前言

嗨，说起探探想必各位程序汪都不陌生(毕竟妹子很多)，能在上面丝滑的翻牌子，探探的的堆叠滑动组件起到了关键的作用，下面就来看看如何用vue写一个探探的堆叠组件 😄

一. 功能分析

简单使用下探探会发现，堆叠滑动的功能很简单，用一张图概括就是:

简单归纳下里面包含的基本功能点:

图片的堆叠
图片第一张的滑动
条件成功后的滑出，条件失败后的回弹
滑出后下一张图片堆叠到顶部

体验优化

根据触摸点的不同，滑动时首图有不同角度偏移
偏移面积判定是否成功滑出

二. 具体实现

有了归纳好的功能点，我们实现组件的思路会更清晰

1. 堆叠效果

堆叠图片效果在网上有大量的实例，实现的方法大同小异，主要通过在父层设定perspective及perspective-origin，来实现子层的透视，子层设定好translate3d Z轴数值即可模拟出堆叠效果，具体代码如下

// 图片堆叠dom
 <!--opacity: 0 隐藏我们不想看到的stack-item层级-->
 <!--z-index: -1 调整stack-item层级"-->
<ul class="stack">
 <li class="stack-item" style="transform: translate3d(0px, 0px, 0px);opacity: 1;z-index: 10;"><img src="1.png" alt="01"></li>
 <li class="stack-item" style="transform: translate3d(0px, 0px, -60px);opacity: 1;z-index: 1"><img src="2.png" alt="02"></li>
 <li class="stack-item" style="transform: translate3d(0px, 0px, -120px);opacity: 1;z-index: 1"><img src="3.png" alt="03"></li>
 <li class="stack-item" style="transform: translate3d(0px, 0px, -180px);opacity: 0;z-index: -1"><img src="4.png" alt="04"></li>
 <li class="stack-item" style="transform: translate3d(0px, 0px, -180px);opacity: 0;z-index: -1"><img src="5.png" alt="05"></li>
</ul>
<style>
.stack {
    width: 100%;
    height: 100%;
    position: relative;
    perspective: 1000px; //子元素视距
    perspective-origin: 50% 150%; //子元素透视位置
    -webkit-perspective: 1000px;
    -webkit-perspective-origin: 50% 150%;
    margin: 0;
    padding: 0;
  }
  .stack-item{
    background: #fff;
    height: 100%;
    width: 100%;
    border-radius: 4px;
    text-align: center;
    overflow: hidden;
  }
  .stack-item img {
    width: 100%;
    display: block;
    pointer-events: none;
  }
</style>

上面只是一组静态代码，我们希望得到的是vue组件，所以需要先建立一个组件模板stack.vue，在模板中我们可以使用v-for，遍历出stack节点，使用:style 来修改各个item的style，代码如下

<template>
    <ul class="stack">
      <li class="stack-item" v-for="(item, index) in pages" :style="[transform(index)]">
        <img :src="item.src">
      </li>
    </ul>
</template>
<script>
export default {
  props: {
    // pages数据包含基础的图片数据
    pages: {
      type: Array,
      default: []
    }
  },
  data () {
    return {
      // basicdata数据包含组件基本数据
      basicdata: {
        currentPage: 0 // 默认首图的序列
      },
      // temporaryData数据包含组件临时数据
      temporaryData: {
        opacity: 1, // 记录opacity
        zIndex: 10, // 记录zIndex
        visible: 3 // 记录默认显示堆叠数visible
      }
    }
  },
  methods: {
    // 遍历样式
    transform (index) {
      if (index >= this.basicdata.currentPage) {
        let style = {}
        let visible = this.temporaryData.visible
        let perIndex = index - this.basicdata.currentPage
        // visible可见数量前滑块的样式
        if (index <= this.basicdata.currentPage + visible - 1) {
          style['opacity'] = '1'
          style['transform'] = 'translate3D(0,0,' + -1 * perIndex * 60 + 'px' + ')'
          style['zIndex'] = visible - index + this.basicdata.currentPage
          style['transitionTimingFunction'] = 'ease'
          style['transitionDuration'] = 300 + 'ms'
        } else {
          style['zIndex'] = '-1'
          style['transform'] = 'translate3D(0,0,' + -1 * visible * 60 + 'px' + ')'
        }
        return style
      }
    }
  }
}
</script>

