Vue2走马灯（Carousel）

移入时暂停，移出后自动轮播

可自定义设置以下属性：

• 轮播图片数组（imageData），默认[]
• 滑动轮播间隔（interval），默认3000ms
• 图片宽度（imageWidth），默认400px
• 图片高度（imageHeight），默认300px

共使用两种滑动效果实现方式：

• 延时调用setInterval（setTimeout类似）
• requestAnimationFrame()（效果更好）

效果如下图：

①创建图片轮播组件Carousel.vue：

• 滑动效果使用setInterval延时调用**（使用setTimeout超时调用类似）**

<template>
  <!-- 方法1：使用 will-change: transform; translateX(-${left}px); -->
  <!-- <div class="m-slider" :style="`width: ${imageWidth}px;`" @mouseenter="onStop" @mouseleave="onStart">
    <div :class="{ 'transition': transition }" :style="`width: ${width}px; will-change: transform; transform: translateX(${-left}px);`"> -->
  <!-- 方法2：使用position: relative;和position: absolute; left: ${-left}px; -->
  <div class="m-slider" :style="`position: relative; width: ${imageWidth}px; height: ${imageHeight + 36}px;`" @mouseenter="onStop" @mouseleave="onStart">
    <div :class="{ 'transition': transition }" :style="`width: ${width}px; position: absolute; left: ${-left}px;`">
      <div
        v-for="(item, index) in imageData"
        :key="index"
        :style="`width: ${imageWidth}px;`"
        class="m-image">
        <img v-lazy="getDefault(item.imgUrl)" :alt="item.title" :style="`width: ${imageWidth}px; height: ${imageHeight}px;`" class="u-img"/>
        <p class="u-img-title" :title="item.title">{
  { item.title }}</p>
      </div>
      <div class="m-image" :style="`width: ${imageWidth}px;`">
        <img v-lazy="getDefault(imageData[0].imgUrl)" :alt="imageData[0].title" :style="`width: ${imageWidth}px; height: ${imageHeight}px;`" class="u-img"/>
        <p class="u-img-title" :title="imageData[0].title">{
  { imageData[0].title }}</p>
      </div>
    </div>
  </div>
</template>
<script>
import Vue from 'vue'
import VueLazyLoad from 'vue-lazyload' // 图片懒加载插件使用版本v1.3.3
Vue.use(VueLazyLoad)
export default {
  name: 'Carousel',
  props: {
    imageData: { // 轮播图片数组
      type: Array,
      default: () => {
        return []
      }
    },
    interval: { // 滑动轮播间隔
      type: Number,
      default: 3000
    },
    imageWidth: { // 图片宽度
      type: Number,
      default: 400
    },
    imageHeight: { // 图片高度
      type: Number,
      default: 300
    }
  },
  data () {
    return {
      left: 0, // 滑动偏移值
      transition: false, // 暂停时未完成滑动的过渡标志
      slideTimer: null, // 自动切换定时器
      moveTimer: null // 向左滑动定时器
    }
  },
  computed: {
    width () { // 容器宽度：(图片数组长度+1) * 图片宽度
      return (this.imageData.length + 1) * this.imageWidth
    },
    len () {
      return this.imageData.length || 0
    }
  },
  mounted () {
    window.onfocus = () => { // 页面激活状态
      this.onStart()
    }
    window.onblur = () => { // 页面未激活状态
      this.onStop()
    }
    this.onStart()
  },
  methods: {
    getDefault (src) { // 获取懒加载默认图
      return {
        src: src,
        error: require('../assets/images/default.png'),
        loading: require('../assets/images/default.png')
      }
    },
    onStart () {
      if (this.len > 1) { // 超过一条时滑动
        this.transition = false
        this.onAutoSlide() // 自动滑动轮播
        console.log('imageSlider start')
      }
    },
    onStop () {
      clearTimeout(this.slideTimer)
      clearInterval(this.moveTimer)
      this.sliderTimer = null
      this.moveTimer = null
      this.transition = true
      this.left = Math.ceil(this.left / this.imageWidth) * this.imageWidth // ceil：向上取整，floor：向下取整
      console.log('imageSlider stop')
    },
    onAutoSlide () {
      this.slideTimer = setTimeout(() => {
        const target = this.left % (this.len * this.imageWidth) + this.imageWidth
        this.autoMoveLeft(target)
      }, this.interval)
    },
    // 滑动使用setInterval延时调用
    autoMoveLeft (target) { // 自动切换，向左滑动效果
      if (this.left === this.len * this.imageWidth) { // 最后一张时，重置left
        this.left = 0
      }
      this.moveTimer = setInterval(() => {
        if (this.left >= target) {
          clearInterval(this.moveTimer)
          this.moveTimer = null
          this.onAutoSlide() // 自动间隔切换下一张
        } else {
          var step = Math.ceil((target - this.left) / 10) // 越来越慢的滑动过程
          this.left += step
        }
      }, 25)
    },
    beforeDestroy () {
      clearTimeout(this.slideTimer)
      clearInterval(this.moveTimer)
      this.slideTimer = null
      this.moveTimer = null
    }
  }
}
</script>
<style lang="less" scoped>
@themeColor: #1890FF;
.m-slider {
  margin: 0 auto;
  overflow: hidden;
  .transition {
    transition: transform 0.3s ease-out;
  }
  .m-image {
    display: inline-block;
    .u-img {
      vertical-align: bottom; // 消除img标签底部的5px
      cursor: pointer;
    }
    .u-img-title {
      font-size: 18px;
      color: #333;
      line-height: 36px;
      text-align: left;
      cursor: pointer;
      overflow: hidden;
      text-overflow: ellipsis;
      white-space: nowrap;
      &:hover {
        color: @themeColor;
      }
    }
  }
}
</style>

