<!DOCTYPE html><head>
<meta charset=utf-8>
<title>HTML5画圆形</title>
<script src="<a href="http://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js"></script">http://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js"></script</a>>
</head>
<script>
$(document).ready(function(){
var c=document.getElementById("drawbox");
var draw=c.getContext("2d"); //获取2d内容的引用，调用绘图API</p>
<p>draw.fillStyle="red"; //颜色
draw.beginPath(); //从新画
draw.arc(50,50,50,0,Math.PI*2,true); //圆心x坐标|圆心y坐标|直径|始|PI为圆周率，Math.PI*2为画圆|true为时针方向：逆时针，0为顺时针，
draw.closePath(); //结束
draw.fill();
})
</script>
</body>
<canvas id="drawbox" width="500" height="500"></canvas>
</body>
</html>
效果图
