convertUnitsAsRatioFromTo method

double? convertUnitsAsRatioFromTo(dynamic fromNumerator, dynamic fromDenominator, dynamic toNumerator, dynamic toDenominator,)

Implementation

double? convertUnitsAsRatioFromTo(
  dynamic fromNumerator,
  dynamic fromDenominator,
  dynamic toNumerator,
  dynamic toDenominator,
) {
  assert(fromNumerator.runtimeType == toNumerator.runtimeType,
      'fromNumberator and toNumerator must be of the same type, e.g. LENGTH');
  assert(fromDenominator.runtimeType == toDenominator.runtimeType,
      'fromNumberator and toNumerator must be of the same type, e.g. LENGTH');

  /// Get the type of unit for the input ratio numerator
  final numeratorProperty = _type(fromNumerator);

  /// Get the type of unit for the input ratio denominator
  final denominatorProperty = _type(fromDenominator);

  /// Get the conversion ready for the Numerator. The passed numerical value
  /// is included in this just as it is for the above function
  ///
  /// 500 mg/L - starts with converting 500 mg
  numeratorProperty?.convert(fromNumerator, toDouble());

  /// for the Denominator, we include the unit, but assume the value is 1
  ///
  /// 500 mg/L = 500 mg / 1 L
  denominatorProperty?.convert(fromDenominator, 1.0);

  /// if any value is null OR the denominator is 0 (undefined by reality) we
  /// just return 0
  if (numeratorProperty?.getUnit(toNumerator).value == null ||
      denominatorProperty?.getUnit(toDenominator).value == null ||
      denominatorProperty?.getUnit(toDenominator).value == 0) {
    return 0;
  } else {
    /// Otherwise we convert the top value and divide by the bottom value
    ///
    /// 500 mg / L => mg / mL
    /// 500 mg = 500 mg
    /// 1 L = 1000 mL
    /// 500 / 1000 = 0.5
    return numeratorProperty!.getUnit(toNumerator).value! /
        denominatorProperty!.getUnit(toDenominator).value!;
  }
}