From: fantasai (fantasai.lists@inkedblade.net)
Date: Mon Jun 13 2005 - 17:14:30 CDT
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
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