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Posted to fop-dev@xmlgraphics.apache.org by Finn Bock <bc...@worldonline.dk> on 2005/12/11 09:12:18 UTC

Letter space [was Re: Kerning]

[Luca]

> ...
> A little doubt concerning letter spaces: at the moment, a letter space 
> is "assigned" to the preceding character. Is this correct? I don't 
> remember any section in the specs stating about the "ownership" of 
> letter spaces ... I think that everything is simpler, from the point of 
> view of both users and implementors, if each letter space is owned by 
> the preceding (or following) formatting object, but this does not mean 
> it is what the specs require!

In [7.16.2 "letter-spacing"], I read it as if each alphabetic letter has 
1/2 a letter space preceding and 1/2 a letter space following the 
character. These space-before and space-after trait values are then 
resolved with whatever other spaces that they are up against according 
to space resolution rules.

The same goes for wordspaces which is split into 2 half word spaces.

"A Word" then becomes:

hls 'A' hls hws hws hls 'W' hls hls 'o' hls hls 'r' hls hls 'd' hls

where 'hls' is half a letter-space and 'hws' is half a word-space.

How the "hls hls" and 'hls hws' sequences are resolved depends the 
.precedence and .conditionality values.

OTOH, it is user agent dependant how letter space is resolved with word 
spaces, so I think your implementation is complient, it is just not what 
I think the spec suggest.

regards,
finn