Tone.js/Tone/signal/ScaleExp.js

import Tone from "../core/Tone";
import "../signal/Scale";
import "../signal/Pow";

/**
 *  @class  Performs an exponential scaling on an input signal.
 *          Scales a NormalRange value [0,1] exponentially
 *          to the output range of outputMin to outputMax.
 *
 *  @constructor
 *  @extends {Tone.SignalBase}
 *  @param {number} [outputMin=0] The output value when the input is 0.
 *  @param {number} [outputMax=1]	The output value when the input is 1.
 *  @param {number} [exponent=2] The exponent which scales the incoming signal.
 *  @example
 * var scaleExp = new Tone.ScaleExp(0, 100, 2);
 * var signal = new Tone.Signal(0.5).connect(scaleExp);
 */
Tone.ScaleExp = function(outputMin, outputMax, exponent){

	Tone.SignalBase.call(this);

	/**
	 *  scale the input to the output range
	 *  @type {Tone.Scale}
	 *  @private
	 */
	this._scale = this.output = new Tone.Scale(outputMin, outputMax);

	/**
	 *  @private
	 *  @type {Tone.Pow}
	 *  @private
	 */
	this._exp = this.input = new Tone.Pow(Tone.defaultArg(exponent, 2));

	this._exp.connect(this._scale);
};

Tone.extend(Tone.ScaleExp, Tone.SignalBase);

/**
 * Instead of interpolating linearly between the <code>min</code> and
 * <code>max</code> values, setting the exponent will interpolate between
 * the two values with an exponential curve.
 * @memberOf Tone.ScaleExp#
 * @type {number}
 * @name exponent
 */
Object.defineProperty(Tone.ScaleExp.prototype, "exponent", {
	get : function(){
		return this._exp.value;
	},
	set : function(exp){
		this._exp.value = exp;
	}
});

/**
 * The minimum output value. This number is output when
 * the value input value is 0.
 * @memberOf Tone.ScaleExp#
 * @type {number}
 * @name min
 */
Object.defineProperty(Tone.ScaleExp.prototype, "min", {
	get : function(){
		return this._scale.min;
	},
	set : function(min){
		this._scale.min = min;
	}
});

/**
 * The maximum output value. This number is output when
 * the value input value is 1.
 * @memberOf Tone.ScaleExp#
 * @type {number}
 * @name max
 */
Object.defineProperty(Tone.ScaleExp.prototype, "max", {
	get : function(){
		return this._scale.max;
	},
	set : function(max){
		this._scale.max = max;
	}
});

/**
 *  Clean up.
 *  @returns {Tone.ScaleExp} this
 */
Tone.ScaleExp.prototype.dispose = function(){
	Tone.SignalBase.prototype.dispose.call(this);
	this._scale.dispose();
	this._scale = null;
	this._exp.dispose();
	this._exp = null;
	return this;
};

export default Tone.ScaleExp;