On Apple OS X, there is ATSUI1. On Windows, there is Uniscribe2. End of story! But on Linux, it is quite a different story! On Linux, there are: (1) Owen Taylor's Pango library, (2) Eric Mader's Layout Engine in IBM's International Components for Unicode (ICU), (3) Trolltech's QT toolkit, and (4) Japan's National Institute of Advanced Science and Technology's (AIST) “m17n” multilingual layout library. In addition to these four, there are also (5) India's TDIL Indix project3, (6) SIL International's Graphite4 project, and, finally, (7) the still vaporous FreeType Layout5 project.
The Complex Text Layout landscape in Linux is ... complex! Different software can exhibit differing levels of support for CTL scripts like Arabic or Kannada. Some scripts, like Burmese and Khmer, are currently hardly supported at all in the majority of software on Linux today. The situation is confusing if you are a software developer or provider. It is even more confusing if you are an end-user of Linux trying to fathom why, for example, Kannada is rendered correctly in a Gnome program, but shows rendering artifacts in OpenOffice even when using the very same OpenType font in both software packages.
In this talk, we focus on the top four projects listed above. We could use many different metrics to compare these projects. For example, developers might want to know whether the software is written in C or in C++. It would also be helpful to know whether the documentation is good or poor. However, the most important metric in my mind is simply how many different CTL scripts does the layout engine actually support? In addition to introducing these four projects, I will be presenting which CTL scripts are currently supported, or will soon be supported, in these libraries.
1. Apple Type Services for Unicode Imaging, http://developer.apple.com/intl/atsui.html. 2. Uniscribe, http://www.microsoft.com/typography/developers/uniscribe. 3. Indix, http://tdil.mit.gov.in/download/INDIX.htm.
4. SIL Graphite, http://scripts.sil.org/. 5. FreeType Layout, http://freetype.sourceforge.net/ftlayout/.