[XeTeX] misplaced combining diacritical marks 2

[Khaled Hosny]

On Wed, Sep 01, 2010 at 08:03:03PM +0200, Alexander Schultheiß wrote:
> Hey David,
> 
> > This is just not true.  The example I sent you works correctly on my
> > machine; I deliberately included y-macron-acute which does not exist in
> > precomposed form in Unicode.
> 
> I don't think they work correctly, in the sense that they are
> positioned according to the anchor points. I've attached a pdf with
> the results of the little investigation I did. For example, I've tried
> various methods to get a m+macron+acute with dotbelow (starting from
> line 2.1). It confirms my suspicion that xelatex doesn't care about
> anchor points in complex glyphs. It "fakes" them. I assembled the
> correct glyphs by hand put them in a different font and printed them
> in line 3.1 and 3.3 respectively.
> 
> I think I roughly figured out how xelatex deals with diacritics in
> otf/ttf fonts (Latin scripts) and it's rather "crude". It dismissed
> them almost completely. The procedure seems to be the following:
> 
> 1.) It checks whether a sequence of commands matches a glyph in a
> Unicode code point (by comparing Unicode names I guess). If so, it
> prints the glyph (if the glyph is not present, it prints a generic
> blank); if not, and the resulting glyph doesn't match any Unicode
> glyph xelatex tries to assemble the glyph via anchor points.

I'm not sure whether this is done by XeTeX or by xunicode, XeTeX should
not be doing any normalisation by default, but you can try:

 \XeTeXinputnormalization=0

and see if it makes any difference (it is supposedly the default).

Regards,
 Khaled

-- 
 Khaled Hosny
 Arabic localiser and member of Arabeyes.org team
 Free font developer