如何将Pixmap保存到本地文件？

static async savePixelMap(pixelMap: image.PixelMap, path: string, name: string,
  format: string = 'image/png'): Promise<string> {
  try {
    if (!fs.accessSync(path)) {
      fs.mkdirSync(path, true); //如果文件夹不存在就创建
    }
    let filePath = path + "/" + name;
    let file = fs.openSync(path, fs.OpenMode.READ_WRITE);
    let packOpts: image.PackingOption = { format: format, quality: 100 }

    const imagePacker: image.ImagePacker = image.createImagePacker();
    await imagePacker.packToFile(pixelMap, file.fd, packOpts).finally(() => {
      imagePacker.release(); //释放
    });
    fs.closeSync(file.fd);//关闭文件
    return filePath;
  } catch (err) {
    let error = err as BusinessError;
    console.log(`ImageUtil-savePixelMap-异常 ~ code: ${error.code} -·- message: ${error.message}`);
    return '';
  }
}