/// <summary>
/// Because the app has registered to support "Photos" extension the agent will be invoked
/// and requested to download each image binary on a per need basis (e.g.: the user
/// has tapped on the photo). We only receive this operation for the albums that require
/// authentication (i.e. : we have explicitly set the property RequiresAuthentication = true)
/// </summary>
/// <param name="operation">The operation that we need to perform</param>
private async Task ProcessOperation(DownloadImageOperation operation)
{
Logger.Log("Agent", "DownloadImageOperation(" + operation.PhotoId + ", " + operation.DesiredImageType + ")");
try
{
OnlinePicture image = await manager.GetPictureByRemoteIdAsync(operation.PhotoId);
// Download according to the desired image type
if (operation.DesiredImageType == ImageType.SmallThumbnail)
{
await image.SetThumbnailSmallAsync(await Helpers.MakeStreamFromUrl(image.ThumbnailSmallUrl));
}
else if (operation.DesiredImageType == ImageType.LargeThumbnail)
{
await image.SetThumbnailLargeAsync(await Helpers.MakeStreamFromUrl(image.ThumbnailLargeUrl));
}
else if (operation.DesiredImageType == ImageType.FullSize)
{
await image.SetContentAsync(await Helpers.MakeStreamFromUrl(image.ContentUrl));
}
await manager.SaveMediaItemAsync(image);
}
catch (Exception e)
{
Helpers.HandleException(e);
}
finally
{
operation.SafeNotifyCompletion();
}
}
/// <summary>
/// Because the app has registered to support "Photos" extension the agent will be invoked
/// and requested to download the album items when the user taps on our tile
/// in the photos hub. This method handles the operation by synchronizing the local
/// store with our web server (Bing Images).
/// </summary>
/// <param name="operation">The operation that we need to perform</param>
private async Task ProcessOperation(DownloadAlbumItemsOperation operation)
{
try
{
Logger.Log("Agent", "DownloadAlbumItemsOperation(" + operation.ParentAlbumId + ")");
if (string.IsNullOrEmpty(operation.ParentAlbumId))
{
// An empty ParentAlbumId means that we need to populate the root album
OnlinePictureAlbum rootAlbum = await manager.GetRootPictureAlbumAsync();
// Let's add the top level albums
// Simulate server request to get the top level albums
// (note: this code sample builds the list statically)
List <BingApi.Album> topLevelAlbums = BingApi.GetAlbums();
foreach (BingApi.Album newAlbum in topLevelAlbums)
{
OnlinePictureAlbum album = await manager.GetPictureAlbumByRemoteIdAsync(newAlbum.id);
if (null == album)
{
album = manager.CreatePictureAlbum(newAlbum.id, rootAlbum.Id);
album.Title = newAlbum.title;
// The albums that have the RequiresAuthentication flag set will
// trigger a DownloadImageOperation every time the Photos app needs
// to display an image that hasn't already been downloaded.
album.RequiresAuthentication = newAlbum.authRequired;
await manager.SavePictureAlbumAsync(album);
}
}
}
else
{
// ParentAlbumId is the remote id of the album that we need to populate
OnlinePictureAlbum album = await manager.GetPictureAlbumByRemoteIdAsync(operation.ParentAlbumId);
// Make a network call to get the most recent VersionStamp
string newVersionStamp = await BingApi.GetVersionStampAsync(operation.ParentAlbumId);
// Is up to the app to use the VersionStamp on the album to best suit its needs.
// The OS doesn't use this value. The app can use it to determine if the album is
// up to date. Only trigger a full sync if the album is not up to date.
if (album.VersionStamp != newVersionStamp)
{
// Get all the pictures that are currently in the album
OnlineMediaItemQueryResult query = album.GetContentsQuery();
IList <IOnlineMediaItem> oldPictures = await query.GetItemsAsync();
// Mark all current pictures for deletion
Dictionary <string, OnlinePicture> photosToDelete = new Dictionary <string, OnlinePicture>();
foreach (IOnlineMediaItem item in oldPictures)
{
OnlinePicture onlinePicture = item as OnlinePicture;
if (null != onlinePicture)
{
photosToDelete.Add(onlinePicture.RemoteId, onlinePicture);
}
}
// Contact server to download the metadata for all the items in the album
List <BingApi.Photo> newPhotos = await BingApi.GetAllPhotosMetadataAsync(operation.ParentAlbumId);
// Fill with new photos
List <OnlinePicture> photosToSave = new List <OnlinePicture>();
// Save a reference to the most recent photo among the new photos to use it as the cover for the album
OnlinePicture mostRecent = null;
foreach (BingApi.Photo newPhoto in newPhotos)
{
OnlinePicture onlinePicture = await manager.GetPictureByRemoteIdAsync(newPhoto.id);
if (null == onlinePicture)
{
OnlinePicture localPhoto = manager.CreatePicture(newPhoto.id, album.Id);
localPhoto.Title = newPhoto.title;
localPhoto.CreationTime = newPhoto.timestamp;
localPhoto.ThumbnailSmallUrl = new Uri(newPhoto.smallThumbnailUrl); // required
localPhoto.ThumbnailLargeUrl = new Uri(newPhoto.largeThumbnailUrl); // required
//localPhoto.ContentUrl = new Uri(newPhoto.fullSizeUrl); // optional
photosToSave.Add(localPhoto);
// Check if the current photo is the most recent one
if (null == mostRecent || (localPhoto.CreationTime > mostRecent.CreationTime))
{
mostRecent = localPhoto;
}
if (photosToSave.Count > 500)
{
// Save the photos in one bulk transaction, note the transaction can't be larger than 1000,
// but we break it into 500 for good measure
await manager.SaveMediaItemsAsync(photosToSave);
photosToSave.Clear();
}
}
else
{
// The photo is still on the server. Keep it.
photosToDelete.Remove(newPhoto.id);
}
}
// Most server APIs will provide a distinct cover image
// Here we use the most recent photo update the cover image
if (null != mostRecent &&
album.CoverImageUrl != mostRecent.ThumbnailSmallUrl)
{
await album.SetCoverImageAsync(null);
album.CoverImageUrl = mostRecent.ThumbnailSmallUrl;
}
// Update last modified time
album.VersionStamp = newVersionStamp;
// Calling SavePictureAlbumAsync will flicker the entire album page.
// It can produce a poor user experience if called everytime
// we receive a newDownloadAlbumItemsOperation.
// For that reason, we only call this when the album has been updated.
// So, we always check if the VersionStamp has been updated.
await manager.SavePictureAlbumAsync(album);
// Save all the photos in one bulk transaction:
if (photosToSave.Count > 0)
{
await manager.SaveMediaItemsAsync(photosToSave);
}
// Purge old photos
if (null != photosToDelete)
{
foreach (OnlinePicture photo in photosToDelete.Values)
{
await manager.DeleteMediaItemAsync(photo);
}
}
}
}
Logger.Log("Agent", "Precessing DownloadAlbumItemsOperation for Id=" + operation.ParentAlbumId);
}
catch (Exception e)
{
Helpers.HandleException(e);
}
finally
{
operation.SafeNotifyCompletion();
}
}
