). Thus, this would be:
>> ...
>>
>>   Another question: should this definition also affect text-indent?
>>>
>>
>> Yes! This underscores the need for defining the inline base direction of
>> a line box.
>>
>
> Ok, I've made edits to that effect and pushed them here:
>  http://dev.w3.org/csswg/css3-**text/#bidi-linebox<http://dev.w3.org/csswg/css3-text/#bidi-linebox>
>
> It's kindof a long complicated section. I'm wondering if there's a better
> place to put it...
>
>
>   What about hanging-punctuation?
>>>
>>
>> I guess. If I understand correctly, the concept comes from East Asian
>> languages, with which I am not familiar.
>>
>
> It's also used in Western typography, although not quite as formally, I
> think;
> for Western typography there isn't a strong grid, so it's more about
> approximating
> optical alignment.
>
> ~fantasai
>
>
Received on Sunday, 29 April 2012 12:58:40 GMT

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