Question

我正在开发一个Android应用程序，以从输入图像中找到最大的轮廓。

我在c ++中找到了一个可行的示例。

我试图将其适应我的项目，并且试图创建一个JNI函数以返回结果。

我一直坚持将找到的轮廓列表从JNI返回到Java。

这是我目前无法使用的JNI代码

extern "C"
jobjectArray
Java_com_grimg_coffretpfe_Activities_CompareActivity_getQuadrilateral(
    JNIEnv *env,
    jobject /* this */,
    jlong grayscale,
    jlong output) {

Mat* mGray = (cv::Mat*) grayscale;
Mat* mOutput = (cv::Mat*) output;

Mat convexHull_mask(mGray->rows, mGray->cols, CV_8UC1);
convexHull_mask = Scalar(0);

vector<vector<Point>> contours;
findContours(*mGray, contours, RETR_EXTERNAL, CHAIN_APPROX_NONE);
vector<int> indices(contours.size());
iota(indices.begin(), indices.end(), 0);

sort(indices.begin(), indices.end(), [&contours](int lhs, int rhs) {
    return contours[lhs].size() > contours[rhs].size();
});

/// Find the convex hull object
vector<vector<Point> >hull(1);
convexHull(Mat(contours[indices[0]]), hull[0], false);

vector<Vec4i> lines;
HoughLinesP(convexHull_mask, lines, 1, CV_PI / 200, 50, 50, 10);

if (lines.size() == 4) // we found the 4 sides
{
    vector<Vec3f> params(4);
    for (int l = 0; l < 4; l++)
    {
        params.push_back(calcParams(Point(lines[l][0], lines[l][1]), Point(lines[l][2], lines[l][3])));
    }

    vector<Point> corners;
    for (int i = 0; i < params.size(); i++)
    {
        for (int j = i; j < params.size(); j++) // j starts at i so we don't have duplicated points
        {
            Point intersec = findIntersection(params[i], params[j]);
            if ((intersec.x > 0) && (intersec.y > 0) && (intersec.x < mGray->cols) && (intersec.y < mGray->rows))
            {
                cout << "corner: " << intersec << endl;
                corners.push_back(intersec);
            }
        }
    }

    if (corners.size() == 4) // we have the 4 final corners
    {
        return(corners);
    }
}

return(vector<Point>());

}

返回值错误，如何更改这段代码以返回那些轮廓？

如何从JNI返回vector <vector <point >>到Java？

0 个答案: