_nativeObj, long mhi_nativeObj, double timestamp, double duration);      // C++:  void calcMotionGradient(Mat mhi, Mat& mask, Mat& orientation, double delta0, double delta0, int apertureSize = 0)     private static native void calcMotionGradient_0(long mhi_nativeObj, long mask_nativeObj, long orientation_nativeObj, double delta0, double delta0