xyseriesiodevice.cpp Example File

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  #include "xyseriesiodevice.h"

  #include <QtCharts/QXYSeries>

  XYSeriesIODevice::XYSeriesIODevice(QXYSeries *series, QObject *parent) :
      QIODevice(parent),
      m_series(series)
  {
  }

  qint64 XYSeriesIODevice::readData(char *data, qint64 maxSize)
  {
      Q_UNUSED(data)
      Q_UNUSED(maxSize)
      return -1;
  }

  qint64 XYSeriesIODevice::writeData(const char *data, qint64 maxSize)
  {
      static const int resolution = 4;

      if (m_buffer.isEmpty()) {
          m_buffer.reserve(sampleCount);
          for (int i = 0; i < sampleCount; ++i)
              m_buffer.append(QPointF(i, 0));
      }

      int start = 0;
      const int availableSamples = int(maxSize) / resolution;
      if (availableSamples < sampleCount) {
          start = sampleCount - availableSamples;
          for (int s = 0; s < start; ++s)
              m_buffer[s].setY(m_buffer.at(s + availableSamples).y());
      }

      for (int s = start; s < sampleCount; ++s, data += resolution)
          m_buffer[s].setY(qreal(uchar(*data) -128) / qreal(128));

      m_series->replace(m_buffer);
      return (sampleCount - start) * resolution;
  }