Method dataToStepLeftLines

qcustomplot.cpp:20608–20644

! \internal Takes raw data points in plot coordinates as \a data, and returns a vector containing pixel coordinate points which are suitable for drawing the line style \ref lsStepLeft. The source of \a data is usually \ref getOptimizedLineData, and this method is called in \a getLines if the line style is set accordingly. \see dataToLines, dataToStepRightLines, dataToStepCenterLines

  \see dataToLines, dataToStepRightLines, dataToStepCenterLines, dataToImpulseLines, getLines, drawLinePlot
*/
QVector<QPointF> QCPGraph::dataToStepLeftLines(const QVector<QCPGraphData> &data) const
{
  QVector<QPointF> result;
  QCPAxis *keyAxis = mKeyAxis.data();
  QCPAxis *valueAxis = mValueAxis.data();
  if (!keyAxis || !valueAxis) { qDebug() << Q_FUNC_INFO << "invalid key or value axis"; return result; }
  
  result.resize(data.size()*2);
  
  // calculate steps from data and transform to pixel coordinates:
  if (keyAxis->orientation() == Qt::Vertical)
  {
    double lastValue = valueAxis->coordToPixel(data.first().value);
    for (int i=0; i<data.size(); ++i)
    {
      const double key = keyAxis->coordToPixel(data.at(i).key);
      result[i*2+0].setX(lastValue);
      result[i*2+0].setY(key);
      lastValue = valueAxis->coordToPixel(data.at(i).value);
      result[i*2+1].setX(lastValue);
      result[i*2+1].setY(key);
    }
  } else // key axis is horizontal
  {
    double lastValue = valueAxis->coordToPixel(data.first().value);
    for (int i=0; i<data.size(); ++i)
    {
      const double key = keyAxis->coordToPixel(data.at(i).key);
      result[i*2+0].setX(key);
      result[i*2+0].setY(lastValue);
      lastValue = valueAxis->coordToPixel(data.at(i).value);
      result[i*2+1].setX(key);
      result[i*2+1].setY(lastValue);
    }
  }
  return result;
}

/*! \internal