[XeTeX] Polytonic greek and XeLaTeX

[Peter Dyballa]

Am 02.01.2008 um 05:09 schrieb Ross Moore:

> When both methods are supported, the lines beginning 'decomposed'
> show the result of "Omega + combining comma" (i.e.  U+039F;U+0313;)
> appearing three times on the line, with the 4th instance being
> 'Omega with psili'  (i.e. U+1F48; ). The difference is usually  
> visible.


The correct way to produce Ὀ (GREEK CAPITAL LETTER OMICRON WITH  
PSILI, U+1F48) would be to use Ο  (GREEK CAPITAL LETTER OMICRON, U 
+039F) with ᾿ (COMBINING COMMA ABOVE, U+0313), which is faked here  
with GREEK PSILI at U+1FBF. The combining effect already failed for  
Johannes (he is referencing a scheme in X11 to compose one character  
from more than one key press event, which seems to have failed), so  
we see the two characters. And since COMBINING COMMA ABOVE, U+0313,  
is a dead character, it should never be printed but lead to sorts of  
failure. To see a psili character the use of GREEK PSILI at U+1FBF is  
needed. To see COMBINING COMMA ABOVE, U+0313, as stand-alone psili  
character, it must be combined with a space character like Latin ^,  
´, `, ~, or ¨.

I'm not sure whether his original post seems to suggest that a method  
exists in at least some fonts that combines a letter with a combining  
letter (via liga table?) ... so it looks most promising to create a  
"greek-tex-text" mapping to pass to XeTeX the already composed  
characters – in case Johannes assumes that by writing down two (or  
more) characters XeTeX should produce only one. I think he did not  
realise that the composition in his editor failed.

--
Greetings

   Pete

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