From: John Hudson (tiro@tiro.com)
Date: Wed Jan 19 2005 - 12:24:14 CST
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 www.tiro.com Vancouver, BC tiro@tiro.com Currently reading: The peasant of the Garonne, by Jacques Maritain The meaning of everything, by Simon Winchester
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