var bildnummer = 0;

function wowex(id, id2){
  document.getElementById(id).style.display = 'none';
  document.getElementById(id2).style.display = 'block';
}

function checkIfRemoteFileExists(fileToCheck)
{
	oHttp = window.XMLHttpRequest ? new XMLHttpRequest() : new ActiveXObject("Microsoft.XMLHTTP"); 
	var tmp=new Image;
	tmp.src=fileToCheck;
	oHttp.open("HEAD", fileToCheck, false);
	oHttp.send();
	if(tmp.complete || tmp.width > 0 || oHttp.status == 200)
	{ 
		document.getElementById('next').style.display = 'block'; 
	}
	else
	 {
		setTimeout('checkIfRemoteFileExists(fileToCheck)', 5000);
	}	
}

function show(what, pfadbild)
{
	var tmp=new Image;
	if (what == 'prev')
	{
		if (--bildnummer == 0)
		{
			document.getElementById('prev').style.display = 'none';
		}
	}
	else 
	{
		bildnummer++;
		document.getElementById('prev').style.display = 'block';
		document.getElementById('next').style.display = 'none'; // erstmal aus
	}
	document.getElementById('bild').src = pfadbild+bildnummer+'.png';
	checkIfRemoteFileExists(pfadbild+(bildnummer+1)+'.png');
}