在 OSX mac 中使用 QT6 和 Opencv 架构 x86_64 的未定义符号答案

【问题标题】：Undefined symbols for architecture x86_64 Using QT6 with Opencv in OSX mac在 OSX mac 中使用 QT6 和 Opencv 架构 x86_64 的未定义符号
【发布时间】：2021-09-08 20:07:41
【问题描述】：

我在 mac osx 上使用 qt6 和 OpenCv4 遇到了这个问题。我检查了这些link1、link2、link3、link4，但都没有解决问题。

这是我得到的日志错误：

Undefined symbols for architecture x86_64:
      "cv::imread(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&, int)", referenced from:
          _main in main.o
    ld: symbol(s) not found for architecture x86_64
    clang: error: linker command failed with exit code 1 (use -v to see invocation)
    make: *** [opencv_test_qmake.app/Contents/MacOS/opencv_test_qmake] Error 1
    15:19:36: The process "/usr/bin/make" exited with code 2.
    Error while building/deploying project opencv_test_qmake (kit: Desktop Qt 6.1.1 clang 64bit)
    When executing step "Make"

【问题讨论】：

标签： c++ qt opencv

【解决方案1】：

这个问题主要发生在不包含库时。

使用 qmake 时，你的 .pro 文件需要是这样的：

QT       += core gui

greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

CONFIG += c++11

SOURCES += \
    main.cpp \
    dialog.cpp

HEADERS += \
    dialog.h

FORMS += \
    dialog.ui


#Added Lines for OpenCV
INCLUDEPATH += /usr/local/include/opencv4
LIBS += -L/usr/local/lib \
LIBS += -lopencv_core -lopencv_imgproc -lopencv_features2d -lopencv_highgui -lopencv_calib3d -lopencv_imgcodecs -lopencv_videoio
QMAKE_MACOSX_DEPLOYMENT_TARGET = 11.0

# Default rules for deployment.
qnx: target.path = /tmp/$${TARGET}/bin
else: unix:!android: target.path = /opt/$${TARGET}/bin
!isEmpty(target.path): INSTALLS += target

请注意，如果您使用 imread，则需要库 -lopencv_imgcodecs - 使用 videoCapture 时需要库 lopencv_videoio。

以下 main.cpp 可用于使用图像和 imread 检查设置：

#include "dialog.h"
#include <QApplication>

#include <opencv2/core/core.hpp>
#include <opencv2/highgui/highgui.hpp>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    Dialog w;

    cv::Mat image= cv::imread("/Users/apple/Desktop/dog.jpg");

    // create image window named "My Image"
    cv::namedWindow("My Image");
    // show the image on window
    cv::imshow("My Image", image);
    // wait key for 5000 ms
    cv::waitKey(5000);

    w.show();
    return a.exec();
}

此 main.cpp 文件可用于检查 Videocapture 和设置：

#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
}

如果使用 Cmake 而不是 qmake，您可以使用相同的 main.cpp 文件。您唯一需要做的就是将这些行添加到 CmakeList.txt 的底部其中opencv_test_102 是项目文件夹的名称。

#1 Specify OpenCV folder, and take care of dependencies and includes
set(OpenCV_DIR /usr/local/include/opencv4)
find_package(OpenCV REQUIRED)
include_directories(${OpenCV_INCLUDE_DIRS})


#2 Specify OpenCV library
target_link_libraries(opencv_test_102 PRIVATE ${OpenCV_LIBS})

【讨论】：