网络工具：http://www.j--d.com/bezier
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>贝塞尔曲线</title>
<style type="text/css">
*{
padding:0px;
margin:0px;
}
</style>
<script type="text/javascript">
function Draw(){
//获取js对象
var c=document.getElementById("canvas");
c.width=500;
c.height=500;
//获取用于绘制图形的2d环境
var ctx=c.getContext("2d");
ctx.lineWidth=6;
ctx.strokeStyle="#ff0000";
ctx.beginPath();
//起点
ctx.moveTo(100,200);
//二次贝塞尔曲线
//ctx.quadraticCurveTo(75,50,300,200);
//三次贝塞尔曲线
ctx.bezierCurveTo(205,56,239,439,429,236);
ctx.stroke();
}
</script>
</head>
<body>
<canvas id="canvas"></canvas>
<input type="button" value="Canvas" onclick="Draw();"/>
</body>
</html>
原文：http://www.cnblogs.com/gf36500/p/6873921.html