基于HTML5 Canvas与三角函数的简易时钟实现

核心代码与三角函数应用

<!DOCTYPE html>
<html lang="en">
<head>
 <meta charset="UTF-8">
 <title>Document</title>
 <style>
  body{
   background: #eee;
  }
  canvas{
   background: #fff;
  }
 </style>
</head>
<body>
 <canvas width="800" height="800">你浏览器不支持，请升级...</canvas>
 <audio id="audio" src="1.wav"></audio>
 <script>
  var oAudio=document.getElementById("audio");
  var oCas=document.getElementsByTagName("canvas")[0];
  var cas=oCas.getContext("2d");
  oAudio.ontimeupdate=function(){
   if(oAudio.currentTime>0.1){
    this.pause();
   }
  }
  /*渐变颜色*/
  var color=cas.createRadialGradient(400,400,10,400,400,200);
   color.addColorStop(0,"#f1f4f5");
   color.addColorStop(1,"#c5c6c7");
  setInterval(function(){
  oAudio.currentTime=0;
  oAudio.play();
  cas.clearRect(0,0,800,800);
  /*画圆框*/
  cas.lineWidth=3;
  cas.shadowColor="#888";
  cas.shadowOffsetX=1;
  cas.shadowOddsetY=1;
  cas.shadowBlur=5;
  cas.arc(400,400,200,0,Math.PI*2,false);
  cas.strokeStyle=color;
  cas.stroke(); 
  
  /*画圆内*/
  cas.fillStyle=color;  
  cas.fill();

  /*画时刻*/
  drawTime();
  function drawTime(){
   var len=8;
   var len1=16;
   cas.strokeStyle="#7f7f7f";
   cas.shadowOffsetX=0;
   cas.shadowOddsetY=0;
   cas.shadowBlur=0;
   cas.beginPath();
   for(var i=0;i<60;i++){
    if(i%5==0){
    cas.moveTo(400+Math.cos(i*6*Math.PI/180)*200,400+Math.sin(i*6*Math.PI/180)*200);
    cas.lineTo(400+(200-len1)*Math.cos(i*6*Math.PI/180),400+(200-len1)*Math.sin(i*6*Math.PI/180));
    }else{
    cas.moveTo(400+Math.cos(i*6*Math.PI/180)*200,400+Math.sin(i*6*Math.PI/180)*200);
    cas.lineTo(400+(200-len)*Math.cos(i*6*Math.PI/180),400+(200-len)*Math.sin(i*6*Math.PI/180));
    }
   }
   cas.stroke(); 
  }

  /*画时针*/
  
  var date=new Date();
  var h=date.getHours();
  var m=date.getMinutes();
  var s=date.getSeconds();
   /*时针*/
  needle(h*5+5*m/60,100,"#579ec5");
  /*分针*/
  needle(m,130,"#5e717c");
  /*秒针*/
  needle(s,150,"#1d1e1e");
  
  /*圆的中心点*/
  cas.fillStyle="#858384";
  cas.beginPath();
  cas.arc(400,400,5,0,2*Math.PI,true);
  cas.shadowOffsetX=1;
  cas.shadowOddsetY=1;
  cas.shadowBlur=5;
  cas.fill();
  },1000);

  /*时针的函数*/
  function needle(t,len,color){
   var angle=Math.PI/180;
   cas.beginPath();
   cas.strokeStyle=color;
   cas.moveTo(400,400);
   cas.lineTo(400+len*Math.cos((t*6-90)*angle),400+len*Math.sin((t*6-90)*angle));
   cas.stroke();
  }

 </script>
</body>
</html>