Qt 5.11 | Qt Multimedia | Media Player Example | player.cpp Example File

Qt 5.11.3 Reference Documentation

# player.cpp Example File

multimediawidgets/player/player.cpp

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      #include "player.h"

      #include "playercontrols.h"
      #include "playlistmodel.h"
      #include "histogramwidget.h"
      #include "videowidget.h"

      #include <QMediaService>
      #include <QMediaPlaylist>
      #include <QVideoProbe>
      #include <QAudioProbe>
      #include <QMediaMetaData>
      #include <QtWidgets>

      Player::Player(QWidget *parent)
          : QWidget(parent)
      {
          m_player = new QMediaPlayer(this);
          m_player->setAudioRole(QAudio::VideoRole);
          qInfo() << "Supported audio roles:";
          for (QAudio::Role role : m_player->supportedAudioRoles())
              qInfo() << "    " << role;
          // owned by PlaylistModel
          m_playlist = new QMediaPlaylist();
          m_player->setPlaylist(m_playlist);

          connect(m_player, &QMediaPlayer::durationChanged, this, &Player::durationChanged);
          connect(m_player, &QMediaPlayer::positionChanged, this, &Player::positionChanged);
          connect(m_player, QOverload<>::of(&QMediaPlayer::metaDataChanged), this, &Player::metaDataChanged);
          connect(m_playlist, &QMediaPlaylist::currentIndexChanged, this, &Player::playlistPositionChanged);
          connect(m_player, &QMediaPlayer::mediaStatusChanged, this, &Player::statusChanged);
          connect(m_player, &QMediaPlayer::bufferStatusChanged, this, &Player::bufferingProgress);
          connect(m_player, &QMediaPlayer::videoAvailableChanged, this, &Player::videoAvailableChanged);
          connect(m_player, QOverload<QMediaPlayer::Error>::of(&QMediaPlayer::error), this, &Player::displayErrorMessage);
          connect(m_player, &QMediaPlayer::stateChanged, this, &Player::stateChanged);

          m_videoWidget = new VideoWidget(this);
          m_player->setVideoOutput(m_videoWidget);

          m_playlistModel = new PlaylistModel(this);
          m_playlistModel->setPlaylist(m_playlist);

          m_playlistView = new QListView(this);
          m_playlistView->setModel(m_playlistModel);
          m_playlistView->setCurrentIndex(m_playlistModel->index(m_playlist->currentIndex(), 0));

          connect(m_playlistView, &QAbstractItemView::activated, this, &Player::jump);

          m_slider = new QSlider(Qt::Horizontal, this);
          m_slider->setRange(0, m_player->duration() / 1000);

          m_labelDuration = new QLabel(this);
          connect(m_slider, &QSlider::sliderMoved, this, &Player::seek);

          m_labelHistogram = new QLabel(this);
          m_labelHistogram->setText("Histogram:");
          m_videoHistogram = new HistogramWidget(this);
          m_audioHistogram = new HistogramWidget(this);
          QHBoxLayout *histogramLayout = new QHBoxLayout;
          histogramLayout->addWidget(m_labelHistogram);
          histogramLayout->addWidget(m_videoHistogram, 1);
          histogramLayout->addWidget(m_audioHistogram, 2);

          m_videoProbe = new QVideoProbe(this);
          connect(m_videoProbe, &QVideoProbe::videoFrameProbed, m_videoHistogram, &HistogramWidget::processFrame);
          m_videoProbe->setSource(m_player);

          m_audioProbe = new QAudioProbe(this);
          connect(m_audioProbe, &QAudioProbe::audioBufferProbed, m_audioHistogram, &HistogramWidget::processBuffer);
          m_audioProbe->setSource(m_player);

          QPushButton *openButton = new QPushButton(tr("Open"), this);

          connect(openButton, &QPushButton::clicked, this, &Player::open);

