Re: [xep-support] XEP with Arabic Typesetting font

From: Chris Lilley (
Date: Fri Feb 20 2004 - 10:51:09 PST

  • Next message: Chris Lilley: "Re: [xep-support] XEP with Arabic Typesetting font"

    On Friday, February 20, 2004, 3:03:40 PM, Nikolai wrote:

    NG> Mete,

    >> Is XEP capable of rendering a Lam-Alef ligature
    >> with a hamza and possibly also a fatha on top of it?

    NG> Treatment of hamza, fatha and similar diacritical
    NG> signs is indeed a hard issue for XEP in its current shape.

    NG> XEP process combining diacritics as if the were
    NG> ordinary symbols. Therefore, to get an Alef+hamza,
    NG> you should use a separate glyph for it (&#x623).
    NG> This glyph will be correctly shaped to isolated/initial
    NG> or medial/final form, and if there is a Lam preceding
    NG> it in the text, it will produce a correct Lam+Alef+hamza
    NG> ligature.

    Am I correct to infer from this that XEP has support for only
    precombined characters in general, so that for example a latin letter
    'e' followed by a combining acute accent will not render as an

    NG> For fatha, the situation is more difficult: there is no
    NG> Unicode point to cover its combinations with Alef
    NG> or Alef+hamza.

    Since Unicode has a policy of not adding new precomposed characters
    unless really necessary (because of the multiplicative explosion of
    code points), there is unlikely to be such a codepoint in the future
    either. Nor is it needed, there are already Unicode points for fatha,
    damma, kasra etc and these are, naturally, combining characters.

    Unlike the acute accent (in French) but like the accents and tone
    marks in Vietnamese, these characters also need to stack.

    NG> Rather than adding such an API, we would better prefer to refine
    NG> our own engine to cover complex cases like these :-).

    A worthy goal, although coverage of basic newspaper Arabic is
    probably a better first target before moving on the the complexities
    of Quranic typesetting.

    Does anyone have short examples of these sorts of more complex script
    renderings (plus images of correct renderings), which could be used
    for test cases? I am thinking of XSL FO test cases of course, though
    also interested in their use for SVG test cases.

     Chris Lilley          
     Chair, W3C SVG Working Group
     Member, W3C Technical Architecture Group
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