// JavaScript Document

/*

* @package  scroll.class.js
* @author   Sergej Müller

*/

BAR = function(obj, attr) {

  var interval;

  var offset = {


    'top': obj.offsetTop || 0,

    'height': obj.offsetHeight || 0
  };


  this.start = function(amount) {
    /* Default setzen */
    attr.top = attr.top || 0;
    attr.width = attr.width || "auto";
    attr.height = attr.height || "auto";

    /* Intervall starten */
    interval = setInterval(
                                 function() {
                                   move(amount);
                                 },
                                 attr.time
                                );
  };


  this.stop = function() {
    if (interval) {
      clearInterval(interval);
    }
  }


  function move(amount) {
    /* Werte refreshen */
    attr.top += amount;
    attr.height += amount;
    offset.top -= amount;

    /* Grenze überschritten? */
    if (attr.top < 0 || attr.height > offset.height) {
      attr.top -= amount;
      attr.height -= amount;
      offset.top += amount;
      return;
    }

    /* Object bewegen */
    obj.style.clip = "rect(" + attr.top + "px " + attr.width + "px " + attr.height + "px 0)";
    obj.style.top = offset.top + "px";
  }
}