No, i know what is setOrigin and getOrigin,
Why getOrigin after setOrigin and moving object doesnt return current pos of origin?
Because getOrigin returns origin. If you have a (50, 50) sized rectangle and setOrigin(25, 25) to place the origin at the center of the rectangle, and then position the rectangle at (1000, 1000) world coordinates, getOrigin would return (25, 25) and getPosition would return (1000,1000). What you are doing by setting origin is changing which pixel of the rectangle will be "sitting on" (1000, 1000).