// Copyright © 2003-2010 Edgar Soberón.  All rights reserved.


var isNetscape4 = false;
if (parseInt(navigator.appVersion) == 4) {
    if (navigator.appName == "Netscape") {
        isNetscape4 = true;
    }
}                         


// Make sure the browser supports the Image object and document.images
// property.  (These aren't available in Netscape 2 or Internet
// Explorer 3.)
if (document.images) {
    // Create the "on" version of each menu button.
    var onMenu = new Array();
    onMenu[0] = new Image;
    onMenu[1] = new Image;
    onMenu[2] = new Image;
    onMenu[3] = new Image;
    onMenu[4] = new Image;
    onMenu[5] = new Image;
    onMenu[6] = new Image;
    onMenu[0].src = "images/but_home_on.gif";
    onMenu[1].src = "images/but_statement_on.gif";
    onMenu[2].src = "images/but_biography_on.gif";
    onMenu[3].src = "images/but_gallery_on.gif";
    onMenu[4].src = "images/but_classes_on.gif";
    onMenu[5].src = "images/but_curriculum_on.gif";
    onMenu[6].src = "images/but_contact_on.gif";

    // Create the "off" version of each menu button.
    // Note:  The "off" and "on" versions must be at the same index
    // within each array.
    var offMenu = new Array();
    offMenu[0] = new Image;
    offMenu[1] = new Image;
    offMenu[2] = new Image;
    offMenu[3] = new Image;
    offMenu[4] = new Image;
    offMenu[5] = new Image;
    offMenu[6] = new Image;
    offMenu[0].src = "images/but_home_off.gif";
    offMenu[1].src = "images/but_statement_off.gif";
    offMenu[2].src = "images/but_biography_off.gif";
    offMenu[3].src = "images/but_gallery_off.gif";
    offMenu[4].src = "images/but_classes_off.gif";
    offMenu[5].src = "images/but_curriculum_off.gif";
    offMenu[6].src = "images/but_contact_off.gif";
}


// Returns the index, of the onMenu or offMenu arrays, containing the
// given image's source files.
//
// Assumes each image's HTML img tag sets its name attribute to the
// indicated string.
function getIndex(imgName) {
    switch (imgName) {
        case "home":
            return 0;
        case "statement":
            return 1;
        case "biography":
            return 2;
        case "gallery":
            return 3;
	case "classes":
	    return 4;
        case "curriculum":
            return 5;
        case "contact":
            return 6;
    }
}


// Changes the image to the "on" version.
//
// Assumes the "on" image has imgName in its file name.
function imageOn(imgName) {
    if (document.images) {
        if (isNetscape4) {
            document [imgName].src = "images/but_" + imgName + "_on.gif";
        }
        else {
            document.images[imgName].src = onMenu[getIndex(imgName)].src;
        }
    }
}


// Changes the image to the "off" version.
//
// Assumes the "on" image has imgName in its file name.
function imageOff(imgName) {
    if (document.images) {
        if (isNetscape4) {
            document [imgName].src = "images/but_" + imgName + "_off.gif";
        }
        else {
            document.images[imgName].src = offMenu[getIndex(imgName)].src;
        }
    }
}