File: src/filters/Scaler.js

 /**
  * Based on Scaler.as originally written in as3.
  * Copyright (c) the Funnel development team
  * http://www.funnel.cc
  *
  * Ported to JavaScript by Jeff Hoefs
  * Copyright (c) 2011-2012 Jeff Hoefs <soundanalogous@gmail.com>
  *
  * Released under the MIT license. See LICENSE file for details.
  */

 JSUTILS.namespace('BO.filters.Scaler');

 BO.filters.Scaler = (function() {
   "use strict";

   var Scaler;

   // dependencies
   var FilterBase = BO.filters.FilterBase;

   /**
    * Scales up an input value from its min and max range to a specified
    * minimum to maximum range. See [Breakout/examples/filters/scaler.html](https://github.com/soundanalogous/Breakout/blob/master/examples/filters/scaler.html) for
    * an example application.
    *
    * @class Scaler
    * @constructor
    * @extends BO.filters.FilterBase
    * @param {Number} inMin minimum input value
    * @param {Number} inMax maximum input value
    * @param {Number} outMin minimum output value
    * @param {Number} outMax maximum output value
    * @param {Function} type The function used to map the input curve
    * @param {Boolean} limiter Whether or not to restrict the input value if it
    * exceeds the specified range.
    */
   Scaler = function(inMin, inMax, outMin, outMax, type, limiter) {

     this.name = "Scaler";

     this._inMin = inMin || 0;
     this._inMax = inMax || 1;
     this._outMin = outMin || 0;
     this._outMax = outMax || 1;
     this._type = type || Scaler.LINEAR;
     this._limiter = limiter || true;

   };


   Scaler.prototype = JSUTILS.inherit(FilterBase.prototype);
   Scaler.prototype.constructor = Scaler;

   /**
    * Override FilterBase.processSample
    */
   Scaler.prototype.processSample = function(val) {
     var inRange = this._inMax - this._inMin;
     var outRange = this._outMax - this._outMin;
     var normalVal = (val - this._inMin) / inRange;
     if (this._limiter) {
       normalVal = Math.max(0, Math.min(1, normalVal));
     }

     return outRange * this._type(normalVal) + this._outMin;
   };

   /**
    * y = x
    * @method Scaler.LINEAR
    * @static
    */
   Scaler.LINEAR = function(val) {
     return val;
   };

   /**
    * y = x * x
    * @method Scaler.SQUARE
    * @static
    */
   Scaler.SQUARE = function(val) {
     return val * val;
   };

   /**
    * y = sqrt(x)
    * @method Scaler.SQUARE_ROOT
    * @static
    */
   Scaler.SQUARE_ROOT = function(val) {
     return Math.pow(val, 0.5);
   };

   /**
    * y = x^4
    * @method Scaler.CUBE
    * @static
    */
   Scaler.CUBE = function(val) {
     return val * val * val * val;
   };

   /**
    * y = pow(x, 1/4)
    * @method Scaler.CUBE_ROOT
    * @static
    */
   Scaler.CUBE_ROOT = function(val) {
     return Math.pow(val, 0.25);
   };


   return Scaler;

 }());