Documentation

Returns a value indicating the display-cell width of the character when used in Asian text, according to the Unicode standard (see p. 6-130 of The Unicode Standard, Version 2.0). The results for various characters are as follows:

ZERO_WIDTH: Characters which are considered to take up no display-cell space: control characters format characters line and paragraph separators non-spacing marks combining Hangul jungseong combining Hangul jongseong unassigned Unicode values

HALF_WIDTH: Characters which take up half a cell in standard Asian text: all characters in the General Scripts Area except combining Hangul choseong and the characters called out specifically above as ZERO_WIDTH alphabetic and Arabic presentation forms halfwidth CJK punctuation halfwidth Katakana halfwidth Hangul Jamo halfwidth forms, arrows, and shapes

FULL_WIDTH: Characters which take up a full cell in standard Asian text: combining Hangul choseong all characters in the CJK Phonetics and Symbols Area all characters in the CJK Ideographs Area all characters in the Hangul Syllables Area CJK compatibility ideographs CJK compatibility forms small form variants fullwidth ASCII fullwidth punctuation and currency signs

NEUTRAL: Characters whose cell width is context-dependent: all characters in the Symbols Area, except those specifically called out above all characters in the Surrogates Area all charcaters in the Private Use Area

For Korean text, this algorithm should work properly with properly normalized Korean text. Precomposed Hangul syllables and non-combining jamo are all considered full- width characters. For combining jamo, we treat we treat choseong (initial consonants) as double-width characters and junseong (vowels) and jongseong (final consonants) as non-spacing marks. This will work right in text that uses the precomposed choseong characters instead of teo choseong characters in a row, and which uses the choseong filler character at the beginning of syllables that don't have an initial consonant. The results may be slightly off with Korean text following different conventions.