OpenCV2.4.9 显示鼠标框选区域，其他部分全为零，鼠标创建ROI区域

#include <iostream>
#include "opencv2/core/core.hpp"
#include "opencv2/imgproc/imgproc.hpp"
#include "opencv2/highgui/highgui.hpp"

using namespace std;
using namespace cv;


Mat src,img1;//原始图像  
Mat roi ;//ROI图像
Point cursor;//初始坐标   
Rect rect;//标记ROI的矩形框
bool draw;

void onMouse(int event, int x, int y, int flags, void *param)  
{  
    Mat img = src.clone();
    switch (event)  
    { 
    //按下鼠标左键
    case CV_EVENT_LBUTTONDOWN:          
        //点击鼠标图像时，清除之前ROI图像的显示窗口  
        cvDestroyWindow("ROI");   
        //存放起始坐标  
        cursor = Point(x, y);  
        //初始化起始矩形框  
        rect = Rect(x, y, 0, 0);  
        draw = true;
        break;  

    //松开鼠标左键      
    case CV_EVENT_LBUTTONUP:           
        if (rect.height > 0 && rect.width > 0)  
        {  
            //cv::Mat img1(src.rows, src.cols, CV_8U, Scalar(0));//新建0矩阵size(cols, rows);
            roi = img(Rect(rect.x, rect.y, rect.width, rect.height));
            Mat imgRoi(img1, Rect(rect.x, rect.y, rect.width, rect.height));
            roi.copyTo(imgRoi);
            rectangle(img, rect, Scalar(255),1);  //画矩形框
            namedWindow("SignROI");  
            imshow("SignROI", img);

            //将画过矩形框的图像用原图像还原  
            src.copyTo(img);  
            imshow("SrcImage", img);  

            //显示ROI图像
            namedWindow("ROI");  
            imshow("ROI", img1);
            waitKey();
        }  
        draw =false;
        break;  

    //移动光标
    case CV_EVENT_MOUSEMOVE:  
        if (draw)
        {  
            //用MIN得到左上点作为矩形框的起始坐标，如果不加这个，画矩形时只能向一个方向进行  
            rect.x = MIN(x, cursor.x);  
            rect.y = MIN(y, cursor.y);  
            rect.width = abs(cursor.x - x);  
            rect.height = abs(cursor.y - y);  
            //防止矩形区域超出图像的范围  
            rect &= Rect(0, 0, src.cols, src.rows);  
        }  
        break;  
    }  
}  

int main()
{
    draw = true;
    src = imread("112-1.jpg",IMREAD_GRAYSCALE);
    img1 = Mat::zeros(src.rows, src.cols, src.type());
    namedWindow("SrcImage");
    imshow("SrcImage", src);
    setMouseCallback("SrcImage", onMouse, NULL); 
    
    while (1){ if (waitKey(1) == 'q') break; }//等待获取按键q执行下一步


    //阈值分割 二值化图像
    Mat BW_image;
    cv::threshold(img1, BW_image, 150, 255, CV_THRESH_BINARY);
    namedWindow("BW_image", CV_WINDOW_NORMAL);
    imshow("BW_image", BW_image);
    
    
    waitKey();
    return 0;
}