<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Canvas</title>
<script src="jQuery.js"></script>
</head>
<style type="text/css">
body{
padding: 0;
margin: 0;
background: black;
}
#canvas{
background: white;
margin: 100px 0 0 300px;
}
#canvas > span{
color: white;
font-size: 14px;
}
</style>
<body>
<canvas id="canvas" width="600" height="500">
<span>您的浏览器不支持</span>
</canvas>
</body>
</html>
<script type="text/javascript">
/*获取绘制环境*/
var oc = $(‘#canvas‘)[0];
canvas = oc.getContext(‘2d‘);
$(‘#canvas‘).on(‘mousedown‘, function(){
/*开始绘制*/
canvas.beginPath();
/*设置动画绘制起点坐标*/
canvas.moveTo(event.pageX - 300 , event.pageY - 100);
$(‘#canvas‘).on(‘mousemove‘, function(){
/*设置下一个点坐标*/
canvas.lineTo(event.pageX - 300 , event.pageY - 100);
/*画线*/
canvas.stroke();
});
}).on(‘mouseup‘, function(){
$(‘#canvas‘).off(‘mousemove‘);
});
</script>
原文：http://www.cnblogs.com/lovling/p/6440677.html