Libunibreak is the successor of liblinebreak, an implementation of the line
breaking algorithm as described in Unicode 6.0.0 Standard Annex 14, Revision
26, available at http://www.unicode.org/reports/tr14/tr14-26.html

It is designed to be used in a generic text renderer. FBReader is one
real-world example, and you may also check some simple sample code, like
showbreak and breaktext.