HarmonyOS如何将PixelMap保存到相册？

// pixelmap使用imagePacker.packing的方法转成arraybuffer，在进行编码 
imagePackerApi.packing(pixelMap, packOpts).then(async (buffer : ArrayBuffer) => 
{ 
  try { 
    const context = getContext(this) 
    let helper = photoAccessHelper.getPhotoAccessHelper(context) 
    let uri = await helper.createAsset(photoAccessHelper.PhotoType.IMAGE, 'png') 
    let file = await fs.open(uri, fs.OpenMode.READ_WRITE | fs.OpenMode.CREATE) await fs.write(file.fd, buffer); // 关闭文件 await fs.close(file.fd);  
  } 
  catch (error) { 
    console.error("error is "+ JSON.stringify(error)) } }) 
  .catch((error : BusinessError) => { 
    console.error('Failed to pack the image. And the error is: ' + error); 
  })