struct custom_point {
	int y;
	int x;
	byte dir;
};

void findContour() {
	char fname[MAX_PATH];
	while (openFileDlg(fname)) {
		Mat src = imread(fname, CV_LOAD_IMAGE_GRAYSCALE);
		Mat dst = Mat(src.size(), CV_LOAD_IMAGE_GRAYSCALE);

		std::vector<custom_point> contur;
		int n = 0;
		byte dir = 7;
		int x, y;

		int dj[8] = { 1, 1, 0, -1, -1, -1, 0, 1 };
		int di[8] = { 0, -1, -1, -1, 0, 1, 1, 1 };

		int I = 0, J = 0;

		for (int i = 0; i < src.rows; i++) {
			for (int j = 0; j < src.cols; j++) {
				dst.at<uchar>(i, j) = 255;
			}
		}

		bool ok = true;
		for (int i = 0; i < src.rows && ok; i++) {
			for (int j = 0; j < src.cols && ok; j++) {
				if (src.at<uchar>(i, j) == 0) {
					dst.at<uchar>(i, j) = 0;
					contur.push_back(custom_point{ i, j, dir });
					I = i;
					J = j;
					ok = false;
				}
			}
		}

		bool finished = false;
		byte d = 0;

		while (!finished) {
			if (dir % 2 == 0) {
				dir = (dir + 7) % 8;
			} else {
				dir = (dir + 6) % 8;
			}

			for (int k = 0; k < 8; k++) {
				d = (dir + k) % 8;
				y = J + dj[d];
				x = I + di[d];

				if (src.at<uchar>(x, y) == 0) {
					dir = d;
					dst.at<uchar>(x, y) = 0;
					contur.push_back(custom_point{ x, y, dir });
					I = x;
					J = y;
					n++;
					break;
				}
			}

			if (n > 1) {
				if ((contur[0].x == contur[n - 1].x) && (contur[1].x == contur[n].x) &&
					(contur[0].y == contur[n - 1].y) && (contur[1].y == contur[n].y)) {
					finished = true;
				}
			}

		}

		imshow("Img", src);
		imshow("New Img", dst);
		waitKey();
	}
}