Qt 5.8 | Qt Multimedia | Spectrum Example | waveform.cpp Example File

Qt 5.8.0 Reference Documentation

# waveform.cpp Example File

multimedia/spectrum/app/waveform.cpp

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      #include "waveform.h"
      #include "utils.h"
      #include <QPainter>
      #include <QResizeEvent>
      #include <QDebug>

      //#define PAINT_EVENT_TRACE
      #ifdef PAINT_EVENT_TRACE
      #   define WAVEFORM_PAINT_DEBUG qDebug()
      #else
      #   define WAVEFORM_PAINT_DEBUG nullDebug()
      #endif

      Waveform::Waveform(QWidget *parent)
          :   QWidget(parent)
          ,   m_bufferPosition(0)
          ,   m_bufferLength(0)
          ,   m_audioPosition(0)
          ,   m_active(false)
          ,   m_tileLength(0)
          ,   m_tileArrayStart(0)
          ,   m_windowPosition(0)
          ,   m_windowLength(0)
      {
          setSizePolicy(QSizePolicy::Preferred, QSizePolicy::Fixed);
          setMinimumHeight(50);
      }

      Waveform::~Waveform()
      {
          deletePixmaps();
      }

      void Waveform::paintEvent(QPaintEvent * /*event*/)
      {
          QPainter painter(this);

          painter.fillRect(rect(), Qt::black);

          if (m_active) {
              WAVEFORM_PAINT_DEBUG << "Waveform::paintEvent"
                                   << "windowPosition" << m_windowPosition
                                   << "windowLength" << m_windowLength;
              qint64 pos = m_windowPosition;
              const qint64 windowEnd = m_windowPosition + m_windowLength;
              int destLeft = 0;
              int destRight = 0;
              while (pos < windowEnd) {
                  const TilePoint point = tilePoint(pos);
                  WAVEFORM_PAINT_DEBUG << "Waveform::paintEvent" << "pos" << pos
                                       << "tileIndex" << point.index
                                       << "positionOffset" << point.positionOffset
                                       << "pixelOffset" << point.pixelOffset;

                  if (point.index != NullIndex) {
                      const Tile &tile = m_tiles[point.index];
                      if (tile.painted) {
                          const qint64 sectionLength = qMin((m_tileLength - point.positionOffset),
                                                           (windowEnd - pos));
                          Q_ASSERT(sectionLength > 0);

                          const int sourceRight = tilePixelOffset(point.positionOffset + sectionLength);
                          destRight = windowPixelOffset(pos - m_windowPosition + sectionLength);

                          QRect destRect = rect();
                          destRect.setLeft(destLeft);
                          destRect.setRight(destRight);

                          QRect sourceRect(QPoint(), m_pixmapSize);
                          sourceRect.setLeft(point.pixelOffset);
                          sourceRect.setRight(sourceRight);

                          WAVEFORM_PAINT_DEBUG << "Waveform::paintEvent" << "tileIndex" << point.index
                                               << "source" << point.pixelOffset << sourceRight
                                               << "dest" << destLeft << destRight;

                          painter.drawPixmap(destRect, *tile.pixmap, sourceRect);

                          destLeft = destRight;

                          if (point.index < m_tiles.count()) {
                              pos = tilePosition(point.index + 1);
                              WAVEFORM_PAINT_DEBUG << "Waveform::paintEvent" << "pos ->" << pos;
                          } else {
                              // Reached end of tile array
                              WAVEFORM_PAINT_DEBUG << "Waveform::paintEvent" << "reached end of tile array";
                              break;
                          }
                      } else {
                          // Passed last tile which is painted
                          WAVEFORM_PAINT_DEBUG << "Waveform::paintEvent" << "tile" << point.index << "not painted";
                          break;
                      }
                  } else {
                      // pos is past end of tile array
                      WAVEFORM_PAINT_DEBUG << "Waveform::paintEvent" << "pos" << pos << "past end of tile array";
                      break;
                  }
              }

              WAVEFORM_PAINT_DEBUG << "Waveform::paintEvent" << "final pos" << pos << "final x" << destRight;
          }
      }

      void Waveform::resizeEvent(QResizeEvent *event)
      {
          if (event->size() != event->oldSize())
              createPixmaps(event->size());
      }

      void Waveform::initialize(const QAudioFormat &format, qint64 audioBufferSize, qint64 windowDurationUs)
      {
          WAVEFORM_DEBUG << "Waveform::initialize"
                         << "audioBufferSize" << audioBufferSize
                         << "windowDurationUs" << windowDurationUs;

          reset();

          m_format = format;

          // Calculate tile size
          m_tileLength = audioBufferSize;

          // Calculate window size
          m_windowLength = audioLength(m_format, windowDurationUs);

