C# AudioTrack.EndEdit方法代码示例

        async Task RunStreamingAsync(AudioTrack track, AudioStreamer streamer)
        {
            IMediaStreamFacade mediaStreamFacade = null;

            try
            {
                if (null == track || null == track.Tag)
                {
                    Debug.WriteLine("AudioTrackStreamer.RunStreamingAsync() null url");
                    return;
                }

                Uri url;
                if (!Uri.TryCreate(track.Tag, UriKind.Absolute, out url))
                {
                    Debug.WriteLine("AudioTrackStreamer.RunStreamingAsync() invalid url: " + track.Tag);
                    return;
                }

                var defaultTitle = "Unknown";

                var mediaTrack = TrackManager.Tracks.Where(t => null != t).FirstOrDefault(t => t.Url == url);

                if (null != mediaTrack)
                    defaultTitle = mediaTrack.Title;

                _metadataHandler.DefaultTitle = defaultTitle;

                if (!string.Equals(track.Title, defaultTitle))
                {
                    track.BeginEdit();
                    track.Title = defaultTitle;
                    track.EndEdit();
                }

                mediaStreamFacade = await InitializeMediaStreamAsync().ConfigureAwait(false);

                Debug.Assert(null != mediaStreamFacade);

                MediaStreamSource mss;
                if (null != mediaTrack)
                    mss = await mediaStreamFacade.CreateMediaStreamSourceAsync(mediaTrack, _cancellationTokenSource.Token).ConfigureAwait(false);
                else
                    mss = await mediaStreamFacade.CreateMediaStreamSourceAsync(url, _cancellationTokenSource.Token).ConfigureAwait(false);

                if (null == mss)
                {
                    Debug.WriteLine("AudioTrackStreamer.RunStreamingAsync() unable to create media stream source");
                }
                else
                {
                    streamer.SetSource(mss);

                    await mediaStreamFacade.PlayingTask.ConfigureAwait(false);

                    return;
                }
            }
            catch (OperationCanceledException)
            {
                return;
            }
            catch (Exception ex)
            {
                Debug.WriteLine("AudioTrackStreamer.RunStreamingAsync() failed: " + ex.ExtendedMessage());
            }

            if (null == mediaStreamFacade)
                return;

            await CleanupMediaStreamFacadeAsync(mediaStreamFacade).ConfigureAwait(false);
        }

        /// <summary>
        /// Called when the playstate changes, except for the Error state (see OnError)
        /// </summary>
        /// <param name="player">The BackgroundAudioPlayer</param>
        /// <param name="track">The track playing at the time the playstate changed</param>
        /// <param name="playState">The new playstate of the player</param>
        /// <remarks>
        /// Play State changes cannot be cancelled. They are raised even if the application
        /// caused the state change itself, assuming the application has opted-in to the callback.
        /// 
        /// Notable playstate events: 
        /// (a) TrackEnded: invoked when the player has no current track. The agent can set the next track.
        /// (b) TrackReady: an audio track has been set and it is now ready for playack.
        /// 
        /// Call NotifyComplete() only once, after the agent request has been completed, including async callbacks.
        /// </remarks>
        protected override void OnPlayStateChanged(BackgroundAudioPlayer player, AudioTrack track, PlayState playState)
        {
            switch (playState)
            {
                case PlayState.TrackEnded:
                    if (currentPlaylist.Count > 0)
                        player.Track = GetNextTrack();
                    break;
                case PlayState.TrackReady:
                    track.BeginEdit();
                    track.Title = currentPlaylist[currentTrackNumber].Title;
                    track.EndEdit();
                    player.Play();
                    break;
                case PlayState.Shutdown:
                    // TODO: Handle the shutdown state here (e.g. save state)
                    player.Close();
                    break;
                case PlayState.Unknown:
                    break;
                case PlayState.Stopped:
                    break;
                case PlayState.Paused:
                    break;
                case PlayState.Playing:
                    break;
                case PlayState.BufferingStarted:
                    track.BeginEdit();
                        track.Title = "Buffering...";
                    track.EndEdit();
                    break;
                case PlayState.BufferingStopped:
                    track.BeginEdit();
                    track.Title = currentPlaylist[currentTrackNumber].Title;
                    track.EndEdit();
                    break;
                case PlayState.Rewinding:
                    track.BeginEdit();
                    track.Title = "Rewinding...";
                    track.EndEdit();
                    break;
                case PlayState.FastForwarding:
                    track.BeginEdit();
                    track.Title = "FastForwarding...";
                    track.EndEdit();
                    break;
            }

            NotifyComplete();
        }