harmony 鸿蒙Managing System Albums

  • 2023-10-30
  • 浏览 (207)

Managing System Albums

The photoAccessHelper module provides APIs for managing system albums, including the Favorites, Videos, Screenshots.

NOTE

Before you start, you need to obtain a PhotoAccessHelper instance and apply for required permissions. For details, see photoAccessHelper Overview.

By default, the PhotoAccessHelper instance obtained in photoAccessHelper Overview is used when photoAccessHelper APIs are used. If the code for obtaining the PhotoAccessHelper instance is not added, an error indicating that PhotoAccessHelper is not defined is reported.

To ensure application running efficiency, most photoAccessHelper APIs are asynchronously implemented in callback or promise mode. The following code samples use promise-based APIs. For details about the APIs, see Album Management. Unless otherwise specified, all the media assets to be obtained in this document exist in the database. If no media asset is obtained when the sample code is executed, check whether the media assets exist in the database.

Favorites

Favorites is a system album. Favoriting a photo or video adds the photo or video to Favorites; unfavoriting a photo or video removes the photo or video from Favorites.

Obtaining a Favorites Object

Use getAlbums to obtain a Favorites object.

Prerequisites

  • A PhotoAccessHelper instance is obtained.
  • The application has the ohos.permission.READ_IMAGEVIDEO permission.

How to Develop

  1. Set the album type to photoAccessHelper.AlbumType.SYSTEM and the album subtype to photoAccessHelper.AlbumSubtype.FAVORITE.
  2. Call getAlbums to obtain a Favorites object.
import photoAccessHelper from '@ohos.file.photoAccessHelper';
const context = getContext(this);
let phAccessHelper = photoAccessHelper.getPhotoAccessHelper(context);

async function example() {
  try {
    let fetchResult: photoAccessHelper.FetchResult<photoAccessHelper.Album> = await phAccessHelper.getAlbums(photoAccessHelper.AlbumType.SYSTEM, photoAccessHelper.AlbumSubtype.FAVORITE);
    let album: photoAccessHelper.Album = await fetchResult.getFirstObject();
    console.info('get favorite Album successfully, albumUri: ' + album.albumUri);
    fetchResult.close();
  } catch (err) {
    console.error('get favorite Album failed with err: ' + err);
  }
}

Favoriting an Image or Video

Use setFavorite to add an image or video to Favorites.

Prerequisites

  • A PhotoAccessHelper instance is obtained.
  • The application has the ohos.permission.READ_IMAGEVIDEO and ohos.permission.WRITE_IMAGEVIDEO permissions.

Example: Favorite an image.

How to Develop

  1. Obtain media assets.
  2. Set favoriteState to true to favorite the image.
  3. Call FileAsset.setFavorite to add the image to Favorites.
import dataSharePredicates from '@ohos.data.dataSharePredicates';
import photoAccessHelper from '@ohos.file.photoAccessHelper';
const context = getContext(this);
let phAccessHelper = photoAccessHelper.getPhotoAccessHelper(context);

async function example() {
  let predicates: dataSharePredicates.DataSharePredicates = new dataSharePredicates.DataSharePredicates();
  predicates.equalTo(photoAccessHelper.PhotoKeys.DISPLAY_NAME, 'test.jpg');
  let fetchOptions: photoAccessHelper.FetchOptions = {
    fetchColumns: [],
    predicates: predicates
  };

  try {
    let photoFetchResult: photoAccessHelper.FetchResult<photoAccessHelper.PhotoAsset> = await phAccessHelper.getAssets(fetchOptions);
    let fileAsset: photoAccessHelper.PhotoAsset = await photoFetchResult.getFirstObject();
    console.info('getAssets fileAsset.displayName : ' + fileAsset.displayName);
    let favoriteState = true;
    await fileAsset.setFavorite(favoriteState);
  } catch (err) {
    console.error('setFavorite failed with err: ' + err);
  }
}

Obtaining Images and Videos in Favorites

Obtain a Favorites object, and call Album.getAssets to obtain the assets in Favorites.

Prerequisites

  • A PhotoAccessHelper instance is obtained.
  • The application has the ohos.permission.READ_IMAGEVIDEO permission.

Example: Obtain an image from Favorites.

How to Develop

  1. Obtain a Favorites object.
  2. Set fetchOptions for obtaining the image.
  3. Call Album.getAssets to obtain the image assets.
  4. Call FetchResult.getFirstObject to obtain the first image from the result set.
import dataSharePredicates from '@ohos.data.dataSharePredicates';
import photoAccessHelper from '@ohos.file.photoAccessHelper';
const context = getContext(this);
let phAccessHelper = photoAccessHelper.getPhotoAccessHelper(context);

async function example() {
  let predicates: dataSharePredicates.DataSharePredicates = new dataSharePredicates.DataSharePredicates();
  let fetchOptions: photoAccessHelper.FetchOptions = {
    fetchColumns: [],
    predicates: predicates
  };