          // Calculate number of tiles required
          int nTiles;
          if (m_tileLength > m_windowLength) {
              nTiles = 2;
          } else {
              nTiles = m_windowLength / m_tileLength + 1;
              if (m_windowLength % m_tileLength)
                  ++nTiles;
          }

          WAVEFORM_DEBUG << "Waveform::initialize"
                         << "tileLength" << m_tileLength
                         << "windowLength" << m_windowLength
                         << "nTiles" << nTiles;

          m_pixmaps.fill(0, nTiles);
          m_tiles.resize(nTiles);

          createPixmaps(rect().size());

          m_active = true;
      }

      void Waveform::reset()
      {
          WAVEFORM_DEBUG << "Waveform::reset";

          m_bufferPosition = 0;
          m_buffer = QByteArray();
          m_audioPosition = 0;
          m_format = QAudioFormat();
          m_active = false;
          deletePixmaps();
          m_tiles.clear();
          m_tileLength = 0;
          m_tileArrayStart = 0;
          m_windowPosition = 0;
          m_windowLength = 0;
      }

      void Waveform::bufferChanged(qint64 position, qint64 length, const QByteArray &buffer)
      {
          WAVEFORM_DEBUG << "Waveform::bufferChanged"
                         << "audioPosition" << m_audioPosition
                         << "bufferPosition" << position
                         << "bufferLength" << length;
          m_bufferPosition = position;
          m_bufferLength = length;
          m_buffer = buffer;
          paintTiles();
      }

      void Waveform::audioPositionChanged(qint64 position)
      {
          WAVEFORM_DEBUG << "Waveform::audioPositionChanged"
                         << "audioPosition" << position
                         << "bufferPosition" << m_bufferPosition
                         << "bufferLength" << m_bufferLength;

          if (position >= m_bufferPosition) {
              if (position + m_windowLength > m_bufferPosition + m_bufferLength)
                  position = qMax(qint64(0), m_bufferPosition + m_bufferLength - m_windowLength);
              m_audioPosition = position;
              setWindowPosition(position);
          }
      }

      void Waveform::deletePixmaps()
      {
          QPixmap *pixmap;
          foreach (pixmap, m_pixmaps)
              delete pixmap;
          m_pixmaps.clear();
      }

      void Waveform::createPixmaps(const QSize &widgetSize)
      {
          m_pixmapSize = widgetSize;
          m_pixmapSize.setWidth(qreal(widgetSize.width()) * m_tileLength / m_windowLength);

          WAVEFORM_DEBUG << "Waveform::createPixmaps"
                         << "widgetSize" << widgetSize
                         << "pixmapSize" << m_pixmapSize;

          Q_ASSERT(m_tiles.count() == m_pixmaps.count());

          // (Re)create pixmaps
          for (int i=0; i<m_pixmaps.size(); ++i) {
              delete m_pixmaps[i];
              m_pixmaps[i] = 0;
              m_pixmaps[i] = new QPixmap(m_pixmapSize);
          }

          // Update tile pixmap pointers, and mark for repainting
          for (int i=0; i<m_tiles.count(); ++i) {
              m_tiles[i].pixmap = m_pixmaps[i];
              m_tiles[i].painted = false;
          }
      }

      void Waveform::setWindowPosition(qint64 position)
      {
          WAVEFORM_DEBUG << "Waveform::setWindowPosition"
                         << "old" << m_windowPosition << "new" << position
                         << "tileArrayStart" << m_tileArrayStart;

          const qint64 oldPosition = m_windowPosition;
          m_windowPosition = position;

          if ((m_windowPosition >= oldPosition) &&
              (m_windowPosition - m_tileArrayStart < (m_tiles.count() * m_tileLength))) {
              // Work out how many tiles need to be shuffled
              const qint64 offset = m_windowPosition - m_tileArrayStart;
              const int nTiles = offset / m_tileLength;
              shuffleTiles(nTiles);
          } else {
              resetTiles(m_windowPosition);
          }

          if (!paintTiles() && m_windowPosition != oldPosition)
              update();
      }

      qint64 Waveform::tilePosition(int index) const
      {
          return m_tileArrayStart + index * m_tileLength;
      }