• 滑动效果使用requestAnimationFrame**()**

• <template>
    <div class="m-slider" :style="`width: ${imageWidth}px;`" @mouseenter="onStop" @mouseleave="onStart">
      <div :class="{ 'transition': transition }" :style="`width: ${width}px; will-change: transform; transform: translateX(${-left}px);`">
        <div
          v-for="(item, index) in imageData"
          :key="index"
          :style="`width: ${imageWidth}px;`"
          class="m-image">
          <img v-lazy="getDefault(item.imgUrl)" :alt="item.title" :style="`width: ${imageWidth}px; height: ${imageHeight}px;`" class="u-img"/>
          <p class="u-img-title" :title="item.title">{
      { item.title }}</p>
        </div>
        <div class="m-image" :style="`width: ${imageWidth}px;`">
          <img v-lazy="getDefault(imageData[0].imgUrl)" :alt="imageData[0].title" :style="`width: ${imageWidth}px; height: ${imageHeight}px;`" class="u-img"/>
          <p class="u-img-title" :title="imageData[0].title">{
      { imageData[0].title }}</p>
        </div>
      </div>
    </div>
  </template>
  <script>
  import Vue from 'vue'
  import VueLazyLoad from 'vue-lazyload'
  Vue.use(VueLazyLoad) // 图片懒加载插件
  export default {
    name: 'Carousel',
    props: {
      imageData: { // 轮播图片数组
        type: Array,
        default: () => {
          return []
        }
      },
      interval: { // 滑动轮播间隔
        type: Number,
        default: 3000
      },
      imageWidth: { // 图片宽度
        type: Number,
        default: 400
      },
      imageHeight: { // 图片高度
        type: Number,
        default: 300
      }
    },
    data () {
      return {
        left: 0, // 滑动偏移值
        transition: false, // 暂停时未完成滑动的过渡标志
        slideTimer: null, // 自动切换定时器
        moveRaf: null, // 动画回调标识
        target: null, // 要移动到的目标位置
        start: 0,
        end: 0,
        fpsRaf: null, // fps回调标识
        step: 15 // 默认移动参数，对应60fps
      }
    },
    computed: {
      width () { // 容器宽度：(图片数组长度+1) * 图片宽度
        return (this.imageData.length + 1) * this.imageWidth
      },
      len () {
        return this.imageData.length || 0
      }
    },
    mounted () {
      window.onfocus = () => { // 页面激活状态
        this.onStart()
      }
      window.onblur = () => { // 页面未激活状态
        this.onStop()
      }
      this.fpsRaf = requestAnimationFrame(this.getFPS) // 获取浏览器的刷新率
    },
    methods: {
      getDefault (src) { // 获取懒加载默认图
        return {
          src: src,
          error: require('../assets/images/default.png'),
          loading: require('../assets/images/default.png')
        }
      },
      getFPS (timestamp) {
        // 单位ms，用1000ms/两个时间的间隔≈刷新频率fps
        // console.log('timestamp:', timestamp)
        if (this.fpsRaf === 2) {
          this.start = timestamp
        }
        if (this.fpsRaf === 3) {
          this.end = timestamp
          const fps = Math.floor(1000 / (this.end - this.start))
          if (fps === 120) {
            this.step = 30
          }
        }
        this.fpsRaf = requestAnimationFrame(this.getFPS)
