/// <summary>
/// Raised when playlist changes to a new track
/// </summary>
/// <param name="sender"></param>
/// <param name="args"></param>
void PlaybackList_CurrentItemChanged(MediaPlaybackList sender, CurrentMediaPlaybackItemChangedEventArgs args)
{
// Get the new item
var item = args.NewItem;
Debug.WriteLine("PlaybackList_CurrentItemChanged: " + (item == null ? "null" : GetTrackId(item).ToString()));
// Update the system view
UpdateUVCOnNewTrack(item);
// Get the current track
Uri currentTrackId = null;
if (item != null)
{
currentTrackId = item.Source.CustomProperties[TrackIdKey] as Uri;
}
// Notify foreground of change or persist for later
if (foregroundAppState == AppState.Active)
{
MessageService.SendMessageToForeground(new TrackChangedMessage(currentTrackId));
}
else
{
ApplicationSettingsHelper.SaveSettingsValue(TrackIdKey, currentTrackId == null ? null : currentTrackId.ToString());
}
}
/// <summary>
/// Fires when a message is recieved from the foreground app
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
void BackgroundMediaPlayer_MessageReceivedFromForeground(object sender, MediaPlayerDataReceivedEventArgs e)
{
foreach (string key in e.Data.Keys)
{
switch (key.ToLower())
{
case Constants.AppSuspended:
Debug.WriteLine("App suspending"); // App is suspended, you can save your task state at this point
foregroundAppState = ForegroundAppStatus.Suspended;
ApplicationSettingsHelper.SaveSettingsValue(Constants.CurrentTrack, Playlist.CurrentTrackName);
ApplicationSettingsHelper.SaveSettingsValue(Constants.BackgroundTaskState, Constants.BackgroundTaskRunning);
break;
case Constants.AppResumed:
Debug.WriteLine("App resuming"); // App is resumed, now subscribe to message channel
foregroundAppState = ForegroundAppStatus.Active;
break;
case Constants.StartPlayback: //Foreground App process has signalled that it is ready for playback
Debug.WriteLine("Starting Playback");
StartPlayback();
break;
case Constants.SkipNext: // User has chosen to skip track from app context.
Debug.WriteLine("Skipping to next");
SkipToNext();
break;
case Constants.SkipPrevious: // User has chosen to skip track from app context.
Debug.WriteLine("Skipping to previous");
SkipToPrevious();
break;
}
}
}
/// <summary>
/// Handles background task cancellation. Task cancellation happens due to:
/// 1. Another Media app comes into foreground and starts playing music
/// 2. Resource pressure. Your task is consuming more CPU and memory than allowed.
/// In either case, save state so that if foreground app resumes it can know where to start.
/// </summary>
private void OnCanceled(IBackgroundTaskInstance sender, BackgroundTaskCancellationReason reason)
{
// You get some time here to save your state before process and resources are reclaimed
Debug.WriteLine("MyBackgroundAudioTask " + sender.Task.TaskId + " Cancel Requested...");
try
{
// immediately set not running
backgroundTaskStarted.Reset();
// save state
ApplicationSettingsHelper.SaveSettingsValue(ApplicationSettingsConstants.TrackId, GetCurrentTrackId() == null ? null : GetCurrentTrackId().ToString());
ApplicationSettingsHelper.SaveSettingsValue(ApplicationSettingsConstants.Position, BackgroundMediaPlayer.Current.Position.ToString());
ApplicationSettingsHelper.SaveSettingsValue(ApplicationSettingsConstants.BackgroundTaskState, BackgroundTaskState.Canceled.ToString());
ApplicationSettingsHelper.SaveSettingsValue(ApplicationSettingsConstants.AppState, Enum.GetName(typeof(AppState), foregroundAppState));
// unsubscribe from list changes
if (playbackList != null)
{
playbackList.CurrentItemChanged -= PlaybackList_CurrentItemChanged;
playbackList = null;
}
// unsubscribe event handlers
BackgroundMediaPlayer.MessageReceivedFromForeground -= BackgroundMediaPlayer_MessageReceivedFromForeground;
smtc.ButtonPressed -= smtc_ButtonPressed;
smtc.PropertyChanged -= smtc_PropertyChanged;
}
catch (Exception ex)
{
Debug.WriteLine(ex.ToString());
}
deferral.Complete(); // signals task completion.
Debug.WriteLine("MyBackgroundAudioTask Cancel complete...");
}
/// <summary>
/// Handles background task cancellation. Task cancellation happens due to :
/// 1. Another Media app comes into foreground and starts playing music
/// 2. Resource pressure. Your task is consuming more CPU and memory than allowed.
/// In either case, save state so that if foreground app resumes it can know where to start.
