/** 本例演示如何播放后台音频（以 AudioPlayerAgent 为例，另 AudioStreamingAgent 用于流式播放音频）* 建议使用 AudioPlaybackAgent 类型的模板创建此项目* * BackgroundAgent - 后台代理类，抽象类，它是 ScheduledTaskAgent、AudioPlayerAgent 和 AudioStreamingAgent 的基类*     NotifyComplete() - 用于通知系统，代理已经完成了当前的任务，调用此方法后，系统才会去准备执行下一次任务*     Abort() - 用于通知系统，放弃此次和以后的任务*     OnCancel() - 后台代理被取消时所执行的方法（由系统调用，比如后台代理转到休眠状态或终止状态前会调用此方法）*     * AudioPlayerAgent - 后台播放音频的代理类*     OnError() - 当播放中出现错误时，系统会调用此方法*     OnPlayStateChanged() - 当播放状态发生改变时，系统会调用此方法（错误状态除外）*     OnUserAction() - 当程序改变播放行为时，系统会调用此方法*     * PlayState - Microsoft.Phone.BackgroundAudio.PlayState 枚举*     Unknown, Stopped, Paused, Playing, BufferingStarted, BufferingStopped, TrackReady, TrackEnded, Rewinding, FastForwarding, Shutdown, Error*     * UserAction - Microsoft.Phone.BackgroundAudio.UserAction 枚举*     Stop, Pause, Play, SkipNext, SkipPrevious, FastForward, Rewind, Seek*     * AudioTrack - 音频对象*     Source - 音频的地址，远程地址或独立存储地址均可*     Title - 音频名称*     Duration - 音频时长*     Album - 专辑名称*     AlbumArt - 专辑封面的 Uri 地址，远程地址或独立存储地址均可，如果使用独立存储地址则其目录必须是 Shared/Media*     Artist - 艺术家*     PlayerControls - 锁屏等状态下的播放器控件显示（Microsoft.Phone.BackgroundAudio.EnabledPlayerControls 枚举）*         None = 0, SkipNext = 1, SkipPrevious = 2, FastForward = 4, Rewind = 8, Pause = 16, All = 31*     Tag - 任意内容，即为 AudioTrack 绑定一个上下文数据*     BeginEdit() - 将 AudioTrack 设置为编辑状态（如果需要修改 AudioTrack 的属性则需要将 AudioTrack 设置为编辑状态）*     EndEdit() - 结束 AudioTrack 的编辑状态*/using System;
using System.Windows;
using Microsoft.Phone.BackgroundAudio;using System.Collections.Generic;namespace MyAudioPlayerAgent
{public class AudioPlayer : AudioPlayerAgent{// 播放列表private static List<AudioTrack> _playList = new List<AudioTrack>{new AudioTrack(new Uri("SuperMario.mp3", UriKind.Relative), "title", "artist", "album", null, null, EnabledPlayerControls.Pause),new AudioTrack(new Uri("http://traffic.libsyn.com/wpradio/WPRadio_29.mp3", UriKind.Absolute), "标题", "艺术家", "专辑", null, null, EnabledPlayerControls.All)};// 当前播放的 Track 在整个播放列表中的位置private static int _currentTrackNumber = 0;/** _classInitialized - 用于标记 AudioPlayer 是否已经被初始化*     标记成 volatile 是为了避免编译器认为此字段无外部修改，而将其优化放入寄存器（标记成 volatile 的字段只会放在内存中）*     一般来说，多任务环境下各任务间共享的字段应该被标记为 volatile*/private static volatile bool _classInitialized;public AudioPlayer(){if (!_classInitialized){_classInitialized = true;Deployment.Current.Dispatcher.BeginInvoke(delegate{Application.Current.UnhandledException += AudioPlayer_UnhandledException;});}}private void AudioPlayer_UnhandledException(object sender, ApplicationUnhandledExceptionEventArgs e){if (System.Diagnostics.Debugger.IsAttached){System.Diagnostics.Debugger.Break();}}// 播放状态发生改变时所调用的方法protected override void OnPlayStateChanged(BackgroundAudioPlayer player, AudioTrack track, PlayState playState){switch (playState){case PlayState.TrackReady:player.Play();break;case PlayState.TrackEnded:PlayNextTrack(player);break;case PlayState.Playing:break;case PlayState.Paused:break;case PlayState.Stopped:break;case PlayState.BufferingStarted:break;case PlayState.BufferingStopped:break;case PlayState.Rewinding:break;case PlayState.FastForwarding:break;case