具体实现
qtcameratest01.h修改如下：

pragma once

include <QtWidgets/QMainWindow>

include "ui_qtcameratest01.h"

include <opencv2/core.hpp>

include <opencv2/highgui.hpp>

include <opencv2/videoio.hpp> // for camera

using namespace cv;

class qtcameratest01 : public QMainWindow
{

Q_OBJECT

public:

qtcameratest01(QWidget *parent = Q_NULLPTR);

private:

Ui::qtcameratest01Class ui;
QTimer *timer;
Mat frame;
QImage image;
VideoCapture cap1;
private slots:
void opencam();
void nextFrame();
void closeCamara();
void camshot();

};
static QImage Mat2QImage(Mat& image);
qtcameratest01.cpp文件修改如下：

include "qtcameratest01.h"

include

include

include <opencv2/core.hpp>

include <opencv2/highgui.hpp>

include <opencv2/videoio.hpp> // for camera

include <opencv.hpp>

using namespace cv;

qtcameratest01::qtcameratest01(QWidget *parent)

: QMainWindow(parent)

{

// 初始化
timer = new QTimer(this);
timer->stop();
ui.setupUi(this);
connect(ui.OpenCamBtn, SIGNAL(clicked()), this, SLOT(opencam()));
connect(timer, SIGNAL(timeout()), this, SLOT(nextFrame()));
connect(ui.CloseCamBtn, SIGNAL(clicked()), this, SLOT(closeCamara()));
connect(ui.CamshotBtn, SIGNAL(clicked()), this, SLOT(camshot()));

}
void qtcameratest01::opencam()
{

if (cap1.isOpened())
    cap1.release();
double rate = cap1.get(CV_CAP_PROP_FPS);
try
{
    cap1.open(0);
    
    cap1 >> frame;
    if (!frame.empty())
    {
        timer->setInterval(rate);
        timer->start();
    }
    
}
catch (const std::exception&)
{
    QMessageBox::critical(NULL, "ERROR", "打开失败",QMessageBox::Close);
}

}
static QImage Mat2QImage(Mat& image)
{

QImage img;

if (image.channels() == 3) {
    cvtColor(image, image, CV_BGR2RGB);
    img = QImage((const unsigned char *)(image.data), image.cols, image.rows,
        image.cols*image.channels(), QImage::Format_RGB888);
}
else if (image.channels() == 1) {
    img = QImage((const unsigned char *)(image.data), image.cols, image.rows,
        image.cols*image.channels(), QImage::Format_ARGB32);
}
else {
    img = QImage((const unsigned char *)(image.data), image.cols, image.rows,
        image.cols*image.channels(), QImage::Format_RGB888);
}

return img;

}

void qtcameratest01::nextFrame()
{

cap1 >> frame;
if (!frame.empty())
{
    image = Mat2QImage(frame);
    QImage* imgScaled = new QImage;
    QImage* imgc = ℑ
    *imgScaled = imgc->scaled(ui.campicreal->width(), ui.campicreal->height(), Qt::KeepAspectRatio);

    ui.campicreal->setPixmap(QPixmap::fromImage(*imgScaled));
}

}
void qtcameratest01::closeCamara()
{

timer->stop();//停止读取数据。
cap1.release();//释放内存；  

}
void qtcameratest01::camshot()
{

QImage* imgScaled = new QImage;
QImage* imgc = ℑ
*imgScaled = imgc->scaled(ui.campicreal->width(), ui.campicreal->height(), Qt::KeepAspectRatio);

ui.campicshot->setPixmap(QPixmap::fromImage(*imgScaled));

}