Antecedents feed

Basic usage of message subscription and publication

1. npm install --save pubsub-js, Install third party libraries pubsub-js.
2. import PubSub from "pubsub-js", Introducing third-party libraries pubsub.
3. Subscribe to news ：id = PubSub.subscribe( Message name ,callback), And callback The first parameter of the default is the message name , Then there are the parameters passed in by the developer .
4. Release the news ：PubSub.publish( Message name , Developer parameters ).
5. Unsubscribe ：PubSub.unsubscribe(id).

Applet project

1. Initialize project . Execute under the root directory of the applet npm init -y, Automatic generation package.json.
2. Download installation dependency .npm install --save pubsub-js.
3. page pages/music/music.js Introduce dependency in .import PusSub from "pubsub-js".
   The following error is reported ： page 【pages/music/music] error :
   Error: module ‘pages/music/pubsub-js.js’ is not defined, require args is ‘pubsub-js’.
4. Wechat developer tools , Tools > structure npm, Will automatically node_modules The third party in depends on converting into packages that can be used by applets , And save it in the same level folder miniprogram_npm in .
   
5. News subscription ： news ID=PubSub.subscribe( Message name ,(msgName, Data received ) => {})
   Unsubscribe ：PubSub.unsubscribe( news ID)
   News release ：PubSub.publish( Message name , Data sent )

The main files involved in the applet code are ：

1. app.json
2. app.wxss
3. app.js
4. pages/index/index.json
5. pages/index/index.wxml
6. pages/index/index.wxss
7. pages/index/index.js
8. pages/music/music.json
9. pages/music/music.wxml
10. pages/music/music.wxss
11. pages/music/music.js

app.json

{
    
  "pages": [
    "pages/index/index",
    "pages/music/music"
  ],
  "window": {
    
    "navigationBarBackgroundColor": "#624d2e",
    "navigationBarTitleText": " home page ",
    "navigationBarTextStyle": "white"
  },
  "requiredBackgroundModes": [
    "audio"
  ],
  "style": "v2",
  "sitemapLocation": "sitemap.json"
}

app.wxss

page{
    
  height: 100%;
}

app.js

App({
    
  globalData:{
    
    isPlayGlobal:false,   // Is there a song currently playing 
    musicIdGlobal:''     // Which song is currently playing 
  }
})

pages/index/index.json

{
    
  "usingComponents": {
    },
  "navigationBarTitleText": " Playlist "
}

pages/index/index.wxml

<view class="index-container">
  <view class="header">
    <image src="/static/images/icon-play-square.png"></image>
    <text> Play all </text>
    <text>{
   {musicList.length}}</text>
  </view>
  <scroll-view class="music-list" enable-flex scroll-y >
    <view class="music-item" wx:for="{
     {musicList}}" wx:key="id" bindtap="handleTap" data-musicindex="{
     {index}}" data-musicitem="{
     {item}}">
      <view class="music-index">{
   {index+1}}</view>
      <image class="music-image" src="{
     {item.picUrl}}"></image>
      <view class="music-info">
        <view class="musci-name">{
   {item.name}}</view>
        <view class="music-author">{
   {item.author}}</view>
      </view>
      <image class="btn-more" src="/static/images/icon-more.png"></image>
    </view>
  </scroll-view>
</view>

pages/index/index.wxss

.index-container{
    
  padding: 20rpx;
  background:#624d2e
}
.header{
    
  display: flex;
  align-items: center;
}
.header image{
    
  width: 28rpx;
  height: 28rpx;
  margin-right: 20rpx;
}
.header text{
    
  color: #fff;
  height: 28rpx;
  line-height: 28rpx;
  margin-right: 20rpx;
  font-size: 28rpx;
}
.music-list{
    
  margin-top: 20rpx;
  color: #fff;
  height: calc(100vh - 88rpx);
}
.music-item{
    
  display: flex;
  align-items: center;
  height: 100rpx;
  margin: 20rpx 0;
  position: relative;
}
.music-item .music-index{
    
  width: 50rpx;
  font-size: 28rpx;
  color: #aaa;
}
.music-item .music-image{
    
  width: 80rpx;
  height: 80rpx;
  border-radius: 6rpx;
  margin-right: 20rpx;
}
.music-item .music-info{
    
  display: flex;
  flex-direction: column;
}
.music-item .music-info .music-author{
    
  font-size: 24rpx;
  color: #aaa;
  margin-top: 10rpx;
}
.music-item .btn-more{
    
  width: 36rpx;
  height: 36rpx;
  position: absolute;
  right: 0;
}

pages/index/index.js

import PubSub from "pubsub-js";
const host = "http://localhost:3000";

