hsl.js

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/*
	Copyright (c) 2004-2006, The Dojo Foundation
	All Rights Reserved.

	Licensed under the Academic Free License version 2.1 or above OR the
	modified BSD license. For more information on Dojo licensing, see:

		http://dojotoolkit.org/community/licensing.shtml
*/



dojo.provide("dojo.gfx.color.hsl");
dojo.require("dojo.lang.array");
dojo.lang.extend(dojo.gfx.color.Color, {toHsl:function () {
	return dojo.gfx.color.rgb2hsl(this.toRgb());
}});
dojo.gfx.color.rgb2hsl = function (r, g, b) {
	if (dojo.lang.isArray(r)) {
		b = r[2] || 0;
		g = r[1] || 0;
		r = r[0] || 0;
	}
	r /= 255;
	g /= 255;
	b /= 255;
	var h = null;
	var s = null;
	var l = null;
	var min = Math.min(r, g, b);
	var max = Math.max(r, g, b);
	var delta = max - min;
	l = (min + max) / 2;
	s = 0;
	if ((l > 0) && (l < 1)) {
		s = delta / ((l < 0.5) ? (2 * l) : (2 - 2 * l));
	}
	h = 0;
	if (delta > 0) {
		if ((max == r) && (max != g)) {
			h += (g - b) / delta;
		}
		if ((max == g) && (max != b)) {
			h += (2 + (b - r) / delta);
		}
		if ((max == b) && (max != r)) {
			h += (4 + (r - g) / delta);
		}
		h *= 60;
	}
	h = (h == 0) ? 360 : Math.ceil((h / 360) * 255);
	s = Math.ceil(s * 255);
	l = Math.ceil(l * 255);
	return [h, s, l];
};
dojo.gfx.color.hsl2rgb = function (h, s, l) {
	if (dojo.lang.isArray(h)) {
		l = h[2] || 0;
		s = h[1] || 0;
		h = h[0] || 0;
	}
	h = (h / 255) * 360;
	if (h == 360) {
		h = 0;
	}
	s = s / 255;
	l = l / 255;
	while (h < 0) {
		h += 360;
	}
	while (h > 360) {
		h -= 360;
	}
	var r, g, b;
	if (h < 120) {
		r = (120 - h) / 60;
		g = h / 60;
		b = 0;
	} else {
		if (h < 240) {
			r = 0;
			g = (240 - h) / 60;
			b = (h - 120) / 60;
		} else {
			r = (h - 240) / 60;
			g = 0;
			b = (360 - h) / 60;
		}
	}
	r = Math.min(r, 1);
	g = Math.min(g, 1);
	b = Math.min(b, 1);
	r = 2 * s * r + (1 - s);
	g = 2 * s * g + (1 - s);
	b = 2 * s * b + (1 - s);
	if (l < 0.5) {
		r = l * r;
		g = l * g;
		b = l * b;
	} else {
		r = (1 - l) * r + 2 * l - 1;
		g = (1 - l) * g + 2 * l - 1;
		b = (1 - l) * b + 2 * l - 1;
	}
	r = Math.ceil(r * 255);
	g = Math.ceil(g * 255);
	b = Math.ceil(b * 255);
	return [r, g, b];
};
dojo.gfx.color.hsl2hex = function (h, s, l) {
	var rgb = dojo.gfx.color.hsl2rgb(h, s, l);
	return dojo.gfx.color.rgb2hex(rgb[0], rgb[1], rgb[2]);
};
dojo.gfx.color.hex2hsl = function (hex) {
	var rgb = dojo.gfx.color.hex2rgb(hex);
	return dojo.gfx.color.rgb2hsl(rgb[0], rgb[1], rgb[2]);
};