为了获取客户、回馈客户，平台一般会推出抽奖活动类的营销页。因此web页面中，有各式各样的抽奖效果。
格子式(九宫格)，背景滚动式(数字/文字/图案)，旋转式(转盘)，游戏式(砸蛋/拼图...)......
这里来讲解下转盘抽奖效果。
当用户进入这个抽奖页面时，一般会“华丽”的设计所吸引，虽然明知中奖几率几乎等于0，图个运气，都会去点“开始抽奖”，于是“折腾”开始了。
你还没有登录，请登录后再来
你还没有抽奖资格，请做做“什么”后再来
你的抽奖机会用完了，请明天再来
很抱歉，你没有中奖
。。。
来看下效果：
在BKY预览效果无语了，弹出插件都不弹出了。
实际是这样的：
贴上代码，仅供参考：
页面代码:
<!doctype html> <html> <head> <meta charset="utf-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0, user-scalable=no"/> <title>旋转-转盘-抽奖</title> <style type="text/css"> *{margin: 0; padding: 0;} #ww_page{ overflow:hidden; width:100%;} #ww_rotate{position: relative; margin: 0 auto; width:640px; height:640px; } #ww_plate{position:absolute; top:0; left:0;width:640px; height:640px; background:url(http://i13.tietuku.com/416f769edc909de0.png) center no-repeat;background-size: 100% 100%; transition: none;} #ww_arrow{position:absolute; top:205px; left:50%; z-index: 10;margin-left: -75px;width:150px;height:190px; background:url(http://i13.tietuku.com/0e0b1c875d346f4d.png) center no-repeat; } </style> </head> <body> <div id="ww_page"> <div id="ww_box"> <div id="ww_rotate"> <div id="ww_plate"></div> <div id="ww_arrow"></div> </div> </div> </div> <link rel="stylesheet" type="text/css" href="js/Tips/mTips.css" /> <script type="text/javascript" src="js/Tips/mTips.min.js"></script> <script type="text/javascript" src="js/utils.js"></script> <script type="text/javascript" src="mRotate.js"></script> <script type="text/javascript"> //缩放 scalePage('#ww_box'); // 奖品数据 var prizeData = [ { id: 1, prize: "一等奖", angle: 3600 }, { id: 2, prize: "二等奖", angle: 3720 }, { id: 3, prize: "三等奖", angle: 3840 }, { id: 4, prize: "再接再厉", angle: 3750 }, { id: 5, prize: "要加油哦", angle: 3865 }, { id: 6, prize: "谢谢参与", angle: 3930 } ]; //旋转 var arrow = document.getElementById('ww_arrow'), plate = document.getElementById('ww_plate'), isRotate = false; arrow.onclick = function() { if (isRotate) return; isRotate = true; var num = (Math.random() * prizeData.length) >> 0, data = prizeData[num]; // console.log(num); // console.time('计时'); new Rotate({ el: plate, //angle: 90, animateTo: data.angle, duration: 5000, easeing: 'easeInOutCirc', end: function() { // console.timeEnd('计时'); isRotate = false; Tips.alert(data.prize); } }); }; </script> </body> </html>
旋转主程序mRotate.js
/** * LBS Rotate * Date: 2014-12-20 * ================================== * opts.el 旋转对象(一个字符串的CSS选择器或者元素对象) * opts.angle 初始角度 默认0 * opts.animateTo 目标角度 * opts.duration 持续时间 默认1000(毫秒) * opts.easing 动画效果 (easeOutSine默认 easeInOutSine easeInOutCirc) * opts.end 旋转完成 执行函数 * ================================== **/ var Rotate = function(opts) { opts = opts || {}; if (typeof opts.el === undefined) return; this.el = typeof opts.el === 'string' ? document.querySelector(opts.el) : opts.el; this.angle = opts.angle || 0; this.animateTo = opts.animateTo || this.angle + 360; this.duration = opts.duration || 1000; this.easing = (opts.easing && this.tween[opts.easing]) || this.tween.easeOutSine; this.end = opts.end || function() {}; this.animated = false; this.init(); }; Rotate.prototype = { init: function() { this.rotate(this.angle); this.start(); }, start: function() { this.animate(); }, animate: