canvas元素绘制太极图

<!DOCTYPE html>
<html>
<head>
   <title>canvas example</title>
    <meta charset="utf-8">
</head>
<body>
<canvas id="canvas" width="600px" height="600px"></canvas>

<script>
    var canvas=document.getElementById("canvas");
    var context=canvas.getContext('2d');
    context.beginPath();
    context.arc(300,300,200,0,2*Math.PI,false);
    context.stroke();
    context.beginPath();
    context.fillStyle="black";
    context.arc(300,300,200,Math.PI/2,Math.PI*3/2,false);
    context.fill();
    context.beginPath();
    context.fillStyle="white";
    context.arc(300,200,100,0,Math.PI*2,false);
    context.fill();
    context.beginPath();
    context.fillStyle="black";
    context.arc(300,400,100,0,Math.PI*2,false);
    context.fill();
    context.beginPath();
    context.fillStyle="black";
    context.arc(300,200,30,0,Math.PI*2,false);
    context.fill();
    context.beginPath();
    context.fillStyle="white";
    context.arc(300,400,30,0,Math.PI*2,false);
    context.fill();
</script>
</body>
</html>

效果图如下：