【项目实战】用CSS实现一个抽奖转盘(附详细代码+思路)
程序源代码
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2020-12-07 13:52
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作者：我不吃饼干呀
https://www.cnblogs.com/wenruo/p/9732704.html
基本是用CSS实现的，没有用图片，加一丢丢JS。完全没有考虑兼容性。
首先画一个转盘
<html lang="en"><head><meta charset="UTF-8"><title>幸运大转盘title><style>/* 重置默认样式 */* {margin: 0;padding: 0;border: none;outline: none;}.wrapper {position: relative;height: 200px;width: 200px;padding: 20px;margin: 20px;background-color: #c0381f;box-shadow: #000000 0px 0px 10px;border-radius: 50%;}.panel {position: relative;height: 200px;width: 200px;background-color: #b7b7b7;border-radius: 100px;}.pointer {position: absolute;left: 79px;top: 79px;z-index: 10;height: 30px;width: 30px;padding: 6px;color: #fff899;line-height: 15px;font-size: 12px;text-align: center;background-color: #dc5b5b;border-radius: 50%;border: 1px solid #c0381f;}style>head><body><div class="wrapper"><div class="panel"><div class="pointer">开始抽奖div>div>div>body>html>
效果如下，配色什么的不要在意，可能比较丑。。。
然后写抽奖指针的小箭头，用CSS画三角形是一个比较常见的问题，通过设置width和height为0，然后用border实现。
如图，矩形是由四个三角形边框组成的，只要设置其它边颜色为透明，就可以获得单独的三角形。
这里通过伪元素after实现三角形，并通过绝对定位将三角形定位到中间小圆的顶端。
.pointer::after {content: '';position: absolute;left: 14px;top: -24px;border-width: 12px 6px;border-style: solid;border-color: transparent;border-bottom-color: #c0381f;}
现在才像一个指针了。
哦 接下来是实现转盘背景，不同的扇区对应不同的奖品，这样就有一个需求：实现任意角度扇形。
可能会想当然的认为和三角形一样，不过是加一个border-radius而已，高度是圆半径，宽度是tan(θ/2)，但是实现出来的效果和想象并不一样……（可能需要做一些其他操作以达到效果，但是我没想到。
最后还是求助了搜索引擎。不得不承认dalao们实在是太nb了，qaq……通过 linear-gradient 实现想法是真的棒。不过还有好多复杂的实现看的不是很懂= =
How to draw a circle sector in CSS?
Segments in a circle using CSS3
3种纯CSS实现中间镂空的12色彩虹渐变圆环方法
实现就是通过两个正方形取相交区域。
我觉图画的还是挺好的:D
没有用伪元素实现，因为我还要加文字，至于文字的位置，我真的是瞎调的，反正正经写代码也不会这么写= =
<html lang="en"><head><meta charset="UTF-8"><title>Documenttitle><style>.sector {position: absolute;width: 100px;height: 200px;margin: 100px;border-radius: 0px 100px 100px 0;overflow: hidden;transform: rotate(-18deg);}.sector-inner {text-align: center;display: block;width: 40px;padding: 5px 3px 0 57px;height: 195px;background: #ffeab1;transform: translateX(-100px) rotate(36deg);transform-origin: right center;border-radius: 100px 0 0 100px;}.sector-inner span {display: block;transform-origin: center;transform: rotate(-19deg);color: #d46854;}style>head><body><div class="sector"><div class="sector-inner"><span>谢谢参与span>div>div>body>html>
效果如下，一个带有文字的小扇形~~
OK，现在写一堆扇形放到一开始的转盘上。
现在的代码是酱紫滴~~太长了折起来。
<html lang="en"><head><meta charset="UTF-8"><title>幸运大转盘title><style>/* 重置默认样式 */* {margin: 0;padding: 0;border: none;outline: none;}.wrapper {position: relative;height: 200px;width: 200px;padding: 20px;margin: 20px;background-color: #c0381f;box-shadow: #000000 0px 0px 10px;border-radius: 50%;}.panel {position: relative;height: 200px;width: 200px;background-color: #b7b7b7;border-radius: 100px;}.sector {position: absolute;width: 100px;height: 200px;border-radius: 0px 100px 100px 0;overflow: hidden;left: 100px;top: 0px;transform-origin: left center;}.sector:nth-child(1) {transform: rotate(-18deg);}.sector:nth-child(2) {transform: rotate(18deg);}.sector:nth-child(3) {transform: rotate(54deg);}.sector:nth-child(4) {transform: rotate(90deg);}.sector:nth-child(5) {transform: rotate(126deg);}.sector:nth-child(6) {transform: