currency_formater.dart

import 'package:flutter/services.dart';
import 'package:intl/intl.dart';

class CurrencyInputFormatter extends TextInputFormatter {
  TextEditingValue formatEditUpdate(
      TextEditingValue oldValue, TextEditingValue newValue) {
    if (newValue.text.length == 0) {
      return newValue.copyWith(text: '');
    } else if (newValue.text.compareTo(oldValue.text) != 0) {
      final f = new NumberFormat.currency(symbol: "\$  ", decimalDigits: 2);

      int selectionIndexFromTheRight =
          newValue.text.length - newValue.selection.end;
     
     
      double num = double.parse(newValue.text
          .replaceAll('\$  ', '')
          .replaceAll(f.symbols.GROUP_SEP, ''));
      final newString = f.format(num);

      int intValue =
          int.parse(intPart.substring(2).replaceAll(f.symbols.GROUP_SEP, ''));
      int newoffset = newString.length - selectionIndexFromTheRight ;

     

      return new TextEditingValue(
        text: newString,
        selection: TextSelection.collapsed(offset: newoffset),
      );
    } else {
      return newValue;
    }
  }
}