W3C home > Mailing lists > Public > www-style@w3.org > June 2005

Re: Arabic letters separated by markup

From: fantasai <fantasai.lists@inkedblade.net>
Date: Mon, 13 Jun 2005 18:14:30 -0400
Message-ID: <42AE0546.7060502@inkedblade.net>
To: Erik van der Poel <erik@vanderpoel.org>
CC: Unicode Mailing List <unicode@unicode.org>, www-style@w3.org, www-international@w3.org

Erik van der Poel wrote:
> [I'm not on the www-style list.]
> 
> fantasai wrote:
> 
>>  For characters within the same inline sequence.
>>
>>   1. Shaping and joining behavior MUST NOT be affected by element
>>      boundaries.
> 
> If the CSS "display" property is set to "none" for a particular element, 
> then perhaps the characters in adjacent displayable elements should not 
> be joined to the characters in the "display: none" element.
> 
> (Maybe you already thought of this, and that is what is meant by "same 
> inline sequence"?)

No, I hadn't thought of that. But if an element is display: none, then
for all rendering purposes it is to be treated as if it wasn't there.

>>   4. Obligatory ligatures MUST NOT be broken if the formatting rules
>>      introduce no extra space between the affected characters, even
>>      if this means some of the characters are rendered in the wrong
>>      font or as part of the wrong visual element.
> 
> Perhaps the spec could say that an implementation MAY honor such things 
> as a color change (which may not be possible in current font 
> technologies such as OpenType?)

Of course if the system is somehow capable of honoring both the style
rules and the ligature formation, it should be allowed to do so. :)

> or MAY instead use the isolated forms of 
> the individual characters. I don't know whether the obligatory ligature 
> rules should trump the style rules.

Yeah, I'm not too set on this one. But I don't know how critical it is
for the affected scripts. If the font isn't changing at all, though, then
the spec should require that the ligature be formed across element
boundaries. I suspect it might be simpler just to make the exception apply
even in cases where the font changes.

>>   5. Combining characters MUST be rendered as the combined grapheme
>>      cluster if the system is capable of rendering the combination,
>>      even if this means some of the characters are rendered in the
>>      wrong font or as part of the wrong visual element. The combined
>>      grapheme cluster SHOULD be rendered as part of the base
>>      character's element, or, in the case of combining jamos, the
>>      initial character's element.
> 
> Here again, shouldn't the style rules trump the Unicode rules? 
> Otherwise, why should we even allow tags to be inserted between such 
> characters?

In this case, I think it's more important for the grapheme cluster to
be rendered as one unit. An 'a' with an acute accent should have its
acute accent on top, and a Hangul syllable expressed as individual
pieces should be presented as its proper syllable block. Breaking
ligatures like alef-lam looks weird, but it wouldn't be as bad as
breaking such combinations: alef and lam appear individually quite
frequently, but combining vowels and diacritics don't.

~fantasai
Received on Tuesday, 14 June 2005 02:17:01 GMT

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