          PlayerControls *controls = new PlayerControls(this);
          controls->setState(m_player->state());
          controls->setVolume(m_player->volume());
          controls->setMuted(controls->isMuted());

          connect(controls, &PlayerControls::play, m_player, &QMediaPlayer::play);
          connect(controls, &PlayerControls::pause, m_player, &QMediaPlayer::pause);
          connect(controls, &PlayerControls::stop, m_player, &QMediaPlayer::stop);
          connect(controls, &PlayerControls::next, m_playlist, &QMediaPlaylist::next);
          connect(controls, &PlayerControls::previous, this, &Player::previousClicked);
          connect(controls, &PlayerControls::changeVolume, m_player, &QMediaPlayer::setVolume);
          connect(controls, &PlayerControls::changeMuting, m_player, &QMediaPlayer::setMuted);
          connect(controls, &PlayerControls::changeRate, m_player, &QMediaPlayer::setPlaybackRate);
          connect(controls, &PlayerControls::stop, m_videoWidget, QOverload<>::of(&QVideoWidget::update));

          connect(m_player, &QMediaPlayer::stateChanged, controls, &PlayerControls::setState);
          connect(m_player, &QMediaPlayer::volumeChanged, controls, &PlayerControls::setVolume);
          connect(m_player, &QMediaPlayer::mutedChanged, controls, &PlayerControls::setMuted);

          m_fullScreenButton = new QPushButton(tr("FullScreen"), this);
          m_fullScreenButton->setCheckable(true);

          m_colorButton = new QPushButton(tr("Color Options..."), this);
          m_colorButton->setEnabled(false);
          connect(m_colorButton, &QPushButton::clicked, this, &Player::showColorDialog);

          QBoxLayout *displayLayout = new QHBoxLayout;
          displayLayout->addWidget(m_videoWidget, 2);
          displayLayout->addWidget(m_playlistView);

          QBoxLayout *controlLayout = new QHBoxLayout;
          controlLayout->setMargin(0);
          controlLayout->addWidget(openButton);
          controlLayout->addStretch(1);
          controlLayout->addWidget(controls);
          controlLayout->addStretch(1);
          controlLayout->addWidget(m_fullScreenButton);
          controlLayout->addWidget(m_colorButton);

          QBoxLayout *layout = new QVBoxLayout;
          layout->addLayout(displayLayout);
          QHBoxLayout *hLayout = new QHBoxLayout;
          hLayout->addWidget(m_slider);
          hLayout->addWidget(m_labelDuration);
          layout->addLayout(hLayout);
          layout->addLayout(controlLayout);
          layout->addLayout(histogramLayout);
      #if defined(Q_OS_QNX)
          // On QNX, the main window doesn't have a title bar (or any other decorations).
          // Create a status bar for the status information instead.
          m_statusLabel = new QLabel;
          m_statusBar = new QStatusBar;
          m_statusBar->addPermanentWidget(m_statusLabel);
          m_statusBar->setSizeGripEnabled(false); // Without mouse grabbing, it doesn't work very well.
          layout->addWidget(m_statusBar);
      #endif

          setLayout(layout);

          if (!isPlayerAvailable()) {
              QMessageBox::warning(this, tr("Service not available"),
                                   tr("The QMediaPlayer object does not have a valid service.\n"\
                                      "Please check the media service plugins are installed."));

              controls->setEnabled(false);
              m_playlistView->setEnabled(false);
              openButton->setEnabled(false);
              m_colorButton->setEnabled(false);
              m_fullScreenButton->setEnabled(false);
          }

          metaDataChanged();
      }

      Player::~Player()
      {
      }

      bool Player::isPlayerAvailable() const
      {
          return m_player->isAvailable();
      }

      void Player::open()
      {
          QFileDialog fileDialog(this);
          fileDialog.setAcceptMode(QFileDialog::AcceptOpen);
          fileDialog.setWindowTitle(tr("Open Files"));
          QStringList supportedMimeTypes = m_player->supportedMimeTypes();
          if (!supportedMimeTypes.isEmpty()) {
              supportedMimeTypes.append("audio/x-m3u"); // MP3 playlists
              fileDialog.setMimeTypeFilters(supportedMimeTypes);
          }
          fileDialog.setDirectory(QStandardPaths::standardLocations(QStandardPaths::MoviesLocation).value(0, QDir::homePath()));
          if (fileDialog.exec() == QDialog::Accepted)
              addToPlaylist(fileDialog.selectedUrls());
      }

      static bool isPlaylist(const QUrl &url) // Check for ".m3u" playlists.
      {
          if (!url.isLocalFile())
              return false;
          const QFileInfo fileInfo(url.toLocalFile());
          return fileInfo.exists() && !fileInfo.suffix().compare(QLatin1String("m3u"), Qt::CaseInsensitive);
      }

      void Player::addToPlaylist(const QList<QUrl> &urls)
      {
          for (auto &url: urls) {
              if (isPlaylist(url))
                  m_playlist->load(url);
              else
                  m_playlist->addMedia(url);
          }
      }

