function popup(image,width,height)
{
	var browser=navigator.userAgent.toLowerCase();
	var isIE=false;
	
	if(browser.indexOf('msie')>-1)
	{
		isIE=true;
	}
	
	var vp=get_viewportsize();
	var y=0;
	var popupbox_height=0;
	if(isIE===true)
	{
		var so=get_scrolloffset();
		y=parseInt(so["y"]+((vp["y"]/2)-(height/2)));//vp["y"]-height)+
		popupbox_height=document.body.offsetHeight;
		//alert(y);
		
	}
	else
	{
		y=(vp["y"]/2)-(height/2);
		popupbox_height=document.getElementsByTagName("html")[0].offsetHeight
	}
	
	
// 	var body=document.getElementsByTagName("body")[0];
	var body=document.getElementById("playground");
	
// 	hide_objects();
	var box=document.createElement("div");
	box.setAttribute("id","popupbox");
	box.onclick=close_popup;
	box.style.height=popupbox_height+"px";
	
	var img=document.createElement("img");
	img.setAttribute("src",image);
	img.setAttribute("id","popupimg");
	img.style.width=width+"px";
	img.style.height=height+"px";
	img.onclick=close_popup;
	
	
	//img.style.position="absolute";
	var x=(vp["x"]/2)-(width/2);
	
	img.style.top=y+"px";
	img.style.left=x+"px";
// 	img.onload=function (){alert("bild geladen");};
// 	img.onload=function (){img.focus();};
	
	body.appendChild(box);
	body.appendChild(img);
	
	return true;
}

function close_popup()
{
	var box=document.getElementById("popupbox");
	if(box===null)
	{
		return false;
	}
	
	var img=document.getElementById("popupimg");
	if(img===null)
	{
		return false;
	}
	
	//var body=document.getElementsByTagName("body")[0];
	var body=document.getElementById("playground");
	body.removeChild(box);
	body.removeChild(img);
	return true;
}

function hide_objects()
{
	var objs=document.getElementsByTagName("object");
	if(objs===null)
	{
		return false;
	}
	
	for(var i=0; i<objs.length; i++)
	{
		objs[i].style.visibility="hidden";
	}
	
	var objs=document.getElementsByTagName("embed");
	
	if(objs!==null)
	{
		for(var i=0; i<objs.length; i++)
		{
			objs[i].style.visibility="hidden";
		}
	}
	return true;
}

function show_objects()
{
	var objs=document.getElementsByTagName("object");
	if(objs===null)
	{
		return false;
	}
	
	for(var i=0; i<objs.length; i++)
	{
		objs[i].style.visibility="visible";
	}
	
	var objs=document.getElementsByTagName("embed");
	
	if(objs!==null)
	{
		for(var i=0; i<objs.length; i++)
		{
			objs[i].style.visibility="visible";
		}
	}
	return true;
}


function get_viewportsize()
{
	//this part is from quirksmode.org (http://www.quirksmode.org/viewport/compatibility.html#link2)
	var viewport_x=0;
	var viewport_y=0;
	if(self.innerHeight)
	{
		viewport_x=self.innerWidth;
		viewport_y=self.innerHeight;
	}
	else if(document.documentElement && document.documentElement.clientHeight)
	{
		viewport_x=document.documentElement.clientWidth;
		viewport_y=document.documentElement.clientHeight;
	}
	else if(document.body)
	{
		viewport_x=document.body.clientWidth;
		viewport_y=document.body.clientHeight;
	}
	
	//new Array
	var returnval={"x":viewport_x,"y":viewport_y}
	return returnval;
}

function get_scrolloffset()
{
	//this part is from quirksmode.org (http://www.quirksmode.org/viewport/compatibility.html#link2)
	var offset_x=0;
	var offset_y=0;
	if(self.pageYOffset) // all except Explorer
	{
		offset_x=self.pageXOffset;
		offset_y=self.pageYOffset;
	}
	else if(document.documentElement && document.documentElement.scrollTop)
	{
		// Explorer 6 Strict
		offset_x=document.documentElement.scrollLeft;
		offset_y=document.documentElement.scrollTop;
	}
	else if (document.body) // all other Explorers
	{
		offset_x=document.body.scrollLeft;
		offset_y=document.body.scrollTop;
	}
	
	//new Array
	var returnval={"x":offset_x,"y":offset_y}
	return returnval;
}