It is expected that there will be different implementations of this
interface, that each expect strings conforming to a certain structure
(e.g., URIs, platform-specific file paths, or newsgroup names). The
abbreviation algorithms will then take into account the structural
information.
Abbreviate a string, so that the resulting abbreviated string is not
wider than some given width.
The width of a string is an abstract concept here, measured via
an XStringWidth interface. Examples are the number of
characters in the string (XStringWidth will measure the
string's length), or the width in pixel when displayed with a specific
font (which XStringWidth would encapsulate).
Parameter xStringWidth
The interface that makes concrete the abstract notion of string width.
Parameter nWidth
The resulting abbreviated string's width will be no larger than this.
