There is pretty neat Python 3.7 implementation, called Pyto.
It supports numpy, matplotlib and ... pandas!
I just wished it had the same Scene interface as Pythonista or even better supported tkinter or pygame.

I have looked at PyTo and it certainly looks promising.
But I like Pythonista more, I think.

@cvp
Well, that's maybe the way to go, although I prefer to stick with my old fashioned scene_drawing code.

Thanks just the same.

Now that I can display the built up picture (as a SpriteNode), I run into another problem. In my scene.draw method, I now update the SpriteNode's texture and then I want to draw some rectangles and texts with the scene_drawing primitives rect and text.
Unfortunately these do not show up at all, as if they are hidden behind the SpriteNode. I tried to set the SpriteNode's z_position to -1, but that doesn't help.
So my concrete question is: "How can I show the scene_drawing results in front of the SpriteNode?".

@JonB
The PIL image is created for each frame by combining several (sometimes hundreds or thousands) small PIL images. For non-retina resolution it is easy to show them in a scene event loop. For retina resolution I have to escape to a SpriteNode which is filled with a texture for each and every frame.

@mikael
I just found out that if change the file format from PNG to BMP speeds up the animation significantly: from 4 to > 16 fps.

@mikael
Thank you so much for the code you provided.
Based on that I have made a small proof of concept in which I let your rectangle shrink with one point on every draw().
I do that by just changing the texture of self.bg.
That works excellent.
I suppose due to the overhead of

        im.save(fp, 'PNG')
        img = ui.Image.from_data(fp.getvalue(),scale)

, I can reach just 4 frames per second.
Not ideal, but enough for me to try and implement it in my salabim package.

Thanks a lot.

@mikael
Here are the answers to your questions:

If you create and display the image as you show, image quality is not sufficient
Sometimes it is not sufficient and then double resolution would be helpful

If you use a full-scale image, only one quarter of the image is shown?
Yes, that's true.

You are committed to using scene
Yes, because I use the same code base for tkinter I have to rely on a PIL images that are shown in a loop.

Do you have some fps requirement?
Not really, because my package automatically corrects for missed frames, but as it is an animation, there are some performance requirements, for sure.

I can see the screen scale.
But how do I put a Pillow image to a scene in pixels and not points?

@mikael
Essentially my code is

                capture_image = Image.new("RGB", (1122, 834, (0, 0, 0))
               #  build up the image with Pillow
                ims = scene.load_pil_image(capture_image)
                scene.image(ims, 0, 0, *capture_image.size)
                scene.unload_image(ims)

This results (on an iPad Pro 10.5") in a full screen picture.

I would like to double the resolution, so build a Pillow image of 2244 x 1668 pixels and then copy that to the screen.

Any idea how to do that?

By the way, this is part of a much bigger open source simulation library that supports animation on both tkinter and Pythonista platforms. If you are interested have a look at www.salabim.org, where you will find the link to the GitHub repository.