/*Copyright (c) 2009 Dimas Begunoff, http://www.farinspace.com Licensed under the MIT license*/

function imgpreload(imgs,settings)
{
	// settings = { each:Function, all:Function }
	if (settings instanceof Function) { settings = {all:settings}; }

	// use of typeof required
	// https://developer.mozilla.org/En/Core_JavaScript_1.5_Reference/Operators/Special_Operators/Instanceof_Operator#Description
	if (typeof imgs == "string") { imgs = [imgs]; }

	var loaded = [];
	var t = imgs.length;
	var i = 0;

	for (i; i<t; i++)
	{
		var img = new Image();
		img.onload = function()
		{
			loaded.push(this);
			if (settings.each instanceof Function) { settings.each.call(this); }
			if (loaded.length>=t && settings.all instanceof Function) { settings.all.call(loaded); }
		};
		img.src = imgs[i];
	}
}

if (typeof jQuery != "undefined")
{
	(function($){

		// extend jquery (because i love jQuery)
		$.imgpreload = imgpreload;

		// public
		$.fn.imgpreload = function(settings)
		{
			settings = $.extend({},$.fn.imgpreload.defaults,(settings instanceof Function)?{all:settings}:settings);

			this.each(function()
			{
				var elem = this;

				imgpreload($(this).attr('src'),function()
				{
					if (settings.each instanceof Function) { settings.each.call(elem); }
				});
			});

			// declare urls and loop here (loop a second time) to prevent
			// pollution of above closure with unnecessary variables

			var urls = [];

			this.each(function()
			{
				urls.push($(this).attr('src'));
			});

			var selection = this;

			imgpreload(urls,function()
			{
				if (settings.all instanceof Function) { settings.all.call(selection); }
			});

			return this;
		};

		// public
		$.fn.imgpreload.defaults =
		{
			each: null // callback invoked when each image in a group loads
			, all: null // callback invoked when when the entire group of images has loaded
		};

	})(jQuery);
}