Raspberry Camera 编译错误：未定义的符号引用

Question

我正在尝试为树莓派编译一个程序。 但是当我在 Geany 中运行构建时，我得到了这个错误：

g++ $(pkg-config opencv4 --cflags --libs) -o g++ $(pkg-config raspicam --cflags --libs) -o camera_2 camera_2.cpp (in directory: /home/pi/Desktop)
/usr/bin/ld: /tmp/ccTDUfOT.o: undefined reference to symbol '_ZN2cv6imshowERKNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEERKNS_11_InputArrayE'
/usr/bin/ld: //usr/local/lib/libopencv_highgui.so.405: error adding symbols: DSO missing from command line
collect2: error: ld returned 1 exit status
Compilation failed.

camera.cpp 文件如下所示：

#include <opencv2/opencv.hpp>
#include <raspicam_cv.h>
#include <iostream>

using namespace std;
using namespace cv;
using namespace raspicam;

Mat frame;

void Setup ( int argc,char **argv, RaspiCam_Cv &Camera )
  {
    Camera.set ( CAP_PROP_FRAME_WIDTH,  ( "-w",argc,argv,400 ) );
    Camera.set ( CAP_PROP_FRAME_HEIGHT,  ( "-h",argc,argv,240 ) );
    Camera.set ( CAP_PROP_BRIGHTNESS, ( "-br",argc,argv,50 ) );
    Camera.set ( CAP_PROP_CONTRAST ,( "-co",argc,argv,50 ) );
    Camera.set ( CAP_PROP_SATURATION,  ( "-sa",argc,argv,50 ) );
    Camera.set ( CAP_PROP_GAIN,  ( "-g",argc,argv ,50 ) );
    Camera.set ( CAP_PROP_FPS,  ( "-fps",argc,argv,100));

  }


int main(int argc,char **argv)
{
    RaspiCam_Cv Camera;
    Setup(argc, argv, Camera);
    cout<<"Connecting to camera"<<endl;
    if (!Camera.open())
    {       
        cout<<"Failed to Connect"<<endl;
        return -1;
    }
    cout<<"Camera Id = "<<Camera.getId()<<endl;
     
    Camera.grab();
    Camera.retrieve(frame);

    imshow("frame", frame);
    waitKey();
    return 0;  
}

到目前为止，我认为当我删除 Mat frame; 错误没有出现。

pkg-config 文件如下所示：

prefix=/usr/local
exec_prefix=${prefix}
libdir=${exec_prefix}/lib
includedir_old=${prefix}/include/opencv4/opencv2
includedir_new=${prefix}/include/opencv4


Name: OpenCV
Description: Open Source Computer Vision Library
Version: 4.5.5
L: -Libs${exec_prefix}/lib -lopencv_calib3d -lopencv_core -lopencv_dnn -lopencv_features2d -lopencv_flann -lopencv_gapi -lopencv_highgui -lopencv_imgcodecs -lopencv_imgproc -lopencv_ml -lopencv_objdetect -lopencv_photo -lopencv_stitching -lopencv_video -lopencv_videoio
Libs.private: -ldl -lm -lpthread -lrt
Cflags: -I${includedir_old} -I${includedir_new}

Geany 中的命令如下所示：

g++ $(pkg-config opencv4 --cflags --libs) -o g++ $(pkg-config raspicam --cflags --libs) -o %e %f

你知道什么是错的，我需要改变什么吗？ 谢谢

Answer 1

我已经解决了这个错误。 我在命令中添加了两个库：

g++ $(pkg-config opencv4 --cflags --libs) $(pkg-config raspicam --cflags --libs) -o %e %f -lopencv_highgui -lopencv_core

我想知道为什么这些库在配置文件中不起作用。

Answer 2

参数-o g++ 非常奇怪，因为它会生成一个名为g++ 的输出文件，这很令人困惑，因为这也是编译器的名称。您可能想要删除它，因为您已经有一个 -o 参数。

其次，在链接程序时，链接在一起的不同对象/库的顺序通常很重要。尝试在命令末尾调用pkg-config。