waveform.cpp Example File

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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;
  }