/// </summary>
private void OnCanceled(IBackgroundTaskInstance sender, BackgroundTaskCancellationReason reason)
{
// You get some time here to save your state before process and resources are reclaimed
Debug.WriteLine("MyBackgroundAudioTask " + sender.Task.TaskId + " Cancel Requested...");
try
{
//save state
ApplicationSettingsHelper.SaveSettingsValue(Constants.CurrentTrack, Playlist.CurrentTrackName);
ApplicationSettingsHelper.SaveSettingsValue(Constants.Position, BackgroundMediaPlayer.Current.Position.ToString());
ApplicationSettingsHelper.SaveSettingsValue(Constants.BackgroundTaskState, Constants.BackgroundTaskCancelled);
ApplicationSettingsHelper.SaveSettingsValue(Constants.AppState, Enum.GetName(typeof(ForegroundAppStatus), foregroundAppState));
backgroundtaskrunning = false;
//unsubscribe event handlers
systemmediatransportcontrol.ButtonPressed -= systemmediatransportcontrol_ButtonPressed;
systemmediatransportcontrol.PropertyChanged -= systemmediatransportcontrol_PropertyChanged;
Playlist.TrackChanged -= playList_TrackChanged;
//clear objects task cancellation can happen uninterrupted
playlistManager.ClearPlaylist();
playlistManager = null;
BackgroundMediaPlayer.Shutdown(); // shutdown media pipeline
}
catch (Exception ex)
{
Debug.WriteLine(ex.ToString());
}
deferral.Complete(); // signals task completion.
Debug.WriteLine("MyBackgroundAudioTask Cancel complete...");
}
/// <summary>
/// Skip track and update UVC via SMTC
/// </summary>
private async Task SkipToNext()
{
int CurrentIndex = Playlist.ToList().FindIndex(m => m.InternalID == CurrentMix.InternalID);
if (CurrentIndex == -1)
{
BackgroundMediaPlayer.Current.Pause();
return;
}
if (CurrentIndex == Playlist.Count() - 1)
{
CurrentIndex = 0;
}
else
{
CurrentIndex++;
}
ApplicationSettingsHelper.SaveSettingsValue(ApplicationSettingsConstants.TrackId, CurrentMix.InternalID);
smtc.PlaybackStatus = MediaPlaybackStatus.Changing;
CurrentMix = Playlist[CurrentIndex];
await PlayCurrentMix();
MessageService.SendMessageToForeground(new TrackChangedMessage(CurrentMix.InternalID));
}
/// <summary>
/// The Run method is the entry point of a background task.
/// </summary>
/// <param name="taskInstance"></param>
public void Run(IBackgroundTaskInstance taskInstance)
{
Debug.WriteLine("Background Audio Task " + taskInstance.Task.Name + " starting...");
// Initialize SystemMediaTransportControls (SMTC) for integration with
// the Universal Volume Control (UVC).
//
// The UI for the UVC must update even when the foreground process has been terminated
// and therefore the SMTC is configured and updated from the background task.
smtc = BackgroundMediaPlayer.Current.SystemMediaTransportControls;
smtc.ButtonPressed += smtc_ButtonPressed;
smtc.PropertyChanged += smtc_PropertyChanged;
smtc.IsEnabled = true;
smtc.IsPauseEnabled = true;
smtc.IsPlayEnabled = true;
smtc.IsNextEnabled = true;
smtc.IsPreviousEnabled = true;
DataObject.DisableDispatcher = true;
// Read persisted state of foreground app
var value = ApplicationSettingsHelper.ReadResetSettingsValue(ApplicationSettingsConstants.AppState);
if (value == null)
{
foregroundAppState = AppState.Unknown;
}
else
{
foregroundAppState = EnumHelper.Parse <AppState>(value.ToString());
}
// Add handlers for MediaPlayer
BackgroundMediaPlayer.Current.CurrentStateChanged += Current_CurrentStateChanged;
BackgroundMediaPlayer.Current.MediaEnded += Current_MediaEnded;
// Initialize message channel
BackgroundMediaPlayer.MessageReceivedFromForeground += BackgroundMediaPlayer_MessageReceivedFromForeground;
// Send information to foreground that background task has been started if app is active
if (foregroundAppState != AppState.Suspended)
{
MessageService.SendMessageToForeground(new BackgroundAudioTaskStartedMessage());
}
ApplicationSettingsHelper.SaveSettingsValue(ApplicationSettingsConstants.BackgroundTaskState, BackgroundTaskState.Running.ToString());
deferral = taskInstance.GetDeferral(); // This must be retrieved prior to subscribing to events below which use it
// Mark the background task as started to unblock SMTC Play operation (see related WaitOne on this signal)
backgroundTaskStarted.Set();
// Associate a cancellation and completed handlers with the background task.
taskInstance.Task.Completed += TaskCompleted;
taskInstance.Canceled += new BackgroundTaskCanceledEventHandler(OnCanceled); // event may raise immediately before continung thread excecution so must be at the end
}
/// <summary>
/// The Run method is the entry point of a background task.
