vue-music（10）music-list元件

<template>
  <div class="music-list">
    <div class="back" @click="back">
      <i class="icon-back"></i>
    </div>
    <h1 class="title" v-html="title"></h1>
    <div class="bg-image" :style="bgStyle" ref="bgImage">
      <div class="play-wrapper">
        <div class="play" v-show="songs.length>0" ref="playBtn" @click="playRandom">
          <i class="icon-play"></i>
          <span class="text">随機全部播放</span>
        </div>
      </div>
      <div class="filter" ref="filter"></div>
    </div>
    <div class="bg-layer" ref="layer"></div>
    <scroll :data="songs" @scroll="scroll" :probe-type="probeType" :listern-scroll="listernScroll" class="list" ref="list">
      <div class="song-list-wrapper">
        <song-list :songs="songs" :rank="rank" @select="selectItem"></song-list>
      </div>
      <div class="loading-container" v-show="!songs.length">
        <loading></loading>
      </div>
    </scroll>
  </div>
</template>
<script>
import Scroll from '../../base/scroll/scroll'
import SongList from '../../base/song-list/song-list'
import {preFixStyle} from '../../common/js/mdom'
import Loading from '../../base/loading/loading'
import {mapActions} from 'vuex'
import {playlistMixin} from 'common/js/mixin'

const RESERVED_HEIGHT =  // 頭部流出的距離
const transform = preFixStyle('transform')
export default {
  mixins: [playlistMixin],
  props: {
    bgImage: {
      type: String, // 實際上是圖像的連結位址 是以要通過計算屬性 獲得完整圖檔
      default: ''
    },
    songs: {
      type: Array,
      default: () => {
        return []
      }
    },
    title: {
      type: String,
      default: ''
    },
    rank: {
      type: Boolean,
      default: false
    }
  },
  data () {
    return {
      scrollY: 
    }
  },
  mounted () {
  // 動态計算listtop值
    // console.log(this.$refs.list)  style在$el中
    this.imgHeight = this.$refs.bgImage.clientHeight
    this.minHeight = -this.$refs.bgImage.clientHeight + RESERVED_HEIGHT
    this.$refs.list.$el.style.top = `${this.imgHeight}px` // 因為list是個元件，是以他的style在$el中
  },
  created () {
    this.probeType = 
    this.listernScroll = true
  },
  methods: {
    handlePlayList (playList) {
      const bottom = playList.length >  ? '60px' : ''
      this.$refs.list.$el.style.bottom = bottom
      this.$refs.list.refresh()
    },
    scroll (position) {
      this.scrollY = position.y // 滾動的y坐标
    },
    back () {
      this.$router.back() // 通過路由傳回上級路由
    },
    selectItem (item, index) {
      this.selectPlay({
        list: this.songs,
        index
      })
    },
    playRandom () {
      this.randomPlay({
        list: this.songs
      })
    },
    ...mapActions([
      'selectPlay', // 調用action中的方法
      'randomPlay'
    ])
  },
  watch: {
    scrollY (newY) {
      let translateY = Math.max(this.minHeight, newY)
      let zIndex = 
      let scale = 
      let blur =  // 模糊度
      // 添加一個遮罩層，用來調節背景圖的高度。它發生變化，它下面的list也跟着變化
      this.$refs.layer.style[transform] = `translate3d(, ${translateY}px, )`
      // this.$refs.layer.style['webkitTransform'] = `translate3d(0, ${translateY}px, 0)`
      const percent = Math.abs(newY / this.imgHeight) // 計算出下滑與圖檔背景的比例
      if (newY > ) { // 往下滑
        scale =  + percent // 縮放
        zIndex = 
      } else {
        blur = Math.min( * percent, ) // 最小模糊度為20
      }
      this.$refs.filter.style['backdrop-filter'] = `blur(${blur}px)`
      this.$refs.filter.style['filter'] = `blur(${blur}px)`
      // this.$refs.filter.style['filter'] = `contrast(${blur}%)`

