/// <summary>
/// Function for other classes to poll to get the status of this service
/// </summary>
/// <returns></returns>
public static DownloadsStatusUpdate GetStatus()
{
string message = $"Downloading article {TotalNumArticles - DownloadQueue.Count} out of {TotalNumArticles}.";
if (DownloadQueue.Count == 0)
{
message = "There are currently no articles queued for download.";
}
DownloadsStatusUpdate update;
// We need to lock here so that the queue consumer does not remove from the list while we are trying to make a copy of it to send away.
// We have to make a copy because there are places where we iterate though the list of articles left to download to copy them into an observable,
// and without a copy this service might make a change while it is copying
lock (queueLock)
{
update = new DownloadsStatusUpdate
{
StatusMessage = message,
TotalNumArticlesToDownload = TotalNumArticles,
ArticlesLeftToDownload = DownloadQueue.ToList()
};
}
return(update);
}
/// <summary>
/// Function to update all properties of this page with new information from the download service
/// </summary>
/// <param name="update"></param>
public async void UpdateDownloadStatus(DownloadsStatusUpdate update)
{
StatusText.Text = update.StatusMessage;
await DownloadProgress.ProgressTo((float)update.NumberOfArticlesDownloaded / (float)update.TotalNumArticlesToDownload, 100, Easing.Linear);
// Load all the articles left to download in the articles left to download
// TODO: Make this faster by instead returning the articles that was just downloaded and removing it from the list
downloads.Clear();
foreach (string article in update.ArticlesLeftToDownload)
{
downloads.Add(article);
}
}
public DownloadsPage()
{
InitializeComponent();
GoBackCommand = new Command(GoBack);
backButton.Command = GoBackCommand;
DownloadList.ItemsSource = DownloadListItems;
DownloadsStatusUpdate update = PersistentDownloadService.GetStatus();
if (update.TotalNumArticlesToDownload == 0)
{
StatusText.Text = "There are currently no articles queued for download.";
DownloadProgress.Progress = 0.0;
}
UpdateDownloadStatus(update);
PersistentDownloadService.AddStatusCallBack(UpdateDownloadStatus);
}
/// <summary>
/// Update all subscribed callbacks with the status of the service
/// </summary>
private static void UpdateStatusCallbacks(string message)
{
if (DownloadQueue.Count == 0)
{
message = "There are currently no articles queued for download.";
}
DownloadsStatusUpdate update;
lock (queueLock)
{
update = new DownloadsStatusUpdate
{
StatusMessage = message,
TotalNumArticlesToDownload = TotalNumArticles,
ArticlesLeftToDownload = DownloadQueue.ToList()
};
}
foreach (Action <DownloadsStatusUpdate> action in subscribedStatusCallbacks)
{
Device.BeginInvokeOnMainThread(() => action?.Invoke(update));
}
}
