var contentsArray = new Array();
var nCurrentDisplay = 0;
var nMaxDisplayNdx = 0;

function initializeDisplayArray() {
    var ndx = document.getElementById("displayLayers").getElementsByTagName("div"); 
    var j = 0;
    for (var i=0; i<ndx.length; i++){
        if (ndx[i].className=="displayContents") {   
            contentsArray[j] = ndx[i].id;
            j++;
 		}
 	} 
    nMaxDisplayNdx = contentsArray.length-1;
}


function setDisplayIndex(sDivID){
//    nCurrentDisplay = contentsArray.indexOf(sDivID); 

    for (var i=0; i<contentsArray.length; i++){
        if(contentsArray[i] == sDivID) {
            nCurrentDisplay = i;
            cycleDisplay('none');
            return i;
        }
    }
    
}

function cycleDisplay(sDirection){

    var nNextDisplay = nPrevDisplay = nCurrentDisplay;   

    nNextDisplay = nCurrentDisplay+1;
    if(nNextDisplay > nMaxDisplayNdx) nNextDisplay = 0; 
    document.getElementById("arrowright").href = "#" + contentsArray[nNextDisplay];

    nPrevDisplay = nCurrentDisplay-1; 
    if(nPrevDisplay < 0) nPrevDisplay = nMaxDisplayNdx;
    document.getElementById("arrowleft").href = "#" + contentsArray[nPrevDisplay];
   
    if(sDirection == 'forward'){
        nCurrentDisplay++;  
    } 
    if(sDirection == 'reverse') {
        nCurrentDisplay--;
    }
      
    if(nCurrentDisplay > nMaxDisplayNdx) nCurrentDisplay = 0; 
    if(nCurrentDisplay < 0) nCurrentDisplay = nMaxDisplayNdx;

}