/*
 *
 *  Copyright (C) 1997-2023, OFFIS e.V.
 *  All rights reserved.  See COPYRIGHT file for details.
 *
 *  This software and supporting documentation were developed by
 *
 *    OFFIS e.V.
 *    R&D Division Health
 *    Escherweg 2
 *    D-26121 Oldenburg, Germany
 *
 *
 *  Module:  dcmdata
 *
 *  Author:  Andreas Barth
 *
 *  Purpose: class DcmPixelData
 *
 */

#include "dcmtk/config/osconfig.h"    /* make sure OS specific configuration is included first */
#include "dcmtk/dcmdata/dcpixel.h"
#include "dcmtk/dcmdata/dccodec.h"
#include "dcmtk/dcmdata/dcpixseq.h"
#include "dcmtk/dcmdata/dcdeftag.h"
#include "dcmtk/dcmdata/dcitem.h"
#include "dcmtk/dcmdata/dcpxitem.h"
#include "dcmtk/dcmdata/dcjson.h"

//
// class DcmRepresentationEntry
//

DcmRepresentationEntry::DcmRepresentationEntry(
    const E_TransferSyntax rt,
    const DcmRepresentationParameter *rp,
    DcmPixelSequence * ps)
  : repType(rt),
    repParam(NULL),
    pixSeq(ps)
{
    if (rp)
        repParam = rp->clone();
}

DcmRepresentationEntry::DcmRepresentationEntry(
    const DcmRepresentationEntry & oldEntry)
  : repType(oldEntry.repType),
    repParam(NULL),
    pixSeq(NULL)
{
    if (oldEntry.repParam)
        repParam = oldEntry.repParam->clone();
    pixSeq = new DcmPixelSequence(*(oldEntry.pixSeq));
}

DcmRepresentationEntry::~DcmRepresentationEntry()
{
    delete repParam;
    delete pixSeq;
}

OFBool
DcmRepresentationEntry::operator==(const DcmRepresentationEntry & x) const
{
    return (repType == x.repType) &&
        ((x.repParam == NULL && repParam == NULL) ||
         ((x.repParam != NULL) && (repParam != NULL) && (*(x.repParam) == *repParam)));
}

//
// class DcmPixelData
//

// Constructors / Deconstructors

DcmPixelData::DcmPixelData(
    const DcmTag & tag,
    const Uint32 len)
  : DcmPolymorphOBOW(tag, len),
    repList(),
    repListEnd(),
    original(),
    current(),
    existUnencapsulated(OFFalse),
    alwaysUnencapsulated(OFFalse),
    unencapsulatedVR(EVR_UNKNOWN),
    pixelSeqForWrite(NULL)
{
    repListEnd = repList.end();
    current = original = repListEnd;
    if ((getTag().getEVR() == EVR_ox) || (getTag().getEVR() == EVR_px))
        setTagVR(EVR_OW);
    unencapsulatedVR = getTag().getEVR();
    recalcVR();
}

DcmPixelData::DcmPixelData(
    const DcmPixelData & oldPixelData)
  : DcmPolymorphOBOW(oldPixelData),
    repList(),
    repListEnd(),
    original(),
    current(),
    existUnencapsulated(oldPixelData.existUnencapsulated),
    alwaysUnencapsulated(oldPixelData.alwaysUnencapsulated),
    unencapsulatedVR(oldPixelData.unencapsulatedVR),
    pixelSeqForWrite(NULL)
{
    repListEnd = repList.end();
    original = repListEnd;
    current = original;
    recalcVR();
    DcmRepresentationListConstIterator oldEnd(oldPixelData.repList.end());
    for (DcmRepresentationListConstIterator it(oldPixelData.repList.begin());
         it != oldEnd;
         ++it)
    {
        DcmRepresentationEntry * repEnt = new DcmRepresentationEntry(**it);
        repList.push_back(repEnt);
        if (it == oldPixelData.original)
            original = --repList.end();

        if (it == oldPixelData.current)
        {
            current = --repList.end();
            recalcVR();
        }
    }
}


DcmPixelData::~DcmPixelData()
{
    for (DcmRepresentationListIterator it(repList.begin());
         it != repListEnd;
         ++it)
    {
        delete *it;
        *it = NULL;
    }
}

DcmPixelData &DcmPixelData::operator=(const DcmPixelData &obj)
{
  if (this != &obj)
  {
    DcmPolymorphOBOW::operator=(obj);
    existUnencapsulated = obj.existUnencapsulated;
    alwaysUnencapsulated = obj.alwaysUnencapsulated;
    unencapsulatedVR = obj.unencapsulatedVR;
    pixelSeqForWrite = NULL;
    repList.clear();
    repListEnd = repList.end();
    original = repListEnd;
    current = original;
    recalcVR();
    DcmRepresentationListConstIterator oldEnd(obj.repList.end());
    DcmRepresentationListConstIterator it(obj.repList.begin());
    while (it != oldEnd)
    {
        DcmRepresentationEntry *repEnt = new DcmRepresentationEntry(**it);
        repList.push_back(repEnt);
        if (it == obj.original) original = --repList.end();
        if (it == current)
        {
            current = --repList.end();
            recalcVR();
        }
        ++it;
    }

