RWUCharTraits provides an EastAsianWidth enum with values that identify the various widths: ZeroWidth, HalfWidth, FullWidth, and NeutralWidth. The values in this enumeration correspond to the East Asian width property values defined in the Unicode Character Database, as described in Unicode Standard Annex #11, “East Asian Width”:

The static method RWUCharTraits::getEastAsianWidth() returns the value in the EastAsianWidth enumeration that identifies the default width associated with a given code point.