关键点

:style可以绑定对象的同时，也可以绑定数组和函数，这在遍历的时候很有用

最基本的dom结构已经构建完毕，下一步是让首张图片“动”起来

2. 图片滑动

图片滑动效果，在很多场景中都有出现，其原理无非是监听touchs事件，得到位移，再通过translate3D改变目标位移，因此我们要实现的步骤如下

对stack进行touchs事件的绑定
监听并储存手势位置变化的数值
改变首图css属性中translate3D的x，y值

具体实现

在vue框架中，不建议直接操作节点，而是通过指令v-on对元素进行绑定，因此我们将绑定都写在v-for遍历里，通过index进行判断其是否是首图，再使用:style修改首页的样式，具体代码如下:

<template>
    <ul class="stack">
      <li class="stack-item" v-for="(item, index) in pages"
      :style="[transformIndex(index),transform(index)]"
      @touchstart.stop.capture="touchstart"
      @touchmove.stop.capture="touchmove"
      @touchend.stop.capture="touchend"
      @mousedown.stop.capture="touchstart"
      @mouseup.stop.capture="touchend"
      @mousemove.stop.capture="touchmove">
        <img :src="item.src">
      </li>
    </ul>
</template>
<script>
export default {
  props: {
    // pages数据包含基础的图片数据
    pages: {
      type: Array,
      default: []
    }
  },
  data () {
    return {
      // basicdata数据包含组件基本数据
      basicdata: {
        start: {}, // 记录起始位置
        end: {}, // 记录终点位置
        currentPage: 0 // 默认首图的序列
      },
      // temporaryData数据包含组件临时数据
      temporaryData: {
        poswidth: '', // 记录位移
        posheight: '', // 记录位移
        tracking: false // 是否在滑动，防止多次操作，影响体验
      }
    }
  },
  methods: {
    touchstart (e) {
      if (this.temporaryData.tracking) {
        return
      }
      // 是否为touch
      if (e.type === 'touchstart') {
        if (e.touches.length > 1) {
          this.temporaryData.tracking = false
          return
        } else {
          // 记录起始位置
          this.basicdata.start.t = new Date().getTime()
          this.basicdata.start.x = e.targetTouches[0].clientX
          this.basicdata.start.y = e.targetTouches[0].clientY
          this.basicdata.end.x = e.targetTouches[0].clientX
          this.basicdata.end.y = e.targetTouches[0].clientY
        }
      // pc操作
      } else {
        this.basicdata.start.t = new Date().getTime()
        this.basicdata.start.x = e.clientX
        this.basicdata.start.y = e.clientY
        this.basicdata.end.x = e.clientX
        this.basicdata.end.y = e.clientY
      }
      this.temporaryData.tracking = true
    },
    touchmove (e) {
      // 记录滑动位置
      if (this.temporaryData.tracking && !this.temporaryData.animation) {
        if (e.type === 'touchmove') {
          this.basicdata.end.x = e.targetTouches[0].clientX
          this.basicdata.end.y = e.targetTouches[0].clientY
        } else {
          this.basicdata.end.x = e.clientX
          this.basicdata.end.y = e.clientY
        }
        // 计算滑动值
        this.temporaryData.poswidth = this.basicdata.end.x - this.basicdata.start.x
        this.temporaryData.posheight = this.basicdata.end.y - this.basicdata.start.y
      }
    },
    touchend (e) {
      this.temporaryData.tracking = false
      // 滑动结束，触发判断
    },
    // 非首页样式切换
    transform (index) {
      if (index > this.basicdata.currentPage) {
        let style = {}
        let visible = 3
        let perIndex = index - this.basicdata.currentPage
        // visible可见数量前滑块的样式
        if (index <= this.basicdata.currentPage + visible - 1) {
          style['opacity'] = '1'
          style['transform'] = 'translate3D(0,0,' + -1 * perIndex * 60 + 'px' + ')'
          style['zIndex'] = visible - index + this.basicdata.currentPage
          style['transitionTimingFunction'] = 'ease'
          style['transitionDuration'] = 300 + 'ms'
        } else {
          style['zIndex'] = '-1'
          style['transform'] = 'translate3D(0,0,' + -1 * visible * 60 + 'px' + ')'
        }
        return style
      }
    },
    // 首页样式切换
    transformIndex (index) {
      // 处理3D效果
      if (index === this.basicdata.currentPage) {
        let style = {}
        style['transform'] = 'translate3D(' + this.temporaryData.poswidth + 'px' + ',' + this.temporaryData.posheight + 'px' + ',0px)'
        style['opacity'] = 1
        style['zIndex'] = 10
        return style
      }
    }
  }
}
</script>

