var slideshowSpeed = 5500;

$(document).ready(function() {
	var imagesNum=7;
	var currentNum=1;
	var container1="header";
	var container2="headerin";
	var activeContainer=container1;
	var cache = [];
	$.preLoadImages = function() {
		var args_len = arguments.length;
		for (var i = args_len; i--;) {
		  var cacheImage = document.createElement('img');
		  cacheImage.src = arguments[i];
		  cache.push(cacheImage);
		}
	}
	for(i=currentNum;i<=imagesNum;i++){
		jQuery.preLoadImages("image" + i + ".jpg");
	}
	
	function showNext(){
		currentNum=currentNum+1;
		if(currentNum>imagesNum){
			currentNum=1;
		}
		if(activeContainer == container1) {
			activeContainer = container2;
		} else {
			activeContainer = container1;
		}
		$("#" + activeContainer).css({
			"background-image" : "url(image" + currentNum + ".jpg)"
		});
		if(activeContainer==container1){
			$("#" + container2).fadeOut(800);
		}else{
			$("#" + container2).fadeIn(800);
		}
	}
	interval = setInterval(function() {showNext();}, slideshowSpeed);
});