[OpenCV] Samples 04: contours2

#include "opencv2/imgproc/imgproc.hpp"
#include "opencv2/highgui/highgui.hpp"
#include <math.h>
#include <iostream>

using namespace cv;
using namespace std;

static void help()
{
    cout
    << "\nThis program illustrates the use of findContours and drawContours\n"
    << "The original image is put up along with the image of drawn contours\n"
    << "Usage:\n"
    << "./contours2\n"
    << "\nA trackbar is put up which controls the contour level from -3 to 3\n"
    << endl;
}

const int w = 500;
int levels = 3;

vector<vector<Point> > contours;
vector<Vec4i> hierarchy;

static void on_trackbar(int, void*)
{
    Mat cnt_img = Mat::zeros(w, w, CV_8UC3);
    int _levels = levels - 3;
    drawContours( cnt_img, contours, _levels <= 0 ? 3 : -1, Scalar(128,255,255),
                  3, LINE_AA, hierarchy, std::abs(_levels) );

    imshow("contours", cnt_img);
}

int main( int argc, char** argv)
{
    cv::CommandLineParser parser(argc, argv, "{help h||}");
    if (parser.has("help"))
    {
        help();
        return 0;
    }
//    Mat img = Mat::zeros(w, w, CV_8UC1);

    //Jeff --> we don‘t need to draw this by ourselves.
    //Draw 6 faces
//    for( int i = 0; i < 6; i++ )
//    {
//        int dx = (i%2)*250 - 30;
//        int dy = (i/2)*150;
//        const Scalar white = Scalar(255);
//        const Scalar black = Scalar(0);

//        if( i == 0 )
//        {
//            for( int j = 0; j <= 10; j++ )
//            {
//                double angle = (j+5)*CV_PI/21;
//                line(img, Point(cvRound(dx+100+j*10-80*cos(angle)),
//                    cvRound(dy+100-90*sin(angle))),
//                    Point(cvRound(dx+100+j*10-30*cos(angle)),
//                    cvRound(dy+100-30*sin(angle))), white, 1, 8, 0);
//            }
//        }

//        ellipse( img, Point(dx+150, dy+100), Size(100,70), 0, 0, 360, white, -1, 8, 0 );
//        ellipse( img, Point(dx+115, dy+70), Size(30,20), 0, 0, 360, black, -1, 8, 0 );
//        ellipse( img, Point(dx+185, dy+70), Size(30,20), 0, 0, 360, black, -1, 8, 0 );
//        ellipse( img, Point(dx+115, dy+70), Size(15,15), 0, 0, 360, white, -1, 8, 0 );
//        ellipse( img, Point(dx+185, dy+70), Size(15,15), 0, 0, 360, white, -1, 8, 0 );
//        ellipse( img, Point(dx+115, dy+70), Size(5,5), 0, 0, 360, black, -1, 8, 0 );
//        ellipse( img, Point(dx+185, dy+70), Size(5,5), 0, 0, 360, black, -1, 8, 0 );
//        ellipse( img, Point(dx+150, dy+100), Size(10,5), 0, 0, 360, black, -1, 8, 0 );
//        ellipse( img, Point(dx+150, dy+150), Size(40,10), 0, 0, 360, black, -1, 8, 0 );
//        ellipse( img, Point(dx+27, dy+100), Size(20,35), 0, 0, 360, white, -1, 8, 0 );
//        ellipse( img, Point(dx+273, dy+100), Size(20,35), 0, 0, 360, white, -1, 8, 0 );
//    }

    Mat img = imread("/home/unsw/lolo.jpg");
    Mat gray;
    cvtColor(img, gray, COLOR_RGB2GRAY );
    Mat binary;
    threshold(gray, binary, 200,255,THRESH_BINARY);

    // (1) Pic One Show: show the faces
    namedWindow( "image", 1 );
    imshow( "image", binary );

    // (2) Pic Two Show
    //Extract the contours so that
    vector<vector<Point> > contours0;
    findContours( binary, contours0, hierarchy, RETR_TREE, CHAIN_APPROX_SIMPLE);

    contours.resize(contours0.size());
    for( size_t k = 0; k < contours0.size(); k++ )
        approxPolyDP(Mat(contours0[k]), contours[k], 3, true);

    // Jeff --> the same name to bind window and trackbar together.
    //          qt qml to draw would be much better.
    //          callback: on_trackbar()
    namedWindow( "contours", 1 );
    createTrackbar( "levels+3", "contours", &levels, 7, on_trackbar );
    on_trackbar(0,0);

    waitKey();
    return 0;
}