Loader = Class.create( {
    initialize: function(){
        Event.observe(window, 'scroll', this.loadImage.bind(this));
        elements = $$('li a[href="'+document.referrer.replace("http://friedemannbartels.de", "")+'"]');
        if (document.referrer && elements.length > 0) {
            this.scrollToElement(elements[0]);
        }else if(window.location.hash == ""){
            this.scrollToElement(document.body);
        }
        this.loadImage();
    },

    loadImage: function() {
        elements = $$('li a[rel]');
        if(elements.length == 0){
            Event.stopObserving(window, 'scroll');
        }
        for (var i = 0; i < elements.length; ++i){
            if(this.getOffsetHeight(elements[i])-1.5*window.innerHeight < document.body.cumulativeScrollOffset()[1] && elements[i].rel != ''){
                img = elements[i].getElementsByTagName('img');
                img[0].src = elements[i].rel;
                elements[i].removeAttribute("rel");
            }
        }        
    },

    getOffsetHeight: function(element) {
        var y = 0;
        while(element != null){
            y += element.offsetTop;
            element = element.offsetParent;
        }
        return y;
    },

    scrollToElement: function(element) {
        window.scrollTo(0,this.getOffsetHeight(element));
    }

});

document.observe('dom:loaded', function(){
    new Loader();   
});