var oldimgid = 2;
var id = 2;

function prevImage(dir)
{
	id--;
	if (document.getElementById('nr' + id))
	{
		nimage = document.getElementById('nr' + id).value;

	    if (dir == "Pres")
        {
            dir = document.getElementById('jsdir').value;
            document.getElementById('imgPres').src = "gfx/" + dir + "/" + nimage;
           	checkArrows(id);
        }
		changeImage(dir,nimage,id);
	}
	else
		id++;

}

function nextImage(dir)
{
	id++;
	if (document.getElementById('nr' + id))
	{
		nimage = document.getElementById('nr' + id).value;

	    if (dir == "Pres")
        {
            dir = document.getElementById('jsdir').value;
            document.getElementById('imgPres').src = "gfx/" + dir + "/" + nimage;
        	checkArrows(id);
        }
		changeImage(dir,nimage,id);
	}
	else
		id--;
	
}

function changeImage(dir,newimage,imgid)
{

	document.getElementById('imgframe').src = "gfx/" + dir + "/" + newimage;
	if (imgid != '')
	{
		document.getElementById('img' + oldimgid).style.backgroundColor = "";
		document.getElementById('img' + imgid).style.backgroundColor = "#ffffff";
	}

	document.getElementById('imgPres').src = "gfx/" + dir + "/" + newimage;

	if (document.getElementById('desc' + imgid))
		document.getElementById('desc' + imgid).style.display = "inline";
	if (document.getElementById('desc' + oldimgid))
		document.getElementById('desc' + oldimgid).style.display = "none";

	oldimgid = imgid;
	id = imgid;

	checkArrows(id);
	
	return id;
}

function imagePresentation(dir,img)
{


	if (!document.getElementById('imgSwitch'))
	{
		document.getElementById('prevPres').style.display = "none";
		document.getElementById('nextPres').style.display = "none";
	}

	if (document.getElementById('imgPres').src == "")
		document.getElementById('imgPres').src = "gfx/" + dir + "/" + img;

	document.getElementById('overlay').style.visibility = "visible";
	document.getElementById('overlay_content').style.visibility = "visible";

	document.body.style.overflow = "hidden";
	document.getElementById('rightfix').style.display = "block";

	document.getElementById('jsdir').value = dir;

	checkArrows(id);

	startFader();
}


var starttime = 5;
var time = starttime;
var minus = 1;
var start1 = 10;
var start2 = 10;
var end1 = 60;
var end2 = 99;
var teiler1 = (end1 - start1) / (starttime - 1);
var teiler2 = (end2 - start2) / (starttime - 1);

var op1 = start1;
var op2 = start2;

function startFader()
{


	if(time == 0)
	{
		time = starttime;
		op1 = start1;
		op2 = start2;
	}

	else
	{
		//op1 = ((starttime*10 - (time - 1) * 10) / 2);
		//op2 = (starttime*10 - (time - 1) * 10);


		document.getElementById('overlay_content').style.MozOpacity = "." +  Math.round(op2);
		document.getElementById('overlay_content').style.filter="Alpha(opacity=" + Math.round(op2) + ")";

		document.getElementById('overlay').style.MozOpacity = "." + Math.round(op1);
		document.getElementById('overlay').style.filter="Alpha(opacity=" + Math.round(op1) + ")";

		//document.getElementById('test').value = op2;


		op1 += teiler1;
		op2 += teiler2;

		time = time-minus;
		setTimeout("startFader()", 10);

	}
}

function closePres()
{
	document.getElementById('overlay').style.visibility = "hidden";
	document.getElementById('overlay_content').style.visibility = "hidden";
	document.getElementById('prevPres').style.visibility = "hidden";
	document.getElementById('nextPres').style.visibility = "hidden";

	document.body.style.overflow = "scroll";
	document.getElementById('rightfix').style.display = "none";
}

function checkArrows(id)
{
	var idp = ++id;
	id--;
	var idm = --id;
	id++;


	if (document.getElementById('nr' + idm))
  {
  	if (document.getElementById('overlay').style.visibility == "visible")
  		document.getElementById('prevPres').style.visibility = "visible";
  		
  	if (document.getElementById('pre_prev'))
  	{
  		document.getElementById('pre_prev').style.visibility = "visible";
  		document.getElementById('pre_prev').style.cursor = "pointer";
  	}	
  	
  }      
  else
  {
  	if (document.getElementById('overlay').style.visibility == "visible")
  		document.getElementById('prevPres').style.visibility = "hidden";
  	
  	if (document.getElementById('pre_prev'))
  	{	
  	  document.getElementById('pre_prev').style.visibility = "hidden";
      document.getElementById('pre_prev').style.cursor = "";
  	}
  } 
     


  if (document.getElementById('nr' + idp))
  {
  	if (document.getElementById('overlay').style.visibility == "visible")
  		document.getElementById('nextPres').style.visibility = "visible";
  		
  	if (document.getElementById('pre_next'))
  	{	
  	  document.getElementById('pre_next').style.visibility = "visible";
      document.getElementById('pre_next').style.cursor = "pointer";
  	}
  }      
  else
  {
  	if (document.getElementById('overlay').style.visibility == "visible")
  		document.getElementById('nextPres').style.visibility = "hidden";
  	
  		
  	if (document.getElementById('pre_next'))
  	{		
  	  document.getElementById('pre_next').style.visibility = "hidden";
      document.getElementById('pre_next').style.cursor = "";
  	}
  }
     
}