(function ($){
$.fn.lazyload=function (options){
var settings={
threshold:0,failurelimit:0,event:"scroll",effect:"show",container:window
};
if(options){
$.extend(settings,options)
}var elements=this;
if("scroll"==settings.event){
$(settings.container).bind("scroll",function (event){
var counter=0;
elements.each(function (){
if(!$.belowthefold(this,settings)&&!$.rightoffold(this,settings)){
$(this).trigger("appear")
}else {
if(counter++>settings.failurelimit){
return false
}
}
});
var temp=$.grep(elements,function (element){
return !element.loaded
});
elements=$(temp)
})
}return this.each(function (){
var self=this;
//$(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")
}self.loaded=false
}else {
$(self).attr("src",$(self).attr("original")) //手动添加这行代码
self.loaded=true
}$(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"))
}
});
if("scroll"!=settings.event){
$(self).bind(settings.event,function (event){
if(!self.loaded){
$(self).trigger("appear")
}
})
}
})
};
$.belowthefold=function (element,settings){
if(settings.container===undefined||settings.container===window){
var fold=$(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
};
$.extend($.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);
