站長資訊網本篇文章給大家帶來的內容是關于Canvas繪制出時鐘的代碼示例，有一定的參考價值，有需要的朋友可以參考一下，希望對你有所幫助。
完整代碼：
<!DOCTYPE html> <html> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <meta http-equiv="X-UA-Compatible" content="ie=edge"> <title>Document</title> <style type="text/css"> div { text-align: center; margin-top: 250px; } </style> </head> <body> <div> <canvas id="clock" height="200px" width="200px">你的瀏覽器不支持canvas</canvas> </div> <script> var dom = document.getElementById('clock'); var ctx = dom.getContext('2d'); var width = ctx.canvas.width; var height = ctx.canvas.height; var r = width / 2; //繪制表盤 function drawBackground() { ctx.save(); ctx.translate(r, r); ctx.beginPath(); ctx.lineWidth = 10; ctx.arc(0, 0, r - 5, 0, 2 * Math.PI, false); ctx.stroke(); var hourNumbers = [3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 1, 2]; ctx.font = '18px Arial'; ctx.textAlign = 'center'; ctx.textBaseline = 'middle'; //小時數字 hourNumbers.forEach(function (number, i) { var rad = 2 * Math.PI / 12 * i; var x = Math.cos(rad) * (r - 30); var y = Math.sin(rad) * (r - 30); ctx.fillText(number, x, y); // console.log(x) }) //繪制分刻度 for (var i = 0; i < 60; i++) { var rad = 2 * Math.PI / 60 * i; var x = Math.cos(rad) * (r - 18); var y = Math.sin(rad) * (r - 18); ctx.beginPath(); if (i % 5 == 0) { ctx.fillStyle = '#000'; ctx.arc(x, y, 2, 0, 2 * Math.PI, false); } else { ctx.fillStyle = '#ccc'; ctx.arc(x, y, 2, 0, 2 * Math.PI, false); } ctx.fill(); } } //繪制時針 function drawHour(hour, minute) { ctx.save(); ctx.beginPath(); var rad = 2 * Math.PI / 12 * hour; var mrad = 2 * Math.PI / 12 / 60 * minute; ctx.rotate(rad + mrad); ctx.lineWidth = 6; ctx.lineCap = 'round'; ctx.moveTo(0, 10); ctx.lineTo(0, -r / 2); ctx.stroke(); ctx.restore(); } //繪制分針 function drawMinute(minute) { ctx.save(); ctx.beginPath(); var rad = 2 * Math.PI / 60 * minute; ctx.rotate(rad); ctx.lineWidth = 3; ctx.lineCap = 'round'; ctx.moveTo(0, 10); ctx.lineTo(0, -r + 30); ctx.stroke(); ctx.restore(); } //繪制秒針 function drawSecond(second) { ctx.save(); ctx.beginPath(); ctx.fillStyle = 'red' var rad = 2 * Math.PI / 60 * second; ctx.rotate(rad); ctx.moveTo(-2, 20); ctx.lineTo(2, 20); ctx.lineTo(1, -r + 18); ctx.lineTo(-1, -r + 18); ctx.fill(); ctx.restore(); } //繪制指針的端點 function drawDot() { ctx.beginPath(); ctx.fillStyle = 'white'; ctx.arc(0, 0, 3, 0, 2 * Math.PI, false); ctx.fill(); } //動起來 function draw() { //清除之前所繪制的 ctx.clearRect(0, 0, width, height); var now = new Date(); var hour = now.getHours(); var minute = now.getMinutes(); var second = now.getSeconds(); drawBackground(); drawHour(hour, minute); drawMinute(minute); drawSecond(second) drawDot(); ctx.restore(); } //draw(); setInterval(draw, 1000); </script> </body> </html>
