<!doctype html>
<html>
<head>
<meta charset="UTF-8">
</head>
<style type="text/css">
canvas{border:dashed 2px #CCC}
</style>
<script type="text/javascript">
function $$(id){
return document.getElementById(id);
}
function pageLoad(){
var can = $$('can');
var cans = can.getContext('2d');
cans.beginPath();
cans.arc(200,150,100,0,Math.PI*2,false);
cans.closePath();
cans.lineWidth = 5;
cans.strokeStyle = 'red';
cans.stroke();
}
</script>
<body onload="pageLoad();">
<canvas id="can" width="400px" height="300px">4</canvas>
</body>
</html>
这里不解释了，和上边的例子相同，lineWidth是控制线条的宽度的。