#include <opencv2/opencv.hpp>

const std::string WINDOW_NAME = "A Scanner Darkly";
const std::string LOWER_THRESHOLD_TRACKBAR_NAME = "Canny: Lower Threshold";
const std::string UPPER_THRESHOLD_TRACKBAR_NAME = "Canny: Upper Threshold";

int g_Canny_lower_threshold = 110;
int g_Canny_upper_threshold = 300;

int main(int argc, char** argv ) {
	cv::VideoCapture cap;
	cap.open(0);

	if (!cap.isOpened()) {
		std::cerr << "Couldn't open capture" << std::endl;
		return -1;
	}

	cv::namedWindow(WINDOW_NAME);
	cv::createTrackbar(LOWER_THRESHOLD_TRACKBAR_NAME, WINDOW_NAME, &g_Canny_lower_threshold, 1000, NULL);
	cv::createTrackbar(UPPER_THRESHOLD_TRACKBAR_NAME, WINDOW_NAME, &g_Canny_upper_threshold, 1000, NULL);

	cv::Mat frame, cannyFrame;
	while (true) {
		cap >> frame;

		cv::Canny(frame, cannyFrame, g_Canny_lower_threshold, g_Canny_upper_threshold);

		cv::imshow(WINDOW_NAME, cannyFrame);

		char c = (char)cv::waitKey(33);
		if (c == 27) {
			break;
		}
	}

	cv::destroyWindow(WINDOW_NAME);
}