var source = new Array(5);
var indice = -2;
var salto = 0;
 
function gestiscitastiera(e)
{
	var evtobj = window.event ? event : e;
	var unicode = evtobj.charCode ? evtobj.charCode : evtobj.keyCode;
	if(unicode == 37)
		cambiaIndice(-1);
	else if (unicode == 39)
		cambiaIndice(1);
}
document.onkeypress = gestiscitastiera;			

function cambiaIndice(salto)
{
	if(document.getElementById("listaIMG").childNodes[indice + salto + 2])
	{
		indice += salto;
		displayGallery();
	}
}

function displayGallery()
{				
	for(var i = 0; i < 5; i++)
	{
		if((indice >= 0 && ! document.getElementById("listaIMG").childNodes[indice + i]) || (indice + i == -1 || indice + i == -2))
			source[i] = "blank.jpg";
		else						
			source[i] = document.getElementById("listaIMG").childNodes[indice + i].childNodes[0].nodeValue;
	}

	document.getElementById("galleryCentrale").childNodes[0].childNodes[0].src = "galleria/" + source[2];

	for(var i = 0; i < 5; i++)
	{
		if(i == 2)
			document.getElementById("galleryList").childNodes[i].childNodes[0].src = "galleria/" + source[i];
		else
			document.getElementById("galleryList").childNodes[i].childNodes[0].childNodes[0].src = "galleria/" + source[i];					
	}
}