html5 canvas绘制钟表

终于没有兼容bug了。。。

[html]
<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title></title>
<style type="text/css">
* {
    margin: 0;
    padding: 0;
}
canvas {
    box-shadow: 0 0 10px 10px #CCCCCC;
    display: block;
    margin: 50px auto 0;
}
</style>
<script type="text/javascript">
window.onload = function() {
    new canvasClock({
        canvas: document.getElementById("canvas"),
        r: 100,
        h: [0, -30],
        m: [0, -60],
        s: [0, -90]
    })
};
function canvasClock(opts) {
    var self = this;
    self.r = opts.r;
    self.h = opts.h;
    self.m = opts.m;
    self.s = opts.s;
    self.PI = Math.PI;
    self.canvas = opts.canvas;
    self.context = self.canvas.getContext("2d");
    window.setInterval(function() {
        self.canvas.width = 0;
        self.canvas.height = 0;
        self.canvas.width = 400;
        self.canvas.height = 400;
        self.context.strokeStyle = "rgba(255,0,0,0.1)";
        self.context.translate(self.r * 2, self.r * 2);
        self.createTime("m");
        self.createTime("h");
        self.createTime("s")
    },
    1000)
};
canvasClock.prototype = {
    createTime: function(str) {
        var self = this;
        var context = self.context;
        context.lineWidth = 1;
        context.beginPath();
        context.arc(0, 0, self.r, 0, 2 * self.PI, true);
        context.stroke();
        context.closePath();
        var s = (new Date()).getSeconds();
        var m = (new Date()).getMinutes();
        var h = (new Date()).getHours();
        if (str == "s") {
            var t = s * 6;
            var x = self.s[0];
            var y = self.s[1]
        } else if (str == "m") {
            var t = (m + s / 60) * 6;
            var x = self.m[0];
            var y = self.m[1]
        } else {
            var t = (h + m / 60) * 30;
            var x = self.h[0];
            var y = self.h[1]
        }
        context.lineWidth = 10;
        context.lineCap = "round";
        context.rotate(t * self.PI / 180);
        context.beginPath();
        context.moveTo(0, 0);
        context.lineTo(x, y);
        context.stroke();
        context.closePath()
    }
}
</script>
</head>

<body>
<canvas width="400" height="400" id="canvas"></canvas>
</body>
</html>

摘自事与愿违

补充：web前端 , HTML 5 ,