[HarfBuzz] A problem in thai shaper

[Khaled Hosny]

On Mon, Apr 16, 2012 at 09:08:49PM -0400, Behdad Esfahbod wrote:
> > Problem 2:
> > 
> > When there is no consonant exist, the dotted circle should be inserted as base
> > character.  The logic should be the first step for the shaping engine to find
> > the invalid combing marks. Refer to
> > http://www.microsoft.com/typography/otfntdev/thaiot/shaping.aspx#comb
> 
> Right.  We do not handle invalid combining marks yet.  That's something I want
> to do at some point but it's not high priority.

I don't know about Thai, but the handling of "invalid" Arabic combining
marks in Uniscribe is completely brain dead and a real PITA and I'd
really like not to see HarfBuzz going there, a shaping engine is not a
spell checker and should not enforce any input pattern.

http://www.microsoft.com/typography/OpenType%20Dev/arabic/shaping.mspx#invalid

Regards,
 Khaled