查看效果：http://keleyi.com/keleyi/phtml/html5/7.htm
完整代码：
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>用html5的canvas画布绘制贝塞尔曲线-柯乐义</title> </head> <body> <div> <a href="http://keleyi.com/a/bjac/j77m9131.htm" target="_blank">原文</a></div> <canvas id="keleyi_com" height="300" width="400"></canvas> <script type="text/javascript"> function draw(id) { var canvas=document.getElementById(id); if(canvas==null) return false; var context=canvas.getContext('2d'); context.fillStyle="#eeeeff"; context.fillRect(0,0,400,300); var n=0; var dx=150; var dy=150; var s=100; context.beginPath(); context.globalCompositeOperation='and'; context.fillStyle='rgb(100,255,100)'; context.strokeStyle='rgb(0,0,100)'; var x=Math.sin(0); var y=Math.cos(0); var dig=Math.PI/15*11; for(var i=0;i<30;i++) { var x=Math.sin(i*dig); var y=Math.cos(i*dig); context.bezierCurveTo(dx+x*s,dy+y*s-100,dx+x*s+100,dy+y*s,dx+x*s,dy+y*s); } context.closePath(); context.fill(); context.stroke(); } draw("keleyi_com"); </script> </body> </html>