camera.cpp Example File

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 #include "camera.h"
 #include "ui_camera.h"
 #include "videosettings.h"
 #include "imagesettings.h"

 #include <QMediaService>
 #include <QMediaRecorder>
 #include <QCameraViewfinder>
 #include <QCameraInfo>
 #include <QMediaMetaData>

 #include <QMessageBox>
 #include <QPalette>

 #include <QtWidgets>

 Q_DECLARE_METATYPE(QCameraInfo)

 Camera::Camera() : ui(new Ui::Camera)
 {
     ui->setupUi(this);

     //Camera devices:

     QActionGroup *videoDevicesGroup = new QActionGroup(this);
     videoDevicesGroup->setExclusive(true);
     const QList<QCameraInfo> availableCameras = QCameraInfo::availableCameras();
     for (const QCameraInfo &cameraInfo : availableCameras) {
         QAction *videoDeviceAction = new QAction(cameraInfo.description(), videoDevicesGroup);
         videoDeviceAction->setCheckable(true);
         videoDeviceAction->setData(QVariant::fromValue(cameraInfo));
         if (cameraInfo == QCameraInfo::defaultCamera())
             videoDeviceAction->setChecked(true);

         ui->menuDevices->addAction(videoDeviceAction);
     }

     connect(videoDevicesGroup, &QActionGroup::triggered, this, &Camera::updateCameraDevice);
     connect(ui->captureWidget, &QTabWidget::currentChanged, this, &Camera::updateCaptureMode);

     setCamera(QCameraInfo::defaultCamera());
 }

 void Camera::setCamera(const QCameraInfo &cameraInfo)
 {
     m_camera.reset(new QCamera(cameraInfo));

     connect(m_camera.data(), &QCamera::stateChanged, this, &Camera::updateCameraState);
     connect(m_camera.data(), QOverload<QCamera::Error>::of(&QCamera::error), this, &Camera::displayCameraError);

     m_mediaRecorder.reset(new QMediaRecorder(m_camera.data()));
     connect(m_mediaRecorder.data(), &QMediaRecorder::stateChanged, this, &Camera::updateRecorderState);

     m_imageCapture.reset(new QCameraImageCapture(m_camera.data()));

     connect(m_mediaRecorder.data(), &QMediaRecorder::durationChanged, this, &Camera::updateRecordTime);
     connect(m_mediaRecorder.data(), QOverload<QMediaRecorder::Error>::of(&QMediaRecorder::error),
             this, &Camera::displayRecorderError);

     m_mediaRecorder->setMetaData(QMediaMetaData::Title, QVariant(QLatin1String("Test Title")));

     connect(ui->exposureCompensation, &QAbstractSlider::valueChanged, this, &Camera::setExposureCompensation);

     m_camera->setViewfinder(ui->viewfinder);

     updateCameraState(m_camera->state());
     updateLockStatus(m_camera->lockStatus(), QCamera::UserRequest);
     updateRecorderState(m_mediaRecorder->state());

     connect(m_imageCapture.data(), &QCameraImageCapture::readyForCaptureChanged, this, &Camera::readyForCapture);
     connect(m_imageCapture.data(), &QCameraImageCapture::imageCaptured, this, &Camera::processCapturedImage);
     connect(m_imageCapture.data(), &QCameraImageCapture::imageSaved, this, &Camera::imageSaved);
     connect(m_imageCapture.data(), QOverload<int, QCameraImageCapture::Error, const QString &>::of(&QCameraImageCapture::error),
             this, &Camera::displayCaptureError);

     connect(m_camera.data(), QOverload<QCamera::LockStatus, QCamera::LockChangeReason>::of(&QCamera::lockStatusChanged),
             this, &Camera::updateLockStatus);

     ui->captureWidget->setTabEnabled(0, (m_camera->isCaptureModeSupported(QCamera::CaptureStillImage)));
     ui->captureWidget->setTabEnabled(1, (m_camera->isCaptureModeSupported(QCamera::CaptureVideo)));

     updateCaptureMode();
     m_camera->start();
 }

 void Camera::keyPressEvent(QKeyEvent * event)
 {
     if (event->isAutoRepeat())
         return;