      Waveform::TilePoint Waveform::tilePoint(qint64 position) const
      {
          TilePoint result;
          if (position >= m_tileArrayStart) {
              const qint64 tileArrayEnd = m_tileArrayStart + m_tiles.count() * m_tileLength;
              if (position < tileArrayEnd) {
                  const qint64 offsetIntoTileArray = position - m_tileArrayStart;
                  result.index = offsetIntoTileArray / m_tileLength;
                  Q_ASSERT(result.index >= 0 && result.index <= m_tiles.count());
                  result.positionOffset = offsetIntoTileArray % m_tileLength;
                  result.pixelOffset = tilePixelOffset(result.positionOffset);
                  Q_ASSERT(result.pixelOffset >= 0 && result.pixelOffset <= m_pixmapSize.width());
              }
          }

          return result;
      }

      int Waveform::tilePixelOffset(qint64 positionOffset) const
      {
          Q_ASSERT(positionOffset >= 0 && positionOffset <= m_tileLength);
          const int result = (qreal(positionOffset) / m_tileLength) * m_pixmapSize.width();
          return result;
      }

      int Waveform::windowPixelOffset(qint64 positionOffset) const
      {
          Q_ASSERT(positionOffset >= 0 && positionOffset <= m_windowLength);
          const int result = (qreal(positionOffset) / m_windowLength) * rect().width();
          return result;
      }

      bool Waveform::paintTiles()
      {
          WAVEFORM_DEBUG << "Waveform::paintTiles";
          bool updateRequired = false;

          for (int i=0; i<m_tiles.count(); ++i) {
              const Tile &tile = m_tiles[i];
              if (!tile.painted) {
                  const qint64 tileStart = m_tileArrayStart + i * m_tileLength;
                  const qint64 tileEnd = tileStart + m_tileLength;
                  if (m_bufferPosition <= tileStart && m_bufferPosition + m_bufferLength >= tileEnd) {
                      paintTile(i);
                      updateRequired = true;
                  }
              }
          }

          if (updateRequired)
              update();

          return updateRequired;
      }

      void Waveform::paintTile(int index)
      {
          const qint64 tileStart = m_tileArrayStart + index * m_tileLength;

          WAVEFORM_DEBUG << "Waveform::paintTile"
                         << "index" << index
                         << "bufferPosition" << m_bufferPosition
                         << "bufferLength" << m_bufferLength
                         << "start" << tileStart
                         << "end" << tileStart + m_tileLength;

          Q_ASSERT(m_bufferPosition <= tileStart);
          Q_ASSERT(m_bufferPosition + m_bufferLength >= tileStart + m_tileLength);

          Tile &tile = m_tiles[index];
          Q_ASSERT(!tile.painted);

          const qint16* base = reinterpret_cast<const qint16*>(m_buffer.constData());
          const qint16* buffer = base + ((tileStart - m_bufferPosition) / 2);
          const int numSamples = m_tileLength / (2 * m_format.channelCount());

          QPainter painter(tile.pixmap);

          painter.fillRect(tile.pixmap->rect(), Qt::black);

          QPen pen(Qt::white);
          painter.setPen(pen);

          // Calculate initial PCM value
          qint16 previousPcmValue = 0;
          if (buffer > base)
              previousPcmValue = *(buffer - m_format.channelCount());

          // Calculate initial point
          const qreal previousRealValue = pcmToReal(previousPcmValue);
          const int originY = ((previousRealValue + 1.0) / 2) * m_pixmapSize.height();
          const QPoint origin(0, originY);

          QLine line(origin, origin);

          for (int i=0; i<numSamples; ++i) {
              const qint16* ptr = buffer + i * m_format.channelCount();

              const int offset = reinterpret_cast<const char*>(ptr) - m_buffer.constData();
              Q_ASSERT(offset >= 0);
              Q_ASSERT(offset < m_bufferLength);
              Q_UNUSED(offset);

              const qint16 pcmValue = *ptr;
              const qreal realValue = pcmToReal(pcmValue);

              const int x = tilePixelOffset(i * 2 * m_format.channelCount());
              const int y = ((realValue + 1.0) / 2) * m_pixmapSize.height();

              line.setP2(QPoint(x, y));
              painter.drawLine(line);
              line.setP1(line.p2());
          }

          tile.painted = true;
      }

      void Waveform::shuffleTiles(int n)
      {
          WAVEFORM_DEBUG << "Waveform::shuffleTiles" << "n" << n;

          while (n--) {
              Tile tile = m_tiles.first();
              tile.painted = false;
              m_tiles.erase(m_tiles.begin());
              m_tiles += tile;
              m_tileArrayStart += m_tileLength;
          }

          WAVEFORM_DEBUG << "Waveform::shuffleTiles" << "tileArrayStart" << m_tileArrayStart;
      }

      void Waveform::resetTiles(qint64 newStartPos)
      {
          WAVEFORM_DEBUG << "Waveform::resetTiles" << "newStartPos" << newStartPos;

          QVector<Tile>::iterator i = m_tiles.begin();
          for ( ; i != m_tiles.end(); ++i)
              i->painted = false;

          m_tileArrayStart = newStartPos;
      }