Displaying counter value in video feed using putText - c++

Question

I'm trying to display live counter value on a video feed from camera , I used putText function but it is not working
this is my code i want to display blinks_number on video feed
while (1)
{
int taw1 = taw2;
Mat frame, ycbcr;
cap >> frame; // get a new frame
taw2 = calc_taw(frame);
int delta_taw = taw2 - taw1;
if (delta_taw >= 5)
{
taw_values.push_back(delta_taw);
blinks_number++;
cout << "blink number " << blinks_number << endl;
cout << "taw_values " << taw_values.size() << endl;
putText(frame, blinks_number, Point(50, 100), FONT_HERSHEY_SIMPLEX, 1, Scalar(0, 200, 200), 4);
imshow("Image", image);
CvPlot::plot("Delta taw", &taw_values[0], taw_values.size(), 5, 0, 0, 255);
//showIntGraph("Rotation Angle", &taw_values[0], taw_values.size());
}
waitKey(40);
}
return 0;
}

Answer 1

The text in putText must be a string. You can use std::to_string, or std::stringstream to get the string from a number.
Here's a working example:
#include <opencv2/opencv.hpp>
#include <string>
#include <sstream>
using namespace cv;
int main(int, char**)
{
VideoCapture cap(0); // open the default camera
if (!cap.isOpened()) // check if we succeeded
return -1;
int blinks_number = 1;
for (;;)
{
Mat frame;
cap >> frame; // get a new frame from camera
string disp = "Frame # " + std::to_string(blinks_number);
// Or using stringstream
//
//std::stringstream ss;
//ss << "Frame # " << blinks_number;
//string disp = ss.str();
putText(frame, disp, Point(50, 100), FONT_HERSHEY_SIMPLEX, 1, Scalar(0, 200, 200), 4);
++blinks_number;
imshow("Frame", frame);
if (waitKey(1) >= 0) break;
}
// the camera will be deinitialized automatically in VideoCapture destructor
return 0;
}