qgscontrastenhancement.cpp

Go to the documentation of this file.

/* **************************************************************************
                qgscontrastenhancement.cpp -  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.                                   *
 *                                                                         *
 ***************************************************************************/

#include "qgslogger.h"

#include "qgscontrastenhancement.h"
#include "qgscontrastenhancementfunction.h"
#include "qgslinearminmaxenhancement.h"
#include "qgslinearminmaxenhancementwithclip.h"
#include "qgscliptominmaxenhancement.h"
#include <QDomDocument>
#include <QDomElement>

QgsContrastEnhancement::QgsContrastEnhancement( QGis::DataType theDataType )
    : mContrastEnhancementAlgorithm( NoEnhancement )
    , mContrastEnhancementFunction( nullptr )
    , mEnhancementDirty( false )
    , mLookupTable( nullptr )
    , mRasterDataType( theDataType )
{
  mMinimumValue = minimumValuePossible( mRasterDataType );
  mMaximumValue = maximumValuePossible( mRasterDataType );
  mRasterDataTypeRange = mMaximumValue - mMinimumValue;

  mLookupTableOffset = mMinimumValue * -1;

  mContrastEnhancementFunction = new QgsContrastEnhancementFunction( mRasterDataType, mMinimumValue, mMaximumValue );

  //If the data type is larger than 16-bit do not generate a lookup table
  if ( mRasterDataTypeRange <= 65535.0 )
  {
    mLookupTable = new int[static_cast <int>( mRasterDataTypeRange+1 )];
  }

}

QgsContrastEnhancement::QgsContrastEnhancement( const QgsContrastEnhancement& ce )
    : mContrastEnhancementFunction( nullptr )
    , mEnhancementDirty( true )
    , mLookupTable( nullptr )
    , mMinimumValue( ce.mMinimumValue )
    , mMaximumValue( ce.mMaximumValue )
    , mRasterDataType( ce.mRasterDataType )
    , mRasterDataTypeRange( ce.mRasterDataTypeRange )
{
  mLookupTableOffset = minimumValuePossible( mRasterDataType ) * -1;

  // setContrastEnhancementAlgorithm sets also QgsContrastEnhancementFunction
  setContrastEnhancementAlgorithm( ce.mContrastEnhancementAlgorithm, false );

  //If the data type is larger than 16-bit do not generate a lookup table
  if ( mRasterDataTypeRange <= 65535.0 )
  {
    mLookupTable = new int[static_cast <int>( mRasterDataTypeRange+1 )];
  }
}

QgsContrastEnhancement::~QgsContrastEnhancement()
{
  delete [] mLookupTable;
  delete mContrastEnhancementFunction;
}
/*
 *
 * Static methods
 *
 */

double QgsContrastEnhancement::maximumValuePossible( QGis::DataType theDataType )
{
  switch ( theDataType )
  {
    case QGis::Byte:
      return std::numeric_limits<unsigned char>::max();
    case QGis::UInt16:
      return std::numeric_limits<unsigned short>::max();
    case QGis::Int16:
      return std::numeric_limits<short>::max();
    case QGis::UInt32:
      return std::numeric_limits<unsigned int>::max();
    case QGis::Int32:
      return std::numeric_limits<int>::max();
    case QGis::Float32:
      return std::numeric_limits<float>::max();
    case QGis::Float64:
      return std::numeric_limits<double>::max();
    case QGis::CInt16:
      return std::numeric_limits<short>::max();
    case QGis::CInt32:
      return std::numeric_limits<int>::max();
    case QGis::CFloat32:
      return std::numeric_limits<float>::max();
    case QGis::CFloat64:
      return std::numeric_limits<double>::max();
    case QGis::ARGB32:
    case QGis::ARGB32_Premultiplied:
    case QGis::UnknownDataType:
      // XXX - mloskot: not handled?
      break;
  }

  return std::numeric_limits<double>::max();
}
double QgsContrastEnhancement::minimumValuePossible( QGis::DataType theDataType )
{
  switch ( theDataType )
  {
    case QGis::Byte:
      return std::numeric_limits<unsigned char>::min();
    case QGis::UInt16:
      return std::numeric_limits<unsigned short>::min();
    case QGis::Int16:
      return std::numeric_limits<short>::min();
    case QGis::UInt32:
      return std::numeric_limits<unsigned int>::min();
    case QGis::Int32:
      return std::numeric_limits<int>::min();
    case QGis::Float32:
      return std::numeric_limits<float>::max() * -1.0;
    case QGis::Float64:
      return std::numeric_limits<double>::max() * -1.0;
    case QGis::CInt16:
      return std::numeric_limits<short>::min();
    case QGis::CInt32:
      return std::numeric_limits<int>::min();
    case QGis::CFloat32:
      return std::numeric_limits<float>::max() * -1.0;
    case QGis::CFloat64:
      return std::numeric_limits<double>::max() * -1.0;
    case QGis::ARGB32:
    case QGis::ARGB32_Premultiplied:
    case QGis::UnknownDataType:
      // XXX - mloskot: not handled?
      break;
  }

