jquery.lazyload.js 图片延迟加载

// 天涯版
(function(jQuery) {

jQuery.fn.lazyload = function(options) {
var settings = {
threshold    : 0,
failurelimit : 0,
event        : "scroll",
effect       : "show",
container    : window
};

if(options) {
jQuery.extend(settings, options);
}

/* Fire one scroll event per scroll. Not one scroll event per image. */
var elements = this;
if ("scroll" == settings.event) {
jQuery(settings.container).bind("scroll", function(event) {

var counter = 0;
elements.each(function() {
if (jQuery.abovethetop(this, settings)) {
/* Nothing. */
} else if (!jQuery.belowthefold(this, settings)) {
jQuery(this).trigger("appear");
} else {
if (counter++ > settings.failurelimit) {
return false;
}
}
});
/* Remove image from array so it is not looped next time. */
var temp = jQuery.grep(elements, function(element) {
return !element.loaded;
});
elements = jQuery(temp);
});
}

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

/* Save original only if it is not defined in HTML. */
if (undefined != jQuery(self).attr("original")){
self.loaded = false;

/* When appear is triggered load original image. */
jQuery(self).one("appear", function() {
if (!this.loaded) {
jQuery("<img />")
.bind("load", function() {
jQuery(self)
.hide()
.removeAttr("height")
.attr("src", jQuery(self).attr("original"))
[settings.effect](settings.effectspeed);
self.loaded = true;
})
.attr("src", jQuery(self).attr("original"));
};
});
}
});

/* Force initial check if images should appear. */
jQuery(settings.container).trigger(settings.event);

return this;
};

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

function checkshow(){

}

jQuery.belowthefold = function(element, settings) {
if (settings.container === undefined || settings.container === window) {
var fold = jQuery(window).height()*2 + jQuery(window).scrollTop();
} else {
var fold = jQuery(settings.container).offset().top + jQuery(settings.container).height()*2;
}
return fold <= jQuery(element).offset().top - settings.threshold;

};

jQuery.abovethetop = function(element, settings) {
if (settings.container === undefined || settings.container === window) {
var fold = jQuery(window).scrollTop();
} else {
var fold = jQuery(settings.container).offset().top;
}
return fold >= jQuery(element).offset().top + settings.threshold  + jQuery(element).height();
};
/* Custom selectors for your convenience.   */
/* Use as jQuery("img:below-the-fold").something() */

jQuery.extend(jQuery.expr[':'], {
"below-the-fold" : "jQuery.belowthefold(a, {threshold : 0, container: window})",
"above-the-fold" : "!jQuery.belowthefold(a, {threshold : 0, container: window})"
});

})(jQuery);

jQuery("#pContentDiv .post img[original]").lazyload({
effect:"fadeIn"
});