Re: Arabic Implementation

Date: Wed Aug 18 2004 - 03:29:28 CDT

  • Next message: Kent Karlsson: "Re: Arabic Implementation"

    On 18/08/2004 07:57:32 "Doug Ewell" wrote:

    >Your display looks at the joining
    >type of the character and its neighbors, and chooses a glyph on that
    >basis. Not a character, a glyph. Internally, you can actually use the
    >Unicode value of the presentation form as a way to index the glyph,

    As has been mentioned previously on this list (and I would like to see it
    added to

    This is not a reliable technique because not all Arabic characters have a
    complete set of presentation forms encoded in Unicode. Ernst Tremel mentioned on this list in February at least a few such:

    1. There are no FINAL forms for U-0692 (REH WITH SMALL V) and U-0995 (REH
    2. There are no FINAL, INITIAL and MEDIAL forms for U-06B5 (LAM WITH SMALL
    3. There are no FINAL and ISOLATED forms for LAM WITH ALEF WITH SMALL V
    ABOVE like in U-FEF5 and U-FEF6 ff.
    4. There are no FINAL, INITIAL and MEDIAL forms for U-06CE (YEH WITH SMALL

    And there are many others: Presentation forms are no longer being added to

    Modern rendering systems use additional data in the font (e.g., OpenType,
    Graphite, or AAT tables) to indicate which glyph to use for a given
    character in a given context, without dependence on presentation form
    glyphs being "encoded" (i.e., given Unicode codepoints)


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