  }
  return *this;
}

// methods in alphabetical order

Uint32
DcmPixelData::calcElementLength(
    const E_TransferSyntax xfer,
    const E_EncodingType enctype)
{
    DcmXfer xferSyn(xfer);
    errorFlag = EC_Normal;
    Uint32 elementLength = 0;

    if (xferSyn.isEncapsulated() && (! writeUnencapsulated(xfer)))
    {
        DcmRepresentationListIterator found;
        errorFlag = findConformingEncapsulatedRepresentation(xfer, NULL, found);
        if (errorFlag == EC_Normal)
            elementLength = (*found)->pixSeq->calcElementLength(xfer, enctype);
    }
    else if (existUnencapsulated)
        elementLength =  DcmPolymorphOBOW::calcElementLength(xfer, enctype);
    else
        errorFlag = EC_RepresentationNotFound;

    return elementLength;
}


OFBool
DcmPixelData::canChooseRepresentation(
    const E_TransferSyntax repType,
    const DcmRepresentationParameter * repParam)
{
    OFBool result = OFFalse;
    DcmXfer toType(repType);

    const DcmRepresentationEntry findEntry(repType, repParam, NULL);
    DcmRepresentationListIterator resultIt(repListEnd);
    // find out whether we have the desired target representation available. Three possibilities:
    // 1. we have uncompressed data, and target is uncompressed (conversion between uncompressed always possible)
    // 2. we have uncompressed and want compressed, but we are forced to write uncompressed anyway
    // 3. we want to go to compressed, and already have the desired representation available
    if ((!toType.isEncapsulated() && existUnencapsulated) ||
        (toType.isEncapsulated() && writeUnencapsulated(repType) && existUnencapsulated) ||
        (toType.isEncapsulated() && findRepresentationEntry(findEntry, resultIt) == EC_Normal))
    {
        // representation found
        result = OFTrue;
    }
    // otherwise let's see whether we know how to convert to the target representation
    else
    {
        // representation not found, check if we have a codec that can create the
        // desired representation.
        if (original == repListEnd)
        {
          // we have uncompressed data, check whether we know how to go from uncompressed to desired compression
          result = DcmCodecList::canChangeCoding(EXS_LittleEndianExplicit, toType.getXfer());
        }
        else if (toType.isEncapsulated())
        {
          // we have already compressed data, check whether we know how to transcode
          result = DcmCodecList::canChangeCoding((*original)->repType, toType.getXfer());
          if (!result)
          {
            // direct transcoding is not possible. Check if we can decode and then encode.
            result = canChooseRepresentation(EXS_LittleEndianExplicit, NULL);
            if (result) result = DcmCodecList::canChangeCoding(EXS_LittleEndianExplicit, toType.getXfer());
          }
        }
        else
        {
          // target transfer syntax is uncompressed, look whether decompression is possible
          result = DcmCodecList::canChangeCoding((*original)->repType, EXS_LittleEndianExplicit);
        }
    }
    return result;
}

OFBool
DcmPixelData::canWriteXfer(
    const E_TransferSyntax newXfer,
    const E_TransferSyntax /*oldXfer*/)
{
    DcmXfer newXferSyn(newXfer);
    DcmRepresentationListIterator found;
    OFBool result = existUnencapsulated && (!newXferSyn.isEncapsulated() || writeUnencapsulated(newXfer));

    if (!result && newXferSyn.isEncapsulated())
        result = (findConformingEncapsulatedRepresentation(newXferSyn, NULL, found) == EC_Normal);
    return result;
}

OFCondition
DcmPixelData::chooseRepresentation(
    const E_TransferSyntax repType,
    const DcmRepresentationParameter * repParam,
    DcmStack & pixelStack)
{
    OFCondition l_error = EC_CannotChangeRepresentation;
    DcmXfer toType(repType);

    const DcmRepresentationEntry findEntry(repType, repParam, NULL);
    DcmRepresentationListIterator result(repListEnd);
    if ((!toType.isEncapsulated() && existUnencapsulated) ||
        (toType.isEncapsulated() && findRepresentationEntry(findEntry, result) == EC_Normal))
    {
        // representation found
        current = result;
        recalcVR();
        l_error = EC_Normal;
    }
    else
    {
        if (original == repListEnd)
            l_error = encode(EXS_LittleEndianExplicit, NULL, NULL,
                             toType, repParam, pixelStack);
        else if (toType.isEncapsulated())
            l_error = encode((*original)->repType, (*original)->repParam,
                             (*original)->pixSeq, toType, repParam, pixelStack);
        else
            l_error = decode((*original)->repType, (*original)->repParam,
                             (*original)->pixSeq, pixelStack);
    }
    if (l_error.bad() && toType.isEncapsulated() && existUnencapsulated && writeUnencapsulated(repType))
        // Encoding failed so this will be written out unencapsulated
        l_error = EC_Normal;
    return l_error;
}


int DcmPixelData::compare(const DcmElement& rhs) const
{
  // check tag and VR
  int result = DcmElement::compare(rhs);
  if (result != 0)
  {
    return result;
  }