rotate(162deg);}.sector:nth-child(7) {transform: rotate(198deg);}.sector:nth-child(8) {transform: rotate(234deg);}.sector:nth-child(9) {transform: rotate(270deg);}.sector:nth-child(10) {transform: rotate(306deg);}.sector:nth-child(2n+1) .sector-inner {background: #fef6e0;}.sector:nth-child(2n) .sector-inner {background: #ffffff;}.sector-inner {text-align: center;display: block;width: 40px;padding: 5px 3px 0 57px;height: 195px;transform: translateX(-100px) rotate(36deg);transform-origin: right center;border-radius: 100px 0 0 100px;}.sector-inner span {display: block;transform-origin: center;transform: rotate(-19deg);color: #d46854;}.pointer {position: absolute;left: 79px;top: 79px;z-index: 10;height: 30px;width: 30px;padding: 6px;color: #fff899;line-height: 15px;font-size: 12px;text-align: center;background-color: #dc5b5b;border-radius: 50%;border: 1px solid #c0381f;}.pointer::after {content: '';position: absolute;left: 14px;top: -24px;border-width: 12px 6px;border-style: solid;border-color: transparent;border-bottom-color: #c0381f;}style>head><body><div class="wrapper"><div class="panel"><div class="sector"><div class="sector-inner"><span>谢谢参与span>div>div><div class="sector"><div class="sector-inner"><span> 50 积分span>div>div><div class="sector"><div class="sector-inner"><span>谢谢参与span>div>div><div class="sector"><div class="sector-inner"><span>100话费span>div>div><div class="sector"><div class="sector-inner"><span> 50 积分span>div>div><div class="sector"><div class="sector-inner"><span>谢谢参与span>div>div><div class="sector"><div class="sector-inner"><span>100话费span>div>div><div class="sector"><div class="sector-inner"><span>谢谢参与span>div>div><div class="sector"><div class="sector-inner"><span> 50 积分span>div>div><div class="sector"><div class="sector-inner"><span>10元话费span>div>div><div class="pointer">开始抽奖div>div>div>body>html>
嘻嘻，现在是抽奖转盘的样子了吧~~~
最后再加点浮夸的灯。
<html lang="en"><head><meta charset="UTF-8"><title>幸运大转盘title><style>/* 重置默认样式 */* {margin: 0;padding: 0;border: none;outline: none;}.wrapper {position: relative;height: 200px;width: 200px;padding: 20px;margin: 20px;background-color: #c0381f;box-shadow: #000000 0px 0px 10px;border-radius: 50%;}.light {position: absolute;height: 10px;width: 10px;border-radius: 50%;top: 5px;left: 115px;transform-origin: 5px 115px;}.light:nth-child(2n) {background-color: #fafce7;}.light:nth-child(2n+1) {background-color: #ffe58b;}.light:nth-child(2) {transform: rotate(36deg);}.light:nth-child(3) {transform: rotate(72deg);}.light:nth-child(4) {transform: rotate(108deg);}.light:nth-child(5) {transform: rotate(144deg);}.light:nth-child(6) {transform: rotate(180deg);}.light:nth-child(7) {transform: rotate(216deg);}.light:nth-child(8) {transform: rotate(252deg);}.light:nth-child(9) {transform: rotate(288deg);}.light:nth-child(10) {transform: rotate(324deg);}.panel {position: relative;height: 200px;width: 200px;background-color: #b7b7b7;border-radius: 100px;}.sector {position: absolute;width: 100px;height: 200px;border-radius: 0px 100px 100px 0;overflow: hidden;left: 100px;top: 0px;transform-origin: left center;}.sector:nth-child(1) {transform: rotate(-18deg);}.sector:nth-child(2) {transform: rotate(18deg);}.sector:nth-child(3) {transform: rotate(54deg);}.sector:nth-child(4) {transform: rotate(90deg);}.sector:nth-child(5) {transform: