/* Author: Helen Read <read@math.uvm.edu> */


// Initialize i

var i=0;

/* manual navigation functions */

function menuSetup(captions,list)

   // populate the jump menu

 {for (var j=0; j<captions.length; j++)
    {var new_item=new Option;
    new_item.text=captions[j];
    list[list.length]=new_item;} 
  }


function swapCaption(cap_id,m)
{var newcap=document.createTextNode(captions[m]);
 var oldcap=document.getElementById(cap_id).firstChild;
 document.getElementById(cap_id).replaceChild(newcap,oldcap);}

function nextPicture(pictures,cap_id,img_id)
{i++;
 if (i==pictures.length)
   {i=0;}
 document.getElementById(img_id).src=pictures[i];
 swapCaption(cap_id,i);}

function lastPicture(pictures,cap_id,img_id)
{i=i-1;
 if (i<0)
   {i=pictures.length-1;}
 document.getElementById(img_id).src=pictures[i]; 
 swapCaption(cap_id,i);}

function jump(pictures,cap_id,img_id,k)
 {if (k!=0)
  {document.getElementById(img_id).src=pictures[k-1];
   swapCaption(cap_id,k-1);
   i=k-1;}
 }

/* automatic slideshow functions */

// declare some global variables

var timer;
var picture_array=new Array();
var imgID;
var capID;


function slideshowSetup(pictures,img_id,cap_id)
 {picture_array=pictures;
  imgID=img_id;
  capID=cap_id;

  // preload images
  
  for (var j=0; j<picture_array.length; j++)
    {new Image().src=picture_array[j];} 
  }


function slideshow(k)
 {k++;
  if (k==picture_array.length)
   {k=0;}
  document.getElementById(imgID).src=picture_array[k];
  swapCaption(capID,k);
  i=k;
  timer=setTimeout("slideshow(" + k + ");",5000);
 }

function stopshow()
 {clearTimeout(timer);}



/* random image generator */

function random_img(pictures,img_id)
 {var n=pictures.length - 1;
  var k=Math.floor(Math.random()*(n+.99));
  document.getElementById(img_id).src=pictures[k];
 }