[XeTeX] Syriac abbreviations, and issues with polyglossia, fontspec and bidi

[Jonathan Kew]

On 22 Dec 2009, at 19:01, Ross Moore wrote:

> Hi Jonathan,
> 
> Thanks for the clarification.
> It helps a lot in understanding what this is about.
> 
> On 23/12/2009, at 5:16 AM, Jonathan Kew wrote:
> 
>> I don't have a handy way to produce the correct rendering, but I can describe it: there should be a line over the top of the word, from the place where the Syriac Abbreviation Mark (SAM) occurs until the end of the word.
> 
> Is this to the right- or left-hand edge,
> given that the individual characters occur RtoL?

From the SAM location to the logical end (visual left-hand edge) of the word.

> 
> So the SAM character could be made active ...

> ... invoking code to determine the end of the word, subject to what
> you have said here. Then it would construct the line (with dots)
> to be placed over the top. Use a box to put this line over the
> remaining letters, then place this so as to finish the word.

This might be possible, though I'm not sure whether the SAM necessarily occurs at a location where the cursive joining of the Syriac letters is interrupted; if not, there'd be a problem (in xetex, at least) of how to get correct shaping/joining across the box edge (and other commands, etc), as OpenType shaping only applies within a contiguous sequence of characters.

But I don't know enough about Syriac to really judge whether this is feasible purely at the macro level.

JK