The library "libotf" provides the following facilites:

    o Read Open Type Layout Tables from OTF file.  Currently these
      tables are supported; head, name, cmap, GDEF, GSUB, and GPOS.

    o Convert a Unicode character sequence to a glyph code sequence by
      using the above tables.

The combination of libotf and the FreeType library (Ver. 2) realizes
CTL (complex text layout) by OpenType fonts.

WWW: http://www.m17n.org/libotf/