Exception in LocExtension when being used by blend designer

26 Feb 2024, 23:48

I've been tracking down an issue in the blend designer where an exception is being thrown when rendering one of my views.

I have a user control that looks like this:

    public partial class VoiceViewSession : UserControl
    {
        public VoiceViewSession()
        {
            InitializeComponent();
        }

        private static readonly DependencyProperty _labelBackgroundProperty =
            DependencyProperty.Register("SessionLabelBackground", typeof(Brush), typeof(VoiceViewSession), new PropertyMetadata(null));

        public Brush SessionLabelBackground
        {
            get { return (Brush)GetValue(_labelBackgroundProperty); }
            set { SetValue(_labelBackgroundProperty, value); }
        }

        private static readonly DependencyProperty _labelTextProperty =
            DependencyProperty.Register("SessionLabelText", typeof(string), typeof(VoiceViewSession), new PropertyMetadata(null));

        public string SessionLabelText
        {
            get { return (string)GetValue(_labelTextProperty); }
            set { SetValue(_labelTextProperty, value); }
        }

#if NOESIS
        private void InitializeComponent()
        {
            NoesisUnity.LoadComponent(this);
        }
#endif
    }

I'm using this user control in another xaml:

I have a xaml using a custom control:

<local:VoiceViewSession DataContext="{Binding Voice.SessionParty}" SessionLabelBackground="Purple" SessionLabelText="{noesis:Loc Text.InGame.Voice.Channel.Party}"/>

and the problem I'm seeing is that an exception is being thrown from the loc extension in LocExtension.cs, line 46, in the ProvideValue function:

	public override object ProvideValue(IServiceProvider serviceProvider)
	{
		if (!(serviceProvider.GetService(typeof(IProvideValueTarget)) is IProvideValueTarget provideValueTarget))
		{
			return null;
		}
		DependencyObject dependencyObject = (DependencyObject)provideValueTarget.TargetObject;
		DependencyProperty targetProperty = (DependencyProperty)provideValueTarget.TargetProperty; //  <==== Exception being thrown here
		LocMonitor locMonitor = (LocMonitor)dependencyObject.GetValue(MonitorProperty);
		if (locMonitor == null)
		{
			locMonitor = new LocMonitor(dependencyObject);
			dependencyObject.SetValue(MonitorProperty, locMonitor);
		}
		return locMonitor.AddDependencyProperty(targetProperty, _resourceKey);
	}

This is the exception being thrown:

System.InvalidCastException
  HResult=0x80004002
  Message=Unable to cast object of type 'System.Reflection.RuntimePropertyInfo' to type 'System.Windows.DependencyProperty'.
  Source=Noesis.GUI.Extensions
  StackTrace:
   at NoesisGUIExtensions.LocExtension.ProvideValue(IServiceProvider serviceProvider) in NoesisGUIExtensions\LocExtension.cs:line 46

I'm not sure what I might be doing wrong exactly. I'll keep fiddling around with the code here, but thought I'd ask here to see if I'm doing something dumb.

thanks,
sam

27 Feb 2024, 02:54

I'm also sometimes seeing an error on line 45:

		DependencyObject dependencyObject = (DependencyObject)provideValueTarget.TargetObject;

the exception being:

System.InvalidCastException: 'Unable to cast object of type 'System.Windows.SharedDp' to type 'System.Windows.DependencyObject'.'

27 Feb 2024, 13:33

Hi samc,

I have reproduced your issue, it is happening when ProvideValue is called for LocExtension when a template it is in is being loaded. During this call there are no valid targets, and a non-null value should be returned.

Could you create a ticket for this on our bugtacker, I'll provide LocExtension.cs with a fix for this for you to test.

Thanks!

Exception in LocExtension when being used by blend designer

Exception in LocExtension when being used by blend designer

Re: Exception in LocExtension when being used by blend designer

Re: Exception in LocExtension when being used by blend designer

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