[XeTeX] Fontspec Bug

[Jonathan Kew]

On 19 Nov 2008, at 07:21, Heba Soliman wrote:

> Dear Mr Will:
>
> First of all thank you for your hard efforts in improving the  
> fontspec package.
>
> Second I have a big problem that is related to my work so I need  
> please a quick answer.
>
> The problem is that I am writing an arabic article and the  
> diacritics in some places are collapsed with the letters and I don't  
> know why this problem generated and how to fix it, the only thing I  
> am sure of is that the font has no problem as I checked with other  
> programs as Adobe illustrator and this problem doesn't exist:
>
> This is my sample file:
>
> \documentclass{amsart}
>
> \usepackage{fontspec}
> \usepackage{xltxtra}
> \usepackage{xunicode}
> \usepackage{bidi}
>
>
> \setmainfont[Script=Arabic]{YakoutLinotypeLight-Regularxx.ttf}
>
> \begin{document}
>
> لمّا ألّا لمًّا آلّلًة لمُا
>
> \end{document}
>
> Please find attached the generated PDF file.

It looks like the diacritics are not placed properly when they occur  
on the initial lam-meem ligature (and perhaps this applies to other  
ligatures as well).

This is not a fontspec problem. It may be a bug in the OpenType layout  
library that xetex is using, but to investigate it I will need to have  
an example of a font where this happens. I don't have the Yakout font  
you're using; can you test whether you see similar problems with any  
freely-available Arabic fonts?

(Why is there "xx" on the end of the font file name in your example --  
is this a font that has been modified in some way?)

JK