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canvas实现时钟效果

2012-12-07 03:30 363 查看
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">

<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>时钟</title>
</head>

<body>
<canvas id="clock" width="500" height="500" style="background-color:black;">你的浏览器不支持canvas</canvas>
<script type="text/javascript">
var canvas = document.getElementById("clock");
var cxt = canvas.getContext("2d");

function drawClock() {
var now = new Date();
var sec = now.getSeconds();
var min = now.getMinutes();
var hour = now.getHours();
hour > 12 ? hour - 12 : hour;
hour += (min / 60);

//先清空画布
cxt.clearRect(0, 0, canvas.width, canvas.height);

//美女图片作为表盘背景
var img = new Image();
img.src = "http://i3.static.olcdn.com/cms/201303/14/MjMw1363244722894_500.jpg";
img.onload = function() {
cxt.drawImage(img, 0, 50, canvas.width, 400);

_innerDraw();
}

function _innerDraw() {
//画表盘大圆 圆心：x=250 y=250
cxt.strokeStyle = "#00FFFF";
cxt.lineWidth = 10;
cxt.beginPath();
cxt.arc(250, 250, 200, 0, 2 * Math.PI, false);
cxt.stroke();
cxt.closePath();

//时刻度
for (var i = 0; i < 12; i++) {
cxt.save(); //保存当前状态
cxt.lineWidth = 7;
cxt.strokeStyle = "#FFFF00";

//设置原点
cxt.translate(250, 250);
//设置旋转角度
cxt.rotate(30 * i * Math.PI / 180); //弧度   角度*Math.PI/180
cxt.beginPath();
cxt.moveTo(0, -175);
cxt.lineTo(0, -195);
cxt.stroke();
cxt.closePath();
cxt.restore(); //把原来状态恢复回来
}

//分刻度
for (var i = 0; i < 60; i++) {
cxt.save();
cxt.lineWidth = 5;
cxt.strokeStyle = "#FFFF00";
cxt.translate(250, 250);
cxt.rotate(i * 6 * Math.PI / 180);
cxt.beginPath();
cxt.moveTo(0, -185);
cxt.lineTo(0, -195);
cxt.stroke();
cxt.closePath();
cxt.restore();
}

//以下的时针、分针、秒针均要转动，所以在这里要设置其异次元空间的位置
//根据当前的小时数、分钟数、秒数分别设置各个针的角度即可
//-----------------------------时针-----------------------------
cxt.save();
cxt.lineWidth = 7;
cxt.strokeStyle = "#00FFFF";
cxt.translate(250, 250);
cxt.rotate(hour * 30 * Math.PI / 180); //每小时旋转30度
cxt.beginPath();
cxt.moveTo(0, -130);
cxt.lineTo(0, 10);
cxt.stroke();
cxt.closePath();
cxt.restore();

//-----------------------------分针-----------------------------
cxt.save();
cxt.lineWidth = 5;
cxt.strokeStyle = "#FFFF00";
cxt.translate(250, 250);
cxt.rotate(min * 6 * Math.PI / 180); //每分钟旋转6度
cxt.beginPath();
cxt.moveTo(0, -150);
cxt.lineTo(0, 10);
cxt.stroke();
cxt.closePath();
cxt.restore();

//-----------------------------秒针-----------------------------
cxt.save();
cxt.lineWidth = 3;
cxt.strokeStyle = "#FF0000";
cxt.translate(250, 250);
cxt.rotate(sec * 6 * Math.PI / 180); //每秒旋转6度
cxt.beginPath();
cxt.moveTo(0, -170);
cxt.lineTo(0, 10);
cxt.stroke();
cxt.closePath();

//美化表盘，画中间的小圆
cxt.beginPath();
cxt.arc(0, 0, 7, 0, 360 * Math.PI / 180);
cxt.fillStyle = "#FFFF00";
cxt.fill();
cxt.strokeStyle = "#FF0000";
cxt.stroke();
cxt.closePath();

//秒针上的小圆
cxt.beginPath();
cxt.arc(0, -140, 7, 0, 360 * Math.PI / 180);
cxt.fillStyle = "#FFFF00";
cxt.fill();
cxt.stroke();
cxt.closePath();
cxt.restore();

//显示时间
cxt.font = "normal 18px microsoft yahei";
cxt.lineWidth = 2;
cxt.fillStyle = "#0000FF";
hour = now.getHours();
var str = (hour > 10 ? hour : ("0" + hour)) + ":" + (min > 10 ? min : ("0" + min));
cxt.fillText(str, 225, 380);

//中国制造
cxt.font = "bold 12px simsun";
cxt.lineWidth = 1;
cxt.fillText("Made In China", 210, 400);
}
}

drawClock();
setInterval(drawClock, 1000);
</script>
</body>

</html>
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