JavaScript Canvas绘制圆形时钟效果

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本文实例为大家分享了Canvas时钟效果展示的具体代码，供大家参考，具体内容如下

<html lang="en"> 
<head> 
 <meta charset="UTF-8"> 
 <title></title> 
 <style> 
 canvas{ 
  display: block; 
  margin: 0 auto; 
  background-color: #fdffad; 
  border: 1px solid #000; 
 } 
 </style> 
 <script type="text/javascript"> 
 
 document.addEventListener('DOMContentLoaded',function(){ 
  var oC=document.querySelector('canvas'); 
  var gd=oC.getContext('2d'); 
  var r=oC.width/2; 
 
  function drawBackground() { 
  gd.save(); 
  //渐变 
 
  var ra = gd.createLinearGradient(600, 0, 400, 0); 
  ra.addColorStop(1, '#2dd9ff'); 
  ra.addColorStop(0, '#8c48dd'); 
 
  //表盘 
  gd.translate(r, r); 
  gd.beginPath(); 
  gd.fillStyle = ra; 
  gd.lineWidth = 10; 
  gd.strokeStyle = '#211f4e'; 
  gd.arc(0, 0, r-5, 0, Math.PI *2, false); 
  gd.fill(); 
  gd.stroke(); 
  //数字 
  for (var i = 1; i < 13; i++) { 
   var rad=i * Math.PI * 2 / 12; 
   var x = Math.sin(rad)*(r-70); 
   var y= -Math.cos(rad)*(r-70); 
   gd.fillStyle = "red"; 
   gd.font = "bold 80px Calibri"; 
   gd.lineWidth = 1; 
   gd.textAlign = 'center'; 
   gd.textBaseline = 'middle'; 
   gd.strokeText(i, x, y); 
  } 
  //点 
  for (var i = 0; i < 60; i++) { 
   gd.beginPath(); 
   var rad=i * Math.PI * 2 / 60; 
   var x = Math.sin(rad)*(r-30); 
   var y= -Math.cos(rad)*(r-30); 
   if (i % 5 == 0) { 
   gd.fillStyle = 'red'; 
   } 
   else { 
   gd.fillStyle = '#ccc' 
   } 
   gd.lineWidth = 2; 
   gd.arc(x, y, 6, 0, Math.PI * 2, false); 
   gd.fill(); 
   gd.stroke(); 
   gd.closePath(); 
  } 
  } 
  //时针 
  function drawHour(h,m){ 
  gd.save(); 
  gd.beginPath(); 
  var rad=2*Math.PI/12*h; 
  var mrad=2*Math.PI/12/60*m; 
  gd.rotate(rad+mrad); 
  gd.lineWidth=20; 
  gd.lineCap='round'; 
  gd.moveTo(0,10); 
  gd.lineTo(0,-r/3); 
  gd.stroke(); 
  gd.closePath(); 
  gd.restore(); 
  } 
  //分针 
  function drawMinutes(m){ 
  gd.save(); 
  gd.beginPath(); 
  var rad=2*Math.PI/60*m; 
  gd.rotate(rad); 
  gd.lineWidth=10; 
  gd.lineCap='round'; 
  gd.moveTo(0,10); 
  gd.lineTo(0,-r/2); 
  gd.stroke(); 
  gd.closePath(); 
  gd.restore(); 
  } 
  //秒针 
  function drawSeconds(s){ 
  gd.save(); 
  gd.beginPath(); 
  var rad=2*Math.PI/60*s; 
  gd.rotate(rad); 
  gd.fillStyle='red'; 
  gd.moveTo(-2,20); 
  gd.lineTo(2,20); 
  gd.lineTo(1,-r+100); 
  gd.lineTo(-1,-r+100); 
  gd.fill(); 
  gd.closePath(); 
  gd.restore(); 
  } 
  //圆点 
  function drawPoint(){ 
  gd.beginPath(); 
  gd.fillStyle='#fff'; 
  gd.arc(0,0,5,Math.PI*2,false); 
  gd.fill(); 
  } 
 
  function drawClock(){ 
  gd.clearRect(0,0,oC.width,oC.height); 
  var oDate=new Date(); 
  var h=oDate.getHours(); 
  var m=oDate.getMinutes(); 
  var s=oDate.getSeconds(); 
  drawBackground(); 
  drawHour(h,m); 
  drawMinutes(m); 
  drawSeconds(s); 
  drawPoint(); 
  gd.restore(); 
 
  } 
  drawClock(); 
  setInterval(drawClock,1000); 
 },false); 
 </script> 
</head> 
<body> 
<canvas width="800" height="800"></canvas> 
</body> 
</html>

效果图：