// 'blank' images for second row buttons
var img1_0 = new Image(118,18),     img2_0 = new Image(118,18);
var img3_0 = new Image(118,18),     img4_0 = new Image(118,18);
var img5_0 = new Image(118,18),     img6_0 = new Image(118,18);
img1_0.src = "images/glr1-2-0.gif"; img2_0.src = "images/glr2-2-0.gif";
img3_0.src = "images/glr3-2-0.gif"; img4_0.src = "images/glr4-2-0.gif";
img5_0.src = "images/glr5-2-0.gif"; img6_0.src = "images/glr6-2-0.gif";

// images for second row buttons
var img1_1 = new Image(118,18), img2_1 = new Image(118,18);
var img3_1 = new Image(118,18), img4_1 = new Image(118,18);
var img5_1 = new Image(118,18), img6_1 = new Image(118,18);
var img1_2 = new Image(118,18), img2_2 = new Image(118,18);
var img3_2 = new Image(118,18), img4_2 = new Image(118,18);
var img5_2 = new Image(118,18), img6_2 = new Image(118,18);
var img1_3 = new Image(118,18), img2_3 = new Image(118,18);
var img3_3 = new Image(118,18), img4_3 = new Image(118,18);
var img5_3 = new Image(118,18), img6_3 = new Image(118,18);
var img1_4 = new Image(118,18), img2_4 = new Image(118,18);
var img3_4 = new Image(118,18), img4_4 = new Image(118,18);
var img5_4 = new Image(118,18), img6_4 = new Image(118,18);

// url arrays for second row buttons
var urls1 = new Array(), urls2 = new Array();
var urls3 = new Array(), urls4 = new Array();

// base url
baseURL = "http://www.math.lsa.umich.edu/~glarose/";

// current projects images
var proj0 = new Image(122,18);  proj0.src = "images/glr6-1.gif";
var proj1 = new Image(122,18);  proj1.src = "images/glr6-1a.gif";

// status of second row buttons
var onStatus = 0;

// timeout number of current timeout
var timeoutID;

function swapimg(state,img) {
// basic image swapping function
//   state = 0 or 1 for 'off' or 'on' image
//   img = name of the image to swap for; we always use the 
//         current project image projN
    eval("document." + img).src = eval('proj' + state).src;
    return 1;
}

function newImages(num) {
// change images and links in second row.
//    num = number of row that is currently moused
    for(var i = 1; i<=6; i++) {
// change images
        eval("document.linkimg"+i+"2").src = eval("img"+i+"_"+num).src;
// change links; would like to do this without hard reference to 
//    link number
        document.links[2*i-1].href = eval("urls" + num)[i];
    }
    onStatus=1;
    if ( defined(timeoutID) ) {
        clearTimeout(timeoutID);
    }
    return 1;
}

function chgStatus(status) {
// reset status flag
    onStatus=status;
    if ( defined(timeoutID) ) {
        clearTimeout(timeoutID);
    }
    if ( status == 0 ) {
        timeoutID = setTimeout('clearImages(onStatus)',150);
    }
}

function clearImages(status) {
// check status; if status = 0, revert images and links in second 
//   row to blank images
   for(var i = 1; i<=6; i++) {
// change images
        eval("document.linkimg"+i+"2").src = eval("img"+i+"_0").src;
// change links; would like to do this without hard reference to 
//    link number
        document.links[2*i-1].href = baseURL;
    }
    return 1;
}

function loadImages() {
//
// image names are row_imageFlag; column is always 2
//
    img1_1.src = "images/glr1-2-1.gif"; 
    img2_1.src = "images/glr2-2-1.gif";
    img3_1.src = "images/glr3-2-1.gif";
    img4_1.src = img4_0.src;        img6_1.src = img6_0.src;
    img5_1.src = "images/glr5-2-1.gif";

    img1_2.src = "images/glr1-2-2.gif"; 
    img2_2.src = "images/glr2-2-2.gif";
    img3_2.src = "images/glr3-2-2.gif";
    img4_2.src = "images/glr4-2-2.gif";
    img5_2.src = "images/glr5-2-2.gif";
    img6_2.src = "images/glr6-2-2.gif";

    img1_3.src = img1_0.src;        img5_3.src = img5_0.src;
    img2_3.src = "images/glr2-2-3.gif";
    img3_3.src = "images/glr3-2-3.gif";
    img4_3.src = "images/glr4-2-3.gif";
    img6_3.src = img6_0.src;

    img1_4.src = img1_0.src;        img2_4.src = img2_0.src;
    img3_4.src = "images/glr3-2-4.gif";
    img4_4.src = "images/glr4-2-4.gif";
    img5_4.src = "images/glr5-2-4.gif";
    img6_4.src = img6_0.src;
//
// load URL arrays
//
    urls1[0] = "";  // we don't use this
    urls1[1] = "courseinfo/calc";       urls1[2] = "courseinfo/diffeq";
    urls1[3] = "courseinfo/model";      urls1[4] = baseURL;
    urls1[5] = "courseinfo/portfolios"; urls1[6] = baseURL;

    urls2[0] = "";  // we don't use this
    urls2[1] = "classes/calcI";    urls2[2] = "classes/calcII";
    urls2[3] = "classes/calcIII"; urls2[4] = "classes/diffeq";
    urls2[5] = "classes/model";   urls2[6] = "classes/linalg";

    urls3[0] = "";  // we don't use this
    urls3[1] = baseURL;  
    urls3[2] = "http://archives.math.utk.edu/projnext/";
    urls3[3] = "pnext/sections/"; urls3[4] = "pnext/nextinfo.html";
    urls3[5] = baseURL;           urls3[5] = baseURL;

    urls4[0] = "";  // we don't use this
    urls4[1] = baseURL; urls4[2] = baseURL;
    urls4[3] = "htmlinfo/wkshops/html/"; urls4[4] = "htmlinfo/wkshops/web/";
    urls4[5] = "htmlinfo/";              urls4[6] = baseURL;
}

function defined(obj) {
    if ( obj == null ) {
        return false;
    } else {
        return true;
    }
}