images = new Array();
currentImage = 0;
delay=50;
showImageTime=4000;
opacityStep=0.02;
currentOpacity=0;


function SetOpacity(elem, opacityAsDecimal) {
	var opacityAsInt = opacityAsDecimal;
	
	if (opacityAsDecimal>1) opacityAsDecimal=1;
	if (opacityAsDecimal<0) opacityAsDecimal=0;
	
	opacityAsInt=opacityAsDecimal*100;
	 	
	if (opacityAsInt < 1) opacityAsInt = 1; // IE7 bug, text smoothing cuts out if 0
		
	elem.style.opacity = (opacityAsDecimal);
	elem.style.filter  = "alpha(opacity=" + opacityAsInt + ")";
}


function slideshow_init(div) {
	slideshow=document.getElementById(div);
	if (slideshow!=null) {
		j=0;
		for (i=0;i<slideshow.childNodes.length;i++) {
			child=slideshow.childNodes[i];
			if (child.tagName=="DIV") {
				images[j]=child;
				j++;
			}
		}return true;
	}else return false;
}


function slideshow_start(div) {
	if (slideshow_init(div)) {
		setTimeout("slideslide()",showImageTime);
	}
}

function slideshow_stop(div) {
	slideshow=document.getElementById(div);  // nome del div contenente le img
	
}


function slideslide() {
	nextImage=currentImage+1;
	if (nextImage>=images.length) nextImage=0;

	currentOpacity=currentOpacity+opacityStep;
	
	SetOpacity(images[nextImage],currentOpacity);
	images[nextImage].style.display="block";

	SetOpacity(images[currentImage],1-currentOpacity);

	if (currentOpacity>=1) {
		images[currentImage].style.display="none";
		SetOpacity(images[currentImage],0);
		currentImage=nextImage;
		images[currentImage].style.display="block";
		SetOpacity(images[currentImage],1);
		currentOpacity=0;
		setTimeout("slideslide()",showImageTime);
	} else {
		setTimeout("slideslide()",delay);
	}
}