PlayState.Shutdown:break;case PlayState.Unknown:break;}NotifyComplete();}// 当程序改变播放行为时所调用的方法protected override void OnUserAction(BackgroundAudioPlayer player, AudioTrack track, UserAction action, object param){switch (action){case UserAction.Play:PlayTrack(player);break;case UserAction.SkipPrevious:PlayPreviousTrack(player);break;case UserAction.SkipNext:PlayNextTrack(player);break;case UserAction.Rewind:player.Rewind();break;case UserAction.FastForward:player.FastForward();break;case UserAction.Seek:player.Position = (TimeSpan)param;break;case UserAction.Pause:player.Pause();break;case UserAction.Stop:player.Stop();break;}NotifyComplete();}// 播放下一个 Trackprivate void PlayNextTrack(BackgroundAudioPlayer player){if (++_currentTrackNumber >= _playList.Count)_currentTrackNumber = 0;PlayTrack(player);}// 播放上一个 Trackprivate void PlayPreviousTrack(BackgroundAudioPlayer player){if (--_currentTrackNumber < 0)_currentTrackNumber = _playList.Count - 1;PlayTrack(player);}// 播放当前 Trackprivate void PlayTrack(BackgroundAudioPlayer player){player.Track = _playList[_currentTrackNumber];}// 出现异常时所调用的方法protected override void OnError(BackgroundAudioPlayer player, AudioTrack track, Exception error, bool isFatal){if (isFatal)Abort();elseNotifyComplete();}// 当后台代理转到休眠状态或终止状态前，系统会自动调用此方法，需要在 5 秒内执行完毕protected override void OnCancel(){}}
}/** 主程序引用此项目后，会在 manifest 中添加如下信息：* <ExtendedTask Name="BackgroundTask">* <BackgroundServiceAgent Specifier="AudioPlayerAgent" Name="MyAudioPlayerAgent" Source="MyAudioPlayerAgent" Type="MyAudioPlayerAgent.AudioPlayer" />* </ExtendedTask>*/

<phone:PhoneApplicationPage x:Class="Demo.Media.BackgroundAudio"xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"xmlns:phone="clr-namespace:Microsoft.Phone.Controls;assembly=Microsoft.Phone"xmlns:shell="clr-namespace:Microsoft.Phone.Shell;assembly=Microsoft.Phone"xmlns:d="http://schemas.microsoft.com/expression/blend/2008"xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"FontFamily="{StaticResource PhoneFontFamilyNormal}"FontSize="{StaticResource PhoneFontSizeNormal}"Foreground="{StaticResource PhoneForegroundBrush}"SupportedOrientations="Portrait" Orientation="Portrait"mc:Ignorable="d" d:DesignHeight="768" d:DesignWidth="480"shell:SystemTray.IsVisible="True"><Grid x:Name="LayoutRoot" Background="Transparent"><StackPanel Orientation="Vertical"><Button x:Name="btnPrev" Content="上一首" Click="btnPrev_Click" /><Button x:Name="btnRewind" Content="快退" Click="btnRewind_Click" /><Button x:Name="btnPlay" Content="播放" Click="btnPlay_Click" /><Button x:Name="btnFastForward" Content="快进" Click="btnFastForward_Click" /><Button x:Name="btnNext" Content="下一首" Click="btnNext_Click" /><TextBlock x:Name="lblCurrentTrack" /><TextBlock x:Name="lblPosition" /></StackPanel></Grid></phone:PhoneApplicationPage>

