Xamarin Forms SKGLView not rendering on iOS

[freever]

Hi

I have a Xamarin.Forms project that renders a 2D map inside a container. The map itself uses an SKCanvasView control to do its drawing, and this works well on iOS, Android and UWP.

I want to switch to an SKGLView to improve performance. The two APIs are almost identical so it's easy to swap in one for the other, and this works on Android and UWP to good effect. The performance boost on Android is particularly significant.

However when I run the same code on iOS I get a black screen and the following error:

Failed to bind EAGLDrawable: <CAEAGLLayer: 0x1c2a3b840> to GL_RENDERBUFFER 1
Failed to make complete multisample framebuffer object 8cd6
Failed to make complete framebuffer object 8cd6

As far as I can tell, this has something to do with rendering on a view that isn't visible, so I've hooked in to Xamarin.Forms OnAppearing and OnDisappearing events to attempt the render only when the view is visible, however it doesn't help.

I don't know if my understanding of the problem is correct, or if it is, are there better ways to solve it. Could you perhaps suggest something?

Thanks

VS bug #770232

[freever]

I thought perhaps this question belongs on Stackoverflow

https://stackoverflow.com/questions/52552213/skiasharp-skglview-fails-to-render-on-ios-failed-to-bind-eagldrawabl

[charlenni]

We have the same problem on iOS. I assume, that if you call InvalidateSurface() of the SKGLView and don't check, if a GrContext exists, than you get this error.

I would suggest to check this before creating the render loop in OnSurfaceInvalidated() of SKGLViewRenderBase. It should be

// the user asked to repaint
private void OnSurfaceInvalidated(object sender, EventArgs eventArgs)
{
	// if we aren't in a loop, then refresh once
	if (GrContext != null && !Element.HasRenderLoop)
	{
		SetupRenderLoop(true);
	}
}

[mattleibow]

This may be a bigger issue... What happens if the view is created, shown and then hidden? The context will still have been created, but may no longer be valid. I must check to see if there are hooks to see if the context (either the GLES or the GR) is still valid. Also need to test on other platforms.

[charlenni]

I tested it only with a one screen app. There work turning off the device and change to another app. But I have not check, what happens, if I display another page and than go back.

[mattleibow]

I know this is a very old issue, but does anyone know if this is still happening? Does this happen with .NET MAUI?