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);
      }
  }

  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();
      }
  }