opencv-鼠标在窗口中画矩形

#include<iostream>
#include <core.hpp>
#include <highgui.hpp>
#include<cv.h>

using namespace cv;
using namespace std;

void my_mouse_callback(
int event, int x, int y, int flags, void* param
);

CvRect box;
bool drawing_box = false;

//绘制矩形函数
void draw_box(IplImage* img, CvRect rect) {
cvRectangle(
img,
CvPoint(box.x, box.y),
CvPoint(box.width, box.height),
CvScalar(0xff, 0x00, 0x00)
);
}

int main(int argc,char** argv) {
box = cvRect(-1, -1, 0, 0);

IplImage* image = cvCreateImage(
cvSize(200, 200),
IPL_DEPTH_8U,
3
);
cvZero(image);
IplImage* temp = cvCloneImage(image);

cvNamedWindow("Box-Example", CV_WINDOW_AUTOSIZE);
cvSetMouseCallback(
"Box-Example",
my_mouse_callback,
(void*)image
);

while (1) {
cvCopy(image, temp);
if (drawing_box) draw_box(temp, box);
cvShowImage("Box-Example", temp);
if (cvWaitKey(15) == 27) break;
}
cvReleaseImage(&image);
cvReleaseImage(&temp);
cvDestroyAllWindows();
return 0;
}

//鼠标操作回调函数
void my_mouse_callback(int event, int x, int y, int flags, void* param) {
IplImage* image = (IplImage*)param;

switch (event)
{
case CV_EVENT_MOUSEMOVE:
if (drawing_box) {
box.width = x - box.x;
box.height = y - box.y;
}
break;
case CV_EVENT_LBUTTONDOWN:
drawing_box = true;
box = cvRect(x, y, 0, 0);
break;
case CV_EVENT_LBUTTONUP:
drawing_box = false;
if (box.width < 0) {
box.x += box.width;
box.width *= -1;
}
if (box.height < 0) {
box.y += box.height;
box.height *= -1;
}
draw_box(image, box);
break;

default:
break;
}
}