qgsfractionnumericformat.h

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/***************************************************************************
                             qgsfractionnumericformat.h
                             --------------------------
    begin                : March 2020
    copyright            : (C) 2020 by Nyall Dawson
    email                : nyall dot dawson at gmail dot com
 ***************************************************************************
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 ***************************************************************************/
#ifndef QGSFRACTIONNUMERICFORMAT_H
#define QGSFRACTIONNUMERICFORMAT_H
 
#include <cmath>
 
#include "qgis.h"
#include "qgis_core.h"
#include "qgis_sip.h"
#include "qgsnumericformat.h"

class CORE_EXPORT QgsFractionNumericFormat : public QgsNumericFormat
{
  public:

    QgsFractionNumericFormat();
 
    QString id() const override;
    QString visibleName() const override;
    int sortKey() override;
    QString formatDouble( double value, const QgsNumericFormatContext &context ) const override;
    QgsNumericFormat *clone() const override SIP_FACTORY;
    QgsNumericFormat *create( const QVariantMap &configuration, const QgsReadWriteContext &context ) const override SIP_FACTORY;
    QVariantMap configuration( const QgsReadWriteContext &context ) const override;
    double suggestSampleValue() const override;

    bool useDedicatedUnicodeCharacters() const;

    void setUseDedicatedUnicodeCharacters( bool enabled );

    bool useUnicodeSuperSubscript() const;

    void setUseUnicodeSuperSubscript( bool enabled );

    bool showThousandsSeparator() const;

    void setShowThousandsSeparator( bool show );

    bool showPlusSign() const;

    void setShowPlusSign( bool show );

    QChar thousandsSeparator() const;

    void setThousandsSeparator( QChar character );

    static bool doubleToVulgarFraction( const double value, unsigned long long &numerator SIP_OUT, unsigned long long &denominator SIP_OUT, int &sign SIP_OUT, const double tolerance = 1e-10 )
    {
      sign = value < 0 ? -1 : 1;
      double g = std::fabs( value );
      unsigned long long a = 0;
      unsigned long long b = 1;
      unsigned long long c = 1;
      unsigned long long d = 0;
      unsigned long long s;
      unsigned int iteration = 0;
      do
      {
        s = std::floor( g );
        numerator = a + s * c;
        denominator = b + s * d;
        a = c;
        b = d;
        c = numerator;
        d = denominator;
        g = 1.0 / ( g - s );
        if ( qgsDoubleNear( static_cast< double >( sign )*static_cast< double >( numerator ) / denominator, value, tolerance ) )
        {
          return true;
        }
      }
      while ( iteration++ < 100 ); // limit to 100 iterations, should be sufficient for realistic purposes
      return false;
    }

    static QString toUnicodeSuperscript( const QString &input );

    static QString toUnicodeSubscript( const QString &input );
 
  protected:

    virtual void setConfiguration( const QVariantMap &configuration, const QgsReadWriteContext &context );
 
  private:
 
    bool mUseDedicatedUnicode = false;
    bool mUseUnicodeSuperSubscript = true;
    bool mShowThousandsSeparator = true;
    bool mShowPlusSign = false;
    QChar mThousandsSeparator;
};
 
#endif // QGSFRACTIONNUMERICFORMAT_H