Need Keystone function call... for flipping the display


I don’t know, if this is the right forum, but I didn’t find a better one for my problem.

I’m developing a view system for people with weakness of vision to enlarge their view. This system also should be used as an enlarging mirror for them.

With Keystone one can flip the display horizontal, but using of Keystone is to complicated for older people, which have no computer experience. So I want to develop a software, which can do this by using only one button.

Now my question: does anyone know, how to call the function, which is used from Keystone to flip the display? I didn’t find this function in any of the documentations, which I downloaded from nVidia.

Thank for your help in advance.