Qt5如何使用摄像头

（DEMO代码）项目名称：myCamera

myCamera.pro

QT += multimedia
QT += multimediawidgets

mycameradialog.h

#ifndef MYCAMERADIALOG_H
#define MYCAMERADIALOG_H

#include <QDialog>
#include <QCamera>
#include <QCameraViewfinder>
#include <QCameraImageCapture>

#include <QLabel>
#include <QPushButton>

class MyCameraDialog : public QDialog
{
    Q_OBJECT

public:
    MyCameraDialog(QWidget *parent = 0);
    ~MyCameraDialog();

private slots:
    void captureBtnResponded();
    void saveBtnResponded();
    void exitBtnResponded();
    void cameraImageCaptured(int id, QImage image);

private:
    // 系统摄像设备（摄像头）
    QCamera *camera;
    // 摄像取景器部件
    QCameraViewfinder *cameraViewFinder;
    // 截图部件
    QCameraImageCapture *cameraImageCapture;

    QPushButton *captureBtn;
    QPushButton *saveBtn;
    QPushButton *exitBtn;

    QLabel *displayLabel;

    void translateLanguage();
};

#endif // MYCAMERADIALOG_H

mycameradialog.cpp

#include "mycameradialog.h"
#include <QHBoxLayout>
#include <QVBoxLayout>

MyCameraDialog::MyCameraDialog(QWidget *parent)
    : QDialog(parent)
{
    this->setFixedSize(700, 400);

    camera = new QCamera();
    cameraViewFinder = new QCameraViewfinder();
    cameraImageCapture = new QCameraImageCapture(camera);

    captureBtn = new QPushButton();
    saveBtn = new QPushButton();
    exitBtn = new QPushButton();

    displayLabel = new QLabel();
    displayLabel->setFixedSize(160, 120);
    displayLabel->setScaledContents(true);

    QVBoxLayout *rightLayout = new QVBoxLayout;
    rightLayout->addWidget(displayLabel);
    rightLayout->addStretch();
    rightLayout->addWidget(captureBtn);
    rightLayout->addWidget(saveBtn);
    rightLayout->addWidget(exitBtn);

    QHBoxLayout *mainLayout = new QHBoxLayout;
    mainLayout->addWidget(cameraViewFinder);
    mainLayout->addLayout(rightLayout);

    connect(captureBtn, SIGNAL(clicked()), this, SLOT(captureBtnResponded()));
    connect(saveBtn, SIGNAL(clicked()), this, SLOT(saveBtnResponded()));
    connect(exitBtn, SIGNAL(clicked()), this, SLOT(exitBtnResponded()));
    connect(cameraImageCapture, SIGNAL(imageCaptured(int,QImage)), this, SLOT(cameraImageCaptured(int,QImage)));

    cameraImageCapture->setCaptureDestination(QCameraImageCapture::CaptureToFile);
    camera->setCaptureMode(QCamera::CaptureStillImage);
    camera->setViewfinder(cameraViewFinder);
    camera->start();

    this->setLayout(mainLayout);
    this->translateLanguage();

}

MyCameraDialog::~MyCameraDialog()
{

}

void MyCameraDialog::translateLanguage()
{
    this->setWindowTitle(tr("testCapture"));
    captureBtn->setText(tr("capture"));
    saveBtn->setText(tr("save"));
    exitBtn->setText(tr("exit"));
}

void MyCameraDialog::captureBtnResponded()
{
    cameraImageCapture->capture();
}

void MyCameraDialog::saveBtnResponded()
{
    const QPixmap *pixmap = displayLabel->pixmap();
    if(pixmap) {pixmap->save("D:/workspace/Qt_Project/test/camera/a.jpg");}
}

void MyCameraDialog::exitBtnResponded()
{
    camera->stop();
    this->close();
}

void MyCameraDialog::cameraImageCaptured(int id, QImage image)
{
    displayLabel->setPixmap(QPixmap::fromImage(image));
}