ubuntu下用Qt实现人脸识别之opencv调用摄像头（二）

opencv调用摄像头

想实现人脸识别就得有一个摄像头，通过摄像头捕获的人脸进行对比，本文主要是讲使用opencv调用摄像头。
新建一个widget项目，在ui文件中拖入一个label，点击栅格布局，并重命名为 videoLabel，打开.pro文件添加一下几行代码：

LIBS += /usr/local/lib/libopencv_highgui.so \
        /usr/local/lib/libopencv_core.so    \
        /usr/local/lib/libopencv_imgproc.so \
        /usr/local/lib/libopencv_imgcodecs.so\
        /usr/local/lib/libopencv_objdetect.so\
        /usr/local/lib/libopencv_shape.so \
        /usr/local/lib/libopencv_videoio.so

.h

#include 
#include 
#include 

#include "opencv2/imgproc/imgproc.hpp"
#include "opencv2/core/core.hpp"
#include "opencv2/objdetect/objdetect.hpp"
#include "opencv2/highgui.hpp"

using namespace cv;
namespace Ui {
class opcvVideo;
}

class opcvVideo : public QWidget
{
    Q_OBJECT

public:
    explicit opcvVideo(QWidget *parent = 0);
    ~opcvVideo();
protected:
    void paintEvent(QPaintEvent *ev);
private slots:
    void slotReadFarme();

private:
    Ui::opcvVideo *ui;
    QTimer  *cvTimer;
    VideoCapture capture;
    Mat cap;
    QImage qImg;

    int OpenCamera();
};

.cpp

#include "opcvvideo.h"
#include "ui_opcvvideo.h"

opcvVideo::opcvVideo(QWidget *parent) :
    QWidget(parent),
    cvTimer(NULL),
    ui(new Ui::opcvVideo)
{
    ui->setupUi(this);
    cvTimer = new QTimer(this);
    connect(cvTimer, SIGNAL(timeout()), this, SLOT(slotReadFarme()));
    OpenCamera();
}

opcvVideo::~opcvVideo()
{
    delete ui;
}

int opcvVideo::OpenCamera() {
     //从摄像头读入视频，如果设备是系统摄像头就传入参数-1
    if(capture.open(-1)) {
        qDebug() << "open success";
    } else {
        qDebug() << "open error";
        return -1;
    }
    //先判断是否已经打开摄像头了
    if (!capture.isOpened()) {
         qDebug("err");
         return -2;
    }
    //每隔40ms读取
    cvTimer->start(40);

    return 0;
}

void opcvVideo::slotReadFarme() {
    capture.read(cap);
    //Mat转换为QImage
    const uchar *pSrc = (const uchar*)cap.data;
    QImage qImage(pSrc, cap.cols, cap.rows, cap.step, QImage::Format_RGB888);
    qImg =  qImage.rgbSwapped();
}

void opcvVideo::paintEvent(QPaintEvent *ev) {
    if(!qImg.isNull()) {
        QPainter painter(&qImg);
        ui->videoLabel->setPixmap(QPixmap::fromImage(qImg));
    }
}

最后，点击运行，就可以看到摄像头拍摄到的内容：

调用摄像头成功，下一步就是检测人脸，并绘制人脸框。