qgscontrastenhancement.h

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/* **************************************************************************
                qgscontrastenhancement.h -  description
                       -------------------
begin                : Mon Oct 22 2007
copyright            : (C) 2007 by Peter J. Ersts
email                : [email protected]

This class contains code that was originally part of the larger QgsRasterLayer
class originally created circa 2004 by T.Sutton, Gary E.Sherman, Steve Halasz
****************************************************************************/

/* **************************************************************************
 *                                                                         *
 *   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 QGSCONTRASTENHANCEMENT_H
#define QGSCONTRASTENHANCEMENT_H

#include "qgis_core.h"
#include <limits>

#include "qgis.h"
#include "qgsraster.h"
#include <memory>

class QgsContrastEnhancementFunction;
class QDomDocument;
class QDomElement;
class QString;

class CORE_EXPORT QgsContrastEnhancement
{

  public:

    enum ContrastEnhancementAlgorithm
    {
      NoEnhancement,                  //this should be the default color scaling algorithm
      StretchToMinimumMaximum,        //linear histogram enhanceContrast
      StretchAndClipToMinimumMaximum,
      ClipToMinimumMaximum,
      UserDefinedEnhancement
    };

    QgsContrastEnhancement( Qgis::DataType datatype = Qgis::Byte );
    QgsContrastEnhancement( const QgsContrastEnhancement &ce );
    ~QgsContrastEnhancement();

    const QgsContrastEnhancement &operator=( const QgsContrastEnhancement & ) = delete;

    /*
     *
     * Static methods
     *
     */
    static double maximumValuePossible( Qgis::DataType );

    static double minimumValuePossible( Qgis::DataType );

    static QString contrastEnhancementAlgorithmString( ContrastEnhancementAlgorithm algorithm );

    static ContrastEnhancementAlgorithm contrastEnhancementAlgorithmFromString( const QString &contrastEnhancementString );

    /*
     *
     * Non-Static Inline methods
     *
     */
    double maximumValue() const { return mMaximumValue; }

    double minimumValue() const { return mMinimumValue; }

    ContrastEnhancementAlgorithm contrastEnhancementAlgorithm() const { return mContrastEnhancementAlgorithm; }

    /*
     *
     * Non-Static methods
     *
     */
    int enhanceContrast( double );

    bool isValueInDisplayableRange( double );

    void setContrastEnhancementAlgorithm( ContrastEnhancementAlgorithm, bool generateTable = true );

    void setContrastEnhancementFunction( QgsContrastEnhancementFunction * );

    void setMaximumValue( double, bool generateTable = true );

    void setMinimumValue( double, bool generateTable = true );

    void writeXml( QDomDocument &doc, QDomElement &parentElem ) const;

    void readXml( const QDomElement &elem );

  private:
#ifdef SIP_RUN
    const QgsContrastEnhancement &operator=( const QgsContrastEnhancement & );
#endif

    ContrastEnhancementAlgorithm mContrastEnhancementAlgorithm = NoEnhancement;

    std::unique_ptr< QgsContrastEnhancementFunction > mContrastEnhancementFunction;

    bool mEnhancementDirty = false;

    double mLookupTableOffset;

    int *mLookupTable = nullptr;

    double mMinimumValue;

    double mMaximumValue;

    Qgis::DataType mRasterDataType;

    double mRasterDataTypeRange;

    bool generateLookupTable();

    int calculateContrastEnhancementValue( double );

};

#endif