#include "opencv2/core/utility.hpp"

#include "opencv2/imgproc.hpp"

#include "opencv2/imgcodecs.hpp"

#include "opencv2/highgui.hpp"

#include <stdio.h>

using namespace cv;

using namespace std;

int edgeThresh = 1;

Mat image, gray, edge, cedge;

// define a trackbar callback

static void onTrackbar(int, void*)

{

    /* Step one */

    blur(gray, edge, Size(3,3));

    // Run the edge detector on grayscale

    Canny(edge, edge, edgeThresh, edgeThresh*3, 3);

    cedge = Scalar::all(0);

    /*

     * Jeff --> the second parameter is mask.

     */

    image.copyTo(cedge, edge);

    imshow("Edge map", cedge);

}

static void help()

{

    printf("\nThis sample demonstrates Canny edge detection\n"

           "Call:\n"

           "    /.edge [image_name -- Default is ../data/fruits.jpg]\n\n");

}

const char* keys =

{

    "{help h||}{@image |../data/fruits.jpg|input image name}"

};

int main( int argc, const char** argv )

{

    CommandLineParser parser(argc, argv, keys);

    if (parser.has("help"))

    {

        help();

        return 0;

    }

    string filename = parser.get<string>(0);

    image = imread(filename, 1);

    if(image.empty())

    {

        printf("Cannot read image file: %s\n", filename.c_str());

        help();

        return -1;

    }

    cedge.create(image.size(), image.type());

    cvtColor(image, gray, COLOR_BGR2GRAY);

    // Create a window

    namedWindow("Edge map", 1);

    // create a toolbar

    createTrackbar("Canny threshold", "Edge map", &edgeThresh, 100, onTrackbar);

    // Show the image

    onTrackbar(0, 0);

    // Wait for a key stroke; the same function arranges events processing

    waitKey(0);

    return 0;

}