<canvas id="myCanvas" width="300" height="150" style="border:1px solid #d3d3d3;">
Your browser does not support the HTML5 canvas tag.
<p>请试着把 miterLimit 设置为 4。如果斜接长度超过 miterLimit 的值,边角会以 lineJoin 的 "bevel" 类型来显示。</p>
var c=document.getElementById("myCanvas");
var ctx=c.getContext("2d");