CommaTextInputFormatter

CommaTextInputFormatter.dart

extension PriceFormat on num? {
  static final f = NumberFormat("###,###,##0.##", "en_US");
  String get format => formatter.format(this);
  String get simpleFormat => f.format(this);
}

class CommaTextInputFormatter extends TextInputFormatter {
  @override
  TextEditingValue formatEditUpdate(
    TextEditingValue oldValue,
    TextEditingValue newValue,
  ) {
    if (newValue.text.isEmpty) return newValue;
    var n = newValue.text.replaceAll(',', '');
    var text = '';

    if (n.startsWith('0.')) {
      double value;
      try {
        value = PriceFormat.f.parse(n).toDouble();
      } on FormatException {
        value = 0.0;
      }
      text = value.simpleFormat;
    }
    if (n.startsWith('.')) {
      if (n.length > 1) {
        final value = PriceFormat.f.parse('0.' + n);
        text = value.simpleFormat;
      } else {
        text = n;
      }
    } else if (n.endsWith('.')) {
      final value = PriceFormat.f.parse(n.replaceAll('.', ''));
      text = value.simpleFormat + '.';
    } else {
      final value = PriceFormat.f.parse(n);
      text = value.simpleFormat;
    }

    return TextEditingValue(
      text: text,
      selection: TextSelection.collapsed(
        offset: text.length,
      ),
    );
  }
}