rickshaw/src/js/Rickshaw.Color.Palette.js

Rickshaw is a JavaScript toolkit for creating interactive time series graphs, developed at [Shutterstock](http://www.shutterstock.com)

Rickshaw.namespace("Rickshaw.Color.Palette");

Rickshaw.Color.Palette = function(args) {

	var color = new Rickshaw.Fixtures.Color();

	args = args || {};
	this.schemes = {};

	this.scheme = color.schemes[args.scheme] || args.scheme || color.schemes.colorwheel;
	this.runningIndex = 0;
	this.generatorIndex = 0;

	if (args.interpolatedStopCount) {
		var schemeCount = this.scheme.length - 1;
		var i, j, scheme = [];
		for (i = 0; i < schemeCount; i++) {
			scheme.push(this.scheme[i]);
			var generator = d3.interpolateHsl(this.scheme[i], this.scheme[i + 1]);
			for (j = 1; j < args.interpolatedStopCount; j++) {
				scheme.push(generator((1 / args.interpolatedStopCount) * j));
			}
		}
		scheme.push(this.scheme[this.scheme.length - 1]);
		this.scheme = scheme;
	}
	this.rotateCount = this.scheme.length;

	this.color = function(key) {
		return this.scheme[key] || this.scheme[this.runningIndex++] || this.interpolateColor() || '#808080';
	};

	this.interpolateColor = function() {
		if (!Array.isArray(this.scheme)) return;
		var color;
		if (this.generatorIndex == this.rotateCount * 2 - 1) {
			color = d3.interpolateHsl(this.scheme[this.generatorIndex], this.scheme[0])(0.5);
			this.generatorIndex = 0;
			this.rotateCount *= 2;
		} else {
			color = d3.interpolateHsl(this.scheme[this.generatorIndex], this.scheme[this.generatorIndex + 1])(0.5);
			this.generatorIndex++;
		}
		this.scheme.push(color);
		return color;
	};

};