/** 本例演示如何播放后台音频* * BackgroundAudioPlayer - 提供调用后台播放音频的相关功能*     Instance - 返回 BackgroundAudioPlayer 实例*     Track - 当前的 AudioTrack 对象。说明参见：MyAudioPlayerAgent/AudioPlayer.cs*     PlayerState - 播放器状态（Microsoft.Phone.BackgroundAudio.PlayState 枚举）。说明参见：MyAudioPlayerAgent/AudioPlayer.cs*     Position - 当前 AudioTrack 的播放位置*     CanPause - 是否可暂停*     CanSeek - 是否可以设置 Position 属性*     BufferingProgress - 缓冲百分比（0 - 1之间）*     Volume - 音量（0 - 1之间，默认值为 0.85）。注：目前 wp 没有提供 uvc（Universal Volume Control） 的接口*     *     Play - 播放当前 AudioTrack 的当前位置*     Pause - 暂停*     Stop - 停止*     Rewind - 快退*     FastForward - 快进 *     SkipPrevious - 跳至上一个音频*     SkipNext - 跳至下一个音频*     Close - 关闭并释放所有资源*     *     PlayStateChanged - PlayState 发生改变时所触发的事件*/using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Shapes;
using Microsoft.Phone.Controls;using Microsoft.Phone.BackgroundAudio;
using System.Windows.Navigation;
using System.IO.IsolatedStorage;
using System.Windows.Resources;namespace Demo.Media
{public partial class BackgroundAudio : PhoneApplicationPage{public BackgroundAudio(){InitializeComponent();Init();}protected override void OnNavigatedTo(NavigationEventArgs e){ProcessPlayState();}private void Init(){// 由于播放本地音频时只能从独立存储中播放，所以此处把示例用音频文件从程序包中复制到独立存储using (IsolatedStorageFile storage = IsolatedStorageFile.GetUserStoreForApplication()){if (!storage.FileExists("SuperMario.mp3")){StreamResourceInfo resource = Application.GetResourceStream(new Uri("Assets/SuperMario.mp3", UriKind.Relative));using (IsolatedStorageFileStream file = storage.CreateFile("SuperMario.mp3")){int chunkSize = 4096;byte[] bytes = new byte[chunkSize];int byteCount;while ((byteCount = resource.Stream.Read(bytes, 0, chunkSize)) > 0){file.Write(bytes, 0, byteCount);}}}}CompositionTarget.Rendering += new EventHandler(CompositionTarget_Rendering);BackgroundAudioPlayer.Instance.PlayStateChanged += new EventHandler(Instance_PlayStateChanged);}// 实时更新当前音频播放的位置void CompositionTarget_Rendering(object sender, EventArgs e){if (BackgroundAudioPlayer.Instance != null)lblPosition.Text = BackgroundAudioPlayer.Instance.Position.TotalSeconds.ToString();}void Instance_PlayStateChanged(object sender, EventArgs e){ProcessPlayState();}void ProcessPlayState(){// 指定播放按钮是显示“播放”还是“暂停”switch (BackgroundAudioPlayer.Instance.PlayerState){case PlayState.Playing:btnPlay.Content = "暂停";break;case PlayState.Paused:case PlayState.Stopped:btnPlay.Content = "播放";break;}// 显示音频的 Title 和 Artistif (BackgroundAudioPlayer.Instance.Track != null)lblCurrentTrack.Text = BackgroundAudioPlayer.Instance.Track.Title + " by " + BackgroundAudioPlayer.Instance.Track.Artist;}// 播放或暂停音频private void btnPlay_Click(object sender, RoutedEventArgs e){if (PlayState.Playing == BackgroundAudioPlayer.Instance.PlayerState){BackgroundAudioPlayer.Instance.Pause();}else{BackgroundAudioPlayer.Instance.Play();}}// 跳至下一首音频private void btnNext_Click(object sender, RoutedEventArgs e){BackgroundAudioPlayer.Instance.SkipNext();}// 跳至上一首音频private void btnPrev_Click(object sender, RoutedEventArgs e){BackgroundAudioPlayer.Instance.SkipPrevious();}// 快退private void btnRewind_Click(object sender, RoutedEventArgs e){if (PlayState.Playing == BackgroundAudioPlayer.Instance.PlayerState)BackgroundAudioPlayer.Instance.Rewind();}// 快进private void btnFastForward_Click(object sender, RoutedEventArgs e){if (PlayState.Playing == BackgroundAudioPlayer.Instance.PlayerState)BackgroundAudioPlayer.Instance.FastForward();}}
}