function opacity(id, opacStart, opacEnd, millisec) {
        //speed for each frame
        var speed = Math.round(millisec / 100);
        var timer = 0;

        //determine the direction for the blending, if start and end are the same nothing happens
        if(opacStart > opacEnd) {
                for(i = opacStart; i >= opacEnd; i--) {
                        setTimeout("changeOpac(" + i + ",'" + id + "')",(timer * speed));
                        timer++;
                }
        } else if(opacStart < opacEnd) {
                for(i = opacStart; i <= opacEnd; i++)
                        {
                        setTimeout("changeOpac(" + i + ",'" + id + "')",(timer * speed));
                        timer++;
                }
        }
}

//change the opacity for different browsers
function changeOpac(opacity, id) {
        var object = document.getElementById(id).style; 
        object.opacity = (opacity / 100);
        object.MozOpacity = (opacity / 100);
        object.KhtmlOpacity = (opacity / 100);
        object.filter = "alpha(opacity=" + opacity + ")";
}

function shiftOpacity(id, millisec) {
        //if an element is invisible, make it visible, else make it ivisible
        if(document.getElementById(id).style.opacity == 0) {
                opacity(id, 0, 100, millisec);
        } else {
                opacity(id, 100, 0, millisec);
        }
}

function rotate_header( header_text, image1, image2, millisec) {
        var speed = Math.round(millisec / 100);
        var timer = 0;
        
        //set the current image as background
        document.getElementById("image1").style.backgroundImage = "url(" + document.getElementById("image1").src + ")";
        document.getElementById("image2").style.backgroundImage = "url(" + document.getElementById("image2").src + ")";
        //make image transparent
        changeOpac(0, "image1");
        changeOpac(0, "image2");
        changeOpac(0, "header_text");
        //make new image
        new_image1 = eval(image1 + ".src");
        document.getElementById("image1").src = new_image1;
        new_image2 = eval(image2 + ".src");
        document.getElementById("image2").src = new_image2;
        document.getElementById("header_text").innerHTML = header_text;
        //fade in image
        for(i = 0; i <= 100; i++) {
                setTimeout("changeOpac(" + i + ",'image1')",(timer * speed));
                setTimeout("changeOpac(" + i + ",'image2')",(timer * speed));
                setTimeout("changeOpac(" + i + ",'header_text')",(timer * speed));
                timer++;
        }
}

function start_rotator() {
        var x = xajax_get_new_header();
        setTimeout("start_rotator()", 3000);
}

function currentOpac(id, opacEnd, millisec) {
        //standard opacity is 100
        var currentOpac = 100;
        
        //if the element has an opacity set, get it
        if(document.getElementById(id).style.opacity < 100) {
                currentOpac = document.getElementById(id).style.opacity * 100;
        }

        //call for the function that changes the opacity
        opacity(id, currentOpac, opacEnd, millisec)
}

if (document.images) {
        img1 = new Image(158,100);
        img1.src = "images/amplifier_header_image.jpg";
        img2 = new Image(158,100);
        img2.src = "images/boxster_header_image.jpg";
        img3 = new Image(158,100);
        img3.src = "images/cobalt_header_image.jpg";
        img4 = new Image(158,100);
        img4.src = "images/dvd_header_image.jpg";
        img5 = new Image(158,100);
        img5.src = "images/girl_header_image.jpg";
        img6 = new Image(158,100);
        img6.src = "images/hummer_header_image.jpg";
        img7 = new Image(158,100);
        img7.src = "images/kicker_header_image.jpg";
        img8 = new Image(158,100);
        img8.src = "images/kicker_sub_header_image.jpg";
        img9 = new Image(158,100);
        img9.src = "images/navigation_header_image.jpg";
        img10 = new Image(158,100);
        img10.src = "images/radio_header_image.jpg";
        img11 = new Image(158,100);
        img11.src = "images/subwoofer_header_image.jpg";
        img12 = new Image(158,100);
        img12.src = "images/viper_header_image.jpg";
}