Re: Fwd: OLPC arabic

Martin Sevior wrote:
> Hi Khaled,
> Thank you very much for the detailed description of the
> problems. Unfortunately I'm totally snowed under at my day job for the
> next 2.5 weeks. I hope Tomas Frydrich, the main author of the
> rendering code can fix some of these issues. Otherwise I'll have a go
> when things ease off at work.

Sorry guys, I will not have a time to look into this in the foreseeable
future, but at least a comment.

> 1) OpenType rendering: Pango does OpenType layout very well, but AbiWord
> some times fail to apply OpenType features witch result in non-joined
> Arabic words. I've reported this upstream a year a ago (#11307) but got
> no response so far. This isn't Arabic specific, it can be tested in
> fonts that has fi, ffi, fl and like ligatures (DejaVu fonts for example)
> and you will see that the ligatures aren't always applied.

My guess would be that the ligature ends up split across two runs; if
that is the case should just be a question of fixing the run merge
mechanism.

> 2) The other issue is those random symbols instead of Arabic text, I
> first thought that it is a problem with font fallback mechanism, but
> this doesn't to be the case and I can't identify a regular pattern for
> this. It occurs randomly with any text and can't tell when to expect it.

That sounds like some kind of memory corruption, possibly OOB somewhere
in the character -> byte offset conversions we do for Pango.

Tomas
Received on Thu Oct 16 08:27:40 2008