Vue+CSS3實現轉盤抽獎

最近有個轉盤抽獎的需求，搜了一下現有的輪子，有的是用jQuery的動畫函數實現的，有的是用canvas繪圖而後再用高頻率的setTimeout調用旋轉方法，前者太老了無法簡單移植到vue項目，後者感受性能表現可能不會太好。也有一些用CSS動畫的方案，設計了加速-勻速-減速三個動畫，再計算偏轉角度讓三個動畫儘量無縫銜接，但我感受繞了大遠路，應該有更簡單輕量的實現方案。我的更傾向於用transition來實現，不過網上的例子感受還不夠好，有的傾斜文字都沒有對齊，最後仍是本身手寫了一個。
無需jQuery，不用js腳本實現動畫細節，動畫效果徹底連續無需銜接，支持動態設置2個以上任意數量的獎項。
核心思路是用transition以及rotate實現旋轉動畫，使用transition-origin和rotate繪製出定位較爲精確的輪盤獎項。

代碼及實例展現

<script src="//unpkg.com/vue/dist/vue.js"></script>
<span id="app">
  <span>Prize number: {{ prizeNumber }}</span>
  <button type="button" @click="!rolling && prizeNumber < 8 && (prizeNumber++)" :disabled="rolling || prizeNumber === 8">Add</button>
  <button type="button" @click="!rolling && prizeNumber > 2 && (prizeNumber--)" :disabled="rolling || prizeNumber === 2">Remove</button>
   <div class="wheel-wrapper">
    <div
      class="wheel-pointer"
      @click="onClickRotate"
    >
      Start
    </div>
    <div
      class="wheel-bg"
      :class="{freeze: freeze}"
      :style="`transform: rotate(${wheelDeg}deg)`"
    >
      <div class="prize-list">
        <div
          class="prize-item-wrapper"
          v-for="(item,index) in prizeList"
          :key="index"
        >
          <div
            class="prize-item"
            :style="`transform: rotate(${(360/ prizeList.length) * index}deg)`"
          >
            <div class="prize-name">
              {{ item.name }}
            </div>
            <div class="prize-icon">
              <img :src="item.icon">
            </div>
          </div>
        </div>
      </div>
    </div>
  </div>
</div>

html {
   background: #DD7C7D;
}

.wheel-wrapper {
    width: 300px;
    height: 300px;
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
  }

  .wheel-pointer {
    width: 60px;
    height: 60px;
    border-radius: 1000px;
    background: yellow;
    position: absolute;
    left: 50%;
    top: 50%;
    transform: translate(-50%, -50%);
    text-align: center;
    line-height: 60px;
    z-index: 10;
  }
  .wheel-bg {
    width: 100%;
    height: 100%;
    border-radius: 1000px;
    overflow: hidden;
    transition: transform 4s ease-in-out;
    background: #7EEF97;
    
    &.freeze {
      transition: none;
      background: red;
    }
  }

  .prize-list {
    width: 100%;
    height: 100%;
    position: relative;
    text-align: center;
  }

  .prize-item-wrapper {
    position: absolute;
    top: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 150px;
    height: 150px;
  }

  .prize-item {
    width: 100%;
    height: 100%;
    transform-origin: bottom;

    .prize-name {
      padding: 16px 0;
    }

    .prize-icon {}
  }

var Main = {
  data() {
    return {
      freeze: false,
      rolling: false,
      wheelDeg: 0,
      prizeNumber: 8,
      prizeListOrigin: [
        {
          icon: "https://picsum.photos/40?random=1",
          name: "$10000"
        },
        {
          icon: "https://picsum.photos/40?random=6",
          name: "Thank you!"
        },
                {
          icon: "https://picsum.photos/40?random=2",
          name: "$500"
        },
        {
          icon: "https://picsum.photos/40?random=3",
          name: "$100"
        },
                {
          icon: "https://picsum.photos/40?random=6",
          name: "Thank you!"
        },
        {
          icon: "https://picsum.photos/40?random=4",
          name: "$50"
        },
        {
          icon: "https://picsum.photos/40?random=5",
          name: "$10"
        },
        {
          icon: "https://picsum.photos/40?random=6",
          name: "Thank you!"
        }
      ]
    };
  },
  computed: {
    prizeList () {
      return this.prizeListOrigin.slice(0, this.prizeNumber)
    }
  },
  methods: {
    onClickRotate() {
      if (this.rolling) {
        return;
      }
      this.rolling = true;
      const { wheelDeg, prizeList } = this;
      const random = Math.floor(Math.random() * (prizeList.length ));
      console.log(random);
      this.wheelDeg =
        wheelDeg -
        wheelDeg % 360 +
        6 * 360 +
        (360 - 360 / prizeList.length * random);
      setTimeout(() => {
        this.rolling = false;
        alert("Result：" + prizeList[random].name);
      }, 4500);
    }
  },
  watch: {
    prizeNumber () {
      this.freeze = true
      this.wheelDeg = 0
     
      setTimeout(() => {
         this.freeze = false
      }, 0)
    }
  }
};
var App = Vue.extend(Main);
new App().$mount("#app");