/// <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; } } }