/*
* 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);