本文實例講述了JS+canvas繪制的動態機械表動畫效果。分享給大家供大家參考，具體如下：
先來看看運行效果：
完整實例代碼：
<!DOCTYPE html><html><head lang="en"> <meta charset="UTF-8"> <title>m.survivalescaperooms.com canvas時鐘</title> <style> canvas { border: 1px solid red; } </style></head><body><canvas width="800" height="600"></canvas></body><script> function Clock(opt) { for (var key in opt) { this[key] = opt[key]; } this.init(); } Clock.prototype = { init: function () { var self = this; var ctx = this.ctx; this.timer = setInterval(function(){ ctx.clearRect(0,0,ctx.canvas.width,ctx.canvas.height); self.drawDial(); self.drawDegreeScale(); self.drawNumber(); self.drawPointers(); },1000); }, drawDial: function () { var ctx = this.ctx; ctx.save(); ctx.beginPath(); ctx.lineWidth = this.clockDialW; ctx.strokeStyle = this.clockDialColor; ctx.arc(this.clockX, this.clockY, this.clockRadius, 0, 2 * Math.PI); ctx.stroke(); ctx.restore(); }, drawDegreeScale: function () { var ctx = this.ctx; var clockRadius = this.clockRadius; var clockX = this.clockX; var clockY = this.clockY; var bigDegreeScaleL = this.bigDegreeScaleL; var smallDegreeScale = this.smallDegreeScale; var startX, startY, endX, endY, radian; ctx.save(); for (var i = 0; i < 12; i++) { radian = i * Math.PI / 6; endX = clockX + clockRadius * Math.cos(radian); endY = clockY + clockRadius * Math.sin(radian); if (radian % (Math.PI / 2) == 0) { startX = clockX + (clockRadius - bigDegreeScaleL) * Math.cos(radian); startY = clockY + (clockRadius - bigDegreeScaleL) * Math.sin(radian); ctx.lineWidth = this.bigDCWidth; } else { startX = clockX + (clockRadius - smallDegreeScale) * Math.cos(radian); startY = clockY + (clockRadius - smallDegreeScale) * Math.sin(radian); ctx.lineWidth = this.smallDCWidth; } ctx.beginPath(); ctx.moveTo(startX, startY); ctx.lineTo(endX, endY); ctx.stroke(); ctx.restore(); } }, drawNumber: function () { var ctx = this.ctx; var textX, textY, textRadian; var clockX = this.clockX; var clockY = this.clockY; var clockRadius = this.clockRadius; ctx.font = '20px 微軟雅黑'; ctx.fillStyle = 'red'; ctx.textAlign = 'center'; ctx.textBaseline = 'middle'; ctx.save(); for (var i = 0; i < 12; i++) { textRadian = i * Math.PI / 6 - Math.PI/3; textX = clockX + (clockRadius - 40) * Math.cos(textRadian); textY = clockY + (clockRadius - 40) * Math.sin(textRadian); ctx.beginPath(); ctx.fillText(i + 1, textX, textY); } ctx.restore(); }, drawPointers: function () { var date = new Date(); var h = date.getHours(); var m = date.getMinutes(); var s = date.getSeconds(); h = h % 12; var hRadian = 2 * Math.PI / 12 * h - Math.PI / 2; this.drawPoint(hRadian,30,'red',8); var mRadian = 2 * Math.PI / 60 * m - Math.PI / 2; this.drawPoint(mRadian,50,'blue',6); var sRadian = 2 * Math.PI / 60 * s - Math.PI / 2; this.drawPoint(sRadian,70,'green',2); }, drawPoint: function (radian, length,color,lineWidth) { var x = this.clockX + Math.cos(radian) * length; var y = this.clockY + Math.sin(radian) * length; var ctx = this.ctx; ctx.save(); ctx.beginPath(); ctx.strokeStyle = color; ctx.lineWidth = lineWidth; ctx.moveTo(this.clockX,this.clockY); ctx.lineTo(x,y); ctx.stroke(); ctx.restore(); } };</script><script> var canvas = document.querySelector('canvas'); var ctx = canvas.getContext('2d'); var clock = new Clock({ ctx: this.ctx, clockRadius: 150, clockX: 300, clockY: 300, clockDialW: 6, clockDialColor: 'blue', bigDegreeScaleL: 20, bigDCWidth: 6, smallDegreeScale: 10, smallDCWidth: 4 });</script></html>更多關于JavaScript相關內容感興趣的讀者可查看本站專題：《JavaScript+HTML5特效與技巧匯總》、《JavaScript動畫特效與技巧匯總》、《JavaScript圖形繪制技巧總結》、《JavaScript切換特效與技巧總結》、《JavaScript錯誤與調試技巧總結》、《JavaScript數據結構與算法技巧總結》及《JavaScript數學運算用法總結》
希望本文所述對大家JavaScript程序設計有所幫助。
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