dojox/color/SimpleColorModel.js

Dojo eXtensions, a rollup of many useful sub-projects and varying states of maturity – from very stable and robust, to alpha and experimental. See individual projects contain README files for details.

define(["dojo/_base/array", "dojo/_base/declare", "dojox/color"], 
	function(arr, declare, color){
	
	return declare("dojox.color.SimpleColorModel", null, {
		// summary:
		//		Base class for color models that return a color from a data value
		//		using an interpolation between two extremum colors.
		
		_startColor: null, 
		_endColor: null, 
	
		constructor: function(startColor, endColor){
			// summary:
			//		Construct a color model interpolating between start and end color.
			//		If only start color is provided use it to compute reasonable start and end
			//		colors from it.
			// startColor: dojo/_base/Color
			//		The start color. 
			// endColor: dojo/_base/Color?
			//		The end color.
			if(endColor != undefined){
				this._startColor = startColor;
				this._endColor = endColor;
			}else{
				// When only one color is provided
				// use only the hue, and compute
				// the start/end colors by playing
				// with the luminance...    			
				var hsl = startColor.toHsl();
				hsl.s = 100; 
				hsl.l = 85; 
				this._startColor = color.fromHsl(hsl.h, hsl.s, hsl.l);
				this._startColor.a = startColor.a;
				hsl.l = 15;
				this._endColor = color.fromHsl(hsl.h, hsl.s, hsl.l);
				this._endColor.a = startColor.a;
			}
		},
		
		_getInterpoledValue: function(from, to, value){
			return(from + (to - from) * value);
		},
	
		getNormalizedValue: function(value){
			// summary:
			//		Return the normalized (between 0 and 1) value for a given data value.
			//		This function must be implemented by implementations.
			// value: Number
			//		The data value. 			
		},
	
		getColor: function(value){
			// summary:
			//		return the color for a given data value.
			// value: Number
			//		The data value. 			
			var completion = this.getNormalizedValue(value);
			var hslFrom = this._startColor.toHsl();
			var hslTo = this._endColor.toHsl();
			var h = this._getInterpoledValue(hslFrom.h, hslTo.h, completion);
			var s = this._getInterpoledValue(hslFrom.s, hslTo.s, completion);
			var l = this._getInterpoledValue(hslFrom.l, hslTo.l, completion);
			var a = this._getInterpoledValue(this._startColor.a, this._endColor.a, completion);
			var c = color.fromHsl(h, s, l);
			c.a = a;
			return c;
		}
	});
});