JS+ Html 畫布實現的時鍾
效果圖：
閑來無聊做了一個網頁的時鍾，效果模擬傳統時鍾的運行方式，
運用了html 的畫布實現指針，背景圖片引用了網絡圖片。
具體原理：
首先將時鍾分為四個不同區域，對每個區域計算cos，sin 來確實指針頂點位置。在通過畫布來繪畫出指針。
通過setInterval 每秒刷新指針位置實現 傳統機械表針的動態跳動。
本人是JS開發程序員，從業1年多。閑來無聊的簡單頁面，
歡迎大家提問，或者建議。共同進步
代碼部分，直接復制HTML 文件中即可查看效果：
<!DOCTYPE html> <html> <head> <meta charset=utf-8> <title>clock</title> </head> <body style="color:green; <!--background-image:url('http://image.lxway.com/upload/b/f0/bf0d97dcee487096548e6edbc89d4963_thumb.png');--> background-size:100%; background-repeat: no-repeat; background-attachment:fixed"> <div style="width: 900px; height: 900px; margin-top: 50px; margin-left: 50px;"> <div style="position: absolute; left:119px;top: 193px; width: 900px; height: 900px; background-image:url('http://image.lxway.com/upload/b/f0/bf0d97dcee487096548e6edbc89d4963_thumb.png'); background-repeat: no-repeat; z-index: -1;"> </div> <canvas id="t" width="800" height="800"></canvas> <div style="position: absolute; left:118px;top: 464px; width: 100px; height: 200px; background-color: white; background-repeat: no-repeat; z-index: 10;"> </div> </div> <script language="javascript"> var s = setInterval(moveI, 1000); function moveI() { var c = document.getElementById("t"); var pc = c.getContext("2d"); c.height = c.height; //秒 pc.lineWidth = 3; pc.strokeStyle = 'rgba(255,0,0,0.8)'; var now = new Date(); var sindex = getxy(150, now.getSeconds()); pc.moveTo(400, 400); pc.lineTo(sindex.x, sindex.y); pc.stroke(); pc.beginPath(); //分 pc.lineWidth = 7; pc.strokeStyle = 'rgba(50,50,50,0.8)'; var mindex = getxy(120, now.getMinutes() + (now.getSeconds() / 60)); pc.moveTo(400, 400); pc.lineTo(mindex.x, mindex.y); pc.stroke(); pc.beginPath(); //時 pc.lineWidth = 10; pc.strokeStyle = 'rgba(0,0,0,0.8)'; var hindex = getxy(80, ((now.getHours() > 12 ? now.getHours() - 12 : now.getHours()) + (now.getMinutes() / 60)) * 5); pc.moveTo(400, 400); pc.lineTo(hindex.x, hindex.y); pc.stroke(); }; function getxy(r, t) { //計算分區 0,1,2,3 var a = parseInt(t / 15); //分區角度 t = t - 15 * a; var y; var x; //基於分區的坐標計算 switch (a) { case 0: y = r - (r * Math.cos(2 * Math.PI / 360 * 90 * (t / 15))); x = r + (r * Math.sin(2 * Math.PI / 360 * 90 * (t / 15))); break; case 1: y = r + (r * Math.sin(2 * Math.PI / 360 * 90 * (t / 15))); x = r + (r * Math.cos(2 * Math.PI / 360 * 90 * (t / 15))); break; case 2: y = r + (r * Math.cos(2 * Math.PI / 360 * 90 * (t / 15))); x = r - (r * Math.sin(2 * Math.PI / 360 * 90 * (t / 15))); break; case 3: y = r - (r * Math.sin(2 * Math.PI / 360 * 90 * (t / 15))); x = r - (r * Math.cos(2 * Math.PI / 360 * 90 * (t / 15))); break; default: break; } y = (400 - r) + y; x = (400 - r) + x; return { 'x': x, 'y': y }; }; </script> </body> </html>
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