  // cast away constness (dcmdata is not const correct...)
  DcmPixelData* myThis = NULL;
  DcmPixelData* myRhs = NULL;
  myThis = OFconst_cast(DcmPixelData*, this);
  myRhs =  OFstatic_cast(DcmPixelData*, OFconst_cast(DcmElement*, &rhs));

  if (myThis->existUnencapsulated && myRhs->existUnencapsulated)
  {
    // we have uncompressed representations, which can be compared using DcmPolymorphOBOW::compare
    return DcmPolymorphOBOW::compare(rhs);
  }

  // both do not have uncompressed data, we must compare compressed ones.
  // check both have a current representation at all.
  if ((myThis->current == myThis->repList.end()) && (myRhs->current != myRhs->repList.end())) return -1;
  if ((myThis->current != myThis->repList.end()) && (myRhs->current == myRhs->repList.end())) return 1;
  if ((myThis->current == myThis->repList.end()) && (myRhs->current == myRhs->repList.end()))
  {
    // if one of both have uncompressed data at least, that one is considered "bigger"
    if (myThis->existUnencapsulated) return 1;
    if (myRhs->existUnencapsulated) return -1;
    else return 0;
  }

  // both have compressed data: compare current representation (only)
  if ((myThis->current != myThis->repList.end()) && (myRhs->current != myRhs->repList.end()) )
  {
    E_TransferSyntax myRep = (*(myThis->current))->repType;
    E_TransferSyntax rhsRep = (*(myRhs->current))->repType;
    DcmXfer myXfer(myRep);
    DcmXfer rhsXfer(rhsRep);
    // if both transfer syntaxes are different, we have to perform more checks to
    // find out whether the related pixel data is comparable; this is the case
    // for all uncompressed transfer syntaxes, except Big Endian with OW data
    // since it uses a different memory layout, and we do not want to byte-swap
    // the values for the comparison.
    if (myRep != rhsRep)
    {
        return 1;
    }
    else
    {
      // For compressed, compare pixel items bytewise
      DcmPixelSequence* myPix = (*(myThis->current))->pixSeq;
      DcmPixelSequence* rhsPix = (*(myRhs->current))->pixSeq;
      if (!myPix && rhsPix) return -1;
      if (myPix && !rhsPix) return 1;
      if (!myPix && !rhsPix) return 0;
      // Check number of pixel items
      long unsigned int myNumPix = myPix->card();
      long unsigned int rhsNumPix = rhsPix->card();
      if (myNumPix < rhsNumPix) return -1;
      if (myNumPix > rhsNumPix) return 1;
      // loop over pixel items, both have the same number of pixel items
      for (unsigned long n = 0; n < myNumPix; n++)
      {
        DcmPixelItem* myPixItem = NULL;
        DcmPixelItem* rhsPixItem = NULL;
        if (myPix->getItem(myPixItem, n).good() && rhsPix->getItem(rhsPixItem, n).good())
        {
          // compare them value by value, using DcmOtherByteOtherWord::compare() method
          result = myPixItem->compare(*rhsPixItem);
          if (result != 0)
          {
            return result;
          }
        }
        else
        {
          DCMDATA_ERROR("Internal error: Could not get pixel item #" << n << " from Pixel Sequence");
          return 1;
        }
      }
      return 0;
    }
  }
  // if one of both have a current representation; consider that one "bigger".
  // if none has a current one, consider both equal (neither uncompressed or compressed data present).
  else
  {
    if (myThis->current != myThis->repList.end()) return 1;
    if (myRhs->current != myRhs->repList.end()) return -1;
    else return 0;
  }
}

OFCondition DcmPixelData::copyFrom(const DcmObject& rhs)
{
  if (this != &rhs)
  {
    if (rhs.ident() != ident()) return EC_IllegalCall;
    *this = OFstatic_cast(const DcmPixelData &, rhs);
  }
  return EC_Normal;
}

void DcmPixelData::clearRepresentationList(
    DcmRepresentationListIterator leaveInList)
{
    /* define iterators to go through all representations in the list */
    DcmRepresentationListIterator it(repList.begin());
    DcmRepresentationListIterator del;

    /* as long as we have not encountered the end of the */
    /* representation list, go through all representations */
    while (it != repListEnd)
    {
        /* if this representation shall not be left in the list */
        if (it != leaveInList)
        {
            /* delete representation and move it to the next representation */
            delete *it;
            del = it++;
            repList.erase(del);
        }
        /* else leave this representation in the list and just go to the next */
        else
            ++it;
    }
}

