// JScript 文件

var xPos = 300;
var yPos = 200; 
var step = 1;
var delay = 30; 
var height = 0;
var Hoffset = 0;
var Woffset = 0;
var yon = 0;
var xon = 0;
var pause = true;
var interval;

function changePos() 
{
    width = document.body.clientWidth;
	height = document.body.clientHeight;
	Hoffset = document.getElementById("img1").offsetHeight;
	Woffset = document.getElementById("img1").offsetWidth;
	
	document.getElementById("img1").style.left = xPos + document.body.scrollLeft;
	document.getElementById("img1").style.top = yPos + document.body.scrollTop;
	if (yon) {
	    yPos = yPos + step;
	}
	else{
	    yPos = yPos - step;
	}
	if (yPos < 0) {
	    yon = 1;
	    yPos = 0;
	}
	if (yPos >= (height - Hoffset)) {
	    yon = 0;
	    yPos = (height - Hoffset);
	}
	if (xon) {
	    xPos = xPos + step;
	}
	else{
	    xPos = xPos - step;
	}
	if (xPos < 0) {
	    xon = 1;
	    xPos = 0;
	}
	if (xPos >= (width - Woffset)) {
	    xon = 0;
	    xPos = (width - Woffset);   
	}
}
	
function start()
{
    document.getElementById("img1").style.top = yPos;
    document.getElementById("img1").style.display = "block";
	
    interval = setInterval('changePos()', delay);
}

function pause_resume() 
{
	if(pause) 
	{
		clearInterval(interval);
		pause = false;
	}
	else 
	{
		interval = setInterval('changePos()',delay);
		pause = true; 
	}
}
function funStop()
{
    document.getElementById("img1").style.display = "none";
    clearInterval(interval);
}