Re: Arabic letters separated by markup

From: fantasai (
Date: Mon Jun 13 2005 - 17:14:30 CDT

  • Next message: John Hudson: "Re: Arabic letters separated by markup"

    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.


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