GLWpfControl.Loaded event doesn't seem to be called, unless an additional delegate is added

[chadvandy]

Having a strange behavior where the GLWpfControl.OnLoaded() method, which just invalidates the visual of the control once it's loaded to be properly drawn, isn't run automatically, unless I specifically assign a new delegate to GLWpfControl.Loaded.

public DrawingDemo()
{
	Debug.WriteLine("Creating the DemoControl!");
	InitializeComponent();

	DemoControl.Loaded += ControlLoaded;
	Loaded += OnLoad;
	Unloaded += OnUnload;
}

private void ControlLoaded(object sender, RoutedEventArgs e)
{
	Debug.WriteLine("DemoControl loaded by OpenGL!");
}

If I comment out DemoControl.Loaded += ControlLoaded:

• The OpenGL Content remains grey until I manually resize the window.

If I keep it in:

• Automatically renders the drawn content, since InvalidateVisual() is called very early.

I'm using the LearnOpenTK tutorial right now, and I do understand there are some differences between the base assumption implementation (having the GameWindow and such) versus how it works in GLWpfControl, so I'm sure I may be misunderstanding something.
 
Using OpenTK 4.8.2, GLWpfControl 4.2.3, .NET Core 8.0.4, Visual Studio 2022 17.9.6.

Thanks for your help, and thanks for this project!

[NogginBops]

Are you calling Start() anywhere? For the GLWpfControl to work you need to call Start.

[NogginBops]

Did a little bit of testing and couldn't easily find a way to reproduce this. Will move it to 4.3.1 if this turns out to be a bug we need to fix.

[NogginBops]

Moving this to the next version. If there are no updates on this issue I'll likely close it next version.

[mathew-odwyer]

This is also the case for me, as a work around I just have a boolean in my render function used to check whether any initialization/loading logic needs to be executed first.

[mathew-odwyer]

actually no, this is not the case for me. Instead, the GLWpfControl.Loaded event is never triggered at all for me. I've had to instead add a condition in my render event to initialize everything first.

The Loaded event fires. The issue I'm having is that the Render event occurs before the Loaded event.

public class TestControl : UserControl
{
    public void TestControl()
    {
	this.glWpfControl.Loaded += this.GlWpfControl_Loaded;
	this.glWpfControl.Render += this.GlWpfControl_Render;
	
        this.glWpfControl.Start(new GLWpfControlSettings()
	{
		MajorVersion = 4,
		MinorVersion = 6,
		GraphicsProfile = ContextProfile.Core,
		GraphicsContextFlags = ContextFlags.ForwardCompatible,
		RenderContinuously = true,
		UseDeviceDpi = true,
	});
    }
    
    private void GlWpfControl_Loaded(object sender, RoutedEventArgs e)
    {
        Console.WriteLine("Loaded"):
    }
	
    private void GlWpfControl_Render(TimeSpan obj)
    {
        Console.WriteLine("Render"):
    }
}

Output is:

Render
Loaded
Render
Render
..etc