isWideGrapheme function

bool isWideGrapheme(String grapheme)

Returns true if the given grapheme cluster is a double-width (wide) character.

Implementation

bool isWideGrapheme(String grapheme) {
  if (grapheme.isEmpty) return false;
  final codePoint = grapheme.runes.first;

  // CJK Unified Ideographs & Extension A
  if (codePoint >= 0x4E00 && codePoint <= 0x9FFF) return true;
  if (codePoint >= 0x3400 && codePoint <= 0x4DBF) return true;

  // Hangul Syllables
  if (codePoint >= 0xAC00 && codePoint <= 0xD7AF) return true;

  // CJK Symbols and Punctuation, Hiragana, Katakana, Hangul Compatibility Jamo, etc.
  if (codePoint >= 0x3000 && codePoint <= 0x31FF) return true;

  // Fullwidth Forms
  if (codePoint >= 0xFF01 && codePoint <= 0xFF60) return true;
  if (codePoint >= 0xFFE0 && codePoint <= 0xFFE6) return true;

  // Emojis & Miscellaneous Symbols and Pictographs
  if (codePoint >= 0x1F300 && codePoint <= 0x1F9FF) return true;
  if (codePoint >= 0x1FA00 && codePoint <= 0x1FAFF) return true;

  // CJK Unified Ideographs Extension B-F
  if (codePoint >= 0x20000 && codePoint <= 0x2EBEF) return true;

  // CJK Compatibility Ideographs
  if (codePoint >= 0xF900 && codePoint <= 0xFAFF) return true;

  // Additional CJK/Emoji ranges:
  if (codePoint >= 0x1100 && codePoint <= 0x11FF) return true; // Hangul Jamo
  if (codePoint >= 0x2E80 && codePoint <= 0x2FFF) {
    return true; // CJK Radicals Supplement & Kangxi Radicals etc
  }
  if (codePoint >= 0x1F000 && codePoint <= 0x1F2FF) return true;

  return false;
}