OFCondition
DcmPixelData::decode(
    const DcmXfer & fromType,
    const DcmRepresentationParameter * fromParam,
    DcmPixelSequence * fromPixSeq,
    DcmStack & pixelStack)
{
    if (existUnencapsulated) return EC_Normal;
    OFBool removeOldPixelRepresentation = OFFalse;
    OFCondition l_error = DcmCodecList::decode(fromType, fromParam, fromPixSeq, *this, pixelStack, removeOldPixelRepresentation);
    if (l_error.good())
    {
        existUnencapsulated = OFTrue;
        current = repListEnd;
        setVR(EVR_OW);
        recalcVR();

        // the codec has indicated that the image pixel module has been modified
        // in a way that may affect the validity of the old representation of pixel data.
        // Thus, we cannot just switch back to the old representation.
        // Thus, remove old representation(s).
        if (removeOldPixelRepresentation) removeAllButCurrentRepresentations();
    }
    else
    {
        DcmPolymorphOBOW::putUint16Array(NULL,0);
        existUnencapsulated = OFFalse;
    }
    return l_error;
}



OFCondition
DcmPixelData::encode(
    const DcmXfer & fromType,
    const DcmRepresentationParameter * fromParam,
    DcmPixelSequence * fromPixSeq,
    const DcmXfer & toType,
    const DcmRepresentationParameter *toParam,
    DcmStack & pixelStack)
{
    OFCondition l_error = EC_CannotChangeRepresentation;
    if (toType.isEncapsulated())
    {
       DcmPixelSequence * toPixSeq = NULL;
       OFBool removeOldPixelRepresentation = OFFalse;
       if (fromType.isEncapsulated())
       {
         l_error = DcmCodecList::encode(fromType.getXfer(), fromParam, fromPixSeq,
                   toType.getXfer(), toParam, toPixSeq, pixelStack, removeOldPixelRepresentation);
       }
       else
       {
         Uint16 * pixelData;
         l_error = DcmPolymorphOBOW::getUint16Array(pixelData);
         Uint32 length = DcmPolymorphOBOW::getLength();
         if (l_error == EC_Normal)
         {
           l_error = DcmCodecList::encode(fromType.getXfer(), pixelData, length,
                     toType.getXfer(), toParam, toPixSeq, pixelStack, removeOldPixelRepresentation);
         }
       }

       if (l_error.good())
       {
           current = insertRepresentationEntry(
             new DcmRepresentationEntry(toType.getXfer(), toParam, toPixSeq));
           recalcVR();
           // the codec has indicated that the image pixel module has been modified
           // in a way that may affect the validity of the old representation of pixel data.
           // Thus, we cannot just switch back to the old representation, but have
           // to actually decode in this case. Thus, remove old representation(s).
           if (removeOldPixelRepresentation) removeAllButCurrentRepresentations();
       } else delete toPixSeq;

       // if it was possible to convert one encapsulated syntax into
       // another directly try it using decoding and encoding!
       if (l_error.bad() && fromType.isEncapsulated())
       {
           l_error = decode(fromType, fromParam, fromPixSeq, pixelStack);
           if (l_error.good()) l_error = encode(EXS_LittleEndianExplicit, NULL, NULL, toType, toParam, pixelStack);
       }
    }
    return l_error;
}

OFCondition
DcmPixelData::findRepresentationEntry(
    const DcmRepresentationEntry & findEntry,
    DcmRepresentationListIterator & result)
{
    result = repList.begin();
    while(result != repListEnd &&
          (*result)->repType < findEntry.repType)
        ++result;

    DcmRepresentationListIterator it(result);

    while(it != repListEnd && **it != findEntry)
        ++it;
    if (it == repListEnd || **it != findEntry)
        return EC_RepresentationNotFound;
    else
    {
        result = it;
        return EC_Normal;
    }
}


OFCondition
DcmPixelData::findConformingEncapsulatedRepresentation(
    const DcmXfer & repTypeSyn,
    const DcmRepresentationParameter * repParam,
    DcmRepresentationListIterator & result)
{
    E_TransferSyntax repType = repTypeSyn.getXfer();
    result = repListEnd;
    OFCondition l_error = EC_RepresentationNotFound;
    // we are looking for an encapsulated representation
    // of this pixel data element which meets both
    // the transfer syntax and (if given) the representation
    // parameter (i.e. quality factor for lossy JPEG).
    if (repTypeSyn.isEncapsulated())
    {
        // first we check the current (active) representation if any.
        if ((current != repListEnd) && ((*current)->repType == repType) &&
            ((repParam==NULL) || (((*current)->repParam != NULL)&&(*(*current)->repParam == *repParam))))
        {
            result = current;
            l_error = EC_Normal;
        }
        else
        {
            // now we check all representations
            DcmRepresentationListIterator it(repList.begin());
            OFBool found = OFFalse;
            while (!found && (it != repListEnd))
            {
              if ((*it)->repType == repType)
              {
                if ((repParam == NULL) || (((*it)->repParam != NULL)&&(*(*it)->repParam == *repParam)))
                {
                  // repParam is NULL or matches the one we are comparing with
                  found = OFTrue;
                  result = it;
                  l_error = EC_Normal;
                } else ++it;
              } else ++it;
            }
        }
    }
    return l_error;
}