rotate(126deg);}.sector:nth-child(6) {transform: rotate(162deg);}.sector:nth-child(7) {transform: rotate(198deg);}.sector:nth-child(8) {transform: rotate(234deg);}.sector:nth-child(9) {transform: rotate(270deg);}.sector:nth-child(10) {transform: rotate(306deg);}.sector:nth-child(2n+1) .sector-inner {background: #fef6e0;}.sector:nth-child(2n) .sector-inner {background: #ffffff;}.sector-inner {text-align: center;display: block;width: 40px;padding: 5px 3px 0 57px;height: 195px;transform: translateX(-100px) rotate(36deg);transform-origin: right center;border-radius: 100px 0 0 100px;}.sector-inner span {display: block;transform-origin: center;transform: rotate(-19deg);color: #d46854;}.pointer {position: absolute;left: 79px;top: 79px;z-index: 10;height: 30px;width: 30px;padding: 6px;color: #fff899;line-height: 15px;font-size: 12px;text-align: center;background-color: #dc5b5b;border-radius: 50%;border: 1px solid #c0381f;}.pointer::after {content: '';position: absolute;left: 14px;top: -24px;border-width: 12px 6px;border-style: solid;border-color: transparent;border-bottom-color: #c0381f;}style>head><body><div class="wrapper"><div class="light">div><div class="light">div><div class="light">div><div class="light">div><div class="light">div><div class="light">div><div class="light">div><div class="light">div><div class="light">div><div class="light">div><div class="panel"><div class="sector"><div class="sector-inner"><span>谢谢参与span>div>div><div class="sector"><div class="sector-inner"><span> 50 积分span>div>div><div class="sector"><div class="sector-inner"><span>谢谢参与span>div>div><div class="sector"><div class="sector-inner"><span>100话费span>div>div><div class="sector"><div class="sector-inner"><span> 50 积分span>div>div><div class="sector"><div class="sector-inner"><span>谢谢参与span>div>div><div class="sector"><div class="sector-inner"><span>100话费span>div>div><div class="sector"><div class="sector-inner"><span>谢谢参与span>div>div><div class="sector"><div class="sector-inner"><span> 50 积分span>div>div><div class="sector"><div class="sector-inner"><span>10元话费span>div>div><div class="pointer">开始抽奖div>div>div>body>html>
现在转盘CSS部分基本完成。简单写一下JS部分。点击中间的指针时，指针会转，可以拉一条贝塞尔曲线，控制动画的速度。
贝塞尔曲线可以简单的看作是时间-距离曲线，斜率就是速度。因为转盘的速度肯定是先快后慢，随便拉一条。
http://cubic-bezier.com/#.2,.93,.43,1
CSS中添加属性
.pointer {// ...transition: transform 3s cubic-bezier(.2,.93,.43,1);}
点击开始抽奖的时候，为中间的指针加一个旋转的角度。这里有一个问题就是不同的扇区抽到的概率是相同的，改成不同应该…也蛮简单的，不过主要是想练下CSS，JS就随便写了。
JS部分代码。。
let getEle = document.getElementsByClassName.bind(document);let pointer = getEle('pointer')[0];let result = getEle('result')[0];let onRotation = false; // 记录当前是否正在旋转，如果正在旋转，就不能继续点击了let reward = ['谢谢参与', '50积分', '谢谢参与', '100元话费', '50积分','谢谢参与', '100元话费', '谢谢参与', '50积分', '10元话费'];// 根据随机角度获取奖励let getReward = (function() {currentDeg = 0;return function() {// 转三圈到四圈let rotateDeg = Math.random() * 360 + 1080;currentDeg += rotateDeg;let rewardText = reward[Math.floor((currentDeg + 18) % 360 / 36)]return {deg: currentDeg,text: rewardText === '谢谢参与' ? '很遗憾，您没有获得奖品。' : '恭喜获得: ' + rewardText}}})();pointer.addEventListener('click', () => {if (onRotation) return;console.log('开始抽奖');onRotation = true;let nextStatus = getReward();console.log(nextStatus)result.innerText = nextStatus.text;result.style.display = 'none';pointer.style.transform = `rotateZ(${nextStatus.deg}deg)`;})pointer.addEventListener('transitionend', () => {console.log('抽奖结束');onRotation = false;result.style.display = 'block';})
