[XeTeX] problem rendering unicode Devanagari dependent vowel signs and ligatures

[Dominik Wujastyk]

I've done some tests on Leo's first problem (see below), and I also cannot
find a way to separate, e.g., the visarga sign (similar to a Latin colon)
from the dotted-circle that is used in Unicode font charts to signify that
the visarga always follows a vowel.

Like this:  ः
If I type the visarga after a vowel, the dotted circle disappears: अः
So, I conjecture, the visarga itself *is* somewhere in the font, and it
should be possible somehow to get at it, for example to discuss it as a
separate character, or teach it to beginners.

It's an identical problem with anusvara:  ं but अं

Similarly, with the Devanagari diacritical accent-like markers that are used
to signify vowels after consonants, the flags on के कै को कौ, or ते तै तो
तौ, etc., apparently can't be typed separately.

I've racked my brains and done several experiments, to no avail.  I think
Leo has put his finger on something here that is probably a stupid error in
the Unicode standard.

Any insights?

Dominik


On 25 January 2011 11:16, Leo Brouwer <singhadaya at googlemail.com> wrote:

> Greetings,
>
> I'm working on producing a critical edition of a Sanskrit text using
> XeLaTex. In the edition, I wan to report cancellation marks in the
> manuscript with multiplication signs around the cancelled akshara, e.g. xकx.
> This works fine for consonants, but I can't get XeTex to render dependent
> vowels without the dotted circle. I've tried inputting it in every possible
> combination with a space (U+0020) and/or Zero Width Joiner (U+200D), but
> nothing seems to work. Is there any way to make XeTex display a dependent
> vowel without the circle?
>
> Secondly, it seems Xetex doesn't render the common ligature त्र्य correctly
> for most freely available Devanagari fonts. I can only get shiDeva, Nakula,
> & Sahadeva to display it. Sanskrit 2003 has dedicated characters for
> ligatures in its Private Use Area, so it's possible (but time-consuming) to
> manually input them, but none of the other fonts do. In the attached sample
> I've only included the fonts I find most attractive, but all the others
> available on the Wazu font gallery<http://www.wazu.jp/gallery/Fonts_Devanagari.html>
>  have the same problem. Ideally, I want to use a font like Surekh or
> Yogesh which includes a real bold font. With these 2 fonts I've noticed an
> additional problem: if ligatures with a superscribed "r" are preceded by a
> dependent vowel "i," the "r" gets moved to the "i." Is it possible to get
> these fonts to display correctly, or are they simply unusable in XeTex?
>
> Here's the tex input for my sample:
>
> \documentclass{article}
>
> \usepackage{fontspec, xunicode, xltxtra}
>
> \usepackage{polyglossia}
>
> \setdefaultlanguage{sanskrit}
>
> \setotherlanguage{english}
>
> \setmainfont{Charis SIL}
>
> \newfontfamily\sanskritfont [Script=Devanagari]{Sanskrit 2003}
>
> \begin{document}
>
> \textenglish{Sanskrit 2003:} स्वातन्त्र्यम्, स्वात\char"E178 म् ,
> त्र्यक्षः, \char"E11Cक्षः $\times$\char"200D\char"093E$\times$
>
>
>  \textenglish {AA Nagari Shree L3:}
> \fontspec[Script=Devanagari]{AA_NAGARI_SHREE_L3}स्वातन्त्र्यम् , त्र्यक्षः,
> $\times$\char"200D\char"093E$\times$
>
>
>  \textenglish{CDAC-GISTYogesh:}
> \fontspec[Script=Devanagari]{CDAC-GISTYogesh}स्वातन्त्र्यम् , त्र्यक्षः,
> विसर्गः, $\times$\char"0020\char"093E$\times$
>
>
>  \textenglish{CDAC-GISTSurekh:}
> \fontspec[Script=Devanagari]{CDAC-GISTSurekh}स्वातन्त्र्यम् , त्र्यक्षः,
> विसर्गः, $\times$\char"0020\char"200D\char"093E$\times$
>
>
>  \textenglish{shiDeva:}
> \fontspec[Script=Devanagari]{shiDeva}स्वातन्त्र्यम् , त्र्यक्षः,
> $\times$\char"200D\char"093E$\times$
>
>
>  \textenglish{Nakula:} \fontspec[Script=Devanagari]{Nakula}स्वातन्त्र्यम्
> , त्र्यक्षः, $\times$\char"200D\char"093E$\times$
>
>
>  \textenglish{Sahadeva:}
> \fontspec[Script=Devanagari]{Sahadeva}स्वातन्त्र्यम् , त्र्यक्षः,
> $\times$\char"200D\char"093E$\times$
>
> \end{document}
>
> Thank you for your help,
>
> Leonard Brouwer
>
>
>
>
>
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