//获取默认摄像头
videocapture = new VideoCapture(0);//把摄像头获取到的某一帧图像传给 Mat matFrame
videocapture->read(matFrame);　　

#pragma execution_character_set("utf-8")
#include "MainWindow.h"//#include <QCameraViewfinder>//QCamera：系统摄像设备（摄像头）
//QCameraViewfinder ：摄像取景器部件
//QCameraImageCapture：截图部件
using namespace cv;QtGuiApplication1::QtGuiApplication1(QWidget *parent): QMainWindow(parent)
{ui.setupUi(this);this->setFixedSize(300, 400);//setWindowState(Qt::WindowMaximized);//maxtimer = new QTimer(this);timer->stop();connect(timer, SIGNAL(timeout()), this, SLOT(readFarme()));  // 时间到，读取当前摄像头信息ok = true;pushButton = new QPushButton(tr("开始/暂停"),this);pushButton->setGeometry(QRect(0, 0, 300, 100));pushButton->setFont(QFont("Times", 32, QFont::Bold));connect(pushButton, SIGNAL(clicked()),this, SLOT(on_pushButton_clicked()));clickLabel = new QLabel(this);clickLabel->setGeometry(0, 100, 300, 300);//打开摄像头，从摄像头中获取视频videocapture = new VideoCapture(0);//videocapture = new VideoCapture(0);//timer->start(33);}QImage QtGuiApplication1::cvMat2QImage(const Mat& mat)    // Mat 改成 QImage
{if (mat.type() == CV_8UC1)                   // 单通道{QImage image(mat.cols, mat.rows, QImage::Format_Indexed8);image.setColorCount(256);              // 灰度级数256for (int i = 0; i < 256; i++){image.setColor(i, qRgb(i, i, i));}uchar *pSrc = mat.data;                    // 复制mat数据for (int row = 0; row < mat.rows; row++){uchar *pDest = image.scanLine(row);memcpy(pDest, pSrc, mat.cols);pSrc += mat.step;}return image;}else if (mat.type() == CV_8UC3)              // 3通道{const uchar *pSrc = (const uchar*)mat.data;         // 复制像素QImage image(pSrc, mat.cols, mat.rows, mat.step, QImage::Format_RGB888); // R, G, B 对应 0,1,2return image.rgbSwapped();               // rgbSwapped是为了显示效果色彩好一些。}else if (mat.type() == CV_8UC4){const uchar *pSrc = (const uchar*)mat.data;           // 复制像素// Create QImage with same dimensions as input Mat  QImage image(pSrc, mat.cols, mat.rows, mat.step, QImage::Format_ARGB32);     // B,G,R,A 对应 0,1,2,3return image.copy();}else{return QImage();}
}Mat QtGuiApplication1::QImage2cvMat(QImage image)          // QImage改成Mat
{Mat mat;switch (image.format()){case QImage::Format_ARGB32:case QImage::Format_RGB32:case QImage::Format_ARGB32_Premultiplied:mat = Mat(image.height(), image.width(), CV_8UC4, (void*)image.constBits(), image.bytesPerLine());break;case QImage::Format_RGB888:mat = Mat(image.height(), image.width(), CV_8UC3, (void*)image.constBits(), image.bytesPerLine());cv::cvtColor(mat, mat, CV_BGR2RGB);break;case QImage::Format_Indexed8:mat = Mat(image.height(), image.width(), CV_8UC1, (void*)image.constBits(), image.bytesPerLine());break;}return mat;
}事件驱动///
//打开摄像头
void QtGuiApplication1::on_pushButton_clicked()
{// 开始计时，超时则发出timeout()信号if(ok)timer->start(33);else timer->stop();ok = !ok;
}
//读取Frame图像 when timeout()
void QtGuiApplication1::readFarme()
{videocapture->read(matFrame);QImage imgg = cvMat2QImage(matFrame);QPixmap qpixmap = QPixmap::fromImage(imgg);// 将图片显示到label上clickLabel->setPixmap(qpixmap);}//exit
void QtGuiApplication1::bnClose()
{timer->stop();         // 停止读取数据。videocapture->release();//exitQApplication* app;app->exit(0);
}

#pragma once#include <QtWidgets/QMainWindow>
#include "ui_QtGuiApplication1.h"
#include <opencv2/opencv.hpp>
#include <opencv2/core/core.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/imgproc/imgproc.hpp>
#include "qimage.h"#include <QFileDialog>
#include <QLabel>
#include <QTimer>
#include <QPushButton>
#include <QCamera>
#include <QCameraImageCapture>
using namespace cv;          //OpenCV命名空间class QtGuiApplication1 : public QMainWindow
{Q_OBJECTpublic:QtGuiApplication1(QWidget *parent = Q_NULLPTR);private:Ui::QtGuiApplication1Class ui;QImage cvMat2QImage(const Mat & mat);Mat QImage2cvMat(QImage image);QTimer *timer;    bool ok;VideoCapture *videocapture;Mat matFrame;QLabel *clickLabel;QPushButton *pushButton;private slots:void on_pushButton_clicked();void readFarme();void bnClose();
};