Allow only two decimal number in flutter input?

Question

I want only two digits after decimal point in the flutter input.User can\'t add more than two digits after decimal point.

Answer 1

And avoiding non necessary zeros... Please debug this code.

import 'dart:math' as math;

import 'package:flutter/services.dart';

class DecimalTextInputFormatter extends TextInputFormatter {
  DecimalTextInputFormatter({this.decimalRange, this.activatedNegativeValues})
      : assert(decimalRange == null || decimalRange >= 0,
            'DecimalTextInputFormatter declaretion error');

  final int decimalRange;
  final bool activatedNegativeValues;

  @override
  TextEditingValue formatEditUpdate(
    TextEditingValue oldValue, // unused.
    TextEditingValue newValue,
  ) {
    TextSelection newSelection = newValue.selection;
    String truncated = newValue.text;

    if (newValue.text.contains(' ')) {
      return oldValue;
    }

    if (newValue.text.isEmpty) {
      return newValue;
    } else if (double.tryParse(newValue.text) == null &&
        !(newValue.text.length == 1 &&
            (activatedNegativeValues == true ||
                activatedNegativeValues == null) &&
            newValue.text == '-')) {
      return oldValue;
    }

    if (activatedNegativeValues == false &&
        double.tryParse(newValue.text) < 0) {
      return oldValue;
    }

    if ((double.tryParse(oldValue.text) == 0 && !newValue.text.contains('.'))) {
      if (newValue.text.length >= oldValue.text.length) {
        return oldValue;
      }
    }

    if (decimalRange != null) {
      String value = newValue.text;

      if (decimalRange == 0 && value.contains(".")) {
        truncated = oldValue.text;
        newSelection = oldValue.selection;
      }

      if (value.contains(".") &&
          value.substring(value.indexOf(".") + 1).length > decimalRange) {
        truncated = oldValue.text;
        newSelection = oldValue.selection;
      } else if (value == ".") {
        truncated = "0.";

        newSelection = newValue.selection.copyWith(
          baseOffset: math.min(truncated.length, truncated.length + 1),
          extentOffset: math.min(truncated.length, truncated.length + 1),
        );
      }

      return TextEditingValue(
        text: truncated,
        selection: newSelection,
        composing: TextRange.empty,
      );
    }
    return newValue;
  }
}