How to organize a looped change of pictures?

Question

Programming

How to organize I/O switch model? I pressed the button - the picture changed. Again clicked on it - back to the original. and so on ad infinitum.
ps with the first I coped. how to do the opposite? algorithms? Cycles? any ideas!
How to check the status of which picture is currently active?
if ( Image.Source("uri") )
???

Answer 1

The switch is an object, its state is the boolean parameter isOn. True - enabled, False - disabled. The object also has a toggle() method that does stupidly:
and then calls a method that redraws the picture. The method of drawing a picture is elementary.

Answer 2

For the general case, you can use a circular queue or similar circular containers. Looked at the first element and at the end of it. Everything is trite and simple!