var scroll_count = 0;
var zoom_count = 0;
var zoom_size = 1;

function scroll_handle(delta) 
{
	zoom_size = parseFloat(document.getElementById('zoom_size').innerHTML);

	if(delta < 0)
	{
		if(zoom_count+4 != zoom_size)
		{
			document.getElementById('zoom_'+zoom_count).style.display  = 'none';
			document.getElementById('zoom_'+(zoom_count+4)).style.display  = 'block';
			zoom_count++;
		}
	}
	else
	{
		if(zoom_count != 0)
		{
			document.getElementById('zoom_'+(zoom_count+3)).style.display  = 'none';
			document.getElementById('zoom_'+(zoom_count-1)).style.display  = 'block';
			zoom_count--;
		}
	}
}

function wheel(event)
{
	var delta = 0;
	if (!event)event = window.event;
	if (event.wheelDelta) {
		delta = event.wheelDelta/120; 
		if (window.opera) delta = -delta;
	} else if (event.detail) {
		delta = -event.detail/3;
	}
	if( event.preventDefault )
		event.preventDefault();
	else
		event.returnValue = false;

	if (delta)
		scroll_handle(delta);
}


/* START SCROLL ZOOM */
function start_scroll_zoom()
{
	if (window.addEventListener)
		window.addEventListener('DOMMouseScroll', wheel, false);
	else
		document.attachEvent ('onmousewheel', wheel);
}


/* END SCROLL ZOOM */
function end_scroll_zoom()
{
	if (window.removeEventListener)
		window.removeEventListener('DOMMouseScroll', wheel, false);
	else
		document.detachEvent ('onmousewheel', wheel);
		
	//document.getElementById('zoom').innerHTML = 0;
	scroll_count = 0;
}