  try {
    let albumFetchResult: photoAccessHelper.FetchResult<photoAccessHelper.Album> = await phAccessHelper.getAlbums(photoAccessHelper.AlbumType.SYSTEM, photoAccessHelper.AlbumSubtype.FAVORITE);
    let album: photoAccessHelper.Album = await albumFetchResult.getFirstObject();
    console.info('get favorite Album successfully, albumUri: ' + album.albumUri);

    let photoFetchResult: photoAccessHelper.FetchResult<photoAccessHelper.PhotoAsset> = await album.getAssets(fetchOptions);
    let fileAsset: photoAccessHelper.PhotoAsset = await photoFetchResult.getFirstObject();
    console.info('favorite album getAssets successfully, albumName: ' + fileAsset.displayName);
    photoFetchResult.close();
    albumFetchResult.close();
  } catch (err) {
    console.error('favorite failed with err: ' + err);
  }
}

Unfavoriting an Image or Video

Use setFavorite to remove images or videos from Favorites.

Prerequisites

  • A PhotoAccessHelper instance is obtained.
  • The application has the ohos.permission.READ_IMAGEVIDEO and ohos.permission.WRITE_IMAGEVIDEO permissions.

Example: Unfavorite an image.

How to Develop

  1. Obtain the images and videos in Favorites.
  2. Set favoriteState to false.
  3. Call FileAsset.setFavorite to unfavorite an image or video.
import dataSharePredicates from '@ohos.data.dataSharePredicates';
import photoAccessHelper from '@ohos.file.photoAccessHelper';
const context = getContext(this);
let phAccessHelper = photoAccessHelper.getPhotoAccessHelper(context);

async function example() {
  let predicates: dataSharePredicates.DataSharePredicates = new dataSharePredicates.DataSharePredicates();
  let fetchOptions: photoAccessHelper.FetchOptions = {
    fetchColumns: [],
    predicates: predicates
  };

  try {
    let albumFetchResult: photoAccessHelper.FetchResult<photoAccessHelper.Album> = await phAccessHelper.getAlbums(photoAccessHelper.AlbumType.SYSTEM, photoAccessHelper.AlbumSubtype.FAVORITE);
    let album: photoAccessHelper.Album = await albumFetchResult.getFirstObject();
    console.info('get favorite Album successfully, albumUri: ' + album.albumUri);

    let photoFetchResult: photoAccessHelper.FetchResult<photoAccessHelper.PhotoAsset> = await album.getAssets(fetchOptions);
    let fileAsset: photoAccessHelper.PhotoAsset = await photoFetchResult.getFirstObject();
    console.info('favorite album getAssets successfully, albumName: ' + fileAsset.displayName);
    let favoriteState = false;
    await fileAsset.setFavorite(favoriteState);
    photoFetchResult.close();
    albumFetchResult.close();
  } catch (err) {
    console.error('setFavorite failed with err: ' + err);
  }
}

Videos

Videos is a system album that holds media assets of the video type in user files.

Obtaining a Video Album Object

Use getAlbums to obtain a video album object.

Prerequisites

  • A PhotoAccessHelper instance is obtained.
  • The application has the ohos.permission.READ_IMAGEVIDEO permission.

How to Develop

  1. Set the album type to photoAccessHelper.AlbumType.SYSTEM and the album subtype to photoAccessHelper.AlbumSubtype.VIDEO.
  2. Use getAlbums to obtain the video album object.
import photoAccessHelper from '@ohos.file.photoAccessHelper';
const context = getContext(this);
let phAccessHelper = photoAccessHelper.getPhotoAccessHelper(context);

async function example() {
  try {
    let fetchResult: photoAccessHelper.FetchResult<photoAccessHelper.Album> = await phAccessHelper.getAlbums(photoAccessHelper.AlbumType.SYSTEM, photoAccessHelper.AlbumSubtype.VIDEO);
    let album: photoAccessHelper.Album = await fetchResult.getFirstObject();
    console.info('get video Album successfully, albumUri: ' + album.albumUri);
    fetchResult.close();
  } catch (err) {
    console.error('get video Album failed with err: ' + err);
  }
}

Obtaining a Video from Videos

Obtain a video album object, and use Album.getAssets to obtain video assets in Videos.

Prerequisites

  • A PhotoAccessHelper instance is obtained.
  • The application has the ohos.permission.READ_IMAGEVIDEO permission.

Example: Obtain a video in Videos.

