#include <cv.h>

 #include <highgui.h>

 #include <stdio.h>

 /*鼠标画矩形*/

     void my_mouse_callback(

         int event,int x,int y,int flag,void* param

         );

     CvRect box;

     bool drawing_box = false;

     void draw_box(IplImage* img,CvRect rect)

     {

         cvRectangle(

             img,

             cvPoint(box.x,box.y),

             cvPoint(box.x+box.width,box.y+box.height),

             cvScalar(0xff,0x00,0x00)

             );

     }

     int main()

     {

         box = cvRect(-,-,,);

         IplImage* image = cvCreateImage(

             cvSize(,),

             IPL_DEPTH_8U,

             );

         cvZero(image);

         IplImage* temp = cvCloneImage(image);

         cvNamedWindow("Box Example");

         cvSetMouseCallback(

             "Box Example",

             my_mouse_callback,

             (void*)image

             );

         while()

         {

             cvCopyImage(image,temp);

             if(drawing_box) draw_box(temp,box);

             cvShowImage("Box Example",temp);

             if(cvWaitKey()==) break;

         }

         cvReleaseImage(&image);

         cvReleaseImage(&temp);

         cvDestroyAllWindows();

     }

     void my_mouse_callback(

         int event,int x,int y,int flag,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,,);

             }

             break;

         case CV_EVENT_LBUTTONUP:

             {

                 drawing_box = false;

                 if(box.width<)

                 {

                     box.x += box.width;

                     box.width*=-;

                 }

                 if(box.height<)

                 {

                     box.y+=box.height;

                     box.height*=-;

                 }

                 draw_box(image,box);

             }

             break;

         }

     }