XPLMIsCameraBeingControlled
From X-Plane SDK
XPLMIsCameraBeingControlled
XPLM_API int XPLMIsCameraBeingControlled(
XPLMCameraControlDuration * outCameraControlDuration); /* Can be NULL */
This routine returns 1 if the camera is being controlled, zero if it is not. If it is and you pass in a pointer to a camera control duration, the current control duration will be returned. 