3. 条件成功后的滑出，条件失败后的回弹

条件的触发判断是在touchend/mouseup后进行，在这里我们先用简单的条件进行判定，同时给予首图弹出及回弹的效果，代码如下

<template>
    <ul class="stack">
      <li class="stack-item" v-for="(item, index) in pages"
      :style="[transformIndex(index),transform(index)]"
      @touchmove.stop.capture="touchmove"
      @touchstart.stop.capture="touchstart"
      @touchend.stop.capture="touchend"
      @mousedown.stop.capture="touchstart"
      @mouseup.stop.capture="touchend"
      @mousemove.stop.capture="touchmove">
        <img :src="item.src">
      </li>
    </ul>
</template>
<script>
export default {
  props: {
     // pages数据包含基础的图片数据
    pages: {
      type: Array,
      default: []
    }
  },
  data () {
    return {
      // basicdata数据包含组件基本数据
      basicdata: {
        start: {}, // 记录起始位置
        end: {}, // 记录终点位置
        currentPage: 0 // 默认首图的序列
      },
      // temporaryData数据包含组件临时数据
      temporaryData: {
        poswidth: '', // 记录位移
        posheight: '', // 记录位移
        tracking: false, // 是否在滑动，防止多次操作，影响体验
        animation: false, // 首图是否启用动画效果，默认为否
        opacity: 1 // 记录首图透明度
      }
    }
  },
  methods: {
    touchstart (e) {
      if (this.temporaryData.tracking) {
        return
      }
      // 是否为touch
      if (e.type === 'touchstart') {
        if (e.touches.length > 1) {
          this.temporaryData.tracking = false
          return
        } else {
          // 记录起始位置
          this.basicdata.start.t = new Date().getTime()
          this.basicdata.start.x = e.targetTouches[0].clientX
          this.basicdata.start.y = e.targetTouches[0].clientY
          this.basicdata.end.x = e.targetTouches[0].clientX
          this.basicdata.end.y = e.targetTouches[0].clientY
        }
      // pc操作
      } else {
        this.basicdata.start.t = new Date().getTime()
        this.basicdata.start.x = e.clientX
        this.basicdata.start.y = e.clientY
        this.basicdata.end.x = e.clientX
        this.basicdata.end.y = e.clientY
      }
      this.temporaryData.tracking = true
      this.temporaryData.animation = false
    },
    touchmove (e) {
      // 记录滑动位置
      if (this.temporaryData.tracking && !this.temporaryData.animation) {
        if (e.type === 'touchmove') {
          this.basicdata.end.x = e.targetTouches[0].clientX
          this.basicdata.end.y = e.targetTouches[0].clientY
        } else {
          this.basicdata.end.x = e.clientX
          this.basicdata.end.y = e.clientY
        }
        // 计算滑动值
        this.temporaryData.poswidth = this.basicdata.end.x - this.basicdata.start.x
        this.temporaryData.posheight = this.basicdata.end.y - this.basicdata.start.y
      }
    },
    touchend (e) {
      this.temporaryData.tracking = false
      this.temporaryData.animation = true
      // 滑动结束，触发判断
      // 简单判断滑动宽度超出100像素时触发滑出
      if (Math.abs(this.temporaryData.poswidth) >= 100) {
        // 最终位移简单设定为x轴200像素的偏移
        let ratio = Math.abs(this.temporaryData.posheight / this.temporaryData.poswidth)
        this.temporaryData.poswidth = this.temporaryData.poswidth >= 0 ? this.temporaryData.poswidth + 200 : this.temporaryData.poswidth - 200
        this.temporaryData.posheight = this.temporaryData.posheight >= 0 ? Math.abs(this.temporaryData.poswidth * ratio) : -Math.abs(this.temporaryData.poswidth * ratio)
        this.temporaryData.opacity = 0
      // 不满足条件则滑入
      } else {
        this.temporaryData.poswidth = 0
        this.temporaryData.posheight = 0
      }
    },
    // 非首页样式切换
    transform (index) {
      if (index > this.basicdata.currentPage) {
        let style = {}
        let visible = 3
        let perIndex = index - this.basicdata.currentPage
        // visible可见数量前滑块的样式
        if (index <= this.basicdata.currentPage + visible - 1) {
          style['opacity'] = '1'
          style['transform'] = 'translate3D(0,0,' + -1 * perIndex * 60 + 'px' + ')'
          style['zIndex'] = visible - index + this.basicdata.currentPage
          style['transitionTimingFunction'] = 'ease'
          style['transitionDuration'] = 300 + 'ms'
        } else {
          style['zIndex'] = '-1'
          style['transform'] = 'translate3D(0,0,' + -1 * visible * 60 + 'px' + ')'
        }
        return style
      }
    },
    // 首页样式切换
    transformIndex (index) {
      // 处理3D效果
      if (index === this.basicdata.currentPage) {
        let style = {}
        style['transform'] = 'translate3D(' + this.temporaryData.poswidth + 'px' + ',' + this.temporaryData.posheight + 'px' + ',0px)'
        style['opacity'] = this.temporaryData.opacity
        style['zIndex'] = 10
        if (this.temporaryData.animation) {
          style['transitionTimingFunction'] = 'ease'
          style['transitionDuration'] = 300 + 'ms'
        }
        return style
      }
    }
  }
}
</script>

