On 25/10/2003 03:24:38 "Chris Whiting" wrote:
"Bob Hallissy" <Bob_Hallissy(_at_)sil(_dot_)org> wrote in message
I presume your algorithm depends on the Arabic presentation forms
available
as separately encoded characters in Unicode. If this is the case, and
given
that lots of Arabic characters in Unicode do not have all their
presentation forms separately encoded, nor will any new presentation
forms
be added to the standard, it would seem such an algorithm would be of
limited, and perhaps, misleading help.
The algorithm, and all that I have seen, convert Arabic characters in the
\x{06--} range to Arabic Presentation Forms A ( starting at \x{FB50} or B
( starting at \x{FE70} ) characters depending on their medial, isolated,
initial, and final values per the Unicode standard.
I am not sure that I understand your point. Isn't this the purpose of
the
Arabic Presentation Forms?
Others have addressed the purpose of the Arabic Presentation Forms in
their replies, so I won't review that.
But lest someone overlook my first comment, namely: "lots of Arabic
characters in Unicode do not have all their presentation forms separately
encoded," I've just done a quick scan of the Unicode 4.0 data files and
determined that the following characters (from the Arabic (0600) and
Syriac (0700) blocks) are missing one or more presentation forms:
066E 066F 0672 0673 0675 0676 0677 0678 067C 067D 0681 0682 0685 0689 068A
068B
068F 0690 0692 0693 0694 0695 0696 0697 0699 069A 069B 069C 069D 069E 069F
06A0
06A1 06A2 06A3 06A5 06A7 06A8 06AA 06AB 06AC 06AE 06B0 06B2 06B4 06B5 06B6
06B7
06B8 06B9 06BA 06BC 06BD 06BF 06C3 06C4 06CA 06CD 06CE 06CF 06D1 06D5 06EE
06EF
06FA 06FB 06FC 06FF 0710 0712 0713 0714 0715 0716 0717 0718 0719 071A 071B
071C
071D 071E 071F 0720 0721 0722 0723 0724 0725 0726 0727 0728 0729 072A 072B
072C
072D 072E 072F 074D 074E 074F
That is, none of the above will properly shaped by an algorithm that
depends on Unicode's presentation forms. It is because of these missing
presentation forms that I don't think it is helpful to promote solutions
that depend on presentation forms.
Rather, as others have said, the recommended approach to rendering complex
scripts such as Arabic is to use intelligent font technologies such as
OpenType, SIL Graphite, or AAT
Regards,
Bob