Method getTickLabelDrawOffset

qcustomplot/qcustomplot.cpp:9709–9800

! \internal This is a \ref placeTickLabel helper function. Calculates the offset at which the top left corner of the specified tick label shall be drawn. The offset is relative to a point right next to the tick the label belongs to. This function is thus responsible for e.g. centering tick labels under ticks and positioning them appropriately when they are rotated. */

  appropriately when they are rotated.
*/
QPointF QCPAxisPainterPrivate::getTickLabelDrawOffset(const TickLabelData &labelData) const
{
  /*
    calculate label offset from base point at tick (non-trivial, for best visual appearance): short
    explanation for bottom axis: The anchor, i.e. the point in the label that is placed
    horizontally under the corresponding tick is always on the label side that is closer to the
    axis (e.g. the left side of the text when we're rotating clockwise). On that side, the height
    is halved and the resulting point is defined the anchor. This way, a 90 degree rotated text
    will be centered under the tick (i.e. displaced horizontally by half its height). At the same
    time, a 45 degree rotated text will "point toward" its tick, as is typical for rotated tick
    labels.
  */
  bool doRotation = !qFuzzyIsNull(tickLabelRotation);
  bool flip = qFuzzyCompare(qAbs(tickLabelRotation), 90.0); // perfect +/-90 degree flip. Indicates vertical label centering on vertical axes.
  double radians = tickLabelRotation/180.0*M_PI;
  int x=0, y=0;
  if ((type == QCPAxis::atLeft && tickLabelSide == QCPAxis::lsOutside) || (type == QCPAxis::atRight && tickLabelSide == QCPAxis::lsInside)) // Anchor at right side of tick label
  {
    if (doRotation)
    {
      if (tickLabelRotation > 0)
      {
        x = -qCos(radians)*labelData.totalBounds.width();
        y = flip ? -labelData.totalBounds.width()/2.0 : -qSin(radians)*labelData.totalBounds.width()-qCos(radians)*labelData.totalBounds.height()/2.0;
      } else
      {
        x = -qCos(-radians)*labelData.totalBounds.width()-qSin(-radians)*labelData.totalBounds.height();
        y = flip ? +labelData.totalBounds.width()/2.0 : +qSin(-radians)*labelData.totalBounds.width()-qCos(-radians)*labelData.totalBounds.height()/2.0;
      }
    } else
    {
      x = -labelData.totalBounds.width();
      y = -labelData.totalBounds.height()/2.0;
    }
  } else if ((type == QCPAxis::atRight && tickLabelSide == QCPAxis::lsOutside) || (type == QCPAxis::atLeft && tickLabelSide == QCPAxis::lsInside)) // Anchor at left side of tick label
  {
    if (doRotation)
    {
      if (tickLabelRotation > 0)
      {
        x = +qSin(radians)*labelData.totalBounds.height();
        y = flip ? -labelData.totalBounds.width()/2.0 : -qCos(radians)*labelData.totalBounds.height()/2.0;
      } else
      {
        x = 0;
        y = flip ? +labelData.totalBounds.width()/2.0 : -qCos(-radians)*labelData.totalBounds.height()/2.0;
      }
    } else
    {
      x = 0;
      y = -labelData.totalBounds.height()/2.0;
    }
  } else if ((type == QCPAxis::atTop && tickLabelSide == QCPAxis::lsOutside) || (type == QCPAxis::atBottom && tickLabelSide == QCPAxis::lsInside)) // Anchor at bottom side of tick label
  {
    if (doRotation)
    {
      if (tickLabelRotation > 0)
      {