var randomImages; var newImage; var oldImage;

function wipeBackground (images) {
    randomImages = images;
    $('div.row').submit(function () {
        var newPos = getBackgroundPosition(-600, $(this));
        $(this).animate({backgroundPosition: "("+newPos+")"}, 1100, "", showNext);
        });    
    $.preload(randomImages, {onComplete:preloadComplete});
}

function preloadComplete (data) {
    $('div.row').css('backgroundColor', '#FFF');
    if (data.loaded==randomImages.length)
    {
	    setInterval(switchBackground, 10 * 1000);
	}
}

function switchBackground () {
    newImage = getRandomImage();
    $('div.row').trigger('submit');
}

function getRandomImage () {
    newImage = randomImages[Math.ceil(Math.random() * randomImages.length-1)];
    if (newImage == oldImage) {newImage = getRandomImage();}
    return newImage;
}

function showNext () {
    var newPos = getBackgroundPosition(600, $(this));
    $(this)
        .css({backgroundImage:'url('+newImage+')'})
        .animate({backgroundPosition: '('+newPos+')'}, 700);
    oldImage = newImage;
}

function getBackgroundPosition (offset, obj) {  
    var pos = obj.css('background-position');
    if (pos==undefined)
    {
        var yPos = obj.css('background-position-y');
        var xPos = obj.css('background-position-x');
    }
    else
    {
        var yPos = pos.split(' ')[1];
        var xPos = pos.split(' ')[0];
    }
    var yPos = parseFloat(yPos); yPos += offset; yPos += "px";
    return xPos + ' ' + yPos;
}