Re: New Tamil Shaping Engine for Pango

[Owen Taylor <otaylor redhat com>]

Vikram <upender vsnl com> writes:

> > Yes, busy, but if you give me a few days, I'm still around :-)
> 
> No problem, There's no hurry.
> 
> > >     I have a Tamil Input method for the CVS GTK+.Is there anyone else
> > > whom I can give it to, to apply this to the CVS??
> >
> > If you post it here, or a link to it, I'll add it.
> 
> I've attached a tar.gz file containing the new file for Tamil and the
> modified Makefile.am to go into modules/input directory. 

Hmm, seems to be missing...

> This should be
> changing pretty quickly now since the current binding is kind of odd.
> I see that there's a gap in the compose sequence - Is it for a Modifier key
> like Alt,Ctrl??For now I have used "x" on the keyboard to get the combining
> form of the vowel.I would like to change this to Ctrl but couldn't figure out
> how to do this.Is using a Ctrl key in general  a bad idea??

The compose stuff in GtkIMContextSimple doesn't have any provision
at all for doing this - it's all about composing key symbols into
other key symbols. So, it will take a little more work than simply
adding a table like some of the other bindings.

I don't think using Ctrl or Alt as modifiers for this is a great idea -
because they are typically used by applications. Probably better is
to use a separate key on the keyboard - the usual name for this is
AltGR.

Of course, if there is a standard for Tamil keyboards which uses
Ctrl or Alt, you should follow that.

There are basically three ways you could approach handling modifiers:

 - Extend GtkIMContextSimple to handle modifiers. I think this is going
   to be hard and make GtkIMContextSimple rather cumbersome.

 - Create a GtkIMContext module that doesn't derive from GtkIMContextSimple,
   or that modifies the GtkIMContextSimple in a more extensive way.
   (It could, for instance, pre-process the input before sending it to
   the compose engine)

 - Use XKB to create a keymap containing the extra keysyms that you need.

   There is some (if not nearly enough) information about Xkb at:

     http://www.pango.org/input-resources.shtml

   If you need keysyms that go beyond the standard X ones, then there
   is a semi-standard convention that GTK+ uses that a keysym corresponding
   to a Unicode code point will be given by:

    0x01000000 + [ unicode code pointer ]

Regards,
                                        Owen