OpenCV基本数据类型：Mat

  ////myopencv.pro文件

  QT       += core gui

  greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

  CONFIG += c++11

  # The following define makes your compiler emit warnings if you use
  # any Qt feature that has been marked deprecated (the exact warnings
  # depend on your compiler). Please consult the documentation of the
  # deprecated API in order to know how to port your code away from it.
  DEFINES += QT_DEPRECATED_WARNINGS

  # You can also make your code fail to compile if it uses deprecated APIs.
  # In order to do so, uncomment the following line.
  # You can also select to disable deprecated APIs only up to a certain version of Qt.
  #DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000    # disables all the  APIs deprecated before Qt 6.0.0

  SOURCES += \
      main.cpp \
      myopencv.cpp

  HEADERS += \
      myopencv.h

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

  INCLUDEPATH +=D:\Professional\OpenCV\OpenCVMinGW\OpenCV-MinGW-Build-OpenCV-4.5.2-x64\include
    
  //动态链接库位置
  LIBS +=D:\Professional\OpenCV\OpenCVMinGW\OpenCV-MinGW-Build-OpenCV-4.5.2-x64\x64\mingw\bin\libopencv_core452.dll
  LIBS +=D:\Professional\OpenCV\OpenCVMinGW\OpenCV-MinGW-Build-OpenCV-4.5.2-x64\x64\mingw\bin\libopencv_highgui452.dll
  LIBS +=D:\Professional\OpenCV\OpenCVMinGW\OpenCV-MinGW-Build-OpenCV-4.5.2-x64\x64\mingw\bin\libopencv_imgproc452.dll
  LIBS +=D:\Professional\OpenCV\OpenCVMinGW\OpenCV-MinGW-Build-OpenCV-4.5.2-x64\x64\mingw\bin\libopencv_calib3d452.dll
  LIBS +=D:\Professional\OpenCV\OpenCVMinGW\OpenCV-MinGW-Build-OpenCV-4.5.2-x64\x64\mingw\bin\libopencv_imgcodecs452.dll
  LIBS +=D:\Professional\OpenCV\OpenCVMinGW\OpenCV-MinGW-Build-OpenCV-4.5.2-x64\x64\mingw\bin\libopencv_videoio452.dll

  ////myopencv.h文件：

  #ifndef MYOPENCV_H
  #define MYOPENCV_H

  #include <QWidget>

  ////核心模块，OpenCV库的基本构建块
  #include "opencv2/core/core.hpp"

  ////图像编码模块，提供read、write等方法
  #include "opencv2/imgcodecs/imgcodecs.hpp"

  ////图像处理模块
  #include "opencv2/imgproc/imgproc.hpp"//image process

  ////包含创建/释放窗口、载入/保存图像、显示图像等方法
  #include "opencv2/highgui/highgui.hpp"

  class myOpenCV : public QWidget
  {
      Q_OBJECT

  public:
      myOpenCV(QWidget *parent = nullptr);
      ~myOpenCV();

  public:
      ////将OpenCV的矩阵数据转换为QPixmap的函数
      QPixmap matricsToPixmap(const cv::Mat& myMat);
  };
  #endif // MYOPENCV_H

////myopencv.cpp文件：

#include "myopencv.h"
#include <QLabel>
#include <QDebug>
#include <iostream>

using namespace cv;

myOpenCV::myOpenCV(QWidget *parent)
    : QWidget(parent)
{
    QLabel* myLabel = new QLabel(this);
    myLabel->setGeometry(0, 0, 960, 540);
        
    //读取一张图片
    Mat myMat = imread("C:/Users/12615/Pictures/Saved Pictures/ZJN.jpeg",1);
        
    ////OpenCV显示图片的方法
    //imshow("myMat", myMat);

    /*
    注意：
    1、Mat对象的数据结构几乎只包括矩阵头Header和指向数据的指针两部分构成。
    2、为了节省资源和处理速度，处理Mat对象的复制运算符（包括拷贝构造、矩阵赋值等）
    仅将矩阵头和指向矩阵数据的指针复制，而不会复制矩阵数据本身。因此，这样创建出来
    的Mat对象都指向同一片矩阵数据，对其中一个修改就会导致其它的复制品的值发生变化。
    3、基于上述，矩阵数据本身会属于多个Mat对象。矩阵数据本身引入了计数器机制，即
    增加一个引用矩阵数据本身的Mat对象时，就会增加一个矩阵头，清理对于Mat对象时，
    矩阵头就会减少。当矩阵头计数器减少为0时，释放矩阵数据本身。
    4、clone()和copyTo()方法与上述不同，是真正的克隆了矩阵数据，对克隆体进行修改不会影响原数据。
    */

    ////矩阵克隆
    Mat myMatA = myMat.clone();

    ////输出矩阵的数据值
    //std::cout<<myMatA<<std::endl<<std::endl;

    ////截取图像的某一区域
    Mat myMatB = Mat(myMat, Rect(20, 20, 400, 400));

    ////Scalar()方法用于将Mat对象所有数据初始化为自定义的值，例如此处为58。
    ////CV_[每个项目的位数][有符号或无符号][类型前缀]C(通道号)
    Mat myMatC = Mat(400, 400, CV_8UC(1), Scalar(58));

    ////CV_[每个项目的位数][有符号或无符号][类型前缀]C[通道数]
    Mat myMatD(2, 2, CV_8UC3, Scalar(168, 140, 0));

    std::cout<<myMatD<<std::endl<<std::endl;
    /*
    打印可得：[168, 140,   0, 168, 140,   0;
              168, 140,   0, 168, 140,   0]
    */

    ////create可以为Mat重新分配尺寸，但不可用于构造初始化！！！
    myMatD.create(1, 1, CV_8UC3);
    std::cout<<myMatD<<std::endl<<std::endl;
    /*
    打印可得：[ 12,   0,   0]
    */

    ////randu()可为矩阵元素用随机值初始化，需要指定随机数上下限。
    randu(myMatD, Scalar::all(0), Scalar::all(255));
        
    //将myMatE的三个通道（R、G、B）的所有元素数据值都赋为0~255中的任意一个数。
    Mat myMatE(960, 540, CV_8UC3);
    randu(myMatE, Scalar::all(0), Scalar::all(255));
        
    //输出结果为像素色彩为随机的图片
    myLabel->setPixmap(matricsToPixmap(myMatE));
}

QPixmap myOpenCV::matricsToPixmap(const cv::Mat& myMat)
{
    cv::Mat myMatA;
    //检测矩阵是否为空
    if(!(myMat.empty()))
    {
        ////色彩空间转换。OpenCV的默认读取方式为BGR
        cv::cvtColor(myMat, myMatA, COLOR_BGR2RGB);
        ////将OpenCV的矩阵数据转换为QImage
        QImage myQImageA = QImage((const unsigned char*)(myMatA.data), myMatA.cols, myMatA.rows, myMatA.step, QImage::Format_RGB888);
        return QPixmap::fromImage(myQImageA);
    }
    else
    {
        qDebug()<<"Failed to convert the matrics !!!"<<endl;
        myMatA = myMat.clone();
        QImage myQImageA = QImage((const unsigned char*)(myMatA.data), myMatA.cols, myMatA.rows, myMatA.step, QImage::Format_RGB888);
        return QPixmap::fromImage(myQImageA);
    }
}

myOpenCV::~myOpenCV()
{
}