  return std::numeric_limits<double>::max() * -1.0;
}

/*
 *
 * Non-Static methods
 *
 */
int QgsContrastEnhancement::enhanceContrast( double theValue )
{
  if ( mEnhancementDirty )
  {
    generateLookupTable();
  }

  if ( mLookupTable && NoEnhancement != mContrastEnhancementAlgorithm )
  {
    return mLookupTable[static_cast <int>( theValue + mLookupTableOffset )];
  }
  else
  {
    // Even if the contrast enhancement algorithms is set to NoEnhancement
    // The input values will still have to be scaled for all data types
    // greater than 1 byte.
    return mContrastEnhancementFunction->enhance( theValue );
  }
}

bool QgsContrastEnhancement::generateLookupTable()
{
  mEnhancementDirty = false;

  if ( !mContrastEnhancementFunction )
    return false;
  if ( NoEnhancement == mContrastEnhancementAlgorithm )
    return false;
  if ( QGis::Byte != mRasterDataType && QGis::UInt16 != mRasterDataType && QGis::Int16 != mRasterDataType )
    return false;
  if ( !mLookupTable )
    return false;

  QgsDebugMsg( "building lookup table" );
  QgsDebugMsg( "***MinimumValue : " + QString::number( mMinimumValue ) );
  QgsDebugMsg( "***MaximumValue : " + QString::number( mMaximumValue ) );
  QgsDebugMsg( "***mLookupTableOffset : " + QString::number( mLookupTableOffset ) );
  QgsDebugMsg( "***mRasterDataTypeRange : " + QString::number( mRasterDataTypeRange ) );

  for ( int myIterator = 0; myIterator <= mRasterDataTypeRange; myIterator++ )
  {
    mLookupTable[myIterator] = mContrastEnhancementFunction->enhance( static_cast< double >( myIterator ) - mLookupTableOffset );
  }

  return true;
}

bool QgsContrastEnhancement::isValueInDisplayableRange( double theValue )
{
  if ( mContrastEnhancementFunction )
  {
    return mContrastEnhancementFunction->isValueInDisplayableRange( theValue );
  }

  return false;
}

void QgsContrastEnhancement::setContrastEnhancementAlgorithm( ContrastEnhancementAlgorithm theAlgorithm, bool generateTable )
{
  switch ( theAlgorithm )
  {
    case StretchToMinimumMaximum :
      delete mContrastEnhancementFunction;
      mContrastEnhancementFunction = new QgsLinearMinMaxEnhancement( mRasterDataType, mMinimumValue, mMaximumValue );
      break;
    case StretchAndClipToMinimumMaximum :
      delete mContrastEnhancementFunction;
      mContrastEnhancementFunction = new QgsLinearMinMaxEnhancementWithClip( mRasterDataType, mMinimumValue, mMaximumValue );
      break;
    case ClipToMinimumMaximum :
      delete mContrastEnhancementFunction;
      mContrastEnhancementFunction = new QgsClipToMinMaxEnhancement( mRasterDataType, mMinimumValue, mMaximumValue );
      break;
    case UserDefinedEnhancement :
      //Do nothing
      break;
    default:
      delete mContrastEnhancementFunction;
      mContrastEnhancementFunction = new QgsContrastEnhancementFunction( mRasterDataType, mMinimumValue, mMaximumValue );
      break;
  }

  mEnhancementDirty = true;
  mContrastEnhancementAlgorithm = theAlgorithm;

  if ( generateTable )
  {
    generateLookupTable();
  }
}

void QgsContrastEnhancement::setContrastEnhancementFunction( QgsContrastEnhancementFunction* theFunction )
{
  QgsDebugMsgLevel( "called", 4 );

  if ( theFunction )
  {
    delete mContrastEnhancementFunction;
    mContrastEnhancementFunction = theFunction;
    mContrastEnhancementAlgorithm = UserDefinedEnhancement;
    generateLookupTable();
  }
}

void QgsContrastEnhancement::setMaximumValue( double theValue, bool generateTable )
{
  QgsDebugMsgLevel( "called value: " + QString::number( theValue ) + " generate lookup table: " + QString::number( static_cast< int >( generateTable ) ), 4 );

  if ( theValue > maximumValuePossible( mRasterDataType ) )
  {
    mMaximumValue = maximumValuePossible( mRasterDataType );
  }
  else
  {
    mMaximumValue = theValue;
  }

