#10b. Point Polygon Test: Part II

#include<iostream>
#include<highgui.h>
#include<cv.h>
using namespace std;
using namespace cv;

Mat img_all_contours;
vector<vector<Point> > closed_contours;
vector<Vec4i> heirarchy;

vector<vector<Point> > make_contours_closed(vector<vector<Point> > contours){
vector<vector<Point> > closed_contours;
closed_contours.resize(contours.size() );
for(int i=0;i<contours.size();i++)
approxPolyDP(contours[i],closed_contours[i],0.1,true);
return closed_contours;
}


int smallest_contour(Point p, vector<vector<Point> > contours, vector<Vec4i> heirarchy){
int idx=0,prev_idx=-1;
while(idx>=0){
vector<Point> c=contours[idx];
double d=pointPolygonTest(c,p,false);
if(d>0){
prev_idx=idx;
idx=heirarchy[idx][2];
}
else
idx=heirarchy[idx][0];
}
return prev_idx;

}


void on_mouse(int event, int x, int y, int, void *){
if(event != EVENT_LBUTTONDOWN) return;

Point p(x,y);
int contour_show_idx=smallest_contour(p,closed_contours,heirarchy);
if(contour_show_idx<0){
imshow("Contours",img_all_contours);
return;
}

vector<vector<Point> > contour_show;
contour_show.push_back(closed_contours[contour_show_idx]);

if(!contour_show.empty()){
Mat img_show=img_all_contours.clone();
drawContours(img_show,contour_show,-1,Scalar(0,0,255),3);
imshow("Contours",img_show);
}
}


int main()
{
Mat img=imread("images/circles3.jpg");
img_all_contours=img.clone();

Mat imgb;
cvtColor(img,imgb,CV_RGB2GRAY);

Mat edges;
Canny(imgb,edges,50,100);
vector<vector<Point> > contours;

findContours(edges,contours,heirarchy,CV_RETR_TREE,CV_CHAIN_APPROX_NONE);

closed_contours=make_contours_closed(contours);

drawContours(img_all_contours,closed_contours,-1,Scalar(0,255,0));
imshow("Contours",img_all_contours);

setMouseCallback("Contours",on_mouse);
while(char(waitKey(1))!='q'){}
return 0;
}

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Input Image:

Output when clicked in different regions: