H5实现可缩放的时钟动画

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这次给大家带来H5实现可缩放的时钟动画，H5实现可缩放时钟动画的注意事项有哪些，下面就是实战案例，一起来看一下。

废话不多说了，直接给大家贴代码了，具体代码如下所示：

<!DOCTYPE html>
<html lang="en">
<head>
 <meta charset="UTF-8">
 <title>canvas_time</title>
 <style type="text/css">
 p {
 text-align: center;
 margin-top: 250px;
 }
 #clock {
 border: 1px solid #cccccc;
 }
 </style>
</head>
<body>
 <p>
 <canvas id="clock" height="600px" width="600px"></canvas>
 </p>
 <script type="text/JavaScript" >
var dom = document.getElementById('clock');
var ctx = dom.getContext('2d');
var width = ctx.canvas.width;
var height = ctx.canvas.height;
var r = width / 2;
var rem = width/200;
function drawBackground() {
 ctx.save(); //存储当前环境变量；
 ctx.translate(r, r); //重置坐标到r，r
 ctx.beginPath(); // 起始一条路径
 ctx.lineWidth = 10*rem; //设置线宽10；
 ctx.arc(0, 0, r - ctx.lineWidth /2, 0, 2 * Math.PI, false);
 ctx.stroke();
 var hourNumbers = [3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 1, 2]; //定义数组
 ctx.font = 18*rem+"px Arial";
 ctx.textAlign = "center";
 ctx.textBaseline = "middle";
 hourNumbers.forEach(function(number, i) {
 var rad = 2 * Math.PI / 12 * i;
 var x = Math.cos(rad) * (r - 30*rem);
 var y = Math.sin(rad) * (r - 30*rem);
 ctx.fillText(number, x, y);
 });
 for (var i = 0; i < 60; i++) {
 var rad = 2 * Math.PI / 60 * i;
 var x = Math.cos(rad) * (r - 18*rem);
 var y = Math.sin(rad) * (r - 18*rem);
 ctx.beginPath();
 if (i % 5 === 0) {
 ctx.arc(x, y, 2*rem, 0, 2 * Math.PI, false);
 ctx.fillStyle = "#000";
 } else {
 ctx.arc(x, y, 2*rem, 0, 2 * Math.PI, false);
 ctx.fillStyle = "#ccc";
 }
 ctx.fill();
 }
}
 function drawHour(hour, minute) {
 ctx.save();
 ctx.beginPath();
 var rad = 2 * Math.PI / 12 * hour;
 var mrad = 2 * Math.PI / 12 / 60 * minute;
 ctx.rotate(rad + mrad);
 ctx.lineWidth = 6*rem;
 ctx.lineCap = "round";
 ctx.moveTo(0, 10*rem);
 ctx.lineTo(0, -r / 2);
 ctx.stroke();
 ctx.restore();
 }
 function drawMinute(minute) {
 ctx.save();
 ctx.beginPath();
 var rad = 2 * Math.PI / 60 * minute;
 ctx.rotate(rad);
 ctx.lineWidth = 3*rem;
 ctx.lineCap = "round";
 ctx.moveTo(0, 10*rem);
 ctx.lineTo(0, -r + 30*rem);
 ctx.stroke();
 ctx.restore();
 }
 function drawSecond(second) {
 ctx.save();
 ctx.beginPath();
 ctx.fillStyle = 'red';
 var rad = 2 * Math.PI / 60 * second;
 ctx.rotate(rad);
 ctx.moveTo(-2*rem, 20*rem);
 ctx.lineTo(2*rem, 20*rem);
 ctx.lineTo(1, -r + 16*rem);
 ctx.lineTo(-1, -r + 16*rem);
 ctx.fill();
 ctx.restore();
 }
 function drawDot() {
 ctx.beginPath();
 ctx.fillStyle = '#fff';
 ctx.arc(0, 0, 3*rem, 0, 2 * Math.PI, false);
 ctx.fill();
 }
 function draw01() {
 ctx.clearRect(0, 0, width, height);
 var now = new Date();
 var hour = now.getHours();
 var minute = now.getMinutes();
 var second = now.getSeconds();
 drawBackground();
 drawHour(hour, minute);
 drawMinute(minute);
 drawSecond(second);
 drawDot();
 ctx.restore();
 }
 draw01();
 setInterval(draw01, 1000);
</script>
</body>
</html>

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H5实现可缩放的时钟动画