How to Develop

  1. Obtain a video album object.
  2. Set fetchOptions for obtaining the video.
  3. Call Album.getAssets to obtain video assets.
  4. Call FetchResult.getFirstObject to obtain the first video.
import dataSharePredicates from '@ohos.data.dataSharePredicates';
import photoAccessHelper from '@ohos.file.photoAccessHelper';
const context = getContext(this);
let phAccessHelper = photoAccessHelper.getPhotoAccessHelper(context);

async function example() {
  let predicates: dataSharePredicates.DataSharePredicates = new dataSharePredicates.DataSharePredicates();
  let fetchOptions: photoAccessHelper.FetchOptions = {
    fetchColumns: [],
    predicates: predicates
  };

  try {
    let albumFetchResult: photoAccessHelper.FetchResult<photoAccessHelper.Album> = await phAccessHelper.getAlbums(photoAccessHelper.AlbumType.SYSTEM, photoAccessHelper.AlbumSubtype.VIDEO);
    let album: photoAccessHelper.Album = await albumFetchResult.getFirstObject();
    console.info('get video Album successfully, albumUri: ' + album.albumUri);

    let videoFetchResult: photoAccessHelper.FetchResult<photoAccessHelper.PhotoAsset> = await album.getAssets(fetchOptions);
    let fileAsset: photoAccessHelper.PhotoAsset = await videoFetchResult.getFirstObject();
    console.info('video album getAssets successfully, albumName: ' + fileAsset.displayName);
    videoFetchResult.close();
    albumFetchResult.close();
  } catch (err) {
    console.error('video failed with err: ' + err);
  }
}

Screenshots

Screenshots is a system album that holds user’s screenshots and screen recording files.

Obtaining a Screenshot Album Object

Use getAlbums to obtain a screenshot album object.

Prerequisites

  • A PhotoAccessHelper instance is obtained.
  • The application has the ohos.permission.READ_IMAGEVIDEO permission.

How to Develop

  1. Set the album type to photoAccessHelper.AlbumType.SYSTEM and the album subtype to photoAccessHelper.AlbumSubtype.SCREENSHOT.
  2. Use getAlbums to obtain a screenshot album object.
import photoAccessHelper from '@ohos.file.photoAccessHelper';
const context = getContext(this);
let phAccessHelper = photoAccessHelper.getPhotoAccessHelper(context);

async function example() {
  try {
    let fetchResult: photoAccessHelper.FetchResult<photoAccessHelper.Album> = await phAccessHelper.getAlbums(photoAccessHelper.AlbumType.SYSTEM, photoAccessHelper.AlbumSubtype.SCREENSHOT);
    let album: photoAccessHelper.Album = await fetchResult.getFirstObject();
    console.info('get screenshot Album successfully, albumUri: ' + album.albumUri);
    fetchResult.close();
  } catch (err) {
    console.error('get screenshot Album failed with err: ' + err);
  }
}

Obtaining Media Assets in Screenshots

Obtain a screenshot album object, and call Album.getAssets to obtain the media assets in the album.

Prerequisites

  • A PhotoAccessHelper instance is obtained.
  • The application has the ohos.permission.READ_IMAGEVIDEO permission.

Example: Obtain a media asset from Screenshots.

How to Develop

  1. Obtain a screenshot album object.
  2. Set fetchOptions for obtaining the media asset.
  3. Call Album.getAssets to obtain media assets.
  4. Call FetchResult.getFirstObject to obtain the first media asset.
import dataSharePredicates from '@ohos.data.dataSharePredicates';
import photoAccessHelper from '@ohos.file.photoAccessHelper';
const context = getContext(this);
let phAccessHelper = photoAccessHelper.getPhotoAccessHelper(context);

async function example() {
  let predicates: dataSharePredicates.DataSharePredicates = new dataSharePredicates.DataSharePredicates();
  let fetchOptions: photoAccessHelper.FetchOptions = {
    fetchColumns: [],
    predicates: predicates
  };

  try {
    let albumFetchResult: photoAccessHelper.FetchResult<photoAccessHelper.Album> = await phAccessHelper.getAlbums(photoAccessHelper.AlbumType.SYSTEM, photoAccessHelper.AlbumSubtype.SCREENSHOT);
    let album: photoAccessHelper.Album = await albumFetchResult.getFirstObject();
    console.info('get screenshot album successfully, albumUri: ' + album.albumUri);

    let screenshotFetchResult: photoAccessHelper.FetchResult<photoAccessHelper.PhotoAsset> = await album.getAssets(fetchOptions);
    let fileAsset: photoAccessHelper.PhotoAsset = await screenshotFetchResult.getFirstObject();
    console.info('screenshot album getAssets successfully, albumName: ' + fileAsset.displayName);
    screenshotFetchResult.close();
    albumFetchResult.close();
  } catch (err) {
    console.error('screenshot album failed with err: ' + err);
  }
}

你可能感兴趣的鸿蒙文章

harmony 鸿蒙File Management

harmony 鸿蒙Accessing Application Files

harmony 鸿蒙Backup and Restoration Accessed by Applications

harmony 鸿蒙Application Data Backup and Restoration Overview

harmony 鸿蒙Backup and Restoration Triggered by System Applications

harmony 鸿蒙Application File Overview

harmony 鸿蒙Uploading and Downloading an Application File

harmony 鸿蒙Obtaining Application and File System Space Statistics

harmony 鸿蒙Application Sandbox Directory

harmony 鸿蒙Developing a File Manager Application (for System Applications Only)

0  赞