//alert ('ajaxlib is geladen');
// stores the reference to the XMLHttpRequest object
var xmlHttp = createXmlHttpRequestObject(); 

// Definieer enkele variabelen om de scroll goed te laten verlopen
var intLocatie = 0;

// Als er op een foto geklikt is, moet de grote versie geplaatst worden 
function getFoto (intFoto) {
	document.getElementById('introfoto').src = document.getElementById('scrollimage'+intFoto).src.replace('120x90','400x300');
}

// Scroll
function getImgArray(intVerplaatsing) {
	intLocatie = intLocatie + intVerplaatsing;
	AjaxImgArray (strFotoAlbum, intLocatie, 4);
}


// retrieves the XMLHttpRequest object
function createXmlHttpRequestObject() 
{	
  // will store the reference to the XMLHttpRequest object
  var xmlHttp;
  // if running Internet Explorer
  if(window.ActiveXObject)
  {
    try
    {
      xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
    }
    catch (e) 
    {
      xmlHttp = false;
    }
  }
  // if running Mozilla or other browsers
  else
  {
    try 
    {
      xmlHttp = new XMLHttpRequest();
    }
    catch (e) 
    {
      xmlHttp = false;
    }
  }
  // return the created object or display an error message
  if (!xmlHttp)
 
    alert("Error creating the XMLHttpRequest object.");
  else 
    return xmlHttp;
}

// make asynchronous HTTP request using the XMLHttpRequest object 
function AjaxImgArray(strAlbum, intLocatie, intAantal)
{
  // proceed only if the xmlHttp object isn't busy
  if (xmlHttp.readyState == 4 || xmlHttp.readyState == 0)
  {
    xmlHttp.open("GET", "bieb/get_foto_strip.php?strAlbum=" + strAlbum + "&intLocatie=" + intLocatie + "&intAantal=" + intAantal, true);  

    // define the method to handle server responses
    xmlHttp.onreadystatechange = handleServerResponseImgArray;
    // make the server request
    xmlHttp.send(null);
  }
}

function handleServerResponseImgArray() 
{
  // move forward only if the transaction has completed
  if (xmlHttp.readyState == 4) 
  {
    // status of 200 indicates the transaction completed successfully
    if (xmlHttp.status == 200) 
    {
      // extract the XML retrieved from the server
      xmlResponse = xmlHttp.responseXML;
	  txtResponse = xmlHttp.responseText;
	  //alert (txtResponse);
      document.getElementById("scroller").innerHTML = txtResponse;
    } 
    // a HTTP status different than 200 signals an error
    else 
    {
      alert("There was a problem accessing the server: " + xmlHttp.statusText);
    }
  }
}