Align images after moving

[mylogon341]

I want to be able to drag and drop these image views, but with them being different sizes I can't see a way to know when they're aligned. With different origin X & Y, widths and heights i'm not sure how to do it.

Can you suggest a way?
Example image here
Thanks

[mylogon341]

I suppose they always intersect, so I could check for that after adding variables for 'neighbouring pieces' or something similar after generating the puzzle.