// Funktionalit?t zum bl?ttern der Inhalte
// Die verschiedenen Seiten m?ssen als Layer (DIV) mit festen Namen (layerName + fortlaufende Nr) vorhanden sein

// Name der Layer
var layerName = "Box";
// immer mit dem Layer Nr. 1 anfangen
var firstLayer = 1;
// letzte Nummer, wird beim Start automatisch ermittelt
var lastLayer = 1;
// Die aktuell angezeigte Box (als Nummer und als Element)
var currentLayer;
var curentElement;  

// Zeigt die Erste Box an und versteckt alle anderen Boxen
// Gleichzeitig wird die Anzahl der Boxen ermittelt
function initBoxes() {
	currentLayer = firstLayer;
	curentElement = document.getElementById(layerName + currentLayer);
    if (curentElement) curentElement.style.visibility = "visible";
	while (curentElement)
	{
	  currentLayer = currentLayer + 1;
      curentElement = document.getElementById(layerName + currentLayer);
	  if (curentElement)
	  {
	    curentElement.style.visibility = "hidden";
		lastLayer = currentLayer;
	  }
	}
	currentLayer = 1;
	setNaviIcons();
}

// Bl?ttert zur angegebenen Seite
function gotoPage(i) {
    if (i>0 && i<=lastLayer) {
	    curentElement = document.getElementById(layerName + currentLayer);
	    if (curentElement) curentElement.style.visibility = "hidden";
		currentLayer = i;
	    curentElement = document.getElementById(layerName + currentLayer);
	    if (curentElement) curentElement.style.visibility = "visible";
		setNaviIcons();
	}
}

// Bl?ttert zur n?chsten Seite
function nextPage() {
    curentElement = document.getElementById(layerName + currentLayer);
    if (curentElement) curentElement.style.visibility = "hidden";
	currentLayer = currentLayer + 1;
    curentElement = document.getElementById(layerName + currentLayer);
    if (curentElement) curentElement.style.visibility = "visible";
	setNaviIcons();
}

// Bl?ttert zur vorherigen Seite
function previousPage() {
    curentElement = document.getElementById(layerName + currentLayer);
    if (curentElement) curentElement.style.visibility = "hidden";
	currentLayer = currentLayer - 1;
    curentElement = document.getElementById(layerName + currentLayer);
    if (curentElement) curentElement.style.visibility = "visible";
	setNaviIcons();
}

// Bl?ttert zur ersten Seite
function firstPage() {
    curentElement = document.getElementById(layerName + currentLayer);
    if (curentElement) curentElement.style.visibility = "hidden";
	currentLayer = firstLayer;
    curentElement = document.getElementById(layerName + currentLayer);
    if (curentElement) curentElement.style.visibility = "visible";
	setNaviIcons();
}

// Bl?ttert zur letzten Seite
function lastPage() {
    curentElement = document.getElementById(layerName + currentLayer);
    if (curentElement) curentElement.style.visibility = "hidden";
	currentLayer = lastLayer;
    curentElement = document.getElementById(layerName + currentLayer);
    if (curentElement) curentElement.style.visibility = "visible";
	setNaviIcons();
}

function setNaviIcons() {
	// Zur?ck-Buttons immer anzeigen, ausser man ist auf der ersten Seite
    navi1 = document.getElementById("NaviFirst");
    navi2 = document.getElementById("NaviPrev");
	if (currentLayer == firstLayer)
	{
      if (navi1) navi1.style.visibility = "hidden";
      if (navi2) navi2.style.visibility = "hidden";
	}	
	else
	{
      if (navi1) navi1.style.visibility = "visible";
      if (navi2) navi2.style.visibility = "visible";
	}
		
	// Weiter-Buttons immer anzeigen, ausser man ist auf der letzten Seite
    navi1 = document.getElementById("NaviLast");
    navi2 = document.getElementById("NaviNext");
	if (currentLayer == lastLayer)
	{
      if (navi1) navi1.style.visibility = "hidden";
      if (navi2) navi2.style.visibility = "hidden";
	}	
	else
	{
      if (navi1) navi1.style.visibility = "visible";
      if (navi2) navi2.style.visibility = "visible";
	}
}