From: Hans Aberg (haberg@math.su.se)
Date: Sun Nov 23 2008 - 06:37:35 CST
On 23 Nov 2008, at 13:08, philip chastney wrote:
>> I experimented a bit, one and a half decade ago, with creating the
>> Swedish letter Å (U00C5) in TeX, which then was necessary to do by
>> combining an A writing a small circle above it. It turns out to be
>> quite complicated, because characters may have a slant, to center
>> the circle on. So one needs to have a more advanced font model,
>> which for each character contains information where to position
>> combining characters. I am not sure about the state of this matter
>> - one can have Chinese fonts that combine the radicals - so it
>> ought to be possible to do for the combining characters as well.
>> as you say, combining marks are not always "centred"
>
> how about changing the terminology, and saying combining marks are
> placed on the "main vertical axis"?
>
> with roman-style letters, the main axis would normally be truly
> vertical, with italic-style letters the main axis might be anything
> from 12 to 18° off the vertical
>
> note that, with italic-style letters, unless it's a perfect circle
> showing no contrast, the circle itself may also need to be slanted
It is in fact even more complicated, because even it is called
LATIN CAPITAL LETTER A WITH RING ABOVE
one can have, as a matter of rendering style, the ring dipping into
the main character, even being partly obscured. So one may not get
around recognizing certain combination and provide special designs
for those.
Hans
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