FormatCoordsUnitsStrategyAbstractBase.cpp

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/******************************************************************************************************
 * (C) 2014 markummitchell@github.com. This file is part of Engauge Digitizer, which is released      *
 * under GNU General Public License version 2 (GPLv2) or (at your option) any later version. See file *
 * LICENSE or go to gnu.org/licenses for details. Distribution requires prior written permission.     *
 ******************************************************************************************************/
 
#include "DocumentModelGeneral.h"
#include "FormatCoordsUnitsStrategyAbstractBase.h"
#include "Logger.h"
#include <qmath.h>
#include "Transformation.h"
 
FormatCoordsUnitsStrategyAbstractBase::FormatCoordsUnitsStrategyAbstractBase ()
{
}
 
int FormatCoordsUnitsStrategyAbstractBase::precisionDigitsForRawNumber (double valueUnformatted,
                                                                        double valueUnformattedOther,
                                                                        bool isXTheta,
                                                                        const DocumentModelGeneral &modelGeneral,
                                                                        const Transformation &transformation) const
{
  //qCDebug(ENGAUGE_LOG) << "FormatCoordsUnitsStrategyAbstractBase::precisionDigitsForRawNumber";
 
  const double PIXEL_SHIFT = 1;
  const int DEFAULT_PRECISION = 5; // Precision used before transformation is available. Equal or greater than x/y pixel counts
 
  if (transformation.transformIsDefined()) {
 
    // Measure the resolution if the point is moved some number of pixels in screen coordinates
    QPointF posGraph;
    if (isXTheta) {
 
      posGraph = QPointF (valueUnformatted,
                          valueUnformattedOther);
 
    } else {
 
      posGraph = QPointF (valueUnformattedOther,
                          valueUnformatted);
 
    }
 
    QPointF posScreen, posScreenShifted, posGraphShifted;
 
    transformation.transformRawGraphToScreen (posGraph,
                                              posScreen);
 
    posScreenShifted = posScreen + QPointF (PIXEL_SHIFT, PIXEL_SHIFT);
 
    transformation.transformScreenToRawGraph (posScreenShifted,
                                              posGraphShifted);
 
    double xResolutionPerPixel = (posGraphShifted.x() - posGraph.x()) / PIXEL_SHIFT;
    double yResolutionPerPixel = (posGraphShifted.y() - posGraph.y()) / PIXEL_SHIFT;
    double resolutionPerPixel = (isXTheta ? xResolutionPerPixel : yResolutionPerPixel);
 
    // Compute number of digits ahead of the decimal point (any single decimal place would work but the decimal point is easiest)
    int powerValue = qFloor (qLn (qAbs (valueUnformatted)) / qLn (10.0));
    int powerResolution = qFloor (qLn (qAbs (resolutionPerPixel)) / qLn (10.0));
 
    int numberDigitsForResolution = powerValue - powerResolution + 1 + modelGeneral.extraPrecision();
 
    return numberDigitsForResolution + 1; // Add one just to be safe
 
  } else {
 
    return DEFAULT_PRECISION;
  }
}