function initialise_window(){
  var scr_element = event.srcElement;  
	
  if (event.srcElement.id != "popup_layer" && event.srcElement.tagName != "BODY") {
    scr_element = event.srcElement.parentElement;
  }  
  if (scr_element.id == "popup_layer"){
    offset_x = event.clientX;
    offset_y = event.clientY;
    current_X = parseInt(document.getElementById("popup_layer").style.left);
    current_Y = parseInt(document.getElementById("popup_layer").style.top);
    ddEnabled = true;
    document.onmousemove = position_window;
  }
}

function position_window(){
  if (!ddEnabled) return;
  document.getElementById("popup_layer").style.left = current_X + event.clientX - offset_x; 
  document.getElementById("popup_layer").style.top = current_Y + event.clientY - offset_y;
  return false;  
}

function scroll_Y() {
	if (window.innerHeight) {
		return window.pageYOffset
	}
	else if (document.documentElement && document.documentElement.scrollTop) {
		return document.documentElement.scrollTop
	}
	else if (document.body) {
		return document.body.scrollTop
	} else
	return 0;
}


document.onmousedown = initialise_window;


function display_zoomed_image(url, type) {
	img = document.getElementById('zoomed_image');
	img.src= ''+url;
	if (document.getElementById("popup_layer").style.top) {
		document.getElementById("popup_layer").style.top=scroll_Y()+100;
	}
  document.getElementById("popup_layer").style.visibility="visible";
	document.getElementById("covertype").value = ''+type;
}

function click_zoomin(url) {
	if (document.getElementById("covertype").value == "front" && !IsBlank(url)) {
		img = document.getElementById('zoomed_image');
		img.src= ''+url;
		if (document.getElementById("popup_layer").style.top) {
			document.getElementById("popup_layer").style.top=scroll_Y()+100;
		}
	  document.getElementById("popup_layer").style.visibility="visible";
		document.getElementById("covertype").value = "rear";
	}
	else {
  	document.getElementById("popup_layer").style.visibility="hidden";
	}
}