Dispose media after playing.

Related issue is #40.

App.xaml.cs:
- add: Global UI dispatcher property, so every class can access the UI conventiently.

VideoPlayerPageViewModel.cs:
- rem: Unneeded using system.diagnostics.

VideoPlayerPage.xaml.cs:
- chg: Dispose the media after playing it by wrapping it in a using. This follows the
official LibVLCSharp UWP sample. Replaced lengthy dispatcher calls with App.Current.

OneDrive-Cloud-Player/App.xaml.cs

@@ -9,6 +9,8 @@
 using System.Threading.Tasks;
 using Windows.ApplicationModel;
 using Windows.ApplicationModel.Activation;
+using Windows.ApplicationModel.Core;
+using Windows.UI.Core;
 using Windows.UI.Xaml;
 using Windows.UI.Xaml.Controls;
 using Windows.UI.Xaml.Navigation;
@@ -22,7 +24,7 @@ sealed partial class App : Application
     {
         //Other classes can now call this class with the use of 'App.Current'. 
         public static new App Current => (App)Application.Current;
-
+        public CoreDispatcher UIDispatcher { get; private set; }
         public IPublicClientApplication PublicClientApplication { get; private set; }
         public string[] Scopes { get; private set; }
         public CacheHelper CacheHelper { get; private set; }
@@ -111,6 +113,8 @@ protected override async void OnLaunched(LaunchActivatedEventArgs e)
                 // Ensure the current window is active
                 Window.Current.Activate();
             }
+
+            UIDispatcher = CoreApplication.MainView.CoreWindow.Dispatcher;
         }
 
         /// <summary>

OneDrive-Cloud-Player/ViewModels/VideoPlayerPageViewModel.cs

@@ -12,7 +12,6 @@
 using System.Threading.Tasks;
 using System.Timers;
 using System.Windows.Input;
-using Windows.ApplicationModel.Core;
 using Windows.Storage;
 using Windows.System;
 using Windows.UI.Core;
@@ -254,7 +253,7 @@ private async void InitializeLibVLC(InitializedEventArgs eventArgs)
         private async void MediaPlayer_Playing(object sender, EventArgs e)
         {
             Debug.WriteLine(DateTime.Now.ToString("hh:mm:ss.fff") + ": Media is playing");
-            await CoreApplication.MainView.CoreWindow.Dispatcher.RunAsync(CoreDispatcherPriority.High, () =>
+            await App.Current.UIDispatcher.RunAsync(CoreDispatcherPriority.High, () =>
             {
                 MediaVolumeLevel = (int)this.localMediaVolumeLevelSetting.Values["MediaVolume"];
                 Debug.WriteLine(DateTime.Now.ToString("hh:mm:ss.fff") + ": Set volume in container: " + this.localMediaVolumeLevelSetting.Values["MediaVolume"]);
@@ -269,15 +268,15 @@ await CoreApplication.MainView.CoreWindow.Dispatcher.RunAsync(CoreDispatcherPrio
 
         private async void MediaPlayer_Paused(object sender, EventArgs e)
         {
-            await CoreApplication.MainView.CoreWindow.Dispatcher.RunAsync(CoreDispatcherPriority.Low, () =>
+            await App.Current.UIDispatcher.RunAsync(CoreDispatcherPriority.Low, () =>
             {
                 PlayPauseButtonFontIcon = "\xE768";
             });
         }
 
         private async void MediaPlayer_TimeChanged(object sender, EventArgs e)
         {
-            await CoreApplication.MainView.CoreWindow.Dispatcher.RunAsync(CoreDispatcherPriority.Low, () =>
+            await App.Current.UIDispatcher.RunAsync(CoreDispatcherPriority.Low, () =>
             {
                 // Updates the value of the seekbar on TimeChanged event
                 // when the user is not seeking.
@@ -300,7 +299,7 @@ private void ReloadIntervalTimer_Elapsed(object sender, ElapsedEventArgs e)
 
         private async void FileNameOverlayTimer_Elapsed(object sender, ElapsedEventArgs e)
         {
-            await CoreApplication.MainView.CoreWindow.Dispatcher.RunAsync(CoreDispatcherPriority.Low, () =>
+            await App.Current.UIDispatcher.RunAsync(CoreDispatcherPriority.Low, () =>
             {
                 FileNameOverlayVisiblity = Visibility.Collapsed;
             });
@@ -338,7 +337,10 @@ private async Task PlayMedia(long startTime = 0)
 
             string mediaDownloadURL = await RetrieveDownloadURLMedia(MediaWrapper);
             // Play the OneDrive file.
-            MediaPlayer.Play(new Media(LibVLC, new Uri(mediaDownloadURL)));
+            using (Media media = new Media(LibVLC, new Uri(mediaDownloadURL)))
+            {
+                MediaPlayer.Play(media);
+            }
 
             if (MediaPlayer is null)
             {

OneDrive-Cloud-Player/Views/VideoPlayerPage.xaml.cs

@@ -1,6 +1,5 @@
 using OneDrive_Cloud_Player.ViewModels;
 using System;
-using System.Diagnostics;
 using Windows.System;
 using Windows.UI.Core;
 using Windows.UI.ViewManagement;