<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>canvas</title>
<script type="text/javascript" src="../js/jQuery.js"></script>
<style type="text/css">
*{
margin: 0;
padding: 0;
outline: none;
border: none;
}
#canvas{
width: 7rem;
margin: .25rem 0 0 1.5rem;
border: 1px solid black;
}
</style>
</head>
<body>
<canvas id="canvas" width="1000" height="600"></canvas>
</body>
</html>
<script type="text/javascript">
/**
* rem 布局初始化
*/
$(‘html‘).css(‘font-size‘, $(window).width()/10);
/**
* 获取 canvas 画布
* 获取 canvas 绘图上下文环境
*/
var canvas = $(‘#canvas‘)[0];
var cxt = canvas.getContext(‘2d‘);
/**
* 阴影
* shadowColor: 阴影的颜色
* shadowOffsetX: 横向偏移
* shadowOffsetY: 纵向偏移
* shadowNlur: 模糊程度
*/
cxt.shadowColor = "red";
cxt.shadowOffsetX = 20;
cxt.shadowOffsetY = 20;
cxt.shadowBlur = 0;
cxt.fillRect(200, 200, 400, 200);
</script>
HTML5 Canvas ( 图形的阴影 ) shadowColor, shadowOffsetX, shadowOffsetY, shadowNlur
原文：http://www.cnblogs.com/lovling/p/6648876.html