Flutter: Using NumberFormat in TextInputFormatter

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无人及你
无人及你 2021-01-12 02:32

I\'m trying to use NumberFromatter in TextInputFormatter but when I try to use it, it completely messed up! This is my TextInputFormatter

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  • 2021-01-12 03:18

    Based on the answer and for people from Europe looking for a quick fix

    class NumericTextFormatter extends TextInputFormatter {
      @override
      TextEditingValue formatEditUpdate(
          TextEditingValue oldValue, TextEditingValue newValue) {
        final currencySymbol = '€';
        if (newValue.text.isEmpty || newValue.text.trim() == currencySymbol) {
          return newValue.copyWith(text: '');
        } else if (newValue.text.compareTo(oldValue.text) != 0) {
          var selectionIndexFromTheRight =
              newValue.text.length - newValue.selection.end;
          final f =
              NumberFormat.currency(locale: 'de', decimalDigits: 0, symbol: '');
          var num = int.parse(newValue.text.replaceAll(RegExp('[^0-9]'), ''));
          final newString = '$currencySymbol ' + f.format(num).trim();
          return TextEditingValue(
            text: newString,
            selection: TextSelection.collapsed(
                offset: newString.length - selectionIndexFromTheRight),
          );
        } else {
          return newValue;
        }
      }
    }
    
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  • 2021-01-12 03:24

    This is because after you format the value you are adding a new char but the the text selection remains at the same position, one char less, this cause an expected behavior

    You can modified your TextInputFormatter like this :

    Fixed to support all locales and to remember cursor position

    class NumericTextFormatter extends TextInputFormatter {
      @override
      TextEditingValue formatEditUpdate(
          TextEditingValue oldValue, TextEditingValue newValue) {
        if (newValue.text.isEmpty) {
          return newValue.copyWith(text: '');
        } else if (newValue.text.compareTo(oldValue.text) != 0) {
          final int selectionIndexFromTheRight =
              newValue.text.length - newValue.selection.end;
          final f = NumberFormat("#,###");
          final number =
              int.parse(newValue.text.replaceAll(f.symbols.GROUP_SEP, ''));
          final newString = f.format(number);
          return TextEditingValue(
            text: newString,
            selection: TextSelection.collapsed(
                offset: newString.length - selectionIndexFromTheRight),
          );
        } else {
          return newValue;
        }
      }
    }
    
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