纯CSS3大转盘抽奖（响应式、可配置）

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源于前段时候微信小程序最初火爆公测时段，把以前用 Canvas 实现的大转盘抽奖移植成微信小程序，无奈当时小程序对 Canvas 支持不够完善，只好降低用 CSS3 实现。虽然比不上 Canvas 绘图的绚丽，但也总算完成了一个抽奖的 Demo，详见：https://github.com/givebest/wechat-turntalbe-canvas。

事后想起，CSS3 实现也并不是无有益处，比如简单、快捷、调试方便、渲染想来也是要比 Canvas 要高效的，更重要的一点是支持媒体查询，大转盘也可以做成响应式的。因此抽空整理，用纯 CSS3 实现一个大转盘抽奖 Demo 并记录下来。

如果有类似需求并不想麻烦了解细节，可移步这里——Canvas 完整的大转盘抽奖项目（可以直接拿来用）https://github.com/givebest/GB-canvas-turntable。

以下就直接贴代码了,后面有演示地址。

代码

HTML

<section class="gb-wheel-container" id="gbWheel">
    <div class="gb-wheel-content gb-wheel-run">
        <ul class="gb-wheel-line"></ul>
        <div class="gb-wheel-list"></div>
    </div>
    <a href="javascript:;" class="gb-wheel-btn" id="gbLottery">抽奖</a>     
</section>

JS

(function() {
    // 奖品配置
    var awards = [
            {'index': 0, 'text': '耳机' , 'name': 'icono-headphone'},
            {'index': 1, 'text': 'iPhone' , 'name': 'icono-iphone'},
            {'index': 2, 'text': '相机' , 'name': 'icono-camera'},
            {'index': 3, 'text': '咖啡杯' , 'name': 'icono-cup'},
            {'index': 4, 'text': '日历', 'name': 'icono-calendar'},
            {'index': 5, 'text': '键盘', 'name': 'icono-keyboard'}
        ],
        len = awards.length,
        turnNum = 1 / len;  // 文字旋转 turn 值

    var gbWheel = $('gbWheel'),
        lineList = gbWheel.querySelector('ul.gb-wheel-line'),
        itemList = gbWheel.querySelector('.gb-wheel-list'),
        lineListHtml = [],
        itemListHtml = [];

    var transform = preTransform();

    awards.forEach(function(v, i, a) {
        // 分隔线
        lineListHtml.push('<li class="gb-wheel-litem" style="' + transform + ': rotate('+ (i * turnNum + turnNum / 2) +'turn)"></li>');

        // 奖项
        itemListHtml.push('<div class="gb-wheel-item">');
        itemListHtml.push('<div class="gb-wheel-icontent" style="' + transform + ': rotate('+ (i * turnNum) +'turn)">');
        itemListHtml.push('<p class="gb-wheel-iicon">');
        itemListHtml.push('<i class="'+v.name+'"></i>');
        itemListHtml.push('</p>');
        itemListHtml.push('<p class="gb-wheel-itext">');
        itemListHtml.push(v.text);
        itemListHtml.push('</p>');
        itemListHtml.push('</div>');
        itemListHtml.push('</div>');
    });           

    lineList.innerHTML = lineListHtml.join('');
    itemList.innerHTML = itemListHtml.join('');

    function $(id) {
        return document.getElementById(id);
    };

    // 旋转
    var i = 0;
    $('gbLottery').onclick = function() {
        i++;
        gbWheel.querySelector('.gb-wheel-content').style = transform + ': rotate('+ i * 3600 +'deg)';  
    }

    // transform兼容
    function preTransform() {
        var cssPrefix,
        vendors = {
          '': '',
          Webkit: 'webkit',
          Moz: '',
          O: 'o',
          ms: 'ms'
        },
        testEle = document.createElement('p'),
        cssSupport = {};

         // 嗅探特性
        Object.keys(vendors).some(function(vendor) {
            if (testEle.style[vendor + (vendor ? 'T' : 't') + 'ransform'] !== undefined) {
              cssPrefix = vendor ? '-' + vendor.toLowerCase() + '-' : '';
              return true;
            }
        });

      function normalizeCss(name) {
        name = name.toLowerCase();
        return cssPrefix ? cssPrefix + name : name;
      }

      cssSupport = {
        transform: normalizeCss('Transform'),
      }

      return cssSupport.transform;
    }
}());

CSS

html {
    font-size: 10px
}

.gb-wheel-container ul,
.gb-wheel-container li,
.gb-wheel-container p {
    margin: 0;
    padding: 0
}

.gb-wheel-container ul,
.gb-wheel-container li {
    list-style: none
}

.gb-wheel-container {
    margin: 0 auto;
    position: relative;
     30rem;
    height: 30rem;
    border-radius: 50%;
    box-shadow: 0 2px 3px #333, 0 0 2px #000;
    overflow: hidden
}