OFCondition
DcmPixelData::getEncapsulatedRepresentation(
    const E_TransferSyntax repType,
    const DcmRepresentationParameter * repParam,
    DcmPixelSequence * & pixSeq)
{
    DcmRepresentationListIterator found;
    DcmRepresentationEntry findEntry(repType, repParam, NULL);
    if (findRepresentationEntry(findEntry, found) == EC_Normal)
    {
        pixSeq = (*found)->pixSeq;
        return EC_Normal;
    }

    return EC_RepresentationNotFound;
}


OFBool
DcmPixelData::hasRepresentation(
    const E_TransferSyntax repType,
    const DcmRepresentationParameter * repParam)
{
    DcmXfer repTypeSyn(repType);
    DcmRepresentationListIterator found;
    if (!repTypeSyn.isEncapsulated() && existUnencapsulated)
        return OFTrue;
    else if (repTypeSyn.isEncapsulated())
        return findConformingEncapsulatedRepresentation(repTypeSyn, repParam, found).good();
    return OFFalse;
}


Uint32
DcmPixelData::getLength(const E_TransferSyntax xfer,
                        const E_EncodingType enctype)
{
    DcmXfer xferSyn(xfer);
    errorFlag = EC_Normal;
    Uint32 valueLength = 0;

    if (xferSyn.isEncapsulated() && !writeUnencapsulated(xfer))
    {
        DcmRepresentationListIterator foundEntry;
        errorFlag = findConformingEncapsulatedRepresentation(
            xferSyn, NULL, foundEntry);
        if (errorFlag == EC_Normal)
            valueLength = (*foundEntry)->pixSeq->getLength(xfer, enctype);
    }
    else if (existUnencapsulated)
        valueLength =  DcmPolymorphOBOW::getLength(xfer, enctype);
    else
        errorFlag = EC_RepresentationNotFound;

    return valueLength;
}


void
DcmPixelData::getCurrentRepresentationKey(
    E_TransferSyntax & repType,
    const DcmRepresentationParameter * & repParam)
{
    if (current != repListEnd)
    {
        repType = (*current)->repType;
        repParam = (*current)->repParam;
    }
    else
    {
        repType = EXS_LittleEndianExplicit;
        repParam = NULL;
    }
}

void
DcmPixelData::getOriginalRepresentationKey(
    E_TransferSyntax & repType,
    const DcmRepresentationParameter * & repParam)
{
    if (original != repListEnd)
    {
        repType = (*original)->repType;
        repParam = (*original)->repParam;
    }
    else
    {
        repType = EXS_LittleEndianExplicit;
        repParam = NULL;
    }
}

DcmRepresentationListIterator
DcmPixelData::insertRepresentationEntry(
    DcmRepresentationEntry * repEntry)
{
    DcmRepresentationListIterator insertedEntry;
    DcmRepresentationListIterator result;
    if (findRepresentationEntry(*repEntry, result).good())
    {
        // this type of representation entry was already present in the list
        if (repEntry != *result)
        {
          insertedEntry = repList.insert(result, repEntry);

          // delete old entry from representation list
          delete *result;
          repList.erase(result);
        }
    }
    else
        insertedEntry = repList.insert(result,repEntry);
    return insertedEntry;
}

void
DcmPixelData::print(
    STD_NAMESPACE ostream &out,
    const size_t flags,
    const int level,
    const char *pixelFileName,
    size_t *pixelCounter)
{
    if (current == repListEnd)
        printPixel(out, flags, level, pixelFileName, pixelCounter);
    else
        (*current)->pixSeq->print(out, flags, level, pixelFileName, pixelCounter);
}

OFCondition
DcmPixelData::putUint8Array(
    const Uint8 * byteValue,
    const unsigned long length)
{
    // clear RepresentationList
    clearRepresentationList(repListEnd);
    OFCondition l_error = DcmPolymorphOBOW::putUint8Array(byteValue, length);
    original = current = repListEnd;
    recalcVR();
    existUnencapsulated = OFTrue;
    return l_error;
}

OFCondition
DcmPixelData::putUint16Array(
    const Uint16 * wordValue,
    const unsigned long length)
{
    // clear RepresentationList
    clearRepresentationList(repListEnd);
    OFCondition l_error = DcmPolymorphOBOW::putUint16Array(wordValue, length);
    original = current = repListEnd;
    recalcVR();
    existUnencapsulated = OFTrue;
    return l_error;
}

OFCondition
DcmPixelData::createUint8Array(
    const Uint32 numBytes,
    Uint8 * & bytes)
{
    OFCondition l_error = DcmPolymorphOBOW::createUint8Array(numBytes, bytes);
    existUnencapsulated = OFTrue;
    return l_error;
}

