问题
If I have an arbitrary String like this:
final family = '\u{1F468}\u{200D}\u{1F469}\u{200D}\u{1F467}'; // 👨👩👧
final myString = 'Let me introduce my $family to you.';
And I know the String index of the character after the family emoji (the space) is 28, how do I find the String index of the first code unit of the family emoji? In other words, how to I find the length in UTF-16 code units of the family emoji?
I've asked a similar question before, but that was before the characters package came out. Is there anything I can do to map the grapheme cluster index to the String index?
The reason I'm asking is that I want to programmatically backspace by grapheme cluster inside a Flutter TextField.
回答1:
It appears that String.characters gives you a list of one grapheme cluster per element. Just remove the stuff a character at a time using a range as described in the docs (https://pub.dev/documentation/characters/latest/characters/CharacterRange-class.html).
来源：https://stackoverflow.com/questions/65445009/how-to-convert-string-index-to-character-index-in-dart