Camera capture via Qt

camera-test.pro

TEMPLATE = app

QT += \
    widgets \
    multimedia

CONFIG += c++11 c++14

SOURCES += \
    main.cpp \
    shooterview.cpp

HEADERS += \
    shooterview.h

main.cpp

#include <QApplication>

#include "shooterview.h"


int main(int argc, char** argv)
{
    QApplication app(argc, argv);

    ShooterView shooter;
    shooter.show();
    shooter.start();

    return app.exec();
}

shooterview.cpp

#include "shooterview.h"

#include <QTimer>
#include <QLabel>
#include <QVBoxLayout>

#include <QCamera>
#include <QCameraImageCapture>
#include <QEventLoop>

ShooterView::ShooterView(QWidget *parent) :
    QWidget(parent),
    m_timer(new QTimer(this)),
    m_image(new QLabel(this))
{    
    resize(640, 480);

    m_timer->setInterval(10000);
    m_timer->setSingleShot(false);

    connect(m_timer.data(), &QTimer::timeout, this, &ShooterView::shoot);

    QVBoxLayout *layout = new QVBoxLayout(this);
    layout->addWidget(m_image);
}

ShooterView::~ShooterView()
{
}

void ShooterView::start()
{
    m_timer->start();
}

void ShooterView::stop()
{
    m_timer->stop();
}

void ShooterView::shoot()
{
    qDebug() << "SHOOT";

    QScopedPointer<QCamera, QScopedPointerDeleteLater> camera(new QCamera);

    /*QScopedPointer<QCameraViewfinder, QScopedPointerDeleteLater>
            viewfinder = new QCameraViewfinder();
    viewfinder->show();

    camera->setViewfinder(viewfinder);*/

    QScopedPointer<QCameraImageCapture, QScopedPointerDeleteLater>
            imageCapture(new QCameraImageCapture(camera.data()));

    connect(imageCapture.data(), &QCameraImageCapture::imageCaptured,
            this, &ShooterView::handleImage);

    camera->setCaptureMode(QCamera::CaptureStillImage);
    imageCapture->setCaptureDestination(QCameraImageCapture::CaptureToBuffer);

    QEventLoop loop;
    connect(imageCapture.data(), &QCameraImageCapture::readyForCaptureChanged,
            &loop, &QEventLoop::quit);
    connect(this, &ShooterView::imageReady, &loop, &QEventLoop::quit);

    camera->start();
    //on half pressed shutter button
    camera->searchAndLock();
    loop.exec();

    //on shutter button pressed
    imageCapture->capture();
    loop.exec();

    //on shutter button released
    camera->unlock();
}

void ShooterView::handleImage(int id, const QImage& image)
{
    qDebug() << "ID:" << id << "IMAGE:" << image.size();
    emit imageReady();
    m_image->setPixmap(QPixmap::fromImage(image));
}

shooterview.h

#ifndef SHOOTERVIEW_H
#define SHOOTERVIEW_H

#include <QWidget>
#include <QPointer>

QT_FORWARD_DECLARE_CLASS(QTimer)
QT_FORWARD_DECLARE_CLASS(QLabel)

class ShooterView : public QWidget
{
    Q_OBJECT
public:
    explicit ShooterView(QWidget *parent = nullptr);
    virtual ~ShooterView();

    void start();
    void stop();

private slots:
    void shoot();
    void handleImage(int id, const QImage &image);

signals:
    void imageReady();

private:
    QScopedPointer<QTimer, QScopedPointerDeleteLater> m_timer;
    QPointer<QLabel> m_image;
};

#endif // SHOOTERVIEW_H