function ImageMouseOver(imageName,imageSrcLow,imageSrcHigh) {
    this.ok = false;
    this.aktive = false;
    this.imgObj = null;
    this.imageName = imageName;
    this.imageObjLow = imageName+'low';
    this.imageObjHigh = imageName+'high';
    this.imageSrcLow = imageSrcLow;
    this.imageSrcHigh = imageSrcHigh;
    this.preloadImg = onpreloadImg;
    this.preloadImg();
    // Methoden
    this.change = changeImg;
    this.setAktive = setAktiveImg;
    this.clearAktive = clearAktiveImg;
    this.height = getHeight;
    this.width = getWidth;
    return this;
}

function onpreloadImg(){
    preload(this.imageObjLow,this.imageSrcLow);
    preload(this.imageObjHigh,this.imageSrcHigh);
    this.ok = true;
}

function changeImg(check) {
	if (!this.ok) return false;
    if (!this.aktive) {
        (check==1) ? this.imgObj=this.imageObjHigh : this.imgObj=this.imageObjLow;
        changeImage(this.imageName,this.imgObj);
    }
}

function setAktiveImg(){
    if (!this.ok) return false;
    this.change(1);
    this.aktive = true;
}

function clearAktiveImg(){
    if (!this.ok) return false;
    this.aktive = false;
    this.change(0);
}

function getHeight(){
    if (!this.ok) return false;
	return document.images[this.imageName].height;
}

function getWidth() {
    if (!this.ok) return false;
	return document.images[this.imageName].width; 
}

// Image Allgemein
function preload (imageObj,imageSrc) 
{
	if (document.images) {
		eval(imageObj+' = new Image();');
		eval(imageObj+'.src = "'+imageSrc+'";');
	}
}

function changeImage(imageName,imageObj) 
{
	if (document.images) {
		document.images[imageName].src = eval(imageObj+".src");
	}
}

// Initialisierung der Hauptnavigation TKKG
var path = "media/nav/";
var pre  = "";
var post = "_h";
var ext = ".jpg"
var myId = ["tkkg","buecher","autor","extras","links"];
var img  = new Array();
for (var i=0; i<myId.length; i++) {
	img[i] = new ImageMouseOver (myId[i], path+pre+myId[i]+ext, path+pre+myId[i]+post+ext);
}