Java 安卓JNI c++；FastFeatureDetector can'；行不通

我正在开发一个Android应用程序，其中JNI代码和这段代码使用OpenCV库。但是我有一些问题

在我的*.cpp文件中，我无法在FastFeatureDetector之后的图像上绘制关键点。我不知道如何调试。谢谢大家!

->*.cpp

JNIEXPORT void JNICALL Java_com_project_pic_1mat_MainActivity_fast (JNIEnv *env, jobject thiz, jintArray buf,jint w, jint h)
{

        jint *cbuf;
        cbuf = env->GetIntArrayElements(buf, NULL);
        if(cbuf == 0)
        {
            return 0;
        }
        Mat image(h, w, CV_8UC4, (unsigned char*) buf);
        vector<KeyPoint> keypoints; 
        FastFeatureDetector fast(100);
        fast.detect(image, keypoints);

        for(unsigned int i=0;i<keypoints.size();i++)
        {
            const KeyPoint& kp = keypoints[i];
            circle(image, Point(kp.pt.x, kp.pt.y), 10, cvScalar(255, 0, 255));
        }
        //drawKeypoints(image, keypoints, image, Scalar::all(255), 1); 
        int size = w * h;
        jintArray result = env->NewIntArray(size);
        env->SetIntArrayRegion(result, 0, size, cbuf); 
        env->ReleaseIntArrayElements(buf, cbuf, 0);
        return result;
}

 Bitmap bmp = BitmapFactory.decodeResource(getResources(), R.drawable.lena);
 int w = bmp.getWidth();
 int h = bmp.getHeight();
 int[] pixels = new int[w * h];
 bmp.getPixels(pixels, 0, w, 0, 0, w, h);
 int[] resultInt = MainActivity.gray(pixels, w, h);
 Bitmap grayimg = Bitmap.createBitmap(w, h, Config.ARGB_8888);
 grayimg.setPixels(resultInt, 0, w, 0, 0, w, h); 
 grayimg.getPixels(pixels, 0, w, 0, 0, w, h);
 int[] result_fast = MainActivity.fast(pixels, w, h);
 Bitmap fastimg = Bitmap.createBitmap(w, h, Config.ARGB_8888);
 fastimg.setPixels(result_fast, 0, w, 0, 0, w, h);
 imgView.setImageBitmap(fastimg);