getBase64FromLocalAsync (imgUrl) {
    return new Promise((resolve, reject) => {
      uni.getFileSystemManager().readFile({
        filePath: imgUrl,
        encoding: "base64",
        success: res => {
          resolve('data:image/png;base64,' + res.data)
        },
        fail: err => {
          reject(err)
        }
      })
    })
  },

  getBase64FromNetAsync (imgUrl) {
    return new Promise(resolve => {
      uni.request({
        url: this.addOssToken(imgUrl),
        method: 'GET',
        responseType: 'arraybuffer', 
        success: res => {
          let base64 = uni.arrayBufferToBase64(res.data)
          base64 && (base64 = 'data:image/jpeg;base64,' + base64)
          resolve(base64)
        },
        fail: () => resolve('')
      })
    })
  },