function imageItem(image_location)
{
	this.image_item = new Image();
	this.image_item.src = image_location;
}

function get_ImageItemLocation(imageObj)
{
	return(imageObj.image_item.src)
}

function getNextImage()
{
	if (currImageNum < totalImages-1 ) {
		currImageNum++ ;
	} else {
		currImageNum = 0 ;
	}
	var new_image = get_ImageItemLocation(imageArray[currImageNum]);
	document['slideImg'].src = new_image;
	switchTextContent( new_image );
}

function getPrevImage()
{
	if (currImageNum > 0 ) {
		currImageNum = currImageNum - 1 ;
	} else {
		currImageNum = totalImages - 1 ;
	}
	var new_image = get_ImageItemLocation(imageArray[currImageNum]);
	document['slideImg'].src = new_image;
	switchTextContent( new_image );
}

/* Bei einigen Bildern ebenfalls die Bildunterschrift austauschen */
function switchTextContent ( imgUrl )
{
	/* wenn keine Container für alternativen Text vorhanden sind, wird auch kein Text ausgetauscht... */
	if ( document.getElementById('textContent2') != null && document.getElementById('textHeadline2') != null )
	{
		if ( imgUrl.indexOf("b_buch_1_11.jpg") != -1 )
		{
			var thisTextContentDiv = document.getElementById("textContent") ;
			var thisHeadlineText = document.getElementById('textHeadline2').firstChild.nodeValue ;
			thisTextContentDiv.childNodes[0].firstChild.nodeValue = thisHeadlineText ;
			var thisContentText = document.getElementById('textContent2').firstChild.nodeValue ;
			thisTextContentDiv.childNodes[2].nodeValue = thisContentText ;
		} else
		{
			var thisTextContentDiv = document.getElementById("textContent") ;
			var thisHeadlineText = document.getElementById('textHeadline1').firstChild.nodeValue ;
			thisTextContentDiv.childNodes[0].firstChild.nodeValue = thisHeadlineText ;
			var thisContentText = document.getElementById('textContent1').firstChild.nodeValue ;
			thisTextContentDiv.childNodes[2].nodeValue = thisContentText ;
		}
	}
}