function() { if (this.animated) return; var start = this.angle, end = this.animateTo, change = end - start, duration = this.duration, startTime = +new Date(), ease = this.easing, _this = this; if (start == end) { this.end && this.end(); return; } this.animated = true; ! function animate() { var nowTime = +new Date(), timestamp = nowTime - startTime, delta = ease(timestamp / duration); _this.rotate(start + delta * change); if (duration <= timestamp) { _this.rotate(end); _this.animated = false; _this.end && _this.end(); } else { setTimeout(animate, 17); } }(); }, rotate: function(angle) { this.setTransform(angle % 360); }, setTransform: function(v) { v = v || 0; this.setStyle(this.el, 'transform', 'rotate(' + v + 'deg)'); }, setStyle: function(el, p, v) { !this.cache && (this.cache = {}); !this.cache[el] && (this.cache[el] = {}); !this.cache[el][p] && (this.cache[el][p] = this.prefix(p)); el.style[this.cache[el][p] || this.prefix(p)] = v; }, prefix: function(p) { var style = document.createElement('div').style; if (p in style) return p; var prefix = ['webkit', 'Moz', 'ms', 'O'], i = 0, l = prefix.length, s = ''; for (; i < l; i++) { s = prefix[i] + '-' + p; s = s.replace(/-D/g, function(match) { return match.charAt(1).toUpperCase(); }); if (s in style) return s; } }, tween: { easeOutSine: function(pos) { return Math.sin(pos * (Math.PI / 2)); }, easeInOutSine: function(pos) { return (-.5 * (Math.cos(Math.PI * pos) - 1)); }, easeInOutCirc: function(pos) { if ((pos /= 0.5) < 1) return -0.5 * (Math.sqrt(1 - pos * pos) - 1); return 0.5 * (Math.sqrt(1 - (pos -= 2) * pos) + 1); } } };
很简单的代码，就是一个动画函数，改变元素的旋转rotate属性。
CSS3 transform 属性：http://www.w3school.com.cn/cssref/pr_transform.asp
动画函数如下，获得元素的初始角度(起点)，目标角度(终点)，要多久(持续的时间)，动画效果(缓动公式)
animate: function() { if (this.animated) return; var start = this.angle, //起点 end = this.animateTo, //目的地 change = end - start, //距离 duration = this.duration, //持续时间 startTime = +new Date(), ease = this.easing, //运动效果 _this = this; if (start == end) { this.end && this.end(); return; } this.animated = true; !function animate() { var nowTime = +new Date(), timestamp = nowTime - startTime, delta = ease(timestamp / duration); _this.rotate(start + delta * change); if (duration <= timestamp) { _this.rotate(end); _this.animated = false; _this.end && _this.end(); } else { setTimeout(animate, 17); } }(); }
设置旋转属性
rotate: function(angle) { this.setTransform(angle % 360); }, setTransform: function(v) { v = v || 0; this.setStyle(this.el, 'transform', 'rotate(' + v + 'deg)'); }, setStyle: function(el, p, v) { !this.cache && (this.cache = {}); !this.cache[el] && (this.cache[el] = {}); !this.cache[el][p] && (this.cache[el][p] = this.prefix(p)); el.style[this.cache[el][p] || this.prefix(p)] = v; }, prefix: function(p) { var style = document.createElement('div').style; if (p in style) return p; var prefix = ['webkit', 'Moz', 'ms', 'O'], i = 0, l = prefix.length, s = ''; for (; i < l; i++) { s = prefix[i] + '-' + p; s = s.replace(/-D/g, function(match) { return match.charAt(1).toUpperCase(); }); if (s in style) return s; } }
实际抽奖流程：点击抽奖按钮，发送ajax，得到一个结果数据，执行抽奖程序，显示结果。
了解动画函数，结合缓动公式，是做出各种炫酷的效果的基础。