/*
 * Lazy Load - jQuery plugin for lazy loading images
 *
 * Copyright (c) 2007-2008 Mika Tuupola
 *
 * Licensed under the MIT license:
 *   http://www.opensource.org/licenses/mit-license.php
 *
 * Project home:
 *   http://www.appelsiini.net/projects/lazyload
 *
 * Revision: $Id$
 * Version:  1.3.1
 *
 */
(function($) {

	$.fn.lazyload = function(options) {
		var settings = {
			threshold	: 0,
			failurelimit: 0,
			event		: "scroll",
			effect		: "show"
		};
		
		if (options) {
			$.extend(settings, options);
		}

		/* Fire one scroll event per scoll. Not one scroll event per image. */
		var elements = this;
		if ("scroll" == settings.event) {
			$(window).bind("scroll", function(event) {
				var counter = 0;
				elements.each(function() {
					if (!$.belowthefold(this, settings) &&
						!$.rightoffold(this, settings)) {
							$(this).trigger("appear");
					} else {
						if (counter++ > settings.failurelimit) {
							return false;
						}
					}
				});
				/* Remove image from array so it is not looped next time. */
				var temp = $.grep(elements, function(element) {
					return !element.loaded;
				});
				elements = $(temp);
			});
		}
		
		return this.each(function() {
			var self = $(this);
			var link = $(this).parent('a');
		
			/* TODO: use .data() instead of .attr() */
			self.attr("original", self.attr("src"));
			if ("scroll" != settings.event 
						 || $.belowthefold(self, settings) 
						 || $.rightoffold(self, settings)) {
				if (settings.placeholder) {
					self.attr("src", settings.placeholder);	  
				} else {
					self.removeAttr("src");
				}
				link.hide();
				self.loaded = false;
			} else {
				self.loaded = true;
			}
			
			/* When appear is triggered load original image. */
			self.one("appear", function() {
				if (!this.loaded) {
					$("<img />")
						.attr("src", self.attr("original"))
						.bind("load", function() {
							self.attr("src", self.attr("original"))
								[settings.effect](settings.effectspeed);
							link
								[settings.effect](settings.effectspeed);
							self.loaded = true;
						});
				};
			});

			/* When wanted event is triggered load original image */
			/* by triggering appear.							  */
			if ("scroll" != settings.event) {
				self.bind(settings.event, function(event) {
					if (!self.loaded) {
						self.trigger("appear");
					}
				});
			}
		});

	};

	/* Convenience methods in jQuery namespace.		   */
	/* Use as  $.belowthefold(element, {threshold : 100}) */

	$.belowthefold = function(element, settings) {
		var fold = $(window).height() + $(window).scrollTop();
		return fold <= $(element).offset().top - settings.threshold;
	};
	
	$.rightoffold = function(element, settings) {
		var fold = $(window).width() + $(window).scrollLeft();
		return fold <= $(element).offset().left - settings.threshold;
	};
	
	/* Custom selectors for your convenience.   */
	/* Use as $("img:below-the-fold").something() */

	$.extend($.expr[':'], {
		"below-the-fold" : "$.belowthefold(a, {threshold : 0})",
		"above-the-fold" : "!$.belowthefold(a, {threshold : 0})",
		"right-of-fold"  : "$.rightoffold(a, {threshold : 0})",
		"left-of-fold"   : "!$.rightoffold(a, {threshold : 0})"
	});
	
})(jQuery);
// JavaScript Document