Graphite is a project under development within SIL's Non-Roman Script
Initiative and Language Software Development groups to provide
rendering capabilities for complex non-Roman writing systems.

Its smart-font engine is the bit that takes a Unicode string, font
formatting information (features, size, etc.), and a font, and returns
a set of positioned glyphs.  Graphite also does more than this, in
that it can handle cursor tracking and interaction with the
application for string selection, etc.