/// </summary>
/// <param name="taskInstance"></param>
public void Run(IBackgroundTaskInstance taskInstance)
{
Debug.WriteLine("Background Audio Task " + taskInstance.Task.Name + " starting...");
// Initialize SMTC object to talk with UVC.
//Note that, this is intended to run after app is paused and
//hence all the logic must be written to run in background process
systemmediatransportcontrol = SystemMediaTransportControls.GetForCurrentView();
systemmediatransportcontrol.ButtonPressed += systemmediatransportcontrol_ButtonPressed;
systemmediatransportcontrol.PropertyChanged += systemmediatransportcontrol_PropertyChanged;
systemmediatransportcontrol.IsEnabled = true;
systemmediatransportcontrol.IsPauseEnabled = true;
systemmediatransportcontrol.IsPlayEnabled = true;
systemmediatransportcontrol.IsNextEnabled = false;
systemmediatransportcontrol.IsPreviousEnabled = false;
systemmediatransportcontrol.IsFastForwardEnabled = false;
// Associate a cancellation and completed handlers with the background task.
taskInstance.Canceled += new BackgroundTaskCanceledEventHandler(OnCanceled);
taskInstance.Task.Completed += Taskcompleted;
var value = ApplicationSettingsHelper.ReadResetSettingsValue(Constants.AppState);
if (value == null)
{
foregroundAppState = ForegroundAppStatus.Unknown;
}
else
{
foregroundAppState = (ForegroundAppStatus)Enum.Parse(typeof(ForegroundAppStatus), value.ToString());
}
//Add handlers for MediaPlayer
BackgroundMediaPlayer.Current.CurrentStateChanged += Current_CurrentStateChanged;
//Add handlers for playlist trackchanged
Playlist.TrackChanged += playList_TrackChanged;
//Initialize message channel
BackgroundMediaPlayer.MessageReceivedFromForeground += BackgroundMediaPlayer_MessageReceivedFromForeground;
//Send information to foreground that background task has been started if app is active
if (foregroundAppState != ForegroundAppStatus.Suspended)
{
ValueSet message = new ValueSet();
message.Add(Constants.BackgroundTaskStarted, "BC Started");
BackgroundMediaPlayer.SendMessageToForeground(message);
}
BackgroundTaskStarted.Set();
backgroundtaskrunning = true;
ApplicationSettingsHelper.SaveSettingsValue(Constants.BackgroundTaskState, Constants.BackgroundTaskRunning);
deferral = taskInstance.GetDeferral();
}
/// <summary>
/// Fires when playlist changes to a new track
/// </summary>
/// <param name="sender"></param>
/// <param name="args"></param>
void playList_TrackChanged(MyPlaylist sender, object args)
{
UpdateUVCOnNewTrack();
ApplicationSettingsHelper.SaveSettingsValue(Constants.CurrentTrack, sender.CurrentTrackName);
if (foregroundAppState == ForegroundAppStatus.Active)
{
//Message channel that can be used to send messages to foreground
ValueSet message = new ValueSet();
message.Add(Constants.Trackchanged, sender.CurrentTrackName);
BackgroundMediaPlayer.SendMessageToForeground(message);
}
}
/// <summary>
/// Raised when playlist changes to a new track
/// </summary>
/// <param name="sender"></param>
/// <param name="args"></param>
void PlaybackList_CurrentItemChanged(MediaPlaybackList sender, CurrentMediaPlaybackItemChangedEventArgs args)
{
//Uri s = GetCurrentTrackId();
// Get the new item
var item = args.NewItem;
Debug.WriteLine("PlaybackList_CurrentItemChanged: " + (item == null ? "null" : Convert.ToString(GetTrackId(item))));
// Update the system view
UpdateUVCOnNewTrack(item);
// Get the current track
Uri currentTrackId = null;
if (item != null)
{
string trackIdKey = item.Source.CustomProperties[TrackIdKey].ToString();
currentTrackId = new Uri(trackIdKey);
}
ApplicationSettingsHelper.SaveSettingsValue(ApplicationSettingsConstants.TrackId, currentTrackId == null ? null : currentTrackId.ToString());
MessageService.SendMessageToForeground(new TrackChangedMessage(currentTrackId));
}
/// <summary>
/// Raised when a message is recieved from the foreground app
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
void BackgroundMediaPlayer_MessageReceivedFromForeground(object sender, MediaPlayerDataReceivedEventArgs e)
{
AppSuspendedMessage appSuspendedMessage;
if (MessageService.TryParseMessage(e.Data, out appSuspendedMessage))
{
Debug.WriteLine("App suspending"); // App is suspended, you can save your task state at this point
foregroundAppState = AppState.Suspended;
var currentTrackId = GetCurrentTrackId();
ApplicationSettingsHelper.SaveSettingsValue(ApplicationSettingsConstants.TrackId, currentTrackId == null ? null : currentTrackId.ToString());
return;
}
AppResumedMessage appResumedMessage;
if (MessageService.TryParseMessage(e.Data, out appResumedMessage))
{
Debug.WriteLine("App resuming"); // App is resumed, now subscribe to message channel
foregroundAppState = AppState.Active;
return;
}
StartPlaybackMessage startPlaybackMessage;
if (MessageService.TryParseMessage(e.Data, out startPlaybackMessage))
{
//Foreground App process has signalled that it is ready for playback
Debug.WriteLine("Starting Playback");
StartPlayback();
return;
}
SkipNextMessage skipNextMessage;
if (MessageService.TryParseMessage(e.Data, out skipNextMessage))
{
// User has chosen to skip track from app context.
