<view bindtap='save'>保存圖片到相冊</view>

//點擊保存圖片
 save () {
  let that = this
  //若二維碼未加載完畢，加個動畫提高用戶體驗
  wx.showToast({
   icon: 'loading',
   title: '正在保存圖片',
   duration: 1000
  })
  //判斷用戶是否授權(quán)"保存到相冊"
  wx.getSetting({
   success (res) {
    //沒有權(quán)限，發(fā)起授權(quán)
    if (!res.authSetting['scope.writePhotosAlbum']) {
     wx.authorize({
      scope: 'scope.writePhotosAlbum',
      success () {//用戶允許授權(quán)，保存圖片到相冊
       that.savePhoto();
      },
      fail () {//用戶點擊拒絕授權(quán)，跳轉(zhuǎn)到設(shè)置頁，引導(dǎo)用戶授權(quán)
       wx.openSetting({
        success () {
         wx.authorize({
          scope: 'scope.writePhotosAlbum',
          success() {
           that.savePhoto();
          }
         })
        }
       })
      }
     })
    } else {//用戶已授權(quán)，保存到相冊
     that.savePhoto()
    }
   }
  })
 },
//保存圖片到相冊，提示保存成功
 savePhoto() {
  let that = this
  wx.downloadFile({
   url: that.data.imgUrl,
   success: function (res) {
    wx.saveImageToPhotosAlbum({
     filePath: res.tempFilePath,
     success(res) {
      wx.showToast({
       title: '保存成功',
       icon: "success",
       duration: 1000
      })
     }
    })
   }
  })
 }