c# - Windows Phone 8.1 媒体元素

Question

我目前有 2 个按钮，Audi TT RS 和 Audi R8当用户点击按钮 TT RS 时，它会播放一个 mp3，当用户点击按钮 R8 时，它会打开一个不同的 mp3 文件。

然而，这有效...如果用户单击其中一个，然后单击另一个。两个 mp3 文件都会打开，但听起来很糟糕。

这些是我的功能:

async void Audir8_Click(object sender, RoutedEventArgs e)
        {
            MediaElement mediaplayer = new MediaElement();
            if (mediaplayer.CurrentState == MediaElementState.Playing)
            {
                mediaplayer.Stop();
            }
            // get folder app is installed to
            var installFolder = Windows.ApplicationModel.Package.Current.InstalledLocation;
            // get folders mp3 files are installed to.
            var resourcesFolder = await installFolder.GetFolderAsync("Resources");
            var mp3FilesFolder = await resourcesFolder.GetFolderAsync("mp3Files");
            // open the mp3 file async
            var audioFile = await mp3FilesFolder.GetFileAsync("audir8.mp3");
            // var stream = await audioFile.OpenAsync(Windows.Storage.FileAccessMode.Read);
            using (var stream = await audioFile.OpenAsync(Windows.Storage.FileAccessMode.Read))
            {
                // play dat funky music
             //   MediaElement mediaplayer = new MediaElement();
                mediaplayer.SetSource(stream, audioFile.ContentType);

                var tcs = new TaskCompletionSource<bool>();
                mediaplayer.CurrentStateChanged += (_, __) =>
                {
                    if (mediaplayer.CurrentState != MediaElementState.Opening &&
                        mediaplayer.CurrentState != MediaElementState.Playing &&
                        mediaplayer.CurrentState != MediaElementState.Buffering)
                    // mediaplayer.CurrentState != MediaElementState.AcquiringLicense)
                    {
                        // Any other state should mean we're done playing
                        tcs.TrySetResult(true);
                    }
                };
                mediaplayer.Play();
                await tcs.Task; // Asynchronously wait for media to finish
            }
        }

还有一个，其实是一样的..

 async void Audittrs_Click(object sender, RoutedEventArgs e)
        {
            MediaElement mediaplayer = new MediaElement();
            if (mediaplayer.CurrentState == MediaElementState.Playing)
            {
                mediaplayer.Stop();
            }
            // get folder app is installed to
            var installFolder = Windows.ApplicationModel.Package.Current.InstalledLocation;
            // get folders mp3 files are installed to.
            var resourcesFolder = await installFolder.GetFolderAsync("Resources");
            var mp3FilesFolder = await resourcesFolder.GetFolderAsync("mp3Files");
            // open the mp3 file async
            var audioFile = await mp3FilesFolder.GetFileAsync("ttrs.mp3");
            // var stream = await audioFile.OpenAsync(Windows.Storage.FileAccessMode.Read);
            using (var stream = await audioFile.OpenAsync(Windows.Storage.FileAccessMode.Read))
            {
                // play dat funky music
              //  MediaElement mediaplayer = new MediaElement();
                mediaplayer.SetSource(stream, audioFile.ContentType);

                var tcs = new TaskCompletionSource<bool>();
                mediaplayer.CurrentStateChanged += (_, __) =>
                {
                    if (mediaplayer.CurrentState != MediaElementState.Opening &&
                        mediaplayer.CurrentState != MediaElementState.Playing &&
                        mediaplayer.CurrentState != MediaElementState.Buffering)
                    // mediaplayer.CurrentState != MediaElementState.AcquiringLicense)
                    {
                        // Any other state should mean we're done playing
                        tcs.TrySetResult(true);
                    }
                };
                mediaplayer.Play();
                await tcs.Task; // Asynchronously wait for media to finish
            }
        }

我认为这不应该发生，因为我正在使用

MediaElement mediaplayer = new MediaElement();
            if (mediaplayer.CurrentState == MediaElementState.Playing)
            {
                mediaplayer.Stop();
            }

Answer 1

当您设置您的媒体播放器局部变量时，您正在创建一个新的媒体播放器，而不是重新使用您之前创建的那个。如果您重新使用之前创建的声音(比如在您的类中将其设为字段加属性)，则 .Stop() 调用应该停止之前的声音。

如果执行此操作，则必须更改每个 ..._Click 方法的第一行以使用持久性 MediaElement。

例如，在你的类里面你可以这样做:

private MediaElement _mediaplayer;

public MediaElement Mediaplayer
{
  get{
    if( _mediaplayer == null )
    {
      _mediaplayer = new MediaElement();
    }
    return _mediaplayer;
  }
}

然后在您的 ..._Click 方法中，换掉这个:

MediaElement mediaplayer = new MediaElement();

...为此:

MediaElement mediaplayer = this.Mediaplayer;

getter 应该完成剩下的工作，确保您始终对播放的各种声音使用相同的 MediaElement，从而允许您根据需要停止之前播放的声音。