4. 滑出后下一张图片堆叠到顶部

重新堆叠是组件最后一个功能，同时也是最重要和复杂的功能。在我们的代码里，stack-item的排序依赖绑定:style的transformIndex和transform函数，函数里判定的条件是currentPage，那是不是改变currentPage，让其+1，即可完成重新堆叠呢？

答案没有那么简单，因为我们滑出是动画效果，会进行300ms的时间，而currentPage变化引起的重排，会立即变化，打断动画的进行。因此我们需要先修改transform函数的排序条件，后改变currentPage。

具体实现

修改transform函数排序条件
让currentPage+1
添加onTransitionEnd事件，在滑出结束后，重新放置stack列表中

代码如下：

<template>
    <ul class="stack">
      <li class="stack-item" v-for="(item, index) in pages"
      :style="[transformIndex(index),transform(index)]"
      @touchmove.stop.capture="touchmove"
      @touchstart.stop.capture="touchstart"
      @touchend.stop.capture="touchend"
      @mousedown.stop.capture="touchstart"
      @mouseup.stop.capture="touchend"
      @mousemove.stop.capture="touchmove"
      @webkit-transition-end="onTransitionEnd"
      @transitionend="onTransitionEnd"
      >
        <img :src="item.src">
      </li>
    </ul>
</template>
<script>
export default {
  props: {
    // pages数据包含基础的图片数据
    pages: {
      type: Array,
      default: []
    }
  },
  data () {
    return {
      // basicdata数据包含组件基本数据
      basicdata: {
        start: {}, // 记录起始位置
        end: {}, // 记录终点位置
        currentPage: 0 // 默认首图的序列
      },
      // temporaryData数据包含组件临时数据
      temporaryData: {
        poswidth: '', // 记录位移
        posheight: '', // 记录位移
        lastPosWidth: '', // 记录上次最终位移
        lastPosHeight: '', // 记录上次最终位移
        tracking: false, // 是否在滑动，防止多次操作，影响体验
        animation: false, // 首图是否启用动画效果，默认为否
        opacity: 1, // 记录首图透明度
        swipe: false // onTransition判定条件
      }
    }
  },
  methods: {
    touchstart (e) {
      if (this.temporaryData.tracking) {
        return
      }
      // 是否为touch
      if (e.type === 'touchstart') {
        if (e.touches.length > 1) {
          this.temporaryData.tracking = false
          return
        } else {
          // 记录起始位置
          this.basicdata.start.t = new Date().getTime()
          this.basicdata.start.x = e.targetTouches[0].clientX
          this.basicdata.start.y = e.targetTouches[0].clientY
          this.basicdata.end.x = e.targetTouches[0].clientX
          this.basicdata.end.y = e.targetTouches[0].clientY
        }
      // pc操作
      } else {
        this.basicdata.start.t = new Date().getTime()
        this.basicdata.start.x = e.clientX
        this.basicdata.start.y = e.clientY
        this.basicdata.end.x = e.clientX
        this.basicdata.end.y = e.clientY
      }
      this.temporaryData.tracking = true
      this.temporaryData.animation = false
    },
    touchmove (e) {
      // 记录滑动位置
      if (this.temporaryData.tracking && !this.temporaryData.animation) {
        if (e.type === 'touchmove') {
          this.basicdata.end.x = e.targetTouches[0].clientX
          this.basicdata.end.y = e.targetTouches[0].clientY
        } else {
          this.basicdata.end.x = e.clientX
          this.basicdata.end.y = e.clientY
        }
        // 计算滑动值
        this.temporaryData.poswidth = this.basicdata.end.x - this.basicdata.start.x
        this.temporaryData.posheight = this.basicdata.end.y - this.basicdata.start.y
      }
    },
    touchend (e) {
      this.temporaryData.tracking = false
      this.temporaryData.animation = true
      // 滑动结束，触发判断
      // 简单判断滑动宽度超出100像素时触发滑出
      if (Math.abs(this.temporaryData.poswidth) >= 100) {
        // 最终位移简单设定为x轴200像素的偏移
        let ratio = Math.abs(this.temporaryData.posheight / this.temporaryData.poswidth)
