Create wallpaper image with scriptable?

I’ve coded a widget to display calendar. This works fine.
Now I want to reuse this code (or extend the code) to create a full black wallpaper which includes 4 calendar sheets.

The widget uses ListWidget with AddStack() to place the multiple calendar parts.
I don’t know how to to do so with an image. I started using DrawContext for the image. But it’s not possible to use AddStack() with that.

Any idea or direction I can do further investigation?