/// <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);
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
{
//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>
/// Fires when playlist changes to a new track
/// </summary>
/// <param name="sender"></param>
/// <param name="args"></param>
void playList_TrackChanged(MyPlaylist sender, object args)
{
string title;
if (args is string)
{
title = args.ToString();
}
else
{
title = Playlist.CurrentTrackName;
}
UpdateUVCOnNewTrack(title);
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, title);
BackgroundMediaPlayer.SendMessageToForeground(message);
}
}
/// <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...");
//SystemMediaTransportControls，是按下音量键后顶部弹出的控制音乐播放的控件。
//设置 SystemMediaTransportControls 的各个按键属性以及事件的订阅
systemmediatransportcontrol = SystemMediaTransportControls.GetForCurrentView();
systemmediatransportcontrol.ButtonPressed += systemmediatransportcontrol_ButtonPressed;
systemmediatransportcontrol.PropertyChanged += systemmediatransportcontrol_PropertyChanged;
systemmediatransportcontrol.IsEnabled = true;
systemmediatransportcontrol.IsPauseEnabled = true;
systemmediatransportcontrol.IsPlayEnabled = true;
systemmediatransportcontrol.IsNextEnabled = true;
systemmediatransportcontrol.IsPreviousEnabled = true;
// 关联取消 后台任务处理完成
taskInstance.Canceled += new BackgroundTaskCanceledEventHandler(OnCanceled);
taskInstance.Task.Completed += Taskcompleted;
//读取应用程序状态
var value = ApplicationSettingsHelper.ReadResetSettingsValue(Constants.AppState);
if (value == null)
{
foregroundAppState = ForegroundAppStatus.Unknown;
}
else
{
foregroundAppState = (ForegroundAppStatus)Enum.Parse(typeof(ForegroundAppStatus), value.ToString());
}
//添加在媒体播放器状态发生更改时处理函数
BackgroundMediaPlayer.Current.CurrentStateChanged += Current_CurrentStateChanged;
//Add handlers for playlist trackchanged
//添加 后台播放列表变更时处理函数
Playlist.TrackChanged += playList_TrackChanged;
Playlist.TrackComplete += playList_TrackComplete;
//初始化消息通道 前台发往后台的信息
BackgroundMediaPlayer.MessageReceivedFromForeground += BackgroundMediaPlayer_MessageReceivedFromForeground;
//Send information to foreground that background task has been started if app is active
//将信息发送到前景中的后台任务已经启动，如果应用程序被激活
if (foregroundAppState != ForegroundAppStatus.Suspended)
{
ValueSet message = new ValueSet();
message.Add(Constants.BackgroundTaskStarted, "");
BackgroundMediaPlayer.SendMessageToForeground(message);
}
BackgroundTaskStarted.Set();
backgroundtaskrunning = true;
ApplicationSettingsHelper.SaveSettingsValue(Constants.BackgroundTaskState, Constants.BackgroundTaskRunning);
object value11 = ApplicationSettingsHelper.ReadResetSettingsValue(Constants.BackgroundTaskState);
deferral = taskInstance.GetDeferral();
}
/// <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 = true;
systemmediatransportcontrol.IsPreviousEnabled = true;
// 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, "");
BackgroundMediaPlayer.SendMessageToForeground(message);
}
BackgroundTaskStarted.Set();
backgroundtaskrunning = true;
ApplicationSettingsHelper.SaveSettingsValue(Constants.BackgroundTaskState, Constants.BackgroundTaskRunning);
deferral = taskInstance.GetDeferral();
}
/// <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 (var one in e.Data)
{
string key = one.Key;
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);
break;
case Constants.AppResumed:
Debug.WriteLine("App resuming"); // App is resumed, now subscribe to message channel
foregroundAppState = ForegroundAppStatus.Active;
break;
case Constants.Trackat: // User has chosen to skip track from app context.
foregroundAppState = ForegroundAppStatus.Active;
Debug.WriteLine("play to Trackat");
Trackat(one.Value.ToString());
break;
case Constants.StartPlayback: //Foreground App process has signalled that it is ready for playback
foregroundAppState = ForegroundAppStatus.Active;
Debug.WriteLine("Starting Playback");
StartPlayback();
break;
case Constants.SkipNext: // User has chosen to skip track from app context.
foregroundAppState = ForegroundAppStatus.Active;
Debug.WriteLine("Skipping to next");
SkipToNext();
break;
case Constants.SkipPrevious: // User has chosen to skip track from app context.
foregroundAppState = ForegroundAppStatus.Active;
Debug.WriteLine("Skipping to previous");
SkipToPrevious();
break;
case Constants.conCurrentFile:
Debug.WriteLine("Play current File");
object value = string.Empty;
bool rev = e.Data.TryGetValue(Constants.conCurrentFile, out value);
if (rev)
{
string fileToken = value.ToString();
StartFile(fileToken);
}
break;
case Constants.conPlaySingleFile:
object v = string.Empty;
bool bl = e.Data.TryGetValue(Constants.conPlaySingleFile, out v);
if (bl)
{
string fileToken = v.ToString();
StartSingleFile(fileToken);
}
break;
case Constants.conPlayByIndex:
object vByindex = string.Empty;
bool bplay = e.Data.TryGetValue(Constants.conPlayByIndex, out vByindex);
if (bplay)
{
int index = Convert.ToInt32(vByindex);
StartPlayback(index);
}
break;
}
}
}
