本文實例為大家分享了使用canvas繪制時鐘的具體代碼，供大家參考，具體內容如下
1. clock.html
<!doctype html><html lang="en"> <head> <meta charset="UTF-8"> <meta name="Description" content=""> <title>canvas時鐘</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(){ //得到當前系統的時分秒 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); //初始化畫布 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 //小時刻度 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(); //分鐘刻度 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(); //畫上時針 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代碼
<script> var canvas=document.getElementById("canvas"); var context=canvas.getContext('2d'); //draw(); function draw(){ //得到當前系統的時分秒 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); //初始化畫布 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 //小時刻度 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(); //分鐘刻度 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(); //畫上時針 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內容，希望對大家學習javascript程序設計有所幫助。
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