The cv window can not be open, how can i solve the problem?

C++
1

Bellow the code is the example program from github opencv.

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

using namespace cv;
using namespace std;

void drawText(Mat & image);

int main()
{
    cout << "Built with OpenCV " << CV_VERSION << endl;
    Mat image;
    VideoCapture capture;
    capture.open(0);
    if(capture.isOpened())
    {
        cout << "Capture is opened" << endl;
        for(;;)
        {
            capture >> image;
            if(image.empty())
                break;
            drawText(image);
            imshow("Sample", image);
            if(waitKey(10) >= 0)
                break;
        }
    }
    else
    {
        cout << "No capture" << endl;
        image = Mat::zeros(480, 640, CV_8UC1);
        drawText(image);
        imshow("Sample", image);
        waitKey(0);
    }
    return 0;
}

void drawText(Mat & image)
{
    putText(image, "Hello OpenCV",
            Point(20, 50),
            FONT_HERSHEY_COMPLEX, 1, // font face and scale
            Scalar(255, 255, 255), // white
            1, LINE_AA); // line thickness and type
}

I type the command line to compile program.

g++ main.cpp -I /usr/local/include/opencv4 -L /usr/local/lib -lopencv_core -lopencv_imgproc -lopencv_highgui -lopencv_videoio

./a.out

but the exception throwed

Built with OpenCV 4.10.0-dev
Capture is opened
terminate called after throwing an instance of 'cv::Exception'
  what():  OpenCV(4.10.0-dev) /opt/opencv-4.x/modules/highgui/src/window.cpp:1301: error: (-2:Unspecified error) The function is not implemented. Rebuild the library with Windows, GTK+ 2.x or Cocoa support. If you are on Ubuntu or Debian, install libgtk2.0-dev and pkg-config, then re-run cmake or configure script in function 'cvShowImage'

Aborted (core dumped)
2

looks like your current opencv installation does not support any gui
(it probably did not find suitable dev-libs, when building opencv)

how did you install this ?

3

from this web site
https://docs.opencv.org/4.x/d7/d9f/tutorial_linux_install.html

4

And during compile, the printing information

-- ocv_init_download: OpenCV source tree is not fetched as git repository. 3rdparty resources will be downloaded from github.com by default.
-- Detected processor: x86_64
-- Looking for ccache - not found
-- Could NOT find OpenJPEG (minimal suitable version: 2.0, recommended version >= 2.3.1). OpenJPEG will be built from sources
-- OpenJPEG: VERSION = 2.5.0, BUILD = opencv-4.10.0-dev-openjp2-2.5.0
-- OpenJPEG libraries will be built from sources: libopenjp2 (version "2.5.0")
-- The imported target "Imath::PyImath_Python3_11" references the file
   "/usr/lib/x86_64-linux-gnu/libPyImath_Python3_11-3_1.so.29.5.0"
but this file does not exist.  Possible reasons include:
* The file was deleted, renamed, or moved to another location.
* An install or uninstall procedure did not complete successfully.
* The installation package was faulty and contained
   "/usr/lib/x86_64-linux-gnu/cmake/Imath/ImathTargets.cmake"
but not all the files it references.