      this.$refs.filter.style['webkitFilter'] = `blur(${blur}px)`
      if (newY < this.minHeight) { // 往上滑
        zIndex = 
        this.$refs.bgImage.style.paddingTop =  // 通過padding-top設定高度
        this.$refs.bgImage.style.height = `${RESERVED_HEIGHT}px`
        this.$refs.playBtn.style.display = 'none'
      } else {
        this.$refs.bgImage.style.paddingTop = '70%' // 通過padding-top設定高度
        this.$refs.bgImage.style.height = 
        this.$refs.playBtn.style.display = 'block'
      }
      this.$refs.bgImage.style.zIndex = zIndex // 改變背景圖的zindex
      this.$refs.bgImage.style[transform] = `scale(${scale})` // scale縮放比例 詳情見transform：scale()
      // this.$refs.bgImage.style['webkitTransform'] = `scale(${scale})`
    }
  },
  computed: {
    bgStyle () {
      return `background-image: url(${this.bgImage})` // 通過屬性給dom動态添加背景圖
    }
  },
  components: {
    Scroll,
    SongList,
    Loading
  }
}
</script>
<style lang="stylus">
  @import "~common/stylus/variable"
  @import "~common/stylus/mixin"

  .music-list
    position: fixed
    z-index: 
    top: 
    left: 
    bottom: 
    right: 
    background: $color-background
    .back
      position absolute
      top: 
      left: px
      z-index: 
      .icon-back
        display: block
        padding: px
        font-size: $font-size-large-x
        color: $color-theme
    .title
      position: absolute
      top: 
      left: %
      z-index: 
      width: %
      no-wrap()
      text-align: center
      line-height: px
      font-size: $font-size-large
      color: $color-text
    .bg-image
      position: relative
      width: %
      height: 
      padding-top: %
      transform-origin: top // 基準點 transform-origin
      background-size: %
      .play-wrapper
        position: absolute
        bottom: px
        z-index: 
        width: %
        .play
          box-sizing: border-box
          width: px
          padding: px 
          margin:  auto
          text-align: center
          border: px solid $color-theme
          color: $color-theme
          border-radius: px
          font-size: 
          .icon-play
            display: inline-block
            vertical-align: middle
            margin-right: px
            font-size: $font-size-medium-x
          .text
            display: inline-block
            vertical-align: middle
            font-size: $font-size-small
      .filter
        position: absolute
        top: 
        left: 
        width: %
        height: %
        background: rgba(, , , )
        background-size: cover
    .bg-layer
      position: relative
      height: %
      background: $color-background
    .list
      position: fixed
      top: 
      bottom: 
      width: %
      // z-index -
      background: $color-background
      .song-list-wrapper
        padding: px px
      .loading-container
        position: absolute
        width: %
        top: %
        transform: translateY(-%)
</style>
           

主要是滑動歌曲list時的互動邏輯需要多多注意

vuex中actions：

// 點選播放：分兩種情況： 順序/随機
export const selectPlay = function ({commit, state}, {list, index}) {
  commit(types.SET_SEQUENCELIST, list) // 映射到state
  if (state.mode === playMode.random) {
    let randomList = shuffle(list) // 洗牌函數，徹底打亂，傳回一個新數組
    commit(types.SET_PLAY_LIST, randomList)
    index = findIndex(randomList, list[index]) // 從數組中尋找該item，并傳回其index
  } else {
    commit(types.SET_PLAY_LIST, list) // 順序播放
  }
  commit(types.CURRENTINDEX, index) 
  commit(types.SET_PLAY_SCREEN, true)
  commit(types.SET_PLAYING_STATE, true)
}
//随機播放模式
export const randomPlay = function ({commit}, {list}) {
  commit(types.MODE, playMode.random)
  commit(types.SET_SEQUENCELIST, list)
  let randomList = shuffle(list)
  commit(types.CURRENTINDEX, )
  commit(types.SET_PLAY_LIST, randomList)
  commit(types.SET_PLAY_SCREEN, true)
  commit(types.SET_PLAYING_STATE, true)
}
           

shuffle洗牌函數

function getRandom (min, max) { // 獲得min max之間的随機整數  
  return Math.floor(Math.random() * (max - min + ) + min) // (max - min + 1) 為了保證能取到max
}
export function shuffle (arr) {
  let _arr = arr.slice() // 傳回一個新數組 以便于不改變原數組
  for (let i = ; i < _arr.length; i++) {
    let j = getRandom(, i)
    let t = _arr[i]
    _arr[i] = _arr[j]
    _arr[j] = t
  }
  return _arr
}

function findIndex (list, song) {
  return list.findIndex((item) => { // es6  api 傳回index序号 如果傳回-1表示沒有
    return item.id === song.id 
  })
}