Re: Forms for invisible ZWJ (and ZWNJ)

From: John Hudson (
Date: Wed Jan 19 2005 - 12:24:14 CST

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    Peter Constable wrote:

    > Even in production fonts designed to depict text as users expect it, a
    > glyph for ZWJ and ZWNJ can be useful since many word-processing or DTP
    > applications include a display mode in which non-printing characters are
    > visibly depicted. Microsoft includes glyphs for ZWJ and ZWNJ in some of
    > their fonts for this purposes.

    Yes, this is normal (although I dislike the forms used in most fonts, and have devised my
    own more intuitive set of control character glyphs). Having visual glyphs for text control
    characters in a font requires layout engines to not paint these glyphs when the 'display
    control character' option is not turned on. Since some of these glyphs may be employed in
    font lookups, it is necessary to paint the glyphs during text shaping, but then remove them.

    I've noticed that some recent OpenType-savvy software, e.g. Mellel, has not quite got this
    sorted yet, and always paint the control character glyphs.

    John Hudson

    Tiro Typeworks
    Vancouver, BC
    Currently reading:
    The peasant of the Garonne, by Jacques Maritain
    The meaning of everything, by Simon Winchester

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