code update with opencv 3.4 tracking module

dnn_tutorial/tracking_demo.cpp

@@ -0,0 +1,39 @@
+#include <opencv2/opencv.hpp>
+#include <opencv2/tracking.hpp>
+#include <iostream>
+
+using namespace cv;
+using namespace std;
+
+int main(int artc, char** argv) {
+	Rect2d roi;
+	Mat frame;
+
+	// create a tracker object
+	Ptr<Tracker> tracker = TrackerKCF::create();
+	VideoCapture capture("D:/images/video/balltest.mp4");
+
+	// select roi
+	capture.read(frame);
+	roi = selectROI("tracker", frame);
+	// roi = selectROI(frame);
+
+	// init tracker with roi
+	tracker->init(frame, roi);
+
+	// update tracking roi for each frame
+	while (true) {
+		bool ret = capture.read(frame);
+		if (!ret) break;
+		tracker->update(frame, roi);
+		rectangle(frame, roi, Scalar(0, 0, 255), 2, 8, 0);
+		imshow("tracker", frame);
+		char c = waitKey(50);
+		if (c == 27) {
+			break;
+		}
+	}
+
+	waitKey(0);
+	return 0;
+}