对一张图片通过画矩形截取它的感兴趣区域并保存下来的程序

程序：

#include<opencv2/opencv.hpp>
#include<iostream>

using namespace cv;
using namespace std;

void on_mouse(int event, int x, int y, int flag,void*);

Mat src, img; /*showImg*/
Rect select;
bool select_flag = false;
int i = 1;

int main()
{
	src = imread("E:/pictures/12.jpg");
	namedWindow("input", WINDOW_AUTOSIZE);
	imshow("input", src);

	img = src.clone();//保持原图
	
	setMouseCallback("input", on_mouse, 0);
	waitKey(0);
	return 0;
}
//利用鼠标画矩形
void on_mouse(int event, int x, int y, int flag, void*)
{
	Point p1, p2;
	if (x<0 || x>src.cols || y<0 || y>src.rows)
	{
		return;
	}
	
	if (event == EVENT_LBUTTONDOWN)
	{
		select.x = x;
		select.y = y;
		select_flag = true;
	}
	else if (event == EVENT_MOUSEMOVE&&select_flag)
	{
		img.copyTo(src);//不断把原图复制到src
		p1 = Point(select.x, select.y);
		p2 = Point(x, y);
		rectangle(src, p1, p2, Scalar(0, 0, 255), 5, 8);
	     
	}
	else if (select_flag&&event == EVENT_LBUTTONUP)
	{
		select_flag = false;
		//提取感兴趣区域
		Rect rect = Rect(Point(select.x, select.y), Point(x, y));
		cout << rect.width << "and" <<rect.height<< endl;
		if (rect.width&&rect.height)
		{
			Mat roi = img(rect);
			imshow("output", roi);
			String finlename = format("E:/%d.jpg", i);
			imwrite(finlename, roi);//保存在E盘
			i++;
		}
	}
		imshow("input", src);
}

截图：