这期内容当中小编将会给大家带来有关如何在JavaScript中使用Canvas绘制一个圆形时钟效果，文章内容丰富且以专业的角度为大家分析和叙述，阅读完这篇文章希望大家可以有所收获。
具体内容如下
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<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" src="js/clock.js"></script>
</body>
</html>js
var dom=document.getElementById('clock');
var cxt=dom.getContext("2d");
var width=cxt.canvas.width;
var height=cxt.canvas.height;
var r=width/2;
function drawBackground(){
cxt.save();
cxt.translate(r,r);
cxt.beginPath();
cxt.lineWidth=10;
cxt.arc(0,0,r-5,0,2*Math.PI,false);
cxt.stroke();
cxt.font="18px Arial";
cxt.textAlign='center'
cxt.textBaseline='middle'
var hourNums=[3,4,5,6,7,8,9,10,11,12,1,2];
hourNums.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);
cxt.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);
cxt.beginPath();
if(i % 5===0){
cxt.fillStyle="#000"
cxt.arc(x,y,2,0,2*Math.PI,false);
}
else{
cxt.fillStyle="#ccc"
cxt.arc(x,y,2,0,2*Math.PI,false);
}
cxt.fill();
}
}
function drawHour(hour,minute){
cxt.save();
cxt.beginPath();
var rad=2*Math.PI/12*hour;
var mrad=2*Math.PI/12/60*minute
cxt.rotate(rad+mrad);
cxt.lineWidth=6;
cxt.lineCap='round'
cxt.moveTo(0,10);
cxt.lineTo(0,-r/2);
cxt.stroke();
cxt.restore();
}
function drawMinute(minute){
cxt.save();
cxt.beginPath();
var rad=2*Math.PI/60*minute;
cxt.rotate(rad);
cxt.lineWidth=3;
cxt.lineCap='round'
cxt.moveTo(0,10);
cxt.lineTo(0,-r+30);
cxt.stroke();
cxt.restore();
}
function drawSecond(second){
cxt.save();
cxt.beginPath();
cxt.fillStyle='#c14543'
var rad=2*Math.PI/60*second;
cxt.rotate(rad);
cxt.moveTo(-2,20);
cxt.lineTo(2,20);
cxt.lineTo(1,-r+18);
cxt.lineTo(-1,-r+18);
cxt.fill();
cxt.restore();
}
function drawDot(){
cxt.beginPath();
cxt.fillStyle='#fff'
cxt.arc(0,0,3,0,2*Math.PI,false);
cxt.fill();
}
function draw(){
cxt.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();
cxt.restore();
}
draw();
setInterval(draw,1000);上述就是小编为大家分享的如何在JavaScript中使用Canvas绘制一个圆形时钟效果了，如果刚好有类似的疑惑，不妨参照上述分析进行理解。如果想知道更多相关知识，欢迎关注亿速云行业资讯频道。
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