var windowHeight = 0;
var windowWidth = 0;
var imageIsVisible = false;
var imgViewer = null;
var divViewerStyle = null;

function setupShowImage() {
	imgTag = document.createElement("img");
	imgTag.onload = centerImage;
	imgTag.id = "imgViewer";
	imgTag.style.border="0";
	
	aTag = document.createElement("a");
	aTag.href = "javascript:hideImage()";
	aTag.appendChild(imgTag);
	
	
	divTag = document.createElement("div");
	divTag.className = "ImageViewer";
	divTag.id = "divViewer";
	divTag.appendChild(aTag);
	
	document.body.appendChild(divTag);
	
	divViewerStyle = document.getElementById("divViewer").style;
	imgViewer = document.getElementById("imgViewer");
	
	getWindowSpecs();
}

function getWindowSpecs() {
	
	/*
	if (document.all && document.documentElement) {
		windowWidth = document.documentElement.clientWidth;
		windowHeight = document.documentElement.clientHeight;
		scrollTop = document.documentElement.scrollTop;
	} else 
	*/
	  if (document.all) {
	  
		windowWidth = document.body.clientWidth;
		windowHeight = document.body.clientHeight;
		scrollTop = document.body.scrollTop;
	
	} else {	
		windowWidth = window.innerWidth;
		windowHeight = window.innerHeight;
		scrollTop = window.pageYOffset;
	}
	
	
	//window.alert("W " +windowWidth +" H "+windowHeight+ " ST "+scrollTop );
	
}

function showImage(imgURL) {
	if (navigator.appName == "Netscape"){
		hideImage();
	}
	if (imageIsVisible){
		hideImage();
	}else{
		setupShowImage();
	}
	getWindowSpecs();
	imgViewer.src = imgURL;
}

function centerImage() {  
	
	//window.alert("ciao "+windowWidth);
	//window.alert("top "+windowHeight);
	
	divViewerStyle.left = Math.round((windowWidth-imgViewer.width)/2) + 'px';
	divViewerStyle.top = (Math.round((windowHeight-imgViewer.height)/2)+scrollTop) + 'px';
	divViewerStyle.visibility = 'visible';
	divViewerStyle.style.position='absolute';
	divViewerStyle.style.zIndex='10';
	//window.alert("ciao "+divViewerStyle.left);
	//window.alert("top "+divViewerStyle.top );
	
	imageIsVisible = true;
}

function hideImage() {
	var n = document.body;
	var kids = n.childNodes;
	var numkids = kids.length;
	for(var i = numkids-1; i >= 0; i--){
		if(kids[i].id=="divViewer"){
			kids[i].style.visibility = "hidden";
		}
	}
	imageIsVisible = false;
	//divViewerStyle.visibility = 'hidden';
	//imageIsVisible = false;
}

function deleteImage() {
	imgViewer.parentNode.removeChild(imgViewer);
	imageIsVisible = false;
}