OFCondition
DcmPixelData::createUint16Array(
    const Uint32 numWords,
    Uint16 * & words)
{
    OFCondition l_error = DcmPolymorphOBOW::createUint16Array(numWords, words);
    existUnencapsulated = OFTrue;
    return l_error;
}

OFCondition
DcmPixelData::createValueFromTempFile(
    DcmInputStreamFactory *factory,
    const Uint32 length,
    const E_ByteOrder byteOrder)
{
    OFCondition l_error = DcmPolymorphOBOW::createValueFromTempFile(factory, length, byteOrder);
    existUnencapsulated = OFTrue;
    return l_error;
}

void
DcmPixelData::putOriginalRepresentation(
    const E_TransferSyntax repType,
    const DcmRepresentationParameter * repParam,
    DcmPixelSequence * pixSeq)
{
    // delete RepresentationList
    clearRepresentationList(repListEnd);
    // delete unencapsulated representation
    DcmPolymorphOBOW::putUint16Array(NULL,0);
    existUnencapsulated = OFFalse;
    // insert new Representation
    current = original = insertRepresentationEntry(
        new DcmRepresentationEntry(repType, repParam, pixSeq));
    recalcVR();
}

OFCondition
DcmPixelData::read(
    DcmInputStream & inStream,
    const E_TransferSyntax ixfer,
    const E_GrpLenEncoding glenc,
    const Uint32 maxReadLength)
{
    /* if this element's transfer state shows ERW_notInitialized, this is an illegal call */
    if (getTransferState() == ERW_notInitialized)
        errorFlag = EC_IllegalCall;
    else
    {
        /* if this is not an illegal call, go ahead */

        /* if the transfer state is ERW_init, we need to prepare the reading of the pixel */
        /* data from the stream: remove all representations from the representation list. */
        if (getTransferState() == ERW_init)
            clearRepresentationList(repListEnd);

        /* create a DcmXfer object based on the transfer syntax which was passed */
        DcmXfer ixferSyn(ixfer);

        /* determine if the pixel data is captured in native (uncompressed) or encapsulated
         * (compressed) format.  We only derive this information from the length field
         * which is set to undefined length for encapsulated data because even in
         * compressed transfer syntaxes the Icon Image Sequence may contain an
         * uncompressed image.
         */
        if (getLengthField() == DCM_UndefinedLength)
        {
            /* the pixel data is captured in encapsulated (compressed) format */

            /* if the transfer state is ERW_init, we need to prepare */
            /* the reading of the pixel data from the stream. */
            if (getTransferState() == ERW_init)
            {
                current = insertRepresentationEntry(
                    new DcmRepresentationEntry(
                        ixfer, NULL, new DcmPixelSequence(getTag(), getLengthField())));
                recalcVR();
                original = current;
                existUnencapsulated = OFFalse;
                setTransferState(ERW_inWork);

                if (! ixferSyn.isEncapsulated())
                {
                  /* Special case: we have encountered a compressed image
                   * although we're decoding an uncompressed transfer syntax.
                   * This could be a compressed image stored without meta-header.
                   * For now, we just accept the data element; however, any attempt
                   * to write the dataset will fail because no suitable decoder
                   * is known.
                   */
                }
            }

            /* conduct the reading process */
            errorFlag =
                (*current)->pixSeq->read(inStream, ixfer, glenc, maxReadLength);

            /* if the errorFlag equals EC_Normal, all pixel data has been */
            /* read; hence, the transfer state has to be set to ERW_ready */
            if (errorFlag == EC_Normal)
                setTransferState(ERW_ready);
        }
        else
        {
            /* the pixel data is captured in native (uncompressed) format */

            /* if the transfer state is ERW_init, we need to prepare */
            /* the reading of the pixel data from the stream. */
            if (getTransferState() == ERW_init)
            {
                current = original = repListEnd;
                unencapsulatedVR = getTag().getEVR();
                recalcVR();
                existUnencapsulated = OFTrue;

                if (ixferSyn.isEncapsulated())
                {
                  /* Special case: we have encountered an uncompressed image
                   * although we're decoding an encapsulated transfer syntax.
                   * This is probably an icon image.
                   */
                  alwaysUnencapsulated = OFTrue;
                }
            }

            /* conduct the reading process */
            errorFlag =
                DcmPolymorphOBOW::read(inStream, ixfer, glenc, maxReadLength);
        }
    }

    /* return result value */
    return errorFlag;
}


void
DcmPixelData::removeAllButCurrentRepresentations()
{
    clearRepresentationList(current);
    if (current != repListEnd && existUnencapsulated)
    {
        DcmPolymorphOBOW::putUint16Array(NULL,0);
        existUnencapsulated = OFFalse;
    }
    original = current;
}


void
DcmPixelData::removeAllButOriginalRepresentations()
{
    clearRepresentationList(original);
    if (original != repListEnd && existUnencapsulated)
    {
        DcmPolymorphOBOW::putUint16Array(NULL,0);
        existUnencapsulated = OFFalse;
    }
    current = original;
    recalcVR();
}

