public static extern tobii_error_t tobii_set_display_area(IntPtr device, ref tobii_display_area_t display_area);
public static extern tobii_error_t tobii_calculate_display_area_basic(IntPtr api, float width_mm, float height_mm, float offset_x_mm, ref tobii_geometry_mounting_t geometry_mounting, out tobii_display_area_t display_area);