canvas绘制一个圆分成六等分颜色随机 

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        canvas {
            border: 1px solid #ccc;
        }
    </style>
</head>
<body>
<canvas width="600" height="400"></canvas>
<script>
    var myCanvas = document.querySelector('canvas');
    var ctx = myCanvas.getContext('2d');
    var w = ctx.canvas.width;
    var h = ctx.canvas.height;
    /*分成几等分*/
    var num = 360;
    /*一份多少弧度*/
    var angle = Math.PI * 2 / num;
    /*原点坐标*/
    var x0 = w / 2;
    var y0 = h / 2;
    /*获取随机颜色*/
    var getRandomColor = function () {
        var r = Math.floor(Math.random() * 256);
        var g = Math.floor(Math.random() * 256);
        var b = Math.floor(Math.random() * 256);
        return 'rgb(' + r + ',' + g + ',' + b + ')';
    }
    /*上一次绘制的结束弧度等于当前次的起始弧度*/
    //var startAngle = 0;
    for (var i = 0; i < num; i++) {
        var startAngle = i * angle;
        var endAngle = (i + 1) * angle;
        ctx.beginPath();
        ctx.moveTo(x0, y0);
        ctx.arc(x0, y0, 150, startAngle, endAngle);
        /*随机颜色*/
        ctx.fillStyle = getRandomColor();
        ctx.fill();
    }
</script>
</body>
</html>

运行结果如下:

posted @ 2020-02-15 17:04  阳神  阅读(549)  评论(0)  编辑  收藏  举报