      void Player::setCustomAudioRole(const QString &role)
      {
          m_player->setCustomAudioRole(role);
      }

      void Player::durationChanged(qint64 duration)
      {
          m_duration = duration / 1000;
          m_slider->setMaximum(m_duration);
      }

      void Player::positionChanged(qint64 progress)
      {
          if (!m_slider->isSliderDown())
              m_slider->setValue(progress / 1000);

          updateDurationInfo(progress / 1000);
      }

      void Player::metaDataChanged()
      {
          if (m_player->isMetaDataAvailable()) {
              setTrackInfo(QString("%1 - %2")
                      .arg(m_player->metaData(QMediaMetaData::AlbumArtist).toString())
                      .arg(m_player->metaData(QMediaMetaData::Title).toString()));

              if (m_coverLabel) {
                  QUrl url = m_player->metaData(QMediaMetaData::CoverArtUrlLarge).value<QUrl>();

                  m_coverLabel->setPixmap(!url.isEmpty()
                          ? QPixmap(url.toString())
                          : QPixmap());
              }
          }
      }

      void Player::previousClicked()
      {
          // Go to previous track if we are within the first 5 seconds of playback
          // Otherwise, seek to the beginning.
          if (m_player->position() <= 5000)
              m_playlist->previous();
          else
              m_player->setPosition(0);
      }

      void Player::jump(const QModelIndex &index)
      {
          if (index.isValid()) {
              m_playlist->setCurrentIndex(index.row());
              m_player->play();
          }
      }

      void Player::playlistPositionChanged(int currentItem)
      {
          clearHistogram();
          m_playlistView->setCurrentIndex(m_playlistModel->index(currentItem, 0));
      }

      void Player::seek(int seconds)
      {
          m_player->setPosition(seconds * 1000);
      }

      void Player::statusChanged(QMediaPlayer::MediaStatus status)
      {
          handleCursor(status);

          // handle status message
          switch (status) {
          case QMediaPlayer::UnknownMediaStatus:
          case QMediaPlayer::NoMedia:
          case QMediaPlayer::LoadedMedia:
              setStatusInfo(QString());
              break;
          case QMediaPlayer::LoadingMedia:
              setStatusInfo(tr("Loading..."));
              break;
          case QMediaPlayer::BufferingMedia:
          case QMediaPlayer::BufferedMedia:
              setStatusInfo(tr("Buffering %1%").arg(m_player->bufferStatus()));
              break;
          case QMediaPlayer::StalledMedia:
              setStatusInfo(tr("Stalled %1%").arg(m_player->bufferStatus()));
              break;
          case QMediaPlayer::EndOfMedia:
              QApplication::alert(this);
              break;
          case QMediaPlayer::InvalidMedia:
              displayErrorMessage();
              break;
          }
      }

      void Player::stateChanged(QMediaPlayer::State state)
      {
          if (state == QMediaPlayer::StoppedState)
              clearHistogram();
      }

      void Player::handleCursor(QMediaPlayer::MediaStatus status)
      {
      #ifndef QT_NO_CURSOR
          if (status == QMediaPlayer::LoadingMedia ||
              status == QMediaPlayer::BufferingMedia ||
              status == QMediaPlayer::StalledMedia)
              setCursor(QCursor(Qt::BusyCursor));
          else
              unsetCursor();
      #endif
      }

      void Player::bufferingProgress(int progress)
      {
          if (m_player->mediaStatus() == QMediaPlayer::StalledMedia)
              setStatusInfo(tr("Stalled %1%").arg(progress));
          else
              setStatusInfo(tr("Buffering %1%").arg(progress));
      }

      void Player::videoAvailableChanged(bool available)
      {
          if (!available) {
              disconnect(m_fullScreenButton, &QPushButton::clicked, m_videoWidget, &QVideoWidget::setFullScreen);
              disconnect(m_videoWidget, &QVideoWidget::fullScreenChanged, m_fullScreenButton, &QPushButton::setChecked);
              m_videoWidget->setFullScreen(false);
          } else {
              connect(m_fullScreenButton, &QPushButton::clicked, m_videoWidget, &QVideoWidget::setFullScreen);
              connect(m_videoWidget, &QVideoWidget::fullScreenChanged, m_fullScreenButton, &QPushButton::setChecked);

              if (m_fullScreenButton->isChecked())
                  m_videoWidget->setFullScreen(true);
          }
          m_colorButton->setEnabled(available);
      }

      void Player::setTrackInfo(const QString &info)
      {
          m_trackInfo = info;

