Re: Re: Regd- ISCII to Unicode Converter!

From: Ram Viswanadha (ram@jtcsv.com)
Date: Thu Apr 04 2002 - 19:43:17 EST


Marco,

> Why do you say that these are not round-trip compatible?
The point I was trying to make is conversion of INV->ZWJ can be thought as
being kind of fallback, you might be able to roundtrip in most cases but
not all. I do agree the conversions you pointed out can be roundtripped. But
does it mean that if I have an ISCII stream, converted it to Unicode would I
be able to render the stream correctly? I think no.

> Does ISCII have
> VOWEL SIGN VOCALLIC L, VOWEL SIGN VOCALLIC RR, VOWEL SIGN VOCALLIC LL?

Yes it does in combination with NUKTA.

        0xAA, 0xE9,/* RI + NUKTA => 0x0960 Vocallic RR*/

        0xDF, 0xE9,/* Vowel sign RI + NUKTA => 0x0944 Vowel Sign Vocallic
RR*/

        0xa6, 0xE9,/* Vowel I + NUKTA => 0x090C Vowel Vocallic L*/

        0xdb, 0xE9,/* Vowel sign I + Nukta => 0x0962 Vowel Sign Vocallic L*/

        0xa7, 0xE9,/* Vowel II + NUKTA => 0x0961 Vowel Vocallic LL*/

        0xdc, 0xE9,/* Vowel sign II + Nukta => 0x0963 Vowel Sign Vocallic
LL*/

        0xa1, 0xE9,/* chandrabindu + Nukta => 0x0950 Om*/

        0xEA, 0xE9, /* Danda + Nukta => 0x093D Avagraha*/

> > 4) INV+HALANT+RA => RAsub
>
> I think that there is no reason why ZWJ+HALANT+RA alone shouldn't
represent
> RAsub in Unicode as well.
> Actually, I think that also HALANT+RA alone should be enough to represent
> RAsub (in Unicode, at least). But ZWJ should not harm, so one may retain
it
> for round-trip compatibility with ISCII's INV.

You are correct if ZWJ is treated like any other consonant, which is unclear
from rendering rules, so
applications have a choice to try and do the right thing or do nothing.
I tried to see how the combinations below are rendered in Notepad on Win2000
and our Layout demo, and they
donot render HALANT+RA as RAsub

ISCII Rendered
==== =======
KA+INV+HALANT+RA KA |RAsub| /*RAsub does not combine with
KA */
INV+HALANT+RA RAsub

Converted to Unicode:

Unicode Rendered
====== =======
KA+ZWJ+HALANT+RA KA |HALANT| RA
ZWJ+HALANT+RA |HALANT|RA

/* Or even */
HALANT+RA |HALANT|RA

Regards,

Ram
---------------------------------------------------
Ram Viswanadha
International Components For Unicode
GCoC San Jose
IBM



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