code: function calculateDraggerPosition() {
      var sl = $container.scrollLeft() / scale;
      var st = $container.scrollTop() / scale;
  
      // sl / dox = dl / cw
      // dl = sl * cw / dox
      var left = sl * canvasSize.x / docSize.x;
      var top = st * canvasSize.y / docSize.y;
      view.setDraggerPosition(left, top);
    }
docs: Calculates and sets the possition of the dragger element.