     switch (event->key()) {
     case Qt::Key_CameraFocus:
         displayViewfinder();
         m_camera->searchAndLock();
         event->accept();
         break;
     case Qt::Key_Camera:
         if (m_camera->captureMode() == QCamera::CaptureStillImage) {
             takeImage();
         } else {
             if (m_mediaRecorder->state() == QMediaRecorder::RecordingState)
                 stop();
             else
                 record();
         }
         event->accept();
         break;
     default:
         QMainWindow::keyPressEvent(event);
     }
 }

 void Camera::keyReleaseEvent(QKeyEvent *event)
 {
     if (event->isAutoRepeat())
         return;

     switch (event->key()) {
     case Qt::Key_CameraFocus:
         m_camera->unlock();
         break;
     default:
         QMainWindow::keyReleaseEvent(event);
     }
 }

 void Camera::updateRecordTime()
 {
     QString str = QString("Recorded %1 sec").arg(m_mediaRecorder->duration()/1000);
     ui->statusbar->showMessage(str);
 }

 void Camera::processCapturedImage(int requestId, const QImage& img)
 {
     Q_UNUSED(requestId);
     QImage scaledImage = img.scaled(ui->viewfinder->size(),
                                     Qt::KeepAspectRatio,
                                     Qt::SmoothTransformation);

     ui->lastImagePreviewLabel->setPixmap(QPixmap::fromImage(scaledImage));

     // Display captured image for 4 seconds.
     displayCapturedImage();
     QTimer::singleShot(4000, this, &Camera::displayViewfinder);
 }

 void Camera::configureCaptureSettings()
 {
     switch (m_camera->captureMode()) {
     case QCamera::CaptureStillImage:
         configureImageSettings();
         break;
     case QCamera::CaptureVideo:
         configureVideoSettings();
         break;
     default:
         break;
     }
 }

 void Camera::configureVideoSettings()
 {
     VideoSettings settingsDialog(m_mediaRecorder.data());
     settingsDialog.setWindowFlags(settingsDialog.windowFlags() & ~Qt::WindowContextHelpButtonHint);

     settingsDialog.setAudioSettings(m_audioSettings);
     settingsDialog.setVideoSettings(m_videoSettings);
     settingsDialog.setFormat(m_videoContainerFormat);

     if (settingsDialog.exec()) {
         m_audioSettings = settingsDialog.audioSettings();
         m_videoSettings = settingsDialog.videoSettings();
         m_videoContainerFormat = settingsDialog.format();

         m_mediaRecorder->setEncodingSettings(
                     m_audioSettings,
                     m_videoSettings,
                     m_videoContainerFormat);

         m_camera->unload();
         m_camera->start();
     }
 }

 void Camera::configureImageSettings()
 {
     ImageSettings settingsDialog(m_imageCapture.data());
     settingsDialog.setWindowFlags(settingsDialog.windowFlags() & ~Qt::WindowContextHelpButtonHint);

     settingsDialog.setImageSettings(m_imageSettings);

     if (settingsDialog.exec()) {
         m_imageSettings = settingsDialog.imageSettings();
         m_imageCapture->setEncodingSettings(m_imageSettings);
     }
 }

 void Camera::record()
 {
     m_mediaRecorder->record();
     updateRecordTime();
 }

 void Camera::pause()
 {
     m_mediaRecorder->pause();
 }

 void Camera::stop()
 {
     m_mediaRecorder->stop();
 }

 void Camera::setMuted(bool muted)
 {
     m_mediaRecorder->setMuted(muted);
 }

 void Camera::toggleLock()
 {
     switch (m_camera->lockStatus()) {
     case QCamera::Searching:
     case QCamera::Locked:
         m_camera->unlock();
         break;
     case QCamera::Unlocked:
         m_camera->searchAndLock();
     }
 }

 void Camera::updateLockStatus(QCamera::LockStatus status, QCamera::LockChangeReason reason)
 {
     QColor indicationColor = Qt::black;

     switch (status) {
     case QCamera::Searching:
         indicationColor = Qt::yellow;
         ui->statusbar->showMessage(tr("Focusing..."));
         ui->lockButton->setText(tr("Focusing..."));
         break;
     case QCamera::Locked:
         indicationColor = Qt::darkGreen;
         ui->lockButton->setText(tr("Unlock"));
         ui->statusbar->showMessage(tr("Focused"), 2000);
         break;
     case QCamera::Unlocked:
         indicationColor = reason == QCamera::LockFailed ? Qt::red : Qt::black;
         ui->lockButton->setText(tr("Focus"));
         if (reason == QCamera::LockFailed)
             ui->statusbar->showMessage(tr("Focus Failed"), 2000);
     }

