processingのmap関数をC#で使えるように。ジェネリックメソッド＆拡張メソッドにしている。

map.cs

public static class MiscUtils
{
  /// <summary>
  /// Re-maps a number from one range to another.
  /// </summary>
  /// <typeparam name="Type">IConvertible-implementing type</typeparam>
  /// <param name="value">the incoming value to be converted</param>
  /// <param name="start1">lower bound of the value's current range</param>
  /// <param name="stop1">upper bound of the value's current range</param>
  /// <param name="start2">lower bound of the value's target range</param>
  /// <param name="stop2">upper bound of the value's target range</param>
  /// <returns></returns>
  public static Type Map<Type>(this Type value, Type start1, Type stop1, Type start2, Type stop2) where Type : IConvertible {

    double mappedValue 
      = start2.ToDouble(NumberFormatInfo.CurrentInfo)
      + (stop2.ToDouble(NumberFormatInfo.CurrentInfo) - start2.ToDouble(NumberFormatInfo.CurrentInfo))
      * ((value.ToDouble(NumberFormatInfo.CurrentInfo) - start1.ToDouble(NumberFormatInfo.CurrentInfo))
      / (stop1.ToDouble(NumberFormatInfo.CurrentInfo) - start1.ToDouble(NumberFormatInfo.CurrentInfo)));

    return (Type)Convert.ChangeType(mappedValue, typeof(Type));
  }

}