.gb-wheel-content {
    position: absolute;
    left: 1rem;
    top: 1rem;
    z-index: 2;
     28rem;
    height: 28rem;
    box-sizing: border-box;
    border-radius: inherit;
    background-clip: padding-box;
    background: -webkit-radial-gradient(rgba(100, 100, 100, 0.1) 15%, transparent 16%) 0 0, -webkit-radial-gradient(rgba(100, 100, 100, 0.1) 15%, transparent 16%) 8px 8px, -webkit-radial-gradient(rgba(255, 255, 255, 0.1) 15%, transparent 20%) 0 1px, -webkit-radial-gradient(rgba(255, 255, 255, 0.1) 15%, transparent 20%) 8px 9px;
    background: radial-gradient(rgba(100, 100, 100, 0.1) 15%, transparent 16%) 0 0, radial-gradient(rgba(100, 100, 100, 0.1) 15%, transparent 16%) 8px 8px, radial-gradient(rgba(255, 255, 255, 0.1) 15%, transparent 20%) 0 1px, radial-gradient(rgba(255, 255, 255, 0.1) 15%, transparent 20%) 8px 9px;
    background-color: #ffcb3f;
    background-size: 12px 14px
}

.gb-wheel-content:before {
    content: ' ';
    position: absolute;
    left: -1rem;
    top: -1rem;
    z-index: -1;
     28rem;
    height: 28rem;
    border-radius: inherit;
    border: 1rem solid #E44025;
    box-shadow: 0 0 2px 2px rgba(0, 0, 0, 0.2) inset
}

.gb-wheel-list {
    position: absolute;
    left: 0;
    top: 0;
     inherit;
    height: inherit;
    z-index: 9999
}

.gb-wheel-item {
    position: absolute;
    left: 0;
    top: 0;
     100%;
    height: 100%;
    color: #e4370e;
    font-weight: bold;
    text-shadow: 0 1px 1px rgba(255, 255, 255, 0.6)
}

.gb-wheel-icontent {
    position: relative;
    display: block;
    padding-top: 1.5rem;
    margin: 0 auto;
    text-align: center;
    -webkit-transform-origin: 50% 14rem;
    -ms-transform-origin: 50% 14rem;
    transform-origin: 50% 14rem
}

.gb-wheel-itext {
    font-size: 1.4rem;
    font-weight: lighter
}

.gb-wheel-iicon [class*=icono-] {
    color: #e4370e
}

.gb-wheel-line {
    position: absolute;
    left: 0;
    top: 0;
     inherit;
    height: inherit;
    z-index: 99
}

.gb-wheel-litem {
    position: absolute;
    left: 14rem;
    top: 0;
     1px;
    height: 14rem;
    background-color: rgba(228, 55, 14, 0.6);
    overflow: hidden;
    -webkit-transform-origin: 50% 14rem;
    -ms-transform-origin: 50% 14rem;
    transform-origin: 50% 14rem
}

.gb-wheel-btn {
    position: absolute;
    left: 11rem;
    top: 11rem;
    z-index: 400;
     8rem;
    height: 8rem;
    border-radius: 50%;
    color: #F4E9CC;
    background-color: #E44025;
    line-height: 8rem;
    text-align: center;
    font-size: 2rem;
    text-shadow: 0 -1px 1px rgba(0, 0, 0, 0.6);
    box-shadow: 0 3px 5px rgba(0, 0, 0, 0.6), 0 0 5px 4px rgba(0, 0, 0, 0.2) inset;
    text-decoration: none
}

a.gb-wheel-btn {
    border-bottom: none
}

.gb-wheel-btn::after {
    position: absolute;
    content: '';
    left: 2.5rem;
    top: -1rem;
     3rem;
    height: 3rem;
    background-color: #E44025;
    -webkit-transform: rotate(45deg);
    -ms-transform: rotate(45deg);
    transform: rotate(45deg);
    box-shadow: 0 3px 5px rgba(0, 0, 0, 0.6), 0 0 5px 4px rgba(0, 0, 0, 0.2) inset
}

.gb-wheel-btn.disabled,
.gb-wheel-btn.disabled::after {
    pointer-events: none;
    background: #B07A7B;
    color: #ccc
}

.gb-wheel-run {
    -webkit-transition: transform 6s ease;
    transition: transform 6s ease
}

@media only screen and (min- 320px) {
    html {
        font-size: 10px
    }
}

@media only screen and (min- 375px) {
    html {
        font-size: 11.71875px
    }
}

@media only screen and (min- 480px) {
    html {
        font-size: 15px
    }
}

演示

http://blog.givebest.cn/GB-css3-wheel.html

项目

https://github.com/givebest/GB-css3-wheel

感谢

奖品Icon来自：https://github.com/saeedalipoor/icono
CSS3转盘背景来自：http://lea.verou.me/css3patterns/

顺便推荐 Lea Verou(W3C CSS小组特邀专家) 的书《CSS Secrets: Better Solutions to Everyday Web Design Problems》，让你震撼，原来 CSS 还可以这样用、可以实现这么多绚丽的特效。 已有中文版《CSS揭秘》，CSS魔法译。