Okay let me be clear.
There is a polygon. U need to either translate or rotate it.

I need this for a computer based imaging system. The polygon is drawn with the help of mouse randomly.

There is a point inside the polygon. Now am able to translate the polygon using some pre-defined options. But there is no provision for translating the point(within the polygon) and hence it has to be done manually by coding. So what should we do to move the point to its new position with respect to the shifted polygon