getCharacterEndBounds function

int getCharacterEndBounds(String text, int startingCodePointIndex)

Returns the code point index for the code point that ends the visual character that begins at startingCodePointIndex.

A single visual character might be comprised of multiple code points. Each code point occupies a slot within a String, which means that an index into a String might refer to a piece of a single visual character.

startingCodePointIndex is the traditional String index for the leading code point of a visual character.

This function starts at the given startingCodePointIndex and walks towards the end of text until it has accumulated an entire visual character. The String index of the final code point for the given character is returned.

Implementation

int getCharacterEndBounds(String text, int startingCodePointIndex) {
  // This implementation was copied and adapted from text_editing_action_target
  // in the Flutter repo.
  assert(startingCodePointIndex >= 0 && startingCodePointIndex <= text.length);

  if (startingCodePointIndex == text.length) {
    return text.length;
  }

  final CharacterRange range = CharacterRange.at(text, 0, startingCodePointIndex);
  // If index is not on a character boundary, return the next character
  // boundary.
  if (range.current.length != startingCodePointIndex) {
    return range.current.length;
  }

  range.expandNext();
  return range.current.length;
}