现在一个抽奖转盘基本完成了，最后一个需求，如果旁边的等能够亮起来就好了。
至于灯怎么亮，就需要用到CSS3的动画了，我还不太熟悉，先去学习一下>_<
我学完回来了，参考教程http://www.ruanyifeng.com/blog/2014/02/css_transition_and_animation.html，内容不是很多。
animation-name 指定动画名称，
animation-duration 指定动画持续时间，
animation-timing-function 指定动画函数，和transition的函数是一样的，
animation-delay 指定动画延迟多久后执行，
animation-iteration-count 指定动画执行多少次，默认为一次，可以指定为infinite，无限循环。
animation-direction 指定动画多次播放时，一次结束，下一次怎么接上一次，如图。
animation-fill-mode 指定动画结束后停在什么位置，默认回到起始状态，forwards表示让动画停留在结束状态，backwards让动画回到第一帧的状态，both根据animation-direction轮流应用forwards和backwards规则。
animation-play-state 动画执行状态，默认为running，可以设置为pause，动画将在当前状态停止，再改为running时，会接着上一次停止的位置继续执行动画。
使用关键字 keyframes 来定义一个动画。通过百分比指定其中任意几个状态。
尝试着写一下=。=
<html lang="en"><head><meta charset="UTF-8"><title>Documenttitle><style>div {height: 30px;width: 30px;animation: 1s twinkling 3, 100ms 3s twinkling 3;}@keyframes twinkling {50% { background: red; }}style>head><body><div>div>body>html>
这是一个方块，先慢速闪三下，再快速闪三下，最后消失。
animation: 1s twinkling 3;
就相当于
animation-name: twinkling;
animation-duration: 1s;
animation-timing-function: ease;
animation-delay: 0s;
animation-iteration-count: 3;
animation-direction: normal;
animation-fill-mode: none;
animation-play-state: running;
效果
我觉得还可以:P 反正我只能写成这样了。
最后把动画加到转盘的灯上。完成代码（好像颜色变了，咳，那是因为我animation学了太久都掉色了）：
<html lang="en"><head><meta charset="UTF-8"><title>幸运大转盘title><style>* { /* 重置默认样式 */margin: 0;padding: 0;border: none;outline: none;user-select: none;}.wrapper {position: relative;height: 200px;width: 200px;padding: 20px;margin: 20px;background-color: #ff5555;box-shadow: #000000 0px 0px 10px;border-radius: 50%;}.light {position: absolute;height: 10px;width: 10px;border-radius: 50%;top: 5px;left: 115px;transform-origin: 5px 115px;}.light-twinkling {animation: 1s twinkling 3, 100ms 3s twinkling 3;}.light:nth-child(2n) {background-color: #fafce7;}.light:nth-child(2n+1) {background-color: #ffe58b;}.light:nth-child(2) {transform: rotate(36deg);}.light:nth-child(3) {transform: rotate(72deg);}.light:nth-child(4) {transform: rotate(108deg);}.light:nth-child(5) {transform: rotate(144deg);}.light:nth-child(6) {transform: rotate(180deg);}.light:nth-child(7) {transform: rotate(216deg);}.light:nth-child(8) {transform: rotate(252deg);}.light:nth-child(9) {transform: rotate(288deg);}.light:nth-child(10) {transform: rotate(324deg);}.panel {position: relative;height: 200px;width: 200px;background-color: #b7b7b7;border-radius: 100px;}.sector {position: absolute;left: 100px;top: 0px;width: 100px;height: 200px;font-size: 14px;border-radius: 0px 100px 100px 0;overflow: hidden;transform-origin: left center;}.sector:nth-child(1) {transform: rotate(-18deg);}.sector:nth-child(2) {transform: rotate(18deg);}.sector:nth-child(3) {transform: rotate(54deg);}.sector:nth-child(4) {transform: rotate(90deg);}.sector:nth-child(5) {transform: rotate(126deg);}.sector:nth-child(6) {transform: rotate(162deg);}.sector:nth-child(7) {transform: rotate(198deg);}.sector:nth-child(8) {transform: rotate(234deg);}.sector:nth-child(9) {transform: rotate(270deg);}.sector:nth-child(10) {transform: rotate(306deg);}.sector:nth-child(2n+1) .sector-inner {background: #fef6e0;}.sector:nth-child(2n) .sector-inner {background: #ffffff;}.sector-inner {text-align: center;display: block;width: 40px;padding: 5px 3px 0 57px;height: 195px;transform: translateX(-100px) rotate(36deg);transform-origin: right center;border-radius: 100px 0 0 100px;}.sector-inner span {display: block;transform-origin: center;transform: rotate(-19deg);color: #d46854;}.pointer {position: absolute;left: 79px;top: 79px;z-index: 10;height: 30px;width: 30px;padding: 6px;color: #fff899;line-height: 15px;font-size: 12px;text-align: center;background-color: #ff5350;border-radius: 50%;border: 1px solid #ff5350;transition: transform 3s cubic-bezier(.2,.93,.43,1);}.pointer::after {content: '';position: absolute;left: 14px;top: -24px;border-width: 12px 6px;border-style: solid;border-color: transparent;border-bottom-color: #ff5350;transform-origin: center;}.result {margin: 20px 60px;}@keyframes twinkling {50% { background: transparent; }}style>head><body><div class="wrapper"><div class="light">div><div class="light">div><div class="light">div><div class="light">div><div class="light">div><div class="light">div><div class="light">div><div class="light">div><div class="light">div><div class="light">div><div class="panel"><div class="sector"><div class="sector-inner"><span>谢谢参与span>div>div><div class="sector"><div class="sector-inner"><span> 5 0 积分span>div>div><div class="sector"><div class="sector-inner"><span>谢谢参与span>div>div><div class="sector"><div class="sector-inner"><span>100元话费span>div>div><div class="sector"><div class="sector-inner"><span> 5 0 积分span>div>div><div class="sector"><div class="sector-inner"><span>谢谢参与span>div>div><div class="sector"><div class="sector-inner"><span>100元话费span>div>div><div class="sector"><div class="sector-inner"><span>谢谢参与span>div>div><div class="sector"><div class="sector-inner"><span> 5 0 积分span>div>div><div class="sector"><div class="sector-inner"><span>10元话费span>div>div><div class="pointer">开始抽奖div>div>div><div class="result">div><script>let getEle = document.getElementsByClassName.bind(document);let pointer = getEle('pointer')[0];let result = getEle('result')[0];let lights = Array.prototype.slice.call(getEle('light'));let onRotation = false; // 记录当前是否正在旋转，如果正在旋转，就不能继续点击了let reward = ['谢谢参与', '50积分', '谢谢参与', '100元话费', '50积分','谢谢参与', '100元话费', '谢谢参与', '50积分', '10元话费'];// 根据随机角度获取奖励let getReward = (function() {currentDeg = 0;return function() {// 转三圈到四圈let rotateDeg = Math.random() * 360 + 1080;currentDeg += rotateDeg;let rewardText = reward[Math.floor((currentDeg + 18) % 360 / 36)]return {deg: currentDeg,text: rewardText === '谢谢参与' ? '很遗憾，您没有获得奖品。' : '恭喜获得: ' + rewardText}}})();pointer.addEventListener('click', () => {if (onRotation) return;console.log('开始抽奖');onRotation = true;lights.forEach(light => { light.className += ' light-twinkling'; });let nextStatus = getReward();console.log(nextStatus)result.innerText = nextStatus.text;result.style.display = 'none';pointer.style.transform = `rotateZ(${nextStatus.deg}deg)`;})pointer.addEventListener('transitionend', () => {console.log('抽奖结束');setTimeout(() => { // 等闪烁三下结束onRotation = false;lights.forEach(light => { light.className = 'light'; });result.style.display = 'block';}, 300);})script>body>html>
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