I have a WPF application for playing a video and then navigating to another screen. The application plays the video first, and navigating to page2.xaml and again navigating to videos page I get the below exception.
My xaml looks like this:
<Grid HorizontalAlignment="Stretch" VerticalAlignment="Stretch" Name="MainGrid">
<ContentControl x:Name="cntctrl" Content="{Binding VlcObject}" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" />
</Grid>
The VlcObject is an instance of Vlc.DotNet.Wpf.VlcControl and I have noticed that VlcObject.MediaPlayer is being disposed on navigating to the second page. So on navigating to videos page, I am creating a new instance of VlcObject. My ViewModel looks like this:
private Vlc.DotNet.Wpf.VlcControl _vlcObject = null;
public Vlc.DotNet.Wpf.VlcControl VlcObject
{
get { return _vlcObject; }
set { Set(nameof(VlcObject), ref _vlcObject, value); }
}
private void InitialiseVLC()
{
if (VlcObject == null || VlcObject.MediaPlayer.IsDisposed)
{
DispatcherHelper.CheckBeginInvokeOnUI(() =>
{
VlcObject = null;
VlcObject = new Vlc.DotNet.Wpf.VlcControl();
VlcObject.MediaPlayer.VlcLibDirectoryNeeded += MediaPlayer_VlcLibDirectoryNeeded;
VlcObject.MediaPlayer.EndInit();
VlcObject.MediaPlayer.Opening += MediaPlayer_Opening;
VlcObject.MediaPlayer.EndReached += MediaPlayer_EndReached;
VlcObject.MediaPlayer.EncounteredError += MediaPlayer_EncounteredError;
VlcObject.MediaPlayer.Disposed += MediaPlayer_Disposed;
});
}
}
private void MediaPlayer_Disposed(object sender, EventArgs e)
{
Logger.LogInfo("Media Player is disposed.");
DispatcherHelper.CheckBeginInvokeOnUI(() =>
{
try
{
VlcObject.MediaPlayer.VlcLibDirectoryNeeded -= MediaPlayer_VlcLibDirectoryNeeded;
VlcObject.MediaPlayer.Opening -= MediaPlayer_Opening;
VlcObject.MediaPlayer.EndReached -= MediaPlayer_EndReached;
VlcObject.MediaPlayer.EncounteredError -= MediaPlayer_EncounteredError;
VlcObject.MediaPlayer.Disposed -= MediaPlayer_Disposed;
//VlcObject = null;
}
catch (Exception ex)
{
Logger.LogError("Error while disposing MediaPlayer: ");
Logger.LogError(ex);
}
});
}
public void OnNavigatedTo(object parameter, bool isBack = false)
{
InitializeVLC();
}
Here is the exception I get:
System.Windows.Markup.XamlParseException: Set property 'System.Windows.Controls.ContentControl.Content' threw an exception. ---> System.InvalidOperationException: Specified element is already the logical child of another element. Disconnect it first. at System.Windows.FrameworkElement.ChangeLogicalParent(DependencyObject newParent) at System.Windows.FrameworkElement.AddLogicalChild(Object child) at System.Windows.Controls.ContentControl.OnContentChanged(Object oldContent, Object newContent) at System.Windows.Controls.ContentControl.OnContentChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) at System.Windows.DependencyObject.OnPropertyChanged(DependencyPropertyChangedEventArgs e) at System.Windows.FrameworkElement.OnPropertyChanged(DependencyPropertyChangedEventArgs e) at System.Windows.DependencyObject.NotifyPropertyChange(DependencyPropertyChangedEventArgs args) at System.Windows.DependencyObject.UpdateEffectiveValue(EntryIndex entryIndex, DependencyProperty dp, PropertyMetadata metadata, EffectiveValueEntry oldEntry, EffectiveValueEntry& newEntry, Boolean coerceWithDeferredReference, Boolean coerceWithCurrentValue, OperationType operationType) at System.Windows.DependencyObject.SetValueCommon(DependencyProperty dp, Object value, PropertyMetadata metadata, Boolean coerceWithDeferredReference, Boolean coerceWithCurrentValue, OperationType operationType, Boolean isInternal) at System.Windows.Baml2006.WpfKnownMemberInvoker.SetValue(Object instance, Object value) at MS.Internal.Xaml.Runtime.ClrObjectRuntime.SetValue(XamlMember member, Object obj, Object value) at MS.Internal.Xaml.Runtime.ClrObjectRuntime.SetValue(Object inst, XamlMember property, Object value) --- End of inner exception stack trace --- at System.Windows.Markup.XamlReader.RewrapException(Exception e, IXamlLineInfo lineInfo, Uri baseUri) at System.Windows.Markup.WpfXamlLoader.Load(XamlReader xamlReader, IXamlObjectWriterFactory writerFactory, Boolean skipJournaledProperties, Object rootObject, XamlObjectWriterSettings settings, Uri baseUri) at System.Windows.Markup.WpfXamlLoader.LoadBaml(XamlReader xamlReader, Boolean skipJournaledProperties, Object rootObject, XamlAccessLevel accessLevel, Uri baseUri) at System.Windows.Markup.XamlReader.LoadBaml(Stream stream, ParserContext parserContext, Object parent, Boolean closeStream) at System.Windows.Application.LoadBamlStreamWithSyncInfo(Stream stream, ParserContext pc) at MS.Internal.AppModel.AppModelKnownContentFactory.BamlConverter(Stream stream, Uri baseUri, Boolean canUseTopLevelBrowser, Boolean sandboxExternalContent, Boolean allowAsync, Boolean isJournalNavigation, XamlReader& asyncObjectConverter) at MS.Internal.AppModel.MimeObjectFactory.GetObjectAndCloseStream(Stream s, ContentType contentType, Uri baseUri, Boolean canUseTopLevelBrowser, Boolean sandboxExternalContent, Boolean allowAsync, Boolean isJournalNavigation, XamlReader& asyncObjectConverter) at System.Windows.Navigation.NavigationService.GetObjectFromResponse(WebRequest request, WebResponse response, Uri destinationUri, Object navState)
at System.Windows.Navigation.NavigationService.DoNavigate(Uri source, NavigationMode f, Object navState) at System.Windows.Navigation.NavigateQueueItem.Dispatch(Object obj) at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs) at MS.Internal.Threading.ExceptionFilterHelper.TryCatchWhen(Object source, Delegate method, Object args, Int32 numArgs, Delegate catchHandler)
Can some one please help me.
