JS+Canvas绘制时钟效果

大地飞鸿

2016-05-24

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。

canvas var context