组件截图怎么保存将pixelMap存储到系统相册或应用沙箱

"requestPermissions": [ 
  { 
    "name": "ohos.permission.WRITE_IMAGEVIDEO", 
    "reason": "$string:reason", 
    "usedScene": { 
      "abilities": [ 
        "EntryFormAbility" 
      ], 
      "when": "inuse" 
    } 
  }, 
]

import { abilityAccessCtrl, common, Permissions } from '@kit.AbilityKit'; 
const permissions: Array<Permissions> = ['ohos.permission.WRITE_IMAGEVIDEO']; 
 
function reqPermissionsFromUser(permissions: Array<Permissions>, context: common.UIAbilityContext): void { 
  let atManager: abilityAccessCtrl.AtManager = 
    abilityAccessCtrl.createAtManager(); 
  // requestPermissionsFromUser会判断权限的授权状态来决定是否唤起弹窗 
  atManager.requestPermissionsFromUser(context, permissions).then((data) => { 
    let grantStatus: Array<number> = data.authResults; 
    let length: number = grantStatus.length; 
    for (let i = 0; i < length; i++) { 
      if (grantStatus[i] === 0) { 
        // 用户授权，可以继续访问目标操作 
      } else { 
        // 用户拒绝授权，提示用户必须授权才能访问当前页面的功能，并引导用户到系统设置中打开相应的权限 
        return; 
      } 
    } 
    // 授权成功 
  }).catch((err: BusinessError) => { 
    console.error(`Failed to request permissions from user. Code is ${err.code}, message is ${err.message}`); 
  }) 
} 
 
aboutToAppear(): void { 
  reqPermissionsFromUser(permissions, this.context) 
}

/* 组件截图 */ 
clickToComponentSnapshot() { 
  // root 为组件ID 
  componentSnapshot.get("root", (error: Error, pixmap: image.PixelMap) => { 
    if (error) { 
      console.log("error: " + JSON.stringify(error)) 
      return; 
    } 
    console.log('截图成功') 
    this.pixmap = pixmap 
  }) 
}

// 保存到系统相册 
async savePixmap2SysHelper() { 
  if (!this.pixmap) { 
    return 
  } 
  const imgBuffer = await this.transferPixelMap2Buffer(this.pixmap) 
 
  /*  获取相册管理模块的实例，用于访问和修改相册中的媒体文件。 */ 
  let helper = photoAccessHelper.getPhotoAccessHelper(getContext(this)) 
 
  /* 指定待创建的文件类型和后缀，创建图片或视频资源，使用callback方式返回结果。 */ 
  const uri = await helper.createAsset(photoAccessHelper.PhotoType.IMAGE, 'png') 
  const file = await fs.open(uri, fs.OpenMode.READ_WRITE | fs.OpenMode.CREATE) 
  await fs.write(file.fd, imgBuffer) 
  /* 关闭文件 */ 
  await fs.close(file.fd) 
} 
 
/* 将 pixelMap 转成图片格式 */ 
transferPixelMap2Buffer(pixelMap: image.PixelMap): Promise<ArrayBuffer> { 
  return new Promise((resolve, reject) => { 
    /** 
     设置打包参数 
     format：图片打包格式，只支持 jpg 和 webp 
     quality：JPEG 编码输出图片质量 
     bufferSize：图片大小，默认 10M 
   */ 
    let packOpts: image.PackingOption = { format: "image/jpeg", quality: 98 } 
    // 创建ImagePacker实例 
    const imagePackerApi = image.createImagePacker() 
    imagePackerApi.packing(pixelMap, packOpts).then((buffer: ArrayBuffer) => { 
      resolve(buffer) 
    }).catch((err: BusinessError) => { 
      reject() 
    }) 
  }) 
} 
 
/* 保存到应用沙箱 */ 
async savePixmal2SystemFileManager() { 
  if (!this.pixmap) { 
    return 
  } 
  const imgBuffer = await this.transferPixelMap2Buffer(this.pixmap) 
  const file = 
    fs.openSync(this.filesDir + `/${DateUtil.getTimeStamp()}.png`, fs.OpenMode.READ_WRITE | fs.OpenMode.CREATE); 
  await fs.write(file.fd, imgBuffer) 
  /* 关闭文件 */ 
  await fs.close(file.fd) 
}