JS+Canvas绘制时钟效果

本文实例为大家分享了使用canvas绘制时钟的具体代码，供大家参考，具体内容如下

1. clock.html

<!doctype html>
<html lang="en">
 <head>
 <meta charset="UTF-8">
 <meta name="Description" content="">
 <title>canvas时钟</title>
 </head>
 <body>
 <canvas id="canvas" width="300" height="300"></canvas>
 <script>
  var canvas=document.getElementById("canvas");
  var context=canvas.getContext('2d');
  //draw();
  function draw(){
   //得到当前系统的时分秒
   var now=new Date();
   var sec=now.getSeconds();
   var min=now.getMinutes();
   var hour=now.getHours();
   hour>=12&&(hour=hour-12);
 
    
   var radius = Math.min(canvas.width/2,canvas.height/2);
   //初始化画布
   context.save();
   context.clearRect(0,0,canvas.width,canvas.height);
    context.translate(canvas.width/2,canvas.height/2); 
   context.rotate(-Math.PI/2);
   context.save();
  
   //表框
    
 
   //小时刻度
   context.strokeStyle="black";
   context.fillStyle="black";
   context.lineWidth=3;
   context.lineCap="round";
   context.beginPath();
   for(var i=0;i<12;i++){
    context.rotate(Math.PI/6);
    context.moveTo(radius-30,0);
    context.lineTo(radius-10,0);
 
   }
   context.stroke();
   context.restore();
   context.save();
 
   //分钟刻度
   context.lineWidth=2;
   context.beginPath();
   for(var i=0;i<60;i++){
    if(!i%5==0){
    context.moveTo(radius-15,0);
    context.lineTo(radius-10,0);
    }
    context.rotate(Math.PI/30);
   }
   context.stroke();
   context.restore();
   context.save();
 
   //画上时针
 
    context.rotate((Math.PI/6)*hour+(Math.PI/360)*min+(Math.PI/21600)*sec);
    context.lineWidth=6;
    context.beginPath();
    context.moveTo(-10,0);
    context.lineTo(radius*0.5,0);
    context.stroke();
   context.restore();
   context.save();
 
    context.rotate((Math.PI/30)*min+(Math.PI/1800)*sec);
  context.strokeStyle="#29A8DE";
  context.lineWidth=4;
  context.lineCap="butt";
  context.beginPath();
  context.moveTo(-20,0);
  context.lineTo(radius*0.7,0);
  context.stroke();
  context.restore();
  context.save();
 
  context.rotate(sec*Math.PI/30);
  context.strokeStyle="red";
  context.lineWidth=2;
  context.lineCap="butt";
  context.beginPath();
  context.moveTo(-30,0);
  context.lineTo(radius*0.9,0);
  context.stroke();
  context.restore();
  context.save();
 
   context.lineWidth=4;
    context.strokeStyle="gray";
   context.beginPath();
     context.arc(0,0,radius,0,Math.PI*2,true);
   context.stroke();
   context.restore();
 
 
   context.restore();
  }
 
  window.onload=function(){
   setInterval(draw,1000)
  }
 </script>
 </body>
</html>

2. JavaScript代码

<script>
  var canvas=document.getElementById("canvas");
  var context=canvas.getContext('2d');
  //draw();
  function draw(){
   //得到当前系统的时分秒
   var now=new Date();
   var sec=now.getSeconds();
   var min=now.getMinutes();
   var hour=now.getHours();
   hour>=12&&(hour=hour-12);
 
    
   var radius = Math.min(canvas.width/2,canvas.height/2);
   //初始化画布
   context.save();
   context.clearRect(0,0,canvas.width,canvas.height);
    context.translate(canvas.width/2,canvas.height/2); 
   context.rotate(-Math.PI/2);
   context.save();
  
   //表框
    
 
   //小时刻度
   context.strokeStyle="black";
   context.fillStyle="black";
   context.lineWidth=3;
   context.lineCap="round";
   context.beginPath();
   for(var i=0;i<12;i++){
    context.rotate(Math.PI/6);
    context.moveTo(radius-30,0);
    context.lineTo(radius-10,0);
 
   }
   context.stroke();
   context.restore();
   context.save();
 
   //分钟刻度
   context.lineWidth=2;
   context.beginPath();
   for(var i=0;i<60;i++){
    if(!i%5==0){
    context.moveTo(radius-15,0);
    context.lineTo(radius-10,0);
    }
    context.rotate(Math.PI/30);
   }
   context.stroke();
   context.restore();
   context.save();
 
   //画上时针
 
    context.rotate((Math.PI/6)*hour+(Math.PI/360)*min+(Math.PI/21600)*sec);
    context.lineWidth=6;
    context.beginPath();
    context.moveTo(-10,0);
    context.lineTo(radius*0.5,0);
    context.stroke();
   context.restore();
   context.save();
 
    context.rotate((Math.PI/30)*min+(Math.PI/1800)*sec);
  context.strokeStyle="#29A8DE";
  context.lineWidth=4;
  context.lineCap="butt";
  context.beginPath();
  context.moveTo(-20,0);
  context.lineTo(radius*0.7,0);
  context.stroke();
  context.restore();
  context.save();
 
  context.rotate(sec*Math.PI/30);
  context.strokeStyle="red";
  context.lineWidth=2;
  context.lineCap="butt";
  context.beginPath();
  context.moveTo(-30,0);
  context.lineTo(radius*0.9,0);
  context.stroke();
  context.restore();
  context.save();
 
   context.lineWidth=4;
    context.strokeStyle="gray";
   context.beginPath();
     context.arc(0,0,radius,0,Math.PI*2,true);
   context.stroke();
   context.restore();
 
 
   context.restore();
  }
 
  window.onload=function(){
   setInterval(draw,1000)
  }
 </script>

以上就是本文的全部内容，希望对大家学习javascript程序设计有所帮助。

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