Debug.WriteLine("Skipping to next");
SkipToNext();
return;
}
SkipPreviousMessage skipPreviousMessage;
if (MessageService.TryParseMessage(e.Data, out skipPreviousMessage))
{
// User has chosen to skip track from app context.
Debug.WriteLine("Skipping to previous");
SkipToPrevious();
return;
}
TrackChangedMessage trackChangedMessage;
if (MessageService.TryParseMessage(e.Data, out trackChangedMessage))
{
var index = playbackList.Items.ToList().FindIndex(i => (Uri)i.Source.CustomProperties[TrackIdKey] == trackChangedMessage.TrackId);
Debug.WriteLine("Skipping to track " + index);
smtc.PlaybackStatus = MediaPlaybackStatus.Changing;
playbackList.MoveTo((uint)index);
return;
}
UpdatePlaylistMessage updatePlaylistMessage;
if (MessageService.TryParseMessage(e.Data, out updatePlaylistMessage))
{
CreatePlaybackList(updatePlaylistMessage.Songs);
return;
}
}
/// <summary>
/// Raised when a message is recieved from the foreground app
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private async void BackgroundMediaPlayer_MessageReceivedFromForeground(object sender, MediaPlayerDataReceivedEventArgs e)
{
AppSuspendedMessage appSuspendedMessage;
if (MessageService.TryParseMessage(e.Data, out appSuspendedMessage))
{
Debug.WriteLine("App suspending"); // App is suspended, you can save your task state at this point
foregroundAppState = AppState.Suspended;
ApplicationSettingsHelper.SaveSettingsValue(ApplicationSettingsConstants.TrackId, CurrentMix == null ? 0 : CurrentMix.InternalID);
return;
}
AppResumedMessage appResumedMessage;
if (MessageService.TryParseMessage(e.Data, out appResumedMessage))
{
Debug.WriteLine("App resuming"); // App is resumed, now subscribe to message channel
foregroundAppState = AppState.Active;
return;
}
StartPlaybackMessage startPlaybackMessage;
if (MessageService.TryParseMessage(e.Data, out startPlaybackMessage))
{
//Foreground App process has signalled that it is ready for playback
Debug.WriteLine("Starting Playback");
await StartPlayback();
}
SkipNextMessage skipNextMessage;
if (MessageService.TryParseMessage(e.Data, out skipNextMessage))
{
// User has chosen to skip track from app context.
Debug.WriteLine("Skipping to next");
await SkipToNext();
}
SkipPreviousMessage skipPreviousMessage;
if (MessageService.TryParseMessage(e.Data, out skipPreviousMessage))
{
// User has chosen to skip track from app context.
Debug.WriteLine("Skipping to previous");
await SkipToPrevious();
}
TrackChangedMessage trackChangedMessage;
if (MessageService.TryParseMessage(e.Data, out trackChangedMessage))
{
await UpdateOptions();
CurrentMix = Playlist.Single(m => m.InternalID == trackChangedMessage.InternalMixID);
Debug.WriteLine("Skipping to track " + trackChangedMessage.InternalMixID);
smtc.PlaybackStatus = MediaPlaybackStatus.Changing;
await PlayCurrentMix();
}
UpdatePlaylistMessage updatePlaylistMessage;
if (MessageService.TryParseMessage(e.Data, out updatePlaylistMessage))
{
try
{
while (true)
{
try
{
await UpdateOptions();
break;
}
catch
{
}
}
if (updatePlaylistMessage.SendUpdateMessage)
{
MessageService.SendMessageToForeground(new UpdateMediaPlayerInfoMessage(CurrentMix == null ? 0 : CurrentMix.InternalID));
}
}
catch
{
}
}
UpdateUVCOnNewTrack(CurrentMix);
}
