In WinUI 3 How do I capture a MediaTransportControl event?

Question

I have a simple MediaPlayerElement defined in xaml and I would like to run some c# code when a user hits the play button on the transport controls but I can't find an event handle exposed to XAML to do that. Can it be done? ...

<MediaPlayerElement
Visibility="Visible"
x:Name="mp" 
Source="C:/Users/Brian/Videos/happy.mp4"
AutoPlay="False"
AreTransportControlsEnabled="True"
Stretch="UniformToFill"
>

 </MediaPlayerElement>

Answer 1

You need to use the MediaPlayer inside the MediaPlayerElement and subscribe to its CurrentStateChanged:

this.MediaPlayerElementConrol.MediaPlayer.CurrentStateChanged += MediaPlayer_CurrentStateChanged;

and

private void MediaPlayer_CurrentStateChanged(MediaPlayer sender, object args)
{
    if (sender.PlaybackSession.PlaybackState is MediaPlaybackState.Playing)
    {
        // Your logic here...
    }
}

or if you need the Click event of the play button, which is an AppBarButton named PlayPauseButton:

this.MediaPlayerElementConrol.Loaded += MediaPlayerElementConrol_Loaded;

then

private void MediaPlayerElementConrol_Loaded(object sender, e)
{
    if (this.MediaPlayerElementConrol.FindDescendant<AppBarButton>(x => x.Name is "PlayPauseButton") is AppBarButton playPauseButton)
    {
        playPauseButton.Click -= PlayPauseButton_Click;
        playPauseButton.Click += PlayPauseButton_Click;
    }
}

private void PlayPauseButton_Click(object sender, e)
{
    if (this.MediaPlayerElementConrol.MediaPlayer.PlaybackSession.PlaybackState is Windows.Media.Playback.MediaPlaybackState.Paused)
    {
        // Your logic here...
    }
}

NOTE:

FindDescendants comes from the CommunityToolkit.WinUI.Extensions NuGet package.