        if (this.fpsRaf > 3) {
          cancelAnimationFrame(this.fpsRaf)
          this.onStart()
        }
      },
      onStart () {
        if (this.len > 1) { // 超过一条时滑动
          this.transition = false
          this.onAutoSlide() // 自动滑动轮播
          console.log('imageSlider start')
        }
      },
      onStop () {
        clearTimeout(this.slideTimer)
        this.slideTimer = null
        cancelAnimationFrame(this.moveRaf)
        this.transition = true
        this.left = Math.ceil(this.left / this.imageWidth) * this.imageWidth // ceil：向上取整，floor：向下取整
        console.log('imageSlider stop')
      },
      onAutoSlide () {
        this.slideTimer = setTimeout(() => {
          const target = this.left % (this.len * this.imageWidth) + this.imageWidth
          this.autoMoveLeft(target)
        }, this.interval)
      },
      // 滑动效果使用requestAnimationFrame
      autoMoveLeft (target) { // 自动切换，向左滑动效果
        if (this.left === this.len * this.imageWidth) { // 最后一张时，重置left
          this.left = 0
        }
        this.target = target
        this.moveRaf = requestAnimationFrame(this.autoLeftSlideEffect)
      },
      autoLeftSlideEffect () { // 自动向左滑动效果
        if (this.left >= this.target) {
          cancelAnimationFrame(this.moveRaf)
          this.onAutoSlide() // 自动间隔切换下一张
        } else {
          const move = Math.ceil((this.target - this.left) / this.step)
          this.left += move
          this.moveRaf = requestAnimationFrame(this.autoLeftSlideEffect)
        }
      },
      beforeDestroy () {
        clearTimeout(this.slideTimer)
        this.slideTimer = null
      }
    }
  }
  </script>
  <style lang="less" scoped>
  @themeColor: #1890FF;
  .m-slider {
    margin: 100px auto;
    overflow: hidden;
    .transition {
      transition: transform 0.3s ease-out;
    }
    .m-image {
      display: inline-block;
      .u-img {
        vertical-align: bottom; // 消除img标签底部的5px
        cursor: pointer;
      }
      .u-img-title {
        font-size: 18px;
        color: #333;
        line-height: 36px;
        text-align: left;
        cursor: pointer;
        overflow: hidden;
        text-overflow: ellipsis;
        white-space: nowrap;
        &:hover {
          color: @themeColor;
        }
      }
    }
  }
  </style>
  

  ②在要使用滑动轮播图片的页面引入使用：

• <Carousel :imageData="imageData" :imageWidth="460" :imageHeight="320" :interval="3000" />
  import Carousel from '@/components/Carousel'
  components: {
      Carousel
  }
  data () {
      return {
        imageData: [
          {
            title: 'image-1,image-1,image-1,image-1,image-1,image-1,image-1,image-1,image-1',
            imgUrl: 'image src...'
          },
          {
            title: 'image-2,image-2,image-2,image-2,image-2,image-2,image-2,image-2,image-2',
            imgUrl: 'image src...'
          },
          {
            title: 'image-3,image-3,image-3,image-3,image-3,image-3,image-3,image-3,image-3',
            imgUrl: 'image src...'
          }
        ]
     }
  }