formatEditUpdate method

Implementation

@override
TextEditingValue formatEditUpdate(TextEditingValue oldValue, TextEditingValue newValue) {
  locale ??= platformLocaleCode;
  var form = NumberFormat.decimalPattern(locale);
  decimalDigits ??= form.decimalDigits ?? 4;
  var simb = form.symbols;
  var decimalSeparator = simb.DECIMAL_SEP;
  var minusSign = simb.MINUS_SIGN;
  var percentSign = simb.PERCENT;

  String formattedValue = "";

  string newValueText = newValue.text.trimAll;

  // Remove any non-digit characters
  for (int i = 0; i < newValueText.length; i++) {
    var e = newValueText.charAt(i);
    if (i == 0 && (e == minusSign)) {
      formattedValue += e;
      continue;
    }
    if (e.isNumber) {
      formattedValue += e;
      continue;
    }
    if (e == decimalSeparator && !formattedValue.contains(decimalSeparator)) {
      formattedValue += e;
      continue;
    }
    if (e == percentSign && i == newValueText.length - 1) {
      formattedValue += e;
      continue;
    }
  }

  // Check if the first character is a plus or minus sign
  bool isNegative = false;
  if (formattedValue.isNotEmpty && (formattedValue[0] == minusSign)) {
    isNegative = formattedValue[0] == minusSign;
    formattedValue = formattedValue.substring(1);
  }

  // Check if the last character is a percent sign
  bool hasPercentSign = false;
  if (formattedValue.isNotEmpty && formattedValue[formattedValue.length - 1] == percentSign) {
    hasPercentSign = true;
    formattedValue = formattedValue.substring(0, formattedValue.length - 1);
  }

  // Check if the newText contains a decimal separator
  bool hasDecimalSeparator = formattedValue.contains(decimalSeparator);

  // Split the newText into integer and decimal parts
  List<String> parts = formattedValue.split(decimalSeparator);
  String integerPart = parts[0];
  String decimalPart = (parts.length > 1 ? parts[1] : '').first(decimalDigits!);

  // Format the integer part
  formattedValue = NumberFormat.decimalPattern(locale).format(int.parse(integerPart));

  // Add the decimal separator and decimal part if necessary
  if (hasDecimalSeparator) {
    formattedValue += '$decimalSeparator$decimalPart';
  }

  // Add the percent sign if necessary
  if (hasPercentSign) {
    if (calculateDecimal) {
      formattedValue = (double.parse(formattedValue.removeAny([percentSign])) / 100).toStringAsFixed(decimalDigits!);
    } else {
      formattedValue += percentSign;
    }
  }

  // Add the plus or minus sign if necessary
  if (isNegative) {
    formattedValue = '$minusSign$formattedValue';
  }

  return TextEditingValue(
    text: formattedValue,
    selection: TextSelection.collapsed(offset: (formattedValue.contains(percentSign) ? formattedValue.indexOf(percentSign) - 1 : formattedValue.length).clamp(0, formattedValue.length - 1)),
  );
}