C++ opencv实现在图片上画一条线示例代码

#include <iostream>
#include<opencv.hpp>
using namespace std;
using namespace cv;
Mat img;
Point p;
void on_monse(int event, int x, int y, int flags, void*)
{
	if (event == 1)//1 左键点击
	{
		p = Point(x, y);
	}
	else if (event == 0 && flags == 1)//0 滑动 1左键拖曳
	{
		Point p1(x, y);
		line(img, p, p1, Scalar(255, 0, 0), 5);
		p = p1;
		imshow("www", img);
	}
}
int main()
{
	img = imread("星空1.png", 1);
	imshow("www", img);
	setMouseCallback("www", on_monse);
	waitKey(0);
}