<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>无标题文档</title>
<style>
body{
background:pink;
}
#c1{
background:white;
}
</style>
<script>
window.onload = function ()
{
var oC = document.getElementById('c1');
var oGC = oC.getContext('2d');
oC.onmousedown = function (ev)
{
var ev = ev || event;
oGC.moveTo(ev.clientX - oC.offsetLeft, ev.clientY - oC.offsetTop);
document.onmousemove = function (ev)
{
var ev = ev || event;
oGC.lineTo(ev.clientX - oC.offsetLeft, ev.clientY - oC.offsetTop);
oGC.stroke();
}
document.onmouseup = function ()
{
document.onmousemove = null;
document.onmouseup = null;
}
}
}
</script>
</head>
<body>
<canvas >
<span>请升级您的浏览器</span>
</canvas>
</body>
</html>