Page({
    
  data:{
    
    musicList:[], // Song list 
    musicindex:0  // After entering a song , Record the index of the song in the list 
  },
  onLoad(){
    
    this.getDataFromServer();

    // receive messages , Receive from page pages/music/music The news of , according to “ On a ”or“ The following piece ”, Determine which song should be displayed currently 
    PubSub.subscribe("switchsong",(msgName,type) => {
    
      // console.log(msgName,type);
      let {
    musicindex,musicList} = this.data;
      if(type === "prev"){
    
        if(musicindex===0) {
    
          musicindex = musicList.length-1;
        }else{
    
          musicindex--;
        }
      }else if(type === "next"){
    
        if(musicindex === musicList.length-1){
    
          musicindex = 0;
        }else{
    
          musicindex++;
        }
      }
      this.setData({
    musicindex});
      const music = musicList[musicindex];
      // Send a message , Tell page pages/music/music, Tell it the details of the song after switching .
      PubSub.publish("refreshmusic",music);
    })
  },
  getDataFromServer(){
    
    const result = [
      {
    id:"001",name:" In torrential rain ","author":" Li Ruoxi ","picUrl":host+"/images/ In torrential rain .jpg","url":host+"/audios/ In torrential rain .mp3",duration:161000},
      {
    id:"002",name:"Last Dance","author":" Five hundred ","picUrl":host+"/images/Last Dance.jpg","url":host+"/audios/Last Dance.mp3",duration:271000},
      {
    id:"003",name:" The king and the beggar ","author":" Hua Chenyu ","picUrl":host+"/images/ The king and the beggar .jpg","url":host+"/audios/ The king and the beggar .mp3",duration:178000},
      {
    id:"004",name:" Chilo Levis reply ","author":" Xue Kaiqi ","picUrl":host+"/images/ Chilo Levis reply .jpg","url":host+"/audios/ Chilo Levis reply .mp3",duration:243000},
      {
    id:"005",name:" Red sun ","author":" Li Keqin ","picUrl":host+"/images/ Red sun .jpg","url":host+"/audios/ Red sun .mp3",duration:291000},
      {
    id:"006",name:" Happy worship ","author":" Wilber Pan   Zhang Shaohan ","picUrl":host+"/images/ Happy worship .jpg","url":host+"/audios/ Happy worship .mp3",duration:329000},
      {
    id:"007",name:" The door is unlocked ","author":" Huangpinguan ","picUrl":host+"/images/ The door is unlocked .jpg","url":host+"/audios/ The door is unlocked .mp3",duration:233000},
      {
    id:"008",name:" Just love you ","author":" David Tao ","picUrl":host+"/images/ Just love you .jpg","url":host+"/audios/ Just love you .mp3",duration:340000},
      {
    id:"009",name:" Happy little frog ","author":" Liu Shiming ","picUrl":host+"/images/ Happy little frog .jpg","url":host+"/audios/ Happy little frog .mp3",duration:130000},
      {
    id:"0010",name:" Years of friendship ","author":" Jordan Chan   Zheng Yijian   Thank God   Lin Xiaofeng   Qian Jiale ","picUrl":host+"/images/ Years of friendship .jpg","url":host+"/audios/ Years of friendship .mp3",duration:209000},
      {
    id:"0011",name:" gentle ","author":" May day ","picUrl":host+"/images/ gentle .jpg","url":host+"/audios/ gentle .mp3",duration:269000}
    ];
    this.setData({
    musicList:result});
  },
  handleTap(event){
    
    const {
    musicitem,musicindex} = event.currentTarget.dataset;
    this.setData({
    musicindex})
    wx.navigateTo({
    
      url: '/pages/music/music?musicitem='+JSON.stringify(musicitem),
    })
  }
})

pages/music/music.json

{
    
  "usingComponents": {
    },
  "navigationBarBackgroundColor": "#2f434e",
  "navigationBarTitleText": " Music details "
}

