/*
* 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;

/* Save original only if it is not defined in HTML. */
if (undefined == $(self).attr("original")) {
$(self).attr("original", $(self).attr("src"));     
}

if ("scroll" != settings.event || 
undefined == $(self).attr("src") || 
settings.placeholder == $(self).attr("src") || 
($.abovethetop(self, settings) ||
$.leftofbegin(self, settings) || 
$.belowthefold(self, settings) || 
$.rightoffold(self, settings) )) {

if (settings.placeholder) {
$(self).attr("src", settings.placeholder);      
} else {
$(self).removeAttr("src");
}
self.loaded = false;
} else {
self.loaded = true;
}

/* 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);