#include<opencv2/opencv.hpp>

 #include<iostream>

 using namespace cv;

 using namespace std;

 Mat img=imread("E://1.jpg");

 Mat temp=img.clone();

 Mat ROI;

 Point pt;

 bool flag=false;

 void onMouse(int event,int x,int y,int flag,void* param){

     switch (event)

     {

     case CV_EVENT_LBUTTONDOWN://鼠标左键按下

         //cout<<"鼠标左键按下"<<endl;

         flag=true;

         pt.x=x;

         pt.y=y;

         break;

     case CV_EVENT_MOUSEMOVE://鼠标移动

         //cout<<"鼠标移动"<<endl;

         if(flag){

             temp.copyTo(img);//temp复制给img（相当于恢复成原图），以便永远只有一个矩形（否则许多矩形会重叠在一起）

             rectangle(img,pt,Point(x,y),Scalar(,,),,);

         }

         break;

     case CV_EVENT_LBUTTONUP://鼠标左键抬起

         //cout<<"鼠标抬起"<<endl;

         flag=false;

         //ROI=img(Rect(pt.x,pt.y,x-pt.x,y-pt.y));//确定ROI区域,有矩形边框

         ROI=temp(Rect(pt.x,pt.y,x-pt.x,y-pt.y));//无矩形边框

         imshow("ROI",ROI);

         imwrite("E://ROI.jpg",ROI);

         break;

     default:

         break;

     }

 }

 void main(){

     namedWindow("mouse",CV_WINDOW_AUTOSIZE);

     setMouseCallback("mouse",onMouse,);

     while(){

         imshow("mouse",img);

         if(==waitKey())//esc跳出循环

             break;

     }

 }

 #include<opencv2/opencv.hpp>

 #include<iostream>

 using namespace cv;

 using namespace std;

 int value;

 void onChange(int,void* param){

     VideoCapture cap=*(VideoCapture*)param;

     cap.set(CV_CAP_PROP_POS_FRAMES,value);//设置视频帧位置

 }

 void main(){

     Mat frame;

     char strFps[];

     VideoCapture cap("E://2.avi");

     namedWindow("video",CV_WINDOW_AUTOSIZE);

     int frameCount=cap.get(CV_CAP_PROP_FRAME_COUNT);//获取视频总帧数

     createTrackbar("Frame","video",&value,frameCount,onChange,&cap);

     if(cap.isOpened()){//如果视频成功打开

         while(){

             double Fps=cap.get(CV_CAP_PROP_FPS);//获得视频帧率

             sprintf(strFps,"Fps%0.1f/s",Fps);//格式化字符串

             int framePos=cap.get(CV_CAP_PROP_POS_FRAMES);//获取视频帧位置

             setTrackbarPos("Frame","video",framePos);//设置滑动条位置

             cap>>frame;

             if(!frame.empty()){//如果该帧不为空

                 putText(frame,strFps,Point(,),CV_FONT_HERSHEY_COMPLEX_SMALL,,Scalar(,,),,);

                 imshow("video",frame);

                 if(==waitKey(/Fps))//esc退出，1000/Fps毫秒刷新

                     break;

             }

         }

     }

 }