From: John Hudson (email@example.com)
Date: Mon Feb 11 2008 - 13:01:32 CST
Philippe Verdy wrote:
> Michael Everson wrote:
>> t + double-inverted-breve + dot above + s, I should think.
> Seems illogical. The dot above is not double. This looks like defective for
> me, the dot above is attached to no letter, so we would get either:
> * t+double-inverted-breve, then the dot would be badly positioned, and the s
> would not be below the souble-inverted-breve; or
> * t+dot-above next to a simple s, and a double inverted breve above all.
> I see no reason why the dot would move in the center between the two base
> letters. This is an unexpected deviation from the expected behavior of the
> dot above.
If the dot is ordered after the double-inverted-breve, it can be positioned relative to
the double-inverted-breve using mark-to-mark positioning. The double-inverted-breve will
likely have dumb positioning, i.e. it will be centered on the division between the
sidebearings of the two letter glyphs (more refined positioning of double-width marks over
specific pairs of letters is very complex and requires multiple contextual positioning
lookups). But the positioning of secondary marks relative to the double-inverted-breve is
easily controllable via mark-to-mark positioning *if that is what is desired*.
A difficulty arises if user expectations vary: i.e. if some users want the dot to be
positioned above the t and others want it centered on the double-inverted-breve. The
default positioning must be one or the other.
It is possible to provide for user-controlled variation in the positioning, but with the
current sent of OpenType Layout features this would require first a stylistic variant
glyph substitution of the secondary mark, which would assume a distinct position.
-- Tiro Typeworks www.tiro.com Gulf Islands, BC firstname.lastname@example.org The Lord entered her to become a servant. The Word entered her to keep silence in her womb. The thunder entered her to be quiet. -- St Ephrem the Syrian
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