     QPalette palette = ui->lockButton->palette();
     palette.setColor(QPalette::ButtonText, indicationColor);
     ui->lockButton->setPalette(palette);
 }

 void Camera::takeImage()
 {
     m_isCapturingImage = true;
     m_imageCapture->capture();
 }

 void Camera::displayCaptureError(int id, const QCameraImageCapture::Error error, const QString &errorString)
 {
     Q_UNUSED(id);
     Q_UNUSED(error);
     QMessageBox::warning(this, tr("Image Capture Error"), errorString);
     m_isCapturingImage = false;
 }

 void Camera::startCamera()
 {
     m_camera->start();
 }

 void Camera::stopCamera()
 {
     m_camera->stop();
 }

 void Camera::updateCaptureMode()
 {
     int tabIndex = ui->captureWidget->currentIndex();
     QCamera::CaptureModes captureMode = tabIndex == 0 ? QCamera::CaptureStillImage : QCamera::CaptureVideo;

     if (m_camera->isCaptureModeSupported(captureMode))
         m_camera->setCaptureMode(captureMode);
 }

 void Camera::updateCameraState(QCamera::State state)
 {
     switch (state) {
     case QCamera::ActiveState:
         ui->actionStartCamera->setEnabled(false);
         ui->actionStopCamera->setEnabled(true);
         ui->captureWidget->setEnabled(true);
         ui->actionSettings->setEnabled(true);
         break;
     case QCamera::UnloadedState:
     case QCamera::LoadedState:
         ui->actionStartCamera->setEnabled(true);
         ui->actionStopCamera->setEnabled(false);
         ui->captureWidget->setEnabled(false);
         ui->actionSettings->setEnabled(false);
     }
 }

 void Camera::updateRecorderState(QMediaRecorder::State state)
 {
     switch (state) {
     case QMediaRecorder::StoppedState:
         ui->recordButton->setEnabled(true);
         ui->pauseButton->setEnabled(true);
         ui->stopButton->setEnabled(false);
         break;
     case QMediaRecorder::PausedState:
         ui->recordButton->setEnabled(true);
         ui->pauseButton->setEnabled(false);
         ui->stopButton->setEnabled(true);
         break;
     case QMediaRecorder::RecordingState:
         ui->recordButton->setEnabled(false);
         ui->pauseButton->setEnabled(true);
         ui->stopButton->setEnabled(true);
         break;
     }
 }

 void Camera::setExposureCompensation(int index)
 {
     m_camera->exposure()->setExposureCompensation(index*0.5);
 }

 void Camera::displayRecorderError()
 {
     QMessageBox::warning(this, tr("Capture Error"), m_mediaRecorder->errorString());
 }

 void Camera::displayCameraError()
 {
     QMessageBox::warning(this, tr("Camera Error"), m_camera->errorString());
 }

 void Camera::updateCameraDevice(QAction *action)
 {
     setCamera(qvariant_cast<QCameraInfo>(action->data()));
 }

 void Camera::displayViewfinder()
 {
     ui->stackedWidget->setCurrentIndex(0);
 }

 void Camera::displayCapturedImage()
 {
     ui->stackedWidget->setCurrentIndex(1);
 }

 void Camera::readyForCapture(bool ready)
 {
     ui->takeImageButton->setEnabled(ready);
 }

 void Camera::imageSaved(int id, const QString &fileName)
 {
     Q_UNUSED(id);
     ui->statusbar->showMessage(tr("Captured \"%1\"").arg(QDir::toNativeSeparators(fileName)));

     m_isCapturingImage = false;
     if (m_applicationExiting)
         close();
 }

 void Camera::closeEvent(QCloseEvent *event)
 {
     if (m_isCapturingImage) {
         setEnabled(false);
         m_applicationExiting = true;
         event->ignore();
     } else {
         event->accept();
     }
 }