Method getSubTickCount

qcustomplot/qcustomplot.cpp:5607–5657

! \internal Takes the \a tickStep, i.e. the distance between two consecutive ticks, and returns an appropriate number of sub ticks for that specific tick step. Note that a returned sub tick count of e.g. 4 will split each tick interval into 5 sections. */

  Note that a returned sub tick count of e.g. 4 will split each tick interval into 5 sections.
*/
int QCPAxisTicker::getSubTickCount(double tickStep)
{
  int result = 1; // default to 1, if no proper value can be found
  
  // separate integer and fractional part of mantissa:
  double epsilon = 0.01;
  double intPartf;
  int intPart;
  double fracPart = modf(getMantissa(tickStep), &intPartf);
  intPart = intPartf;
  
  // handle cases with (almost) integer mantissa:
  if (fracPart < epsilon || 1.0-fracPart < epsilon)
  {
    if (1.0-fracPart < epsilon)
      ++intPart;
    switch (intPart)
    {
      case 1: result = 4; break; // 1.0 -> 0.2 substep
      case 2: result = 3; break; // 2.0 -> 0.5 substep
      case 3: result = 2; break; // 3.0 -> 1.0 substep
      case 4: result = 3; break; // 4.0 -> 1.0 substep
      case 5: result = 4; break; // 5.0 -> 1.0 substep
      case 6: result = 2; break; // 6.0 -> 2.0 substep
      case 7: result = 6; break; // 7.0 -> 1.0 substep
      case 8: result = 3; break; // 8.0 -> 2.0 substep
      case 9: result = 2; break; // 9.0 -> 3.0 substep
    }
  } else
  {
    // handle cases with significantly fractional mantissa:
    if (qAbs(fracPart-0.5) < epsilon) // *.5 mantissa
    {
      switch (intPart)
      {
        case 1: result = 2; break; // 1.5 -> 0.5 substep
        case 2: result = 4; break; // 2.5 -> 0.5 substep
        case 3: result = 4; break; // 3.5 -> 0.7 substep
        case 4: result = 2; break; // 4.5 -> 1.5 substep
        case 5: result = 4; break; // 5.5 -> 1.1 substep (won't occur with default getTickStep from here on)
        case 6: result = 4; break; // 6.5 -> 1.3 substep
        case 7: result = 2; break; // 7.5 -> 2.5 substep
        case 8: result = 4; break; // 8.5 -> 1.7 substep
        case 9: result = 4; break; // 9.5 -> 1.9 substep
      }
    }
    // if mantissa fraction isn't 0.0 or 0.5, don't bother finding good sub tick marks, leave default
  }
  
  return result;
}

/*! \internal