前端canvas时钟学习成果
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前端开发项目实战 前端开发项目论文 web前端开发项目经验描述
html 代码
<!DOCTYPE html>
<html lang=”en”>
<head>
<meta charset=”UTF-8″>
<title>canvas clock</title>
<style type=”text/css”>
div {
text-align: center;
margin-top: 250px;
}
</style>
</head>
<body>
<div>
<canvas id=”clock” width=”300″ height=”300″>您的浏览器不支持canvas</canvas>
</div>
<script type=”text/javascript”>
window.onload = function () {
var c = document.getElementById(“clock”);
var ctx = c.getContext(‘2d’);
var width = ctx.canvas.width;
var height = ctx.canvas.width;
var r = width / 2;
var rem = width / 200;
function drawBackground() {
ctx.save();
ctx.translate(r, r);
ctx.beginPath();
ctx.lineWidth = 10 * rem;
ctx.arc(0, 0, r – ctx.lineWidth / 2, 0, 2 * Math.PI);
ctx.stroke();
var hourNumbers = [3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 1, 2];
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 – 15 * rem);
var y = Math.sin(rad) * (r – 15 * rem);
ctx.beginPath();
if (i % 5 == 0) {
ctx.fillStyle = ‘#000’;
ctx.arc(x, y, 2 * rem, 0, 2 * Math.PI)
}
else {
ctx.fillStyle = ‘#ccc’;
ctx.arc(x, y, 2 * rem, 0, 2 * Math.PI)
}
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 + 35 * rem);
ctx.stroke();
ctx.restore()
}
function drawSecond(second) {
ctx.save();
ctx.beginPath();
ctx.fillStyle = ‘#c14543’;
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 + 18 * rem);
ctx.lineTo(-1, -r + 18 * rem);
ctx.fill();
ctx.restore()
}
function drawDot() {
ctx.beginPath();
ctx.fillStyle = ‘#fff’;
ctx.arc(0, 0, 3 * rem, 0, 2 * Math.PI);
ctx.fill();
}
function draw() {
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();
}
draw();
setInterval(draw, 1000)
}
</script>
</body>
</html>
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