How to draw a circle from three mouse clicks in OpenCV? - c++

Question

I want to draw a circle on an image given 3 mouse clicks.
What I mean is that I have an image and when I click 3 times on this image the circle is drawn. In addition I already have the code to find the parameters of the circle given 3 points.
Mat cember_denklemi(Point2f A,Point2f B,Point2f C) {
double W[3][3]={{A.x,A.y,1},
{B.x,B.y,1},
{C.x,C.y,1}};
double T[3][1]={-(A.x*A.x+A.y*A.y),
-(B.x*B.x+B.y*B.y),
-(C.x*C.x+C.y*C.y)};
Mat M=Mat(3,3,CV_64F,W);
Mat N=Mat(3,1,CV_64F,T);
Mat L=M.inv()*N;
return L;
}
And this my main:
#include <iostream>
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/imgproc/imgproc.hpp>
#include <stdio.h>
#include <iostream>
using namespace std;
using namespace cv;
void mouseKordinat(int evt, int x, int y, int flags, void* ptr);
void getPixelValue(Mat img, int x, int y);
Mat image;
int main() {
image = imread("c:/opencv2.4.6./atlas15.jpg");
imshow("MyWindow", image);
setMouseCallback("MyWindow", mouseKordinat, 0 );
waitKey(0);
return 0;
}
void mouseKordinat(int evt, int c, int r, int flags, void* ptr) {
if(evt==CV_EVENT_LBUTTONDOWN) {
getPixelValue(image,r,c);
}
}
void getPixelValue(Mat img, int r, int c) {
Vec3b pix=img.at<Vec3b>(r,c);
int B = pix.val[0];
int G = pix.val[1];
int R = pix.val[2];
cout<<"Row:"<<r<<" "<<"Column:"<<c<<" - "; // mouse kordinatlari
cout<<"B:"<<B<<" "<<"G:"<<G<<" "<<"R:"<<R<<"\n"; // kordinatın pixel değerleri
}

Answer 1

I can't combine these cods; but I hve done it
#include <iostream>
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/imgproc/imgproc.hpp>
#include <stdio.h>
#include <iostream>
using namespace std;
using namespace cv;
static int mouse_x = -1;
static int mouse_y = -1;
Mat circle_eq(Point2f A,Point2f B,Point2f C)
{
double W[3][3]={{A.x,A.y,1},
{B.x,B.y,1},
{C.x,C.y,1}};
double T[3][1]={-(A.x*A.x+A.y*A.y),
-(B.x*B.x+B.y*B.y),
-(C.x*C.x+C.y*C.y)};
Mat M=Mat(3,3,CV_64F,W);
Mat N=Mat(3,1,CV_64F,T);
Mat L=M.inv()*N;
return L;
}
void mouseKordinat(int evt, int x, int y, int flags, void* ptr)
{
if(evt == CV_EVENT_MOUSEMOVE)
{
mouse_x = x;
mouse_y = y;
}
int tik;
tik = tik + 1;
}
void getPixelValue(Mat img, int x, int y);
Mat image;
int main()
{
image = imread("c:/qwz/1q.jpg");
imshow("MyWindow", image);
setMouseCallback("MyWindow", mouseKordinat, 0 );
tik = tik%=3;
if(tik==0)
{
int merkez=circle_eq(nokta(0), nokta(1), nokta(2));
circle(image,merkez,3, Scalar(255,255,255),-1,8, nokta(0));
}
if(tik>3)
{
int nokta[0][0]=0;
}
waitKey(0);
return 0;
}
void mouseKordinat(int evt, int c, int r, int flags, void* ptr)
{
if(evt==CV_EVENT_LBUTTONDOWN)
{
getPixelValue(image,r,c);
}
}
void getPixelValue(Mat img, int r, int c)
{
Vec3b pix=img.at<Vec3b>(r,c);
int B = pix.val[0];
int G = pix.val[1];
int R = pix.val[2];
cout<<"Row:"<<r<<" "<<"Column:"<<c<<" - ";
cout<<"B:"<<B<<" "<<"G:"<<G<<" "<<"R:"<<R<<"\n";
}