js Canvas绘制圆形时钟教程

更新时间：2020-04-21 00:39:00 作者：startmvc

本文实例为大家分享了Canvas绘制圆形时钟的具体代码，供大家参考，具体内容如下<!DOCTYPE

本文实例为大家分享了Canvas绘制圆形时钟的具体代码，供大家参考，具体内容如下


<!DOCTYPE html> 
<html> 
<head lang="en"> 
 <meta charset="UTF-8"> 
 <title>canvas-clock</title> 
</head> 
<body> 
 <canvas id="canvas" width="500px" height="500px"> 
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 </canvas> 
 <script> 
 //获取到canvas元素 
 var canvas = document.getElementById('canvas'); 
 //获取canvas中的画图环境 
 var context = canvas.getContext('2d'); 
 
 
 //时钟的大小 
 function drowClock(){ 
 //钟表的大小：初始值设置 
 var clockDimensions = 150; 
 
 //清理当前画布，以便后期绘制 
 context.clearRect(0,0,canvas.width,canvas.height); 
 //绘制表盘 
 context.beginPath(); //开启新路径 
 context.lineWidth = clockDimensions/15; 
 context.strokeStyle = "#A7C0DC"; 
 //绘制表盘圆圈 
 context.arc(canvas.width/2,canvas.height/2,clockDimensions,0,Math.PI*2,false); 
 context.stroke();//描边绘制 
 
 //绘制表盘的刻度线 
 for(var i=1;i<=60;i++){ 
 if(i%5==0){ 
 context.save();//保存当前绘制环境 
 context.beginPath(); 
 context.lineWidth =clockDimensions/30; 
 context.strokeStyle = "#9AABB1"; 
 //重置坐标原点（0,0） 
 context.translate(canvas.width/2,canvas.height/2); 
 //绘制环境旋转方法,以（0,0）为参考点进行旋转 
 context.rotate(Math.PI*2/60 * i); 
 context.moveTo(0,clockDimensions-clockDimensions/30); 
 context.lineTo(0,clockDimensions-clockDimensions/8); 
 context.stroke(); 
 context.beginPath(); 
 context.textAlign = 'center'; 
 context.textBaseline = 'middle'; 
 context.font = 'bold '+Math.floor(clockDimensions/10)+'px 宋体'; 
 context.fillStyle = "#03671F"; 
 context.fillText(i/5,0,0-(clockDimensions-clockDimensions/5)); 
 context.fill(); 
 context.restore();//恢复当前保存的绘制环境 
 }else { 
 context.save(); 
 context.beginPath(); 
 context.lineWidth = Math.floor(clockDimensions/100); 
 context.strokeStyle = "#8EA5AB"; 
 //重置坐标原点（0,0） 
 context.translate(canvas.width / 2, canvas.height / 2); 
 //绘制环境旋转方法,以（0,0）为参考点进行旋转 
 context.rotate(Math.PI * 2 / 60 * i); 
 context.moveTo(0, clockDimensions-clockDimensions/20); 
 context.lineTo(0, clockDimensions-clockDimensions/10); 
 context.stroke(); 
 context.restore(); 
 } 
 } 
 
 //获取当前windows的时间 
 var now = new Date(); 
 var sec = now.getSeconds(); 
 var min = now.getMinutes(); 
 var hour = now.getHours(); 
 
 //获取精准的小时数 
 hour = hour +min/60 + sec/3600; 
 //转换为12进制 
 hour = hour>12?(hour-12):hour; 
 //获取精准的分钟数 
 min = min + sec/60; 
 
 //绘制时针 
 context.save(); 
 context.beginPath(); 
 context.lineWidth = clockDimensions/30; 
 context.strokeStyle = "#596C74"; 
 //重置坐标原点（0,0） 
 context.translate(canvas.width / 2, canvas.height / 2); 
 //绘制环境旋转方法,以（0,0）为参考点进行旋转 
 context.rotate(Math.PI * 2 / 12 * hour); 
 context.moveTo(0, clockDimensions/10); 
 context.lineTo(0, 0-clockDimensions/2); 
 context.stroke(); 
 context.restore(); 
 
 //绘制分针 
 context.save(); 
 context.beginPath(); 
 context.lineWidth = clockDimensions/40; 
 context.strokeStyle = "#596C74"; 
 //重置坐标原点（0,0） 
 context.translate(canvas.width / 2, canvas.height / 2); 
 //绘制环境旋转方法,以（0,0）为参考点进行旋转 
 context.rotate(Math.PI * 2 / 60 * min); 
 context.moveTo(0, clockDimensions/8); 
 context.lineTo(0, 0-(clockDimensions-clockDimensions/5)); 
 context.stroke(); 
 context.restore(); 
 
 //绘制秒针 
 context.save(); 
 //重置坐标原点（0,0） 
 context.translate(canvas.width / 2, canvas.height / 2); 
 context.beginPath(); 
 context.lineWidth = clockDimensions/50; 
 context.strokeStyle = "#738B93"; 
 //绘制环境旋转方法,以（0,0）为参考点进行旋转 
 context.rotate(Math.PI * 2 / 60 * sec); 
 context.moveTo(0, clockDimensions/6); 
 context.lineTo(0, 0-(clockDimensions-clockDimensions/10)); 
 context.stroke(); 
 //修饰秒针 
 context.beginPath(); 
 context.arc(0,0-(clockDimensions-clockDimensions/3),clockDimensions/20,0,Math.PI*2,true); 
 context.fillStyle = "#2FFC14"; 
 context.fill(); 
 context.lineWidth = clockDimensions/50; 
 context.stroke(); 
 //修饰圆心 
 context.beginPath(); 
 context.fillStyle = "#738B93"; 
 context.arc(0,0,clockDimensions/20,0,Math.PI*2,true); 
 context.fill(); 
 context.restore(); 
 } 
 drowClock(); 
 setInterval(drowClock,1000); 
 
 </script> 
</body> 
</html>

效果图：