function slideshow( slideshowname, image ) {
  this.name = slideshowname
  this.image = image
  this.timeout = 4000

  this.images = new Array()
  this.links = new Array()
  this.current = 0
  this.timeoutid = 0
  this.add_slide = slideshow_add_slide
  this.set_image = slideshow_set_image
  this.play = slideshow_play
  this.pause = slideshow_pause
  this.next = slideshow_next
  this.previous = slideshow_previous
  this.hotlink = slideshow_goto
  this.loop = slideshow_loop
  this.valid_image = slideshow_valid_image
}


function slideshow_add_slide(image_url,link_url) {
  if (!document.images)
    return
  var i = this.images.length;
  this.images[i] = new Image()
  this.images[i].src = image_url
  this.links[i] = link_url
}


function slideshow_set_image( imageobject ) {
  if (!document.images)
    return
  this.image = imageobject
}


function slideshow_valid_image() {
  if (!this.image)
  {
    this.pause
    window.status = "Error: slideshow image not initialized for " + this.name
    return 0
  }
  else
    return 1
}

function slideshow_goto() {
  location.href = this.links[ this.current ]
}


function slideshow_next() {
  if (! this.valid_image()) return;
  if (this.current < this.images.length - 1)
    this.current++
  else
    this.current = 0
  this.image.src = this.images[ this.current ].src
}


function slideshow_previous() {
  if (! this.valid_image()) return;
  if (this.current > 0)
    this.current--
  else
    this.current = this.images.length - 1
  this.image.src = this.images[ this.current ].src
}


function slideshow_loop() {
  this.next()
  this.play()
}

function slideshow_play() {
  this.timeoutid = setTimeout( this.name + ".loop()", this.timeout)
}

function slideshow_pause() {
  if (this.timeoutid != 0)
  {
    clearTimeout(this.timeoutid)
    this.timeoutid = 0
  }
}