微信小程序实战–集阅读与电影于一体的小程序项目（三）

14.wx.showtoast交互反馈

wx.showtoast文档

post-detail.js添加个消息提示框

oncollectiontap: function(ev) {
    var postscollected = wx.getstoragesync('posts_collected')
    var postcollected = postscollected[this.data.currentpostid]
    postcollected = !postcollected;
    postscollected[this.data.currentpostid] = postcollected;
    // 更新文章是否收藏的缓存值
    wx.setstoragesync('posts_collected', postscollected)
    // 更新数据绑定变量，实现切换图片
    this.setdata({
      collected: postcollected
    })

    wx.showtoast({
      title: postcollected ? "收藏成功" : "取消成功",
      duration: 1000,
      icon: "success"
    })
  } 

效果

---

15.音乐播放功能

音乐播放api文档

在posts-data.js里面给每篇文章添加一个music属性

 music: {
    url: "http://music.163.com/song/media/outer/url?id=108242.mp3",
    title: "她说-林俊杰",
    coverimg: "http://y.gtimg.cn/music/photo_new/t002r150x150m000001tec6v0kjpvc.jpg?max_age=2592000"
  }

post-detail.wxml

• 没播放音乐就显示文章图片，播放音乐就显示音乐歌手图片
• 绑定事件，添加播放和暂停音乐以及图片切换功能

 <!-- <image class="head-image" src="{{postdata.headimgsrc}}"></image> -->
  <image class='head-image' src="{{isplayingmusic?postdata.music.coverimg:postdata.headimgsrc}}"></image>
  <image catchtap='onmusictap' class='audio' src="{{isplayingmusic? '/images/music/music-stop.png': '/images/music/music-start.png'}}"></image>

post-detail.js

// 播放音乐
  onmusictap: function (ev) {
    var currentpostid = this.data.currentpostid;
    var postdata = postsdata.postlist[currentpostid];
    var isplayingmusic = this.data.isplayingmusic;
    if (isplayingmusic) {
      wx.pausebackgroundaudio();
      this.setdata({
        isplayingmusic: false
      })
    }
    else {
      wx.playbackgroundaudio({
        dataurl: postdata.music.url,
        title: postdata.music.title,
        coverimgurl: postdata.music.coverimg,
      })
      this.setdata({
        isplayingmusic: true
      })
    }
  }

16.监听音乐播放事件

post-detail.js的onload函数里面添加监听事件

var that = this;
    wx.onbackgroundaudioplay(function(){
      that.setdata({
        isplayingmusic: true
      })
    });
    wx.onbackgroundaudiopause(function () {
      that.setdata({
        isplayingmusic: false
      })
    });
  },

绑定监听事件后，播放按钮的状态就可以同步切换了

17.完善音乐播放功能

在文章详情页，点击播放音乐后，然后返回到文章列表页，再进到详情页，发现播放按钮是暂停状态，这是因为应用程序存在生命周期，下面就解决这个问题。

app.js绑定一个全局的变量（音乐播放状态）

app({
  globaldata: {
    g_isplayingmusic: false,
    g_currentmusicpostid: null,
  },
})

post-detail.js

var app = getapp();

page({

  data: {
    isplayingmusic: false
  },

  onload: function(options) {
    .
    .
    .

    if (app.globaldata.g_isplayingmusic && app.globaldata.g_currentmusicpostid === postid) {
      this.setdata({
        isplayingmusic: true
      })
    }
    this.setmusicmonitor()
  },

  setmusicmonitor:function(){
    var that = this;
    wx.onbackgroundaudioplay(function () {
      that.setdata({
        isplayingmusic: true
      })
      app.globaldata.g_currentmusicpostid = that.data.currentpostid
      app.globaldata.g_isplayingmusic = true
    });
    wx.onbackgroundaudiopause(function () {
      that.setdata({
        isplayingmusic: false
      })
      app.globaldata.g_currentmusicpostid = null
      app.globaldata.g_isplayingmusic = false
    });  
  },

18.轮播图跳转到文章详情

post.wxml

<swiper catchtap='onswipertap' indicator-dots='true' autoplay='true' interval='2000'>

post.js

onswipertap(event) {
    var postid = event.target.dataset.postid
    wx.navigateto({
      url: 'post-detail/post-detail?id=' + postid
    })
  },