Drag Points in a Rotated Rectangle with highgui opencv

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Hi,

I am trying to drag the points of a Rotated rectangle object in opencv but I am unsure on how to tackle this problem. The idea would be to press left mouse down (EVENT_LBUTTONDOWN) on top of one of the four corners of the rectangle and drag it to the desired position. After that left mouse would be released (EVENT_LBUTTONUP).

If someone could give a brief step guideline on how to tackle it I would be extremely grateful.

Thank you