TAMIL PANGO USING UNICODE BASED FONT

This is a quick descritpiton of how to get the new tamil module for pango, which uses a Unicode based font, running
in your Linux system.This is only a test release and the font encoding is not finalised.If you don't plan to run the module or pango,please download the fonts and give your comments on the glyph and their positions, especially in the ligature block at 0xEB80.

What is PANGO?
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"The goal of the Pango project is to provide an open-source framework for the layout and rendering of internationalized text."

"Pango uses Unicode for all of its encoding, and will eventually support output in all the worlds major languages."

Pango is currently used in the development version of GTK+ and will be part of GTK+-2.0 and the GNOME-2.0 desktop.This means that developers all over the world will support lots of languages without them having to do anything very special.

"... however there is nothing fundamentally GTK+ or GNOME specific about Pango" - www.pango.org

What is TAMIL PANGO
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Pango uses loadable modules for the script specific part so that different localization teams can work seperately on a particular script.Tamil PANGO is the implementation of such a module to add Tamil support to PangoThis means that the next generation GNOME-2.0 Desktop will have Tamil support in it and additionally would support the Unicode standard which is the right way to go in the long run.

     For Interested developers
     ------------------------------------
        The initial implementation of such a module for Tamil was written by Sivaraj D.It uses TSCII based fonts and so a conversion from Unicode to TSCII was used in the module.

The current development is going in the direction of using a Unicode based Tamil font and an initial implementation is available(See below).This is definitely more efficient than conversion to TSCII (By how much? Haven't got any numbers to show) and more importantly allows us to integrate fonts of various languages into a single Unicode font.

The Unicode font has a seperate ligature block(Let's just say a seperate block) for Ikarams, IIkarams, Ukarams, UUkarams and Meys.These are required for high quality output and have been currently placed in the block 0xEB80 - 0xEBFF in the unicode font which is known as the Private Usage Area(PUA).

Currently this space doesn't explain everything.Visit www.pango.org and do join us in the discussions in the tamilinix e-group.CVS for this tamil module should be up shortly.

FILES
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This is the list of things you need to dowload to get the new Unicode font based Tamil module.Actually it's quite a lot of things and will take some time to get it set up.

The basic Pango system can be got from
www.pango.org/download.shtml

Extra Things you need to download from here for the newer tamil module :

1) The loadable module
2) The Unicode based Tamil fonts
3) An altered pangox.aliases file for Pango to see the new fonts

Optional
4) The source for the tamil module to help us perfect it

INSTALL
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1) Install the fonts in your font path.(Hope you know how to do it)

2) Backup your existing tamil module - pango-tamil.so and pango-tamil.la (Mine's in /usr/local/lib/pango/modules)
Refer your pangorc for the module path.

3) Put the new libs in the directory

4) Backup your pangox.aliases(Refer your pangorc for it's path) and put the new pangox.aliases

And Run "pango-viewer muru.utf" (muru.utf is in the example/ dir of the pango source tar ball)
ENJOY!

To install the source backup your old tamil module directory and untar at PANGO_SRC_TOPDIR/modules/.
I haven't tested whether it compiles with the CVS version as well.

The installation woes should be resolved once the new module and fonts are integrated into the current Pango tree.

SCREENSHOT
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For those who don't have the time to tweak pango to get the module running here's a screenshot showing muru.utf in pango-viewer running at font pixel size of 24.

FEATURES
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1) Unicode based font. No more conversion to TSCII.This saves some processing time and also makes it possible to integrate the glyphs with a grand unified Unicode font containing lots of languages.

2) Ligature block at 0xEB80 - 0xEBFF for Ikaram,IIIkaram,ukaram,UUkaram and Meys.Ikarams look a little better.

3) Glyph for KSHA has been put at 0x0BBA in the font but not recognized as a valid consonant as of now in the Shaping module.(The ligature block might be shifted to a different place later).Similarly Number 0 is put in the font but not used.

BUGS
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1) Double modifiers are not handled properly.(Currently they should be displayed properly but the cluster info will be wrong)

2) Some of the glyphs have been assembled by me !! Numerals and Numbers have been taken from a different font(Yuck)

3) The "Meys" in the ligature block seem as though they don't deserve a seperate position there.Need improved glyphs for them.

THANKS
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A big thanks to Sivaraj D for writing the well annotated TSCII tamil module for PANGO.

Fonts have been created using FontLab under Windows by cutting and pasting Glyphs from the public domain KALAINGARTAM True Type font downloaded at tamilnet99.org and converted using ttf2bdf, xemacs(!!) and bdftopcf.

TODO
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1) Review Glyphs in the Ligature block and co-ordinate with XFree people to get it properly documented.

2) Integrate with the small changes in the tamil module in the PANGO CVS, but which is not in the source tar ball.

3) Get FreeType support for the Shaping engine or even better get Xft rendering support and enjoy anti-aliased goodness under Xfree 4.0.2 and later.

Last Modified : Feb 14th, 2001
S.Vikram <upender@vsnl.com>