[XeTeX] XETEX cannot access OpenType features in PUA?

[Keith J. Schultz]

Hi Everybody,

I have been loosely following this thread.

>From my lay point of view. Using two different colors can
work unicode for composing the output in (Xe)Tex.

>From my simplistic view, it would be just a having a two color
"T" where the top cross should be red and the rest black. 

(Xe)Tex uses boxes. one for each color. So, once you use a different
color those glyphs are set in a box of their own. This is a feature
of (Xe)TeX. 

So, naturally, using different colors for composed characters/glyphs will have 
to break anything unicode wants to do. You have to do it in (Xe)Tex.

As comparing firefox to XeTeX is like comparing apples to oranges, they
use completely different layout engines. 

One should be aware of the fact that XeTeX uses unicode for composing
glyphs during input, yet the it is processes further before it is output in
a completely different form. That is the way XeTeX is designed.

So the only solution would be to use a command like \twocolor{c1, c2}{glyph1}{glyph2}
or the like. 

regards
	Keith.


Am 27.11.2011 um 23:49 schrieb Aleksandr Andreev:

> mskala writes:
> 
>>> I've been watching this discussion with interest, having had similar
> problems.
> 
> Basically, after I added cyrillic and latin to the subtables and
> removed the color, the OpenType features started working.
> 
> Now, for the color. Searching this list reveals that there was some
> discussion a while back about coloring vowels in Hebrew text
> (basically, an identical problem). Judging from the discussion here:
> http://tug.org/mailman/htdig/xetex/2007-July/006987.html it appears to
> be impossible. The solution proposed was to print the text twice --
> first the Hebrew consonants in black and then overprint the vowels in
> color. I wouldn't call that a solution, but rather a workaround.
> 
> It appears that XeTeX colors are handled by inserting pdfliteral nodes
> around colored items, which breaks the access to GPOS.
> 
> Unless there's been some work on this issue since 2007, it appears
> that I will need to look for a different way of typesetting my
> document.
> 
> A
> 
> 
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