Then, while making this mockup, I discovered a bit of a recurring issue with animations: even though the starting and the final states are laid out with parent-child relations (in this case, the child picture is scaled to fit inside the parent black rectangle), in the middle of the animation you *don't* want this. It makes the animation nonlinear and bad looking.

This is the same reason GNOME Shell overview animation sends windows on slightly curved paths btw.