window.onload = initPage;

function initPage() {
    initHeaderbox();
}

function initHeaderbox() {
    document.getElementById('headerbox_internet').style.backgroundImage = "url(/fileadmin/img/internet-sw.jpg)";
    document.getElementById('headerbox_it').style.backgroundImage = "url(/fileadmin/img/it-sw.jpg)";
    document.getElementById('headerbox_software').style.backgroundImage = "url(/fileadmin/img/software-sw.jpg)";
    document.getElementById('headerbox_grafik').style.backgroundImage = "url(/fileadmin/img/grafik-sw.jpg)";
    document.getElementById('headerbox_marketing').style.backgroundImage = "url(/fileadmin/img/marketing-sw.jpg)";
    
    /* preload mouseover images */
    img1 = new Image;
    img1.src = "/fileadmin/img/internet-f.jpg";
    img2 = new Image;
    img2.src = "/fileadmin/img/it-f.jpg";
    img3 = new Image;
    img3.src = "/fileadmin/img/software-f.jpg";
    img4 = new Image;
    img4.src = "/fileadmin/img/grafik-f.jpg";
    img5 = new Image;
    img5.src = "/fileadmin/img/marketing-f.jpg";
}

function ChangeImage(obj) {

    oldBg = obj.style.backgroundImage;
    muster = /-f.jpg/;
    
    if (oldBg.search(muster) > 0) {
        newBg = oldBg.replace(/-f/,"-sw");
    }
    else {
        newBg = oldBg.replace(/-sw/,"-f");
    }
    obj.style.backgroundImage = newBg;
}