  if ( mContrastEnhancementFunction )
  {
    mContrastEnhancementFunction->setMaximumValue( theValue );
  }

  mEnhancementDirty = true;

  if ( generateTable )
  {
    generateLookupTable();
  }
}

void QgsContrastEnhancement::setMinimumValue( double theValue, bool generateTable )
{
  QgsDebugMsgLevel( "called value: " + QString::number( theValue ) + " generate lookup table: " + QString::number( static_cast< int >( generateTable ) ), 4 );

  if ( theValue < minimumValuePossible( mRasterDataType ) )
  {
    mMinimumValue = minimumValuePossible( mRasterDataType );
  }
  else
  {
    mMinimumValue = theValue;
  }

  if ( mContrastEnhancementFunction )
  {
    mContrastEnhancementFunction->setMinimumValue( theValue );
  }

  mEnhancementDirty = true;

  if ( generateTable )
  {
    generateLookupTable();
  }
}

void QgsContrastEnhancement::writeXML( QDomDocument& doc, QDomElement& parentElem ) const
{
  //minimum value
  QDomElement minElem = doc.createElement( "minValue" );
  QDomText minText = doc.createTextNode( QString::number( mMinimumValue ) );
  minElem.appendChild( minText );
  parentElem.appendChild( minElem );

  //maximum value
  QDomElement maxElem = doc.createElement( "maxValue" );
  QDomText maxText = doc.createTextNode( QString::number( mMaximumValue ) );
  maxElem.appendChild( maxText );
  parentElem.appendChild( maxElem );

  //algorithm
  QDomElement algorithmElem = doc.createElement( "algorithm" );
  QDomText algorithmText = doc.createTextNode( contrastEnhancementAlgorithmString( mContrastEnhancementAlgorithm ) );
  algorithmElem.appendChild( algorithmText );
  parentElem.appendChild( algorithmElem );
}

void QgsContrastEnhancement::readXML( const QDomElement& elem )
{
  QDomElement minValueElem = elem.firstChildElement( "minValue" );
  if ( !minValueElem.isNull() )
  {
    mMinimumValue = minValueElem.text().toDouble();
  }
  QDomElement maxValueElem = elem.firstChildElement( "maxValue" );
  if ( !maxValueElem.isNull() )
  {
    mMaximumValue = maxValueElem.text().toDouble();
  }
  QDomElement algorithmElem = elem.firstChildElement( "algorithm" );
  if ( !algorithmElem.isNull() )
  {
    QString algorithmString = algorithmElem.text();
    ContrastEnhancementAlgorithm algorithm = NoEnhancement;
    // old version ( < 19 Apr 2013) was using enum directly -> for backward compatibility
    if ( algorithmString == "0" )
    {
      algorithm = NoEnhancement;
    }
    else if ( algorithmString == "1" )
    {
      algorithm = StretchToMinimumMaximum;
    }
    else if ( algorithmString == "2" )
    {
      algorithm = StretchAndClipToMinimumMaximum;
    }
    else if ( algorithmString == "3" )
    {
      algorithm = ClipToMinimumMaximum;
    }
    else if ( algorithmString == "4" )
    {
      algorithm = UserDefinedEnhancement;
    }
    else
    {
      algorithm = contrastEnhancementAlgorithmFromString( algorithmString );
    }

    setContrastEnhancementAlgorithm( algorithm );
  }
}

QString QgsContrastEnhancement::contrastEnhancementAlgorithmString( ContrastEnhancementAlgorithm algorithm )
{
  switch ( algorithm )
  {
    case NoEnhancement:
      return "NoEnhancement";
    case StretchToMinimumMaximum:
      return "StretchToMinimumMaximum";
    case StretchAndClipToMinimumMaximum:
      return "StretchAndClipToMinimumMaximum";
    case ClipToMinimumMaximum:
      return "ClipToMinimumMaximum";
    case UserDefinedEnhancement:
      return "UserDefinedEnhancement";
  }
  return "NoEnhancement";
}

QgsContrastEnhancement::ContrastEnhancementAlgorithm QgsContrastEnhancement::contrastEnhancementAlgorithmFromString( const QString& contrastEnhancementString )
{
  if ( contrastEnhancementString == "StretchToMinimumMaximum" )
  {
    return StretchToMinimumMaximum;
  }
  else if ( contrastEnhancementString == "StretchAndClipToMinimumMaximum" )
  {
    return StretchAndClipToMinimumMaximum;
  }
  else if ( contrastEnhancementString == "ClipToMinimumMaximum" )
  {
    return ClipToMinimumMaximum;
  }
  else if ( contrastEnhancementString == "UserDefinedEnhancement" )
  {
    return UserDefinedEnhancement;
  }
  else
  {
    return NoEnhancement;
  }
}