Re: [smc-devel] Re: Malayalam OpenType font (GPLed)

[Baiju M]

> Hi!
>
> On Sun, 10 Nov 2002, Baiju M wrote:
>> There is small problem with rendering of Malayalam vovel sign AU
>> (U0D4C). Nowadays we are not using the shape of that character as
>> specified in Unicode Malayalam chart
>> (http://www.unicode.org/charts/PDF/U0D00.pdf), instead we are using
>> the shape of U0D57 (Malayalam AU length mark). Minstry of IT ( Govt.
>> of India ), a member of unicode consortium has prosed a change in this
>> (Its not making any backward compatibility problem,
>> just the character shape is changing). So the rendering of that
>> charcter can
>> be changed in yudit.
>
> Here's what I don't understand: If the "au" vowel is consistently
> shown with the glyph of U+0D57 in modern Malayalam, why couldn't you
> encode it as such, too, and leave U+0D4C just for the old style of the
> script?

I dont know whether U0D4C is used ever in Malayalam as given in the chart,
but there is a chance because in Tamil they still using a similar sign
(spliting into both sides). I searched a lot to find a single document
written like that, but I faild, though I will continue my search.

And I dont know what is the purpose of AU length mark in Malayalam.
But it will be very usefull for font developers, they only required to
design that character once and put it there. The same shape is coming in
lots of glyphs, so that they can just refer to that, it will reduce font
size considerably.

But we cannot use length mark AU instead of vowel sign AU anywhere.
While sorting it will make problem, or should we give same value
for both chars (I dont know the deatails of the alogithm).

>
> I don't speak Malayalam myself, so please forgive me my ignorance if
> I'm missing the point, but from the technical point of view this would
> seem like the simplest solution. Changing a vowel sign to be a
> right-side-only combining mark instead of a two-part combining mark
> breaks implementations, if not the standard itself.
>
> (Besides, I think it _would_ break even the standard, since then you
> would have to alter the canonical decomposition of U+0D4C, which is
> strictly against the policy of the Unicode Consortium.)

Why unicode should specify display of characters?
I think only code points are important we can render it as we like.

OpenType has single substitution feature. cannt I use that,
even if Yudit split it into both sides?

But single substitution is not working in Yudit, I tested raghu.ttf
(Devanagari) font , there is some single substitution for
vowel sign I (U093F), its not working, may be a bug.

I am also not expert in this area, so please correct me if anything
I missed here.


Regards,
Baiju M