Method getOptimizedPoint

projects/gui/3rdparty/qcustomplot/qcustomplot.cpp:23313–23409

! \internal This function is part of the curve optimization algorithm of \ref getCurveLines. This method is used in case the current segment passes from inside the visible rect (region 5, see \ref getRegion) to any of the outer regions (\a otherRegion). The current segment is given by the line connecting (\a key, \a value) with (\a otherKey, \a otherValue). It returns the inters

  equal to 5.
*/
QPointF QCPCurve::getOptimizedPoint(int otherRegion, double otherKey, double otherValue, double key, double value, double keyMin, double valueMax, double keyMax, double valueMin) const
{
  // The intersection point interpolation here is done in pixel coordinates, so we don't need to
  // differentiate between different axis scale types. Note that the nomenclature
  // top/left/bottom/right/min/max is with respect to the rect in plot coordinates, wich may be
  // different in pixel coordinates (horz/vert key axes, reversed ranges)
  
  const double keyMinPx = mKeyAxis->coordToPixel(keyMin);
  const double keyMaxPx = mKeyAxis->coordToPixel(keyMax);
  const double valueMinPx = mValueAxis->coordToPixel(valueMin);
  const double valueMaxPx = mValueAxis->coordToPixel(valueMax);
  const double otherValuePx = mValueAxis->coordToPixel(otherValue);
  const double valuePx = mValueAxis->coordToPixel(value);
  const double otherKeyPx = mKeyAxis->coordToPixel(otherKey);
  const double keyPx = mKeyAxis->coordToPixel(key);
  double intersectKeyPx = keyMinPx; // initial key just a fail-safe
  double intersectValuePx = valueMinPx; // initial value just a fail-safe
  switch (otherRegion)
  {
    case 1: // top and left edge
    {
      intersectValuePx = valueMaxPx;
      intersectKeyPx = otherKeyPx + (keyPx-otherKeyPx)/(valuePx-otherValuePx)*(intersectValuePx-otherValuePx);
      if (intersectKeyPx < qMin(keyMinPx, keyMaxPx) || intersectKeyPx > qMax(keyMinPx, keyMaxPx)) // check whether top edge is not intersected, then it must be left edge (qMin/qMax necessary since axes may be reversed)
      {
        intersectKeyPx = keyMinPx;
        intersectValuePx = otherValuePx + (valuePx-otherValuePx)/(keyPx-otherKeyPx)*(intersectKeyPx-otherKeyPx);
      }
      break;
    }
    case 2: // left edge
    {
      intersectKeyPx = keyMinPx;
      intersectValuePx = otherValuePx + (valuePx-otherValuePx)/(keyPx-otherKeyPx)*(intersectKeyPx-otherKeyPx);
      break;
    }
    case 3: // bottom and left edge
    {
      intersectValuePx = valueMinPx;
      intersectKeyPx = otherKeyPx + (keyPx-otherKeyPx)/(valuePx-otherValuePx)*(intersectValuePx-otherValuePx);
      if (intersectKeyPx < qMin(keyMinPx, keyMaxPx) || intersectKeyPx > qMax(keyMinPx, keyMaxPx)) // check whether bottom edge is not intersected, then it must be left edge (qMin/qMax necessary since axes may be reversed)
      {
        intersectKeyPx = keyMinPx;
        intersectValuePx = otherValuePx + (valuePx-otherValuePx)/(keyPx-otherKeyPx)*(intersectKeyPx-otherKeyPx);
      }
      break;
    }
    case 4: // top edge
    {
      intersectValuePx = valueMaxPx;
      intersectKeyPx = otherKeyPx + (keyPx-otherKeyPx)/(valuePx-otherValuePx)*(intersectValuePx-otherValuePx);
      break;
    }
    case 5:
    {
      break; // case 5 shouldn't happen for this function but we add it anyway to prevent potential discontinuity in branch table
    }
    case 6: // bottom edge