Support for Indic OpenType Font rendering with ICU 'Shaping'

[springmeyer]

Arabic font rendering with ICU is clearly supported, as I can see the routines here:

http://trac.mapnik.org/browser/trunk/include/mapnik/font_engine_freetype.hpp#L257 and the news here: http://mapnik.org/news/2008/feb/20/mapnik_unicode/

Indic font rendering apparently needs its own special routines which are discussed in the context of OpenType? fonts here:

http://trac.osgeo.org/mapserver/ticket/2591

Context: when gargi.ttf is configured based on this readme: http://mapnik-utils.googlecode.com/svn/example_code/fonts/README.txt the result is the same as the graphics attached to the mapserver ticket.

Thus, enhanced support for OpenType? Indic fonts is highly desirable within Mapnik.

[springmeyer]

See Ticket #19 for context on why ICU can solve this problem.

[springmeyer]

I tried applying the patch from http://lists.openstreetmap.org/pipermail/dev/2008-October/012005.html

and I've attached a graphic comparing the raw text in the postgres insert of sample indic data (from the linked mapserver ticket) to the rendered text. I'm not sure which is right and which is wrong, so feedback is welcome.

[springmeyer]

Screen shot of text, before and after rendering

[springmeyer]

data and test case script's to produce the previously attached image are here: http://mapnik-utils.googlecode.com/svn/trunk/tutorials/fonts/

[springmeyer]

The link has now moved for the testcase to:

http://mapnik-utils.googlecode.com/svn/sandbox/indic_fonts/