微信小程序循环等待加载图片 - Wait and Load Image

{
  load_activity: function () {
    var that = this;
    wx.showLoading({
      title: '图片生成中',
    })
    wx.request({
      url: app.globalData.webservice_url + 'biz/activity/saveSharePic',
      data: JSON.stringify(app.encode({
        activityId: that.data.activityid,
        width: that.data.width,
        height: that.data.height
      })),
      header: {
        'X-Token': wx.getStorageSync('token')
      },
      method: 'POST',
      success: function (res) {
        if (res.data.code === 1) {
          if (res.data.data) {
          that.setData({
            activity: res.data.data
          }, function () {
            that.timer_helper(res.data.data.shareActivityPath);
          })
          } else {
            app.showModal('提示', res.data.desc);
          }
        } else {
          app.showModal('提示', res.data.desc);
        }
      },
      fail: function (res) {
        app.showModal('提示', res.errMsg);
      },
      complete: function (res) {
        console.log(res);
      }
    })
  },

  timer_helper: function (path) {
    var that = this;
    app.globalData.timer_canvas = setInterval(function () {
      clearInterval(app.globalData.timer_canvas);
      wx.getImageInfo({
        src: app.globalData.file_url_server + path,
        success(res1) {
          that.setData({
            path: res1.path
          }, function () {
            wx.saveImageToPhotosAlbum({
              filePath: res1.path,
              success(res) {
                wx.showToast({
                  title: '已保存到本地相册',
                })
              }
            })
          })
        },
        fail(res1) {
          that.timer_helper(path);
        },
        complete(res1) {
        }
      })
    }, 2000)
  }
}