<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Canvas Clock</title> </head> <body> <div style="margin:100px 100px;"> <canvas id="clock" height="200" width="200"></canvas> </div> </body> <script> var obj = document.getElementById('clock'); var ctx = obj.getContext('2d'); var width = ctx.canvas.width; var height = ctx.canvas.height; var r = width / 2; var rem = width / 200; //比例 //画圆 function drawBackground() { ctx.save(); ctx.translate(r, r); ctx.beginPath(); ctx.lineWidth = 10 * rem; //以0，0为原点，r为半径，0为起始角，2*Math.PI为结束角，顺时针画圆 ctx.arc(0, 0, r - ctx.lineWidth / 2, 0, 2 * Math.PI, false); ctx.stroke(); var hourNumber = [3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 1, 2]; ctx.font = 18 * rem + 'px Arial'; ctx.textAlign = 'center'; ctx.textBaseline = 'middle'; //画出1-12的数字 hourNumber.forEach(function (number, i) { var rad = 2 * Math.PI / 12 * i; var x = Math.cos(rad) * (r - 30 * rem); var y = Math.sin(rad) * (r - 30 * rem); ctx.fillText(number, x, y); }); //画出秒针走动的60个点 for (var i = 0; i < 60; i++) { var rad = 2 * Math.PI / 60 * i; var x = Math.cos(rad) * (r - 18 * rem); var y = Math.sin(rad) * (r - 18 * rem); ctx.beginPath(); if (i % 5 === 0) { ctx.fillStyle = '#000'; ctx.arc(x, y, 2 * rem, 0, 2, 2 * Math.PI, false); } else { ctx.fillStyle = '#ccc'; ctx.arc(x, y, 2 * rem, 0, 2, 2 * Math.PI, false); } ctx.fill(); } } //绘制时针 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 * rem); ctx.lineTo(0, -r / 2); ctx.stroke(); ctx.restore(); } //绘制分针 function drawMinute(minute) { ctx.save(); ctx.beginPath(); var rad = 2 * Math.PI / 60 * minute; ctx.rotate(rad); ctx.lineWidth = 3 * rem; ctx.lineCap = 'round'; ctx.moveTo(0, 10); ctx.lineTo(0, -r + 30 * rem); ctx.stroke(); ctx.restore(); } //绘制秒针 function drawSecond(second) { ctx.save(); ctx.beginPath(); ctx.fillStyle = '#c14443'; var rad = 2 * Math.PI / 60 * second; ctx.rotate(rad); ctx.moveTo(-2, 20 * rem); ctx.lineTo(2, 20 * rem); ctx.lineTo(1, -r + 18 * rem); ctx.lineTo(-1, -r + 18 * rem); ctx.fill(); ctx.restore(); } //画时钟上的中心白色原点 function drawDot() { ctx.beginPath(); ctx.fillStyle = '#fff'; ctx.arc(0, 0, 3 * rem, 0, 2 * Math.PI, false); ctx.fill(); } function draw() { ctx.clearRect(0, 0, width, height); var now = new Date(); var hour = now.getHours(); var minutes = now.getMinutes(); var seconds = now.getSeconds(); drawBackground(); drawHour(hour, minutes); drawMinute(minutes); drawSecond(seconds); drawDot(); ctx.restore(); } setInterval(draw, 1000); //每秒执行一次 </script>