pages/music/music.wxml

<view class="music-container">
  <view class="music-name">{
   {music.name}}</view>
  <view class="music-author">{
   {music.author}}</view>
  <image class="arm {
     {isPlay&&'arm-reset'}}" src="/static/images/arm.png"></image>
  <view class="disc-container {
     {isPlay&&'disc-animate'}}">
    <image class="disc" src="/static/images/disc.png"></image>
    <image class="music-image" src="{
     {music.picUrl}}"></image>
  </view>
  <view class="player">
    <view class="btns">
      <image class="loop-btn" src="/static/images/loop.png"></image>
      <image class="prev-btn" src="/static/images/prev.png" id="prev" bindtap="handleSwitch"></image>
      <image class="play-btn" src="{
     {isPlay?'/static/images/stop.png':'/static/images/play.png'}}" bindtap="handlePlay"></image>
      <image class="next-btn" src="/static/images/next.png" id="next" bindtap="handleSwitch"></image>
      <image class="list-btn" src="/static/images/list.png"></image>
    </view>
  </view>
</view>

pages/music/music.wxss

.music-container{
    
  height: 100%;
  display: flex;
  flex-direction: column;
  align-items: center;
  background: #2f434e;
  position: relative;
}
.music-container .music-name{
    
  margin: 10rpx 0;
  color: #fff;
  font-size: 36rpx;
}
.music-container .music-author{
    
  color: #bbb;
  font-size: 28rpx;
  margin: 6rpx 0;
}
.music-container .arm{
    
  width:204rpx;
  height: 358rpx;
  position: relative;
  left: 72rpx;
  z-index: 99;
  transform: rotate(-15deg);
  transform-origin: 30rpx 30rpx;
  transition: transform .7s linear;
}
.disc-container{
    
  position: relative;
  top: -128rpx;
  width: 490rpx;
  height: 490rpx;
}
.disc-container .disc{
    
  width: 100%;
  height: 100%;
}
.disc-container .music-image{
    
  width: 270rpx;
  height: 270rpx;
  border-radius: 100%;
  position: absolute;
  left: 0;right: 0;top: 0;bottom: 0;
  margin: auto;
}
.music-container .arm-reset{
    
  transform: rotate(0deg);
}
.disc-animate{
    
  animation: rotate 2.5s 1s linear infinite;
}
@keyframes rotate{
    
  from{
    
    transform: rotate(0deg);
  }
  to{
    
    transform: rotate(360deg);
  }
}
.player{
    
  width: 100%;
  position: absolute;
  bottom: 60rpx;
}
.btns{
    
  display: flex;
  align-items: center;
  justify-content: space-evenly;
}
.btns image{
    
  width: 36rpx;
  height: 36rpx;
}
.btns .play-btn,.btns .stop-btn{
    
  width: 90rpx;
  height: 90rpx;
}

pages/music/music.js

import PubSub from "pubsub-js";
const appInstance = getApp();

Page({
    
  data:{
    
    isPlay:false,
    music:{
    }
  },
  onLoad(options){
    
    const music = JSON.parse(options.musicitem);
    this.setData({
    music})
    const {
    isPlayGlobal,musicIdGlobal} = appInstance.globalData;
    const {
    id} = this.data.music;
    if(isPlayGlobal && musicIdGlobal === id) {
    
      this.setData({
    isPlay:true});
    }
  
    this.bam = wx.getBackgroundAudioManager();
    this.bam.onPlay(() => {
    
      this.setData({
    isPlay:true})
      appInstance.globalData.isPlayGlobal = true;
      appInstance.globalData.musicIdGlobal = this.data.music.id;
    })
    this.bam.onPause(() => {
    
      this.setData({
    isPlay:false})
      appInstance.globalData.isPlayGlobal = false;
    })
    this.bam.onStop(() => {
    
      this.setData({
    isPlay:false})
      appInstance.globalData.isPlayGlobal = false;
    })
    this.bam.onEnded(() => {
    
      this.setData({
    isPlay:false});
      appInstance.globalData.isPlayGlobal = false;
    })
  },
  handlePlay(){
    
    const isPlay = !this.data.isPlay;
    this.setData({
    isPlay});
    this.musicControl();
  },
  musicControl(){
    
    const {
    isPlay} = this.data;
    if(isPlay){
    
      this.bam.src = this.data.music.url;
      this.bam.title = this.data.music.name;
    }else{
    
      this.bam.pause();
    }
  },
  handleSwitch(event){
    
    const type = event.target.id;
    // Send a message , tell pages/index/index： Cut one or the next .prev Represents cutting a song ,next Represents cutting off a song .
    PubSub.publish("switchsong",type);

    // receive messages , Receive from pages/index/index The news of , Show the song details after switching 
    const eventId = PubSub.subscribe("refreshmusic",(msgName,music) => {
    
      // console.log(msgName,music);
      PubSub.unsubscribe(eventId);
      this.setData({
    music})
      this.musicControl();
    })
  }
})

Related links

todoList Case study （vue edition ）（ Message subscription and publishing implement component communication ）
pubsubjs