/*
Constructor Ticker(name, id, shiftBy, interval)

Methods
=======
Ticker.start()
       starts the animation of the ticker
       
Ticker.stop()
       stops the animation of the ticker
       
Ticker.changeInterval(newinterval)
       changes the shifting interval to newinterval

Properties
==========
Ticker.name
	String : name of global variable containing reference to the ticker object

Ticker.id
	String : id of the DIV containing the Ticker data

Ticker.shiftBy
	Number : Number of pixels to shift the Ticker each time it fires.
	
Ticker.interval
    Number : Number of millisecond intervals between times Ticker fires
    
Ticker.runId
    Number : Value returned from setTimeout or null if the Ticker is not 
             running
             
Ticker.div
    HTMLElement : Reference to DIV containing the Ticker data.
  
*/

function Ticker(name, id, shiftBy, interval)
{
  this.name     = name;
  this.id       = id;
  this.shiftBy  = shiftBy ? shiftBy : 1;
  this.interval = interval ? interval : 100;
  this.runId	= null;

  this.div = document.getElementById(id);

  // remove extra textnodes that may separate the child nodes
  // of the ticker div

  var node = this.div.firstChild;
  var next;

  while (node)
  {
    next = node.nextSibling;
    if (node.nodeType == 3)
      this.div.removeChild(node);
    node = next;
  }

  //end of extra textnodes removal
 
  this.left = 520;
  this.shiftLeftAt = this.div.firstChild.offsetWidth;
  this.div.style.height	= this.div.firstChild.offsetHeight;
  this.div.style.width = 2 * screen.availWidth;
  this.div.style.visibility = 'visible';
}

function startTicker()
{
  this.stop();
  
  this.left -= this.shiftBy;

  if (this.left <= -this.shiftLeftAt)
  {
    this.left = 520;
    this.div.appendChild(this.div.firstChild);
  
    this.shiftLeftAt = this.div.firstChild.offsetWidth;
  }

  this.div.style.left = (this.left + 'px');

  this.runId = setTimeout(this.name + '.start()', this.interval);
}

function stopTicker()
{
  if (this.runId)
    clearTimeout(this.runId);
    
  this.runId = null;
}

function changeTickerInterval(newinterval)
{

  if (typeof(newinterval) == 'string')
    newinterval =  parseInt('0' + newinterval, 10); 
	
  if (typeof(newinterval) == 'number' && newinterval > 0)
    this.interval = newinterval;
    
    this.stop();
    this.start();
}

/* Prototypes for Ticker */
Ticker.prototype.start = startTicker;
Ticker.prototype.stop = stopTicker;
Ticker.prototype.changeInterval = changeTickerInterval;