W3School TIY 亲自试一试！

<html>
<head>
<style>
div
{
width:160px;
height:120px;
}
img
{
position:relative;
}
span
{
position:absolute;
left:0px;
top:0px;
}
</style>
<script type="text/javascript">
mouseover=true

function coordinates()
{
if (!moveMe)
	{
	return
	}
if (event.srcElement.id=="moveMe")
	{
	mouseover=true
	pleft=document.getElementById('moveMe').style.pixelLeft
	ptop=document.getElementById('moveMe').style.pixelTop
	xcoor=event.clientX
	ycoor=event.clientY
	document.onmousemove=moveImage
	}
}

function moveImage()
{
if (mouseover&&event.button==1)
	{
	document.getElementById('moveMe').style.pixelLeft=pleft+event.clientX-xcoor
	document.getElementById('moveMe').style.pixelTop=ptop+event.clientY-ycoor
	return false
	}
}
function mouseup()
{
mouseover=false
}
document.onmousedown=coordinates
document.onmouseup=mouseup
</script>

</head>
<body>
<span>请移动这个图形：</span>
<br />
<div style="position:absolute;left:0;top:20;">
<img src="/i/eg_landscape.jpg" width="160" height="120" /></div>
<div style="position:absolute;left:0;top:20;filter:mask(color=#ffffff);width:160;height:120">
<img id="moveMe" src="/i/eg_smile.gif" width="40" height="40"></div>
</body>
</html>

W3School TIY Editor