canvas 绘制圆形时钟
效果如下：
代码如下：
<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width,initial-scale=1"/>
<title>canvas clock</title>
<style type="text/css">
div{
text-align: center;
margin-top: 250px;
}
#clock{
border: 1px solid #ccc;
}
</style>
</head>
<body>
<div>
<canvas id="clock" height="200px" width="200px"></canvas>
</div>
<script type="text/javascript">
var dom=document.getElementById("clock");
var ctx=dom.getContext("2d");
var width=ctx.canvas.width;
var heigth=ctx.canvas.height;
var r=width/2;
//描绘时分秒小数和小数点
function drawBackground(){
ctx.save();
ctx.translate(r,r); //中心原点位置
ctx.beginPath(); //起始位置
ctx.lineWidth=10;
//圆
ctx.arc(0,0,r-5,0,2*Math.PI,false);
ctx.stroke();
var hourNumbers=[3,4,5,6,7,8,9,10,11,12,1,2];
ctx.font="18px 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);
var y=Math.sin(rad)*(r-30);
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);
var y=Math.sin(rad)*(r-18);
ctx.beginPath();
if(i%5===0){
ctx.fillStyle="#000";
ctx.arc(x,y,2,2*Math.PI,false);
}else{
ctx.fillStyle="#ccc";
ctx.arc(x,y,2,2*Math.PI,false);
}
ctx.fill();
}
}
//描绘时针
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;
ctx.lineCap="round";
ctx.moveTo(0,10);
ctx.lineTo(0,-r/2);
ctx.stroke();
ctx.restore();
}
//描绘分针
function drawMinute(minute){
ctx.save();
ctx.beginPath();
var rad=2*Math.PI/60*minute;
ctx.rotate(rad);
ctx.lineWidth=3;
ctx.lineCap="round";
ctx.moveTo(0,10);
ctx.lineTo(0,-r+30);
ctx.stroke();
ctx.restore();
}
//描绘秒针
function drawSecond(second){
ctx.save();
ctx.beginPath();
ctx.fillStyle="#C14543";
var rad=2*Math.PI/60*second;
ctx.rotate(rad);
ctx.moveTo(-2,20);
ctx.lineTo(2,20);
ctx.lineTo(1,-r+18);
ctx.lineTo(-1,-r+18)
ctx.fill();
ctx.restore();
}
//中间固定园点
function drawDot(){
ctx.beginPath();
ctx.fillStyle="#fff";
ctx.arc(0,0,3,0,2*Math.PI,false);
ctx.fill();
}
function draw(){
ctx.clearRect(0,0,width,heigth);
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>
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