/*
* 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);