Re: Sequential Fathatan Final Form (Items 9 and 10)

[Mete Kural <metekural at yahoo dot com>]

Salaam Abdulhaq,

> > And in terms of the redundancy you
> > mention, all of this dynamic substitution
> > functionality is built into OpenType, it's not
> like
> > you're writing C++ code here. You can use
> Microsoft's
> > WYSIWYG tools if you wish.
>
> That's not true is it? My understanding is that it
> is the responsibility of 
> the text client to inspect GSUB and GPOS tables and
> to apply the lookups as 
> and when it desires. The font server does nothing
> but supply the table info.

Doing the dynamic glyph substitution at the text
client level would be a very redundant approach.
Again, I am not that familiar with the way font are
served in Linux, but in Windows all programs share
Uniscribe functions to handle OpenType shaping
behaviour. There is no need to write this code in the
text client. For instance I can open up the dumbest
text client in the world, NotePad, and still write
Arabic text in elegant Quran'ic typography using the
Arabic Typesetting font. Obviously NotePad knows
nothing about complex Arabic shaping, it simply calls
the Uniscribe functions for this shaping behaviour.

> Therefore, it can involve a lot of C++ code in fact.
> This code resides (in 
> linux for instance) in Qt, Pango etc. etc. What
> about apps that don't use 
> these librarys or where the libraries are not fully
> compliant?

In order to support OpenType, you have to upgrade the
text client to support OpenType, there is no other way
around it. And yes it will take some programming to
support OpenType. But once OpenType is supported then
the text client can simply depend on a rendering
engine to handle all shaping behaviour.

> On Windows you have uniscribe to do the job if the
> programmer  accepts 
> default substitution behaviour. Is your solution
> only for those willing to 
> pay the MS tax to view qur'aan;-)?

No, of course not. OpenType is meant to be a
cross-platform font format. This means that you can
take the specification and implement it on any
platform you wish. This Indian Linux group claims that
they have succeeded in supporting OpenType on Linux,
maybe you might want to contact them and ask for their
help:
http://www.ncst.ernet.in/projects/indix/technical_details.shtml

They say they did this by adding OpenType font support
in Xserver. So once OpenType support is part of the
Xserver then text clients can simply call the
necessary functions in Xserver to handle the shaping
behaviour.

Kind regards,
Mete