var http_request = false;
var oldIndex = 1;
var newIndex = 1;

function fetchImage(base, size, offset) {
		var url;
	oldIndex = eval(document.galleryImageSelectedForm.galleryImageSelectedIndex.value);

	newIndex = eval(oldIndex + offset);
	document.galleryImageSelectedForm.galleryImageSelectedIndex.value = newIndex;
	url = base + "?id=" + newIndex + "&size=" + size;
		
		
	http_request = false;

	if (window.XMLHttpRequest) { // Mozilla, Safari,...
	    http_request = new XMLHttpRequest();
	    if (http_request.overrideMimeType) {
		http_request.overrideMimeType('text/xml');
		// zu dieser Zeile siehe weiter unten
	    }
	} else if (window.ActiveXObject) { // IE
	    try {
		http_request = new ActiveXObject("Msxml2.XMLHTTP");
	    } catch (e) {
		try {
		    http_request = new ActiveXObject("Microsoft.XMLHTTP");
		} catch (e) {}
	    }
	}

	if (!http_request) {
	    alert('Ende :( Kann keine XMLHTTP-Instanz erzeugen');
	    return false;
	}

	document.getElementById("loading-indicator").style.display='';
	document.getElementById("galleryImageSelected").style.display='none';

	http_request.onreadystatechange = fetchImageResult;
	document.galleryImageSelected.src = "/site/ajax-loader.gif";
	http_request.open('GET', url, true);
	http_request.send(null);

}

function fetchImageResult() {

	if (http_request.readyState == 4) {
	    if (http_request.status == 200) {
		document.getElementById("loading-indicator").style.display='none';
		document.getElementById("galleryImageSelected").style.display='';
		if (http_request.responseText == "-1") {
			document.galleryImageSelectedForm.galleryImageSelectedIndex.value = oldIndex;
		} else {
			document.galleryImageSelected.src=http_request.responseText;
			document.galleryImageSelectedForm.galleryImageSelectedIndex.value = newIndex;
		}
	    } else {
		alert('Bei dem Request ist ein Problem aufgetreten.');
	    }
	}
}