/*  

 * Lazy Load - jQuery plugin for lazy loading images  

 *  

 * Copyright (c) 2007-2009 Mika Tuupola  

 *  

 * Licensed under the MIT license:  

 *   http://www.opensource.org/licenses/mit-license.php  

 *  

 * Project home:  

 *   http://www.appelsiini.net/projects/lazyload  

 *  

 * Version:  1.5.0  

 *  

 */  

 (function($) {  

 $.fn.lazyload = function(options) {  

 var settings = {  

 threshold    : 0,  

 failurelimit : 0,  

 event        : "scroll",  

 effect       : "show",  

 container    : window  

 };  

 if(options) {  

 $.extend(settings, options);  

 }  

 /* Fire one scroll event per scroll. Not one scroll event per image. */  

 var elements = this;  

 if ("scroll" == settings.event) {  

 $(settings.container).bind("scroll", function(event) {  

 var counter = 0;  

 elements.each(function() {  

 if ($.abovethetop(this, settings) ||  

 $.leftofbegin(this, settings)) {  

 /* Nothing. */  

 } else 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);  

 });  

 }  

 this.each(function() {  

 var self = this;  

 //我就把这里的一段代码删除了  

 /* When appear is triggered load original image. */  

 $(self).one("appear", function() {  

 if (!this.loaded) {  

 $("<img />")  

 .bind("load", function() {  

 $(self)  

 .hide()  

 .attr("src", $(self).attr("original"))  

 [settings.effect](settings.effectspeed);  

 self.loaded = true;  

 })  

 .attr("src", $(self).attr("original"));  

 };  

 });  

 /* 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");  

 }  

 });  

 }  

 });  

 /* Force initial check if images should appear. */  

 $(settings.container).trigger(settings.event);  

 return this;  

 };  

 /* Convenience methods in jQuery namespace.           */  

 /* Use as  $.belowthefold(element, {threshold : 100, container : window}) */  

 $.belowthefold = function(element, settings) {  

 if (settings.container === undefined || settings.container === window) {  

 var fold = $(window).height() + $(window).scrollTop();  

 } else {  

 var fold = $(settings.container).offset().top + $(settings.container).height();  

 }  

 return fold <= $(element).offset().top - settings.threshold;  

 };  

 $.rightoffold = function(element, settings) {  

 if (settings.container === undefined || settings.container === window) {  

 var fold = $(window).width() + $(window).scrollLeft();  

 } else {  

 var fold = $(settings.container).offset().left + $(settings.container).width();  

 }  

 return fold <= $(element).offset().left - settings.threshold;  

 };  

 $.abovethetop = function(element, settings) {  

 if (settings.container === undefined || settings.container === window) {  

 var fold = $(window).scrollTop();  

 } else {  

 var fold = $(settings.container).offset().top;  

 }  

 return fold >= $(element).offset().top + settings.threshold  + $(element).height();  

 };  

 $.leftofbegin = function(element, settings) {  

 if (settings.container === undefined || settings.container === window) {  

 var fold = $(window).scrollLeft();  

 } else {  

 var fold = $(settings.container).offset().left;  

 }  

 return fold >= $(element).offset().left + settings.threshold + $(element).width();  

 };  

 /* Custom selectors for your convenience.   */  

 /* Use as $("img:below-the-fold").something() */ 

 $.extend($.expr[':'], {  

 "below-the-fold" : "$.belowthefold(a, {threshold : 0, container: window})",  

 "above-the-fold" : "!$.belowthefold(a, {threshold : 0, container: window})",  

 "right-of-fold"  : "$.rightoffold(a, {threshold : 0, container: window})",  

 "left-of-fold"   : "!$.rightoffold(a, {threshold : 0, container: window})" 

 });  

 })(jQuery);