// JavaScript Document
var xPos = 300; //初始左边距
var yPos = 200; //初始上边距
var step = 1;
var delay = 30; //移动速度,越小越快
var f_height = 0;
var Hoffset = 0;
var Woffset = 0;
var yon = 0;
var xon = 0;
var pause = true;
var interval;
var img1=document.getElementById("ad1");//id
img1.style.top = yPos;

function changePos()
{
 f_width = document.documentElement.clientWidth;
 f_height = document.documentElement.clientHeight;
 Hoffset = img1.offsetHeight;
 Woffset = img1.offsetWidth;
 img1.style.left = xPos + document.documentElement.scrollLeft+"px";
 img1.style.top = yPos + document.documentElement.scrollTop+"px";
 if (yon)
  {yPos = yPos + step;}
 else
  {yPos = yPos - step;}
 if (yPos < 0)
  {yon = 1;yPos = 0;}
 if (yPos >= (f_height - Hoffset))
  {yon = 0;yPos = (f_height - Hoffset);}
 if (xon)
  {xPos = xPos + step;}
 else
  {xPos = xPos - step;}
 if (xPos < 0)
  {xon = 1;xPos = 0;}
 if (xPos >= (f_width - Woffset))
  {xon = 0;xPos = (f_width - Woffset);   }
 }
 
 function start()
  {
   img1.visibility = "visible";
  interval = setInterval('changePos()', delay);
 }
 
 function pause_resume()
 {
  if(pause)
  {
   clearInterval(interval);
   pause = false;}
  else
  {
   interval = setInterval('changePos()',delay);
   pause = true;
   }
  }
 start();
function close_left1(){
    ad1.style.visibility='hidden';
}