html5 lineTo的使用例子

demo.js

function draw(id)  {
    var CANVAS=document.getElementById(id);
    var  context=CANVAS.getContext('2d');
    context.fillStyle="#eeeeef";
    context.fillRect(0,0,300,400);
    var dx=150;
    var dy=150;
    var s=100;
    context.beginPath();
    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.lineTo(dx+x*s,dy+y*s);
    }
    context.closePath();
    context.fill();
    context.stroke();
}

　　demo.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>canvas</title>
    <script type="text/javascript" src="demo.js"></script>
</head>
<body  onload="draw('mycanvas')">
<canvas  id="mycanvas"   width="300" height="400" >
    <span>你的浏览器不支持canvas</span>
</canvas>
</body>
</html>

　　效果：

2017-09-08 09:24:38