          if (m_statusBar) {
              m_statusBar->showMessage(m_trackInfo);
              m_statusLabel->setText(m_statusInfo);
          } else {
              if (!m_statusInfo.isEmpty())
                  setWindowTitle(QString("%1 | %2").arg(m_trackInfo).arg(m_statusInfo));
              else
                  setWindowTitle(m_trackInfo);
          }
      }

      void Player::setStatusInfo(const QString &info)
      {
          m_statusInfo = info;

          if (m_statusBar) {
              m_statusBar->showMessage(m_trackInfo);
              m_statusLabel->setText(m_statusInfo);
          } else {
              if (!m_statusInfo.isEmpty())
                  setWindowTitle(QString("%1 | %2").arg(m_trackInfo).arg(m_statusInfo));
              else
                  setWindowTitle(m_trackInfo);
          }
      }

      void Player::displayErrorMessage()
      {
          setStatusInfo(m_player->errorString());
      }

      void Player::updateDurationInfo(qint64 currentInfo)
      {
          QString tStr;
          if (currentInfo || m_duration) {
              QTime currentTime((currentInfo / 3600) % 60, (currentInfo / 60) % 60,
                  currentInfo % 60, (currentInfo * 1000) % 1000);
              QTime totalTime((m_duration / 3600) % 60, (m_duration / 60) % 60,
                  m_duration % 60, (m_duration * 1000) % 1000);
              QString format = "mm:ss";
              if (m_duration > 3600)
                  format = "hh:mm:ss";
              tStr = currentTime.toString(format) + " / " + totalTime.toString(format);
          }
          m_labelDuration->setText(tStr);
      }

      void Player::showColorDialog()
      {
          if (!m_colorDialog) {
              QSlider *brightnessSlider = new QSlider(Qt::Horizontal);
              brightnessSlider->setRange(-100, 100);
              brightnessSlider->setValue(m_videoWidget->brightness());
              connect(brightnessSlider, &QSlider::sliderMoved, m_videoWidget, &QVideoWidget::setBrightness);
              connect(m_videoWidget, &QVideoWidget::brightnessChanged, brightnessSlider, &QSlider::setValue);

              QSlider *contrastSlider = new QSlider(Qt::Horizontal);
              contrastSlider->setRange(-100, 100);
              contrastSlider->setValue(m_videoWidget->contrast());
              connect(contrastSlider, &QSlider::sliderMoved, m_videoWidget, &QVideoWidget::setContrast);
              connect(m_videoWidget, &QVideoWidget::contrastChanged, contrastSlider, &QSlider::setValue);

              QSlider *hueSlider = new QSlider(Qt::Horizontal);
              hueSlider->setRange(-100, 100);
              hueSlider->setValue(m_videoWidget->hue());
              connect(hueSlider, &QSlider::sliderMoved, m_videoWidget, &QVideoWidget::setHue);
              connect(m_videoWidget, &QVideoWidget::hueChanged, hueSlider, &QSlider::setValue);

              QSlider *saturationSlider = new QSlider(Qt::Horizontal);
              saturationSlider->setRange(-100, 100);
              saturationSlider->setValue(m_videoWidget->saturation());
              connect(saturationSlider, &QSlider::sliderMoved, m_videoWidget, &QVideoWidget::setSaturation);
              connect(m_videoWidget, &QVideoWidget::saturationChanged, saturationSlider, &QSlider::setValue);

              QFormLayout *layout = new QFormLayout;
              layout->addRow(tr("Brightness"), brightnessSlider);
              layout->addRow(tr("Contrast"), contrastSlider);
              layout->addRow(tr("Hue"), hueSlider);
              layout->addRow(tr("Saturation"), saturationSlider);

              QPushButton *button = new QPushButton(tr("Close"));
              layout->addRow(button);

              m_colorDialog = new QDialog(this);
              m_colorDialog->setWindowTitle(tr("Color Options"));
              m_colorDialog->setLayout(layout);

              connect(button, &QPushButton::clicked, m_colorDialog, &QDialog::close);
          }
          m_colorDialog->show();
      }

      void Player::clearHistogram()
      {
          QMetaObject::invokeMethod(m_videoHistogram, "processFrame", Qt::QueuedConnection, Q_ARG(QVideoFrame, QVideoFrame()));
          QMetaObject::invokeMethod(m_audioHistogram, "processBuffer", Qt::QueuedConnection, Q_ARG(QAudioBuffer, QAudioBuffer()));
      }