        this.temporaryData.poswidth = this.temporaryData.poswidth >= 0 ? this.temporaryData.poswidth + 200 : this.temporaryData.poswidth - 200
        this.temporaryData.posheight = this.temporaryData.posheight >= 0 ? Math.abs(this.temporaryData.poswidth * ratio) : -Math.abs(this.temporaryData.poswidth * ratio)
        this.temporaryData.opacity = 0
        this.temporaryData.swipe = true
        // 记录最终滑动距离
        this.temporaryData.lastPosWidth = this.temporaryData.poswidth
        this.temporaryData.lastPosHeight = this.temporaryData.posheight
        // currentPage+1 引发排序变化
        this.basicdata.currentPage += 1
        // currentPage切换，整体dom进行变化，把第一层滑动置零
        this.$nextTick(() => {
          this.temporaryData.poswidth = 0
          this.temporaryData.posheight = 0
          this.temporaryData.opacity = 1
        })
      // 不满足条件则滑入
      } else {
        this.temporaryData.poswidth = 0
        this.temporaryData.posheight = 0
        this.temporaryData.swipe = false
      }
    },
    onTransitionEnd (index) {
      // dom发生变化后，正在执行的动画滑动序列已经变为上一层
      if (this.temporaryData.swipe && index === this.basicdata.currentPage - 1) {
        this.temporaryData.animation = true
        this.temporaryData.lastPosWidth = 0
        this.temporaryData.lastPosHeight = 0
        this.temporaryData.swipe = false
      }
    },
    // 非首页样式切换
    transform (index) {
      if (index > this.basicdata.currentPage) {
        let style = {}
        let visible = 3
        let perIndex = index - this.basicdata.currentPage
        // visible可见数量前滑块的样式
        if (index <= this.basicdata.currentPage + visible - 1) {
          style['opacity'] = '1'
          style['transform'] = 'translate3D(0,0,' + -1 * perIndex * 60 + 'px' + ')'
          style['zIndex'] = visible - index + this.basicdata.currentPage
          style['transitionTimingFunction'] = 'ease'
          style['transitionDuration'] = 300 + 'ms'
        } else {
          style['zIndex'] = '-1'
          style['transform'] = 'translate3D(0,0,' + -1 * visible * 60 + 'px' + ')'
        }
        return style
      // 已滑动模块释放后
      } else if (index === this.basicdata.currentPage - 1) {
        let style = {}
        // 继续执行动画
        style['transform'] = 'translate3D(' + this.temporaryData.lastPosWidth + 'px' + ',' + this.temporaryData.lastPosHeight + 'px' + ',0px)'
        style['opacity'] = '0'
        style['zIndex'] = '-1'
        style['transitionTimingFunction'] = 'ease'
        style['transitionDuration'] = 300 + 'ms'
        return style
      }
    },
    // 首页样式切换
    transformIndex (index) {
      // 处理3D效果
      if (index === this.basicdata.currentPage) {
        let style = {}
        style['transform'] = 'translate3D(' + this.temporaryData.poswidth + 'px' + ',' + this.temporaryData.posheight + 'px' + ',0px)'
        style['opacity'] = this.temporaryData.opacity
        style['zIndex'] = 10
        if (this.temporaryData.animation) {
          style['transitionTimingFunction'] = 'ease'
          style['transitionDuration'] = 300 + 'ms'
        }
        return style
      }
    }
  }
}
</script>

ok~ 完成了上面的四步，堆叠组件的基本功能就已经实现，快来看看效果吧

堆叠滑动效果已经出来了，但是探探在体验上，还增加了触碰角度偏移，以及判定滑出面积比例

角度偏移的原理，是在用户每次进行touch时，记录用户触碰位置，计算出最大的偏移角度，在滑动出现位移时，线性增加角度以至最大的偏移角度。使用在stack中具体要做的是：

touchmove中计算出所需角度和方向
touchend及onTransitionEnd中将角度至零

判定滑出面积比例，主要通过偏移量计算出偏移面积，从而得到面积比例，完成判断

完整的代码和demo可以在github上查看源码，这里就不贴出来了

谢谢大家看完这篇文章，喜欢可以在github上给个⭐️ ，最后祝大家在探探上都能找到前女友💚

分享我写的另一个vue-slider组件vue-consise-slider

最近在找新工作，坐标广州，三年前端经验，熟悉vue，有工作介绍的朋友可以邮箱联系我warpcgd@qq.com