OFCondition
DcmPixelData::removeOriginalRepresentation(
    const E_TransferSyntax repType,
    const DcmRepresentationParameter * repParam)
{
    OFCondition l_error = EC_Normal;
    DcmXfer repTypeSyn(repType);

    if (!repTypeSyn.isEncapsulated())
    {
        if (original != repListEnd)
        {
            if (current == original)
            {
                current = repListEnd;
                recalcVR();
            }
            repList.erase(original);
            original = repListEnd;
        }
        else
            l_error = EC_IllegalCall;
    }
    else
    {
        DcmRepresentationListIterator result;
        DcmRepresentationEntry findEntry(repType, repParam, NULL);
        if (findRepresentationEntry(findEntry, result) == EC_Normal)
        {
            if (result != original)
            {
                if (current == original)
                {
                    current = result;
                    recalcVR();
                }
                if (original == repListEnd)
                {
                    DcmPolymorphOBOW::putUint16Array(NULL, 0);
                    existUnencapsulated = OFFalse;
                }
                else
                    repList.erase(original);
                original = result;
            }
            else
                l_error = EC_IllegalCall;
        }
        else
            l_error = EC_RepresentationNotFound;
    }
    return l_error;
}

OFCondition
DcmPixelData::removeRepresentation(
    const E_TransferSyntax repType,
    const DcmRepresentationParameter * repParam)
{
    OFCondition l_error = EC_Normal;
    DcmXfer repTypeSyn(repType);

    if (!repTypeSyn.isEncapsulated())
    {
        if (original != repListEnd && existUnencapsulated)
        {
            DcmPolymorphOBOW::putUint16Array(NULL, 0);
            existUnencapsulated = OFFalse;
        }
        else
            l_error = EC_CannotChangeRepresentation;
    }
    else
    {
        DcmRepresentationListIterator result;
        DcmRepresentationEntry findEntry(repType, repParam, NULL);
        if (findRepresentationEntry(findEntry, result) == EC_Normal)
        {
            if (original != result)
                repList.erase(result);
            else l_error = EC_CannotChangeRepresentation;
        }
        else
            l_error = EC_RepresentationNotFound;
    }
    return l_error;
}


OFCondition
DcmPixelData::setCurrentRepresentationParameter(
    const DcmRepresentationParameter * repParam)
{
    if (current != repListEnd)
    {
        if (repParam == NULL)
            (*current)->repParam = NULL;
        else
            (*current)->repParam = repParam->clone();
        return EC_Normal;
    }
    return EC_RepresentationNotFound;
}

OFCondition
DcmPixelData::setVR(DcmEVR vr)
{
    unencapsulatedVR = vr;
    return DcmPolymorphOBOW::setVR(vr);
}

void
DcmPixelData::transferEnd()
{
    DcmPolymorphOBOW::transferEnd();
    for (DcmRepresentationListIterator it(repList.begin());
         it != repListEnd;
         ++it)
        (*it)->pixSeq->transferEnd();
}

void
DcmPixelData::transferInit()
{
    DcmPolymorphOBOW::transferInit();
    for (DcmRepresentationListIterator it(repList.begin());
         it != repListEnd;
         ++it)
        (*it)->pixSeq->transferInit();
}

OFCondition DcmPixelData::write(
    DcmOutputStream &outStream,
    const E_TransferSyntax oxfer,
    const E_EncodingType enctype,
    DcmWriteCache *wcache)
{
  errorFlag = EC_Normal;
  if (getTransferState() == ERW_notInitialized) errorFlag = EC_IllegalCall;
  else
  {
    // check if the output transfer syntax is encapsulated
    // and we are not requested to write an uncompressed dataset
    // for example because this is within an Icon Image Sequence
    DcmXfer xferSyn(oxfer);
    if (xferSyn.isEncapsulated() && (! writeUnencapsulated(oxfer)))
    {
      // write encapsulated representation (i.e., compressed image)
      if (getTransferState() == ERW_init)
      {
        DcmRepresentationListIterator found;
        // find a compressed image matching the output transfer syntax
        errorFlag = findConformingEncapsulatedRepresentation(xferSyn, NULL, found);
        if (errorFlag == EC_Normal)
        {
          current = found;
          recalcVR();
          pixelSeqForWrite = (*found)->pixSeq;
          setTransferState(ERW_inWork);
        }
      }
      // write compressed image
      if (errorFlag == EC_Normal && pixelSeqForWrite) errorFlag = pixelSeqForWrite->write(outStream, oxfer, enctype, wcache);
      if (errorFlag == EC_Normal) setTransferState(ERW_ready);
    }
    else if (existUnencapsulated)
    {
      // we're supposed to write an uncompressed image, and we happen to have one available.
      current = repListEnd;
      recalcVR();
      // write uncompressed image
      errorFlag = DcmPolymorphOBOW::write(outStream, oxfer, enctype, wcache);
    }
    else if ((getValue() == NULL) && (current == repListEnd))
    {
      // the PixelData is empty. Write an empty element.
      errorFlag = DcmPolymorphOBOW::write(outStream, oxfer, enctype, wcache);
    } else errorFlag = EC_RepresentationNotFound;
  }
  return errorFlag;
}

