Can OpenCV be developed using C++ and C together - opencv

Question

Can OpenCV be developed using C++ and C together? Following is the program where i meet this problem.It is coded with C and works well.But if I use
cv::Mat saveImage=cv::imread("D:\\opencvStudy\\opencv_test\\TaskDemo\\TaskDemo\\save.jpg");
cv::imshow("save",saveImage);
to replace
IplImage* saveImge =cvLoadImage("D:\\opencvStudy\\opencv_test\\TaskDemo\\TaskDemo\\save.jpg");
cvShowImage("saveimage",saveImge);
I met this:
Unhandled exception at 0x75709673 in TaskDemo.exe: Microsoft C++ exception: cv::Exception at memory location 0x0039ea0c..
Following is the whole program. Hope anyone could help me .Thanks very much
#include<opencv/cv.h>
#include<opencv/highgui.h>
#include "opencv2/highgui/highgui.hpp"
#include "opencv2/imgproc/imgproc.hpp"
#include "opencv2/video/tracking.hpp"
#include <iostream>
#include <ctype.h>
CvPoint pt1 = cvPoint(0,0);
CvPoint pt2 = cvPoint(0,0);
bool is_selecting = false;
void cvMouseCallback(int mouseEvent,int x,int y,int flags,void* param)
{
switch(mouseEvent)
{
case CV_EVENT_LBUTTONDOWN:
pt1 = cvPoint(x,y);
pt2 = cvPoint(x,y);
is_selecting = true;
break;
case CV_EVENT_MOUSEMOVE:
if(is_selecting)
pt2 = cvPoint(x,y);
break;
case CV_EVENT_LBUTTONUP:
pt2 = cvPoint(x,y);
is_selecting = false;
break;
}
return;
}
int main(int argc,char* argv[])
{
char img_path[80] = "D:\\opencvStudy\\pic\\boldt.jpg";
char save_path[80] = "save.jpg";
char* window = "img";
IplImage* img = cvLoadImage(img_path);
IplImage* img_show = cvCloneImage(img);
cvNamedWindow(window,CV_WINDOW_AUTOSIZE);
cvSetMouseCallback(window,cvMouseCallback);
char text[80];
CvFont font;
cvInitFont(&font,CV_FONT_HERSHEY_PLAIN,1.0,1.0);
while(true)
{
cvCopy(img,img_show);
cvRectangle(img_show,pt1,pt2,cvScalar(255,255,255));
sprintf(text,"roi = cvRect(%d,%d,%d,%d)",pt1.x,pt1.y,std::abs(pt2.x-pt1.x),std::abs(pt2.y-pt1.y));
cvPutText(img_show,text,cvPoint(10,20),&font,cvScalar(0,0,255));
cvShowImage(window,img_show);
char key = cvWaitKey(10);
if (key='r')
{
cvSetImageROI(img,cvRect(pt1.x,pt1.y,std::abs(pt2.x-pt1.x),std::abs(pt2.y-pt1.y)));
cvSaveImage(save_path,img);
cvResetImageROI(img);
IplImage* saveImge = cvLoadImage("D:\\opencvStudy\\opencv_test\\TaskDemo\\TaskDemo\\save.jpg");
cvShowImage("saveimage",saveImge);
//cv::Mat saveImage=cv::imread("D:\\opencvStudy\\opencv_test\\TaskDemo\\TaskDemo\\save.jpg");
//cv::imshow("save",saveImage);
}
else if(key==27)
break;
}
cvReleaseImage(&img);
cvReleaseImage(&img_show);
return 0;
}
Update
#include "opencv2/highgui/highgui.hpp"
#include "opencv2/core/core.hpp"
#include <iostream>
#include <ctype.h>
using namespace std;
using namespace cv;
cv::Point pt1=Point(0,0);
cv::Point pt2=Point(0,0);
bool is_selecting=false;
static void onMouse(int mouseEvent,int x,int y,int flags,void* param)
{
switch(mouseEvent)
{
case CV_EVENT_LBUTTONDOWN://CV_EVENT_LBUTTONDOWN
pt1 = Point(x,y);
pt2 = Point(x,y);
is_selecting = true;
break;
case CV_EVENT_MOUSEMOVE:
if(is_selecting)
pt2 = Point(x,y);
break;
case CV_EVENT_LBUTTONUP:
pt2 = Point(x,y);
is_selecting = false;
break;
}
}
int main()
{
cv::Mat img=cv::imread("D:\\opencvStudy\\pic\\boldt.jpg");
cv::Mat img_show=img.clone();
cv::namedWindow("Task2",0);
cv::setMouseCallback("Task2",onMouse,0);
char text[80];
while(true)
{
img.copyTo(img_show);
cv::rectangle(img_show,pt1,pt2,cv::Scalar(255,255,255));
sprintf(text,"roi = cvRect(%d,%d,%d,%d)",pt1.x,pt1.y,std::abs(pt2.x-pt1.x),std::abs(pt2.y-pt1.y));
cv::putText(img_show,text,cvPoint(10,20),10,10,Scalar(0,0,255));
cv::imshow("Task2",img_show);
char key=cv::waitKey(10);
if (key='r')
{
cv::Mat save=img(cv::Rect(pt1.x,pt1.y,std::abs(pt2.x-pt1.x),std::abs(pt2.y-pt1.y)));
cv::imwrite("save.jpg",save);
cv::Mat saveImage=cv::imread("D:\\opencvStudy\\opencv_test\\TaskDemo\\TaskDemo\\save.jpg");
cv::imshow("save",saveImage);
}
else if(key==27)
break;
}
return 0;
}

Answer 1

The problem is with conflicting headers. You should not include old and new at the same time like this:
#include<opencv/cv.h>
#include<opencv/highgui.h>
#include "opencv2/highgui/highgui.hpp"
Instead, include the new headers only, like this:
#include <opencv2/core/core.hpp>
#include <opencv2/highgui/highgui.hpp>
The reason for this is that the C++ headers also include the C interface.
UPDATE:
Of course if you use cv::Mat then you need to use the new functions for that as well.
CvCopy becomes cv::copy, there is no cvReleaseImage needed, cvRectangle becomes cv::rectangle, cvSetImageROI is img(rect), cvPoint becomes cv::Point cvRect becomes cv::Rect
cvCloneImage becomes img.clone() and so on...
Or you need some conversion from cv::Mat to IplImage to use the old functions. There are some questions on SO dealing with converting back-and-forth.
UPDATE2:
It is best to remove all cv:: since you are using using namespace cv.
Then check for functions and variables left with the old cv prefix, and remove those prefixes. (I've still found one: cvPoint).
Hang on, you are using char text[80]!
I think that is again a source of problems. It is best to switch it to
#include <sstream>
//...
stringstream ss;
ss << "Rect(" << pt1.x << ", " << ... << ")";
//...
putText(img_show, ss.str(), Point(10,20), FONT_HERSHEY_PLAIN, 1, Scalar(0, 0, 255) );
Note that the font (I use) is not 10, but FONT_HERSHEY_PLAIN (or some other FONT_ constant).