[XeTeX] Color Hebrew Vowel Points

[Joshua Grauman]

Thank you for your input and suggestions. I'm not 100% sure, but I think 
there *are* occassions where adding a diacritic changes the spacing 
somewhat. However, I think this is rare, so your suggestion is still 
probably valid in most cases.

I would like to try your last suggestion about overprinting. However, I 
don't have any idea how to "overprint" either in XeTeX or OpenOffice or 
whatever. Frankly, I would like to use OpenOffice to create the charts. 
For making a critical edition XeTeX is great, for a simple chart... 
Anyway, I was wondering if any of you ps/pdf experts knew how to overlay 
two ps files like Jonathan is suggesting... Thanks.

Josh

>> Hello,
>>
>> I've been trying to create some Hebrew charts (using SIL's Ezra 2.5
>> Hebrew
>> Unicode font) and I'm having difficulty coloring the vowel points a
>> different color than the consonants they are on. If I color them
>> different
>> colors, the vowel points are no longer positioned correctly (they
>> move to
>> the left side of the consonant). What is interesting is that the exact
>> same behavior is displayed in OpenOffice 2.2.0, Qt 4.3.0 QTextEdit,
>> and
>> XeTeX 0.996 (I'm using a texlive 2007 install on Linux). I had just
>> wanted
>> to create a few charts in OpenOffice, but when that didn't work was
>> trying
>> to find any way to color vowels and their consonants differently.
>> Is this
>> even possible with Unicode fonts?
>
> In theory, it could be possible; in practice, I am not aware of any
> current rendering engine that will support this. When you apply a
> different color to the diacritics, you are breaking the text into
> separate "style runs" (or whatever the particular implementation
> calls them), and shaping rules (including the mark positioning that
> is used for the diacritics in Ezra SIL) are applied separately to the
> runs. So the diacritics no longer "see" the base consonants that you
> want to position them on.
>
> MS Word in Windows has an option to "color diacritics", which might
> come close, but even that will fail whenever the font implements a
> particular base+diacritic combination using a single composite glyph.
> And that's a global option, not something you can apply to specific
> fragments of text within a document (it's not implemented at the
> level of individual character styling at all).
>
> You could of course produce your charts in XeTeX by writing custom
> macros that tweak the diacritic positions as needed, but that would
> be a pretty tedious job for more than a handful of cases.
>
> Or you could create a couple of customized versions of the font, one
> where all the consonant glyphs are replaced by blanks (with the exact
> same metrics), and another where the vowels are similarly removed.
> Then you could set the text twice, once with each font, using
> different colors, and overlay the two versions. :-)
>
> Actually, that gives me an idea: assuming the presence of the vowels
> does not affect the positioning of the consonants at all (is this the
> case?), you could simply print the vowelled text in one color, and
> then overprint with the consonants only in a second color. Might be
> worth a try!
>
> JK
>
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