OFCondition DcmPixelData::writeXML(
    STD_NAMESPACE ostream &out,
    const size_t flags)
{
    if (current == repListEnd)
    {
        errorFlag = DcmPolymorphOBOW::writeXML(out, flags);
    } else {
        /* pixel sequence (encapsulated data) */
        errorFlag = (*current)->pixSeq->writeXML(out, flags);
    }
    return errorFlag;
}

OFCondition DcmPixelData::writeSignatureFormat(
    DcmOutputStream &outStream,
    const E_TransferSyntax oxfer,
    const E_EncodingType enctype,
    DcmWriteCache *wcache)
{
  errorFlag = EC_Normal;
  if (getTransferState() == ERW_notInitialized) errorFlag = EC_IllegalCall;
  else if (getTag().isSignable())
  {
    DcmXfer xferSyn(oxfer);
    if (xferSyn.isEncapsulated() && (! writeUnencapsulated(oxfer)))
    {
      if (getTransferState() == ERW_init)
      {
        DcmRepresentationListIterator found;
        errorFlag = findConformingEncapsulatedRepresentation(xferSyn, NULL, found);
        if (errorFlag == EC_Normal)
        {
          current = found;
          recalcVR();
          pixelSeqForWrite = (*found)->pixSeq;
          setTransferState(ERW_inWork);
        }
      }
      if (errorFlag == EC_Normal && pixelSeqForWrite) errorFlag = pixelSeqForWrite->writeSignatureFormat(outStream, oxfer, enctype, wcache);
      if (errorFlag == EC_Normal) setTransferState(ERW_ready);
    }
    else if (existUnencapsulated)
    {
      current = repListEnd;
      recalcVR();
      errorFlag = DcmPolymorphOBOW::writeSignatureFormat(outStream, oxfer, enctype, wcache);
    }
    else if (getValue() == NULL)
    {
      errorFlag = DcmPolymorphOBOW::writeSignatureFormat(outStream, oxfer, enctype, wcache);
    } else errorFlag = EC_RepresentationNotFound;
  } else errorFlag = EC_Normal;
  return errorFlag;
}

OFCondition DcmPixelData::loadAllDataIntoMemory(void)
{
    if (current == repListEnd)
        return DcmElement::loadAllDataIntoMemory();
    else
        return (*current)->pixSeq->loadAllDataIntoMemory();
}

void DcmPixelData::setNonEncapsulationFlag(OFBool flag)
{
    alwaysUnencapsulated = flag;
}

OFCondition DcmPixelData::getUncompressedFrame(
    DcmItem *dataset,
    Uint32 frameNo,
    Uint32& startFragment,
    void *buffer,
    Uint32 bufSize,
    OFString& decompressedColorModel,
    DcmFileCache *cache)
{
    if ((dataset == NULL) || (buffer == NULL)) return EC_IllegalCall;

    Sint32 numberOfFrames = 1;
    dataset->findAndGetSint32(DCM_NumberOfFrames, numberOfFrames); // don't fail if absent
    if (numberOfFrames < 1) numberOfFrames = 1;

    Uint32 frameSize;
    OFCondition result = getUncompressedFrameSize(dataset, frameSize, existUnencapsulated);
    if (result.bad()) return result;

    // determine the minimum buffer size, which may be frame size plus one pad byte if frame size is odd.
    // We need this extra byte, because the image might be in a different
    // endianness than our host cpu. In this case the decoder will swap
    // the data to the host byte order which could overflow the buffer.
    Uint32 minBufSize = frameSize;
    if (minBufSize & 1) ++minBufSize;

    if (bufSize < minBufSize) return EC_IllegalCall;

    // check frame number
    if (frameNo >= OFstatic_cast(Uint32, numberOfFrames)) return EC_IllegalCall;

    if (existUnencapsulated)
    {
      // we already have an uncompressed version of the pixel data
      // either in memory or in file. We can directly access this using
      // DcmElement::getPartialValue.
      result = getPartialValue(buffer, frameNo * frameSize, frameSize, cache);
      if (result.good()) result = dataset->findAndGetOFString(DCM_PhotometricInterpretation, decompressedColorModel);
    }
    else
    {
      // we only have a compressed version of the pixel data.
      // Identify a codec for decompressing the frame.
      result = DcmCodecList::decodeFrame(
        (*original)->repType, (*original)->repParam, (*original)->pixSeq,
        dataset, frameNo, startFragment, buffer, bufSize, decompressedColorModel);
    }
    return result;
}


OFCondition DcmPixelData::getDecompressedColorModel(
    DcmItem *dataset,
    OFString &decompressedColorModel)
{
    OFCondition result = EC_IllegalParameter;
    if (dataset != NULL)
    {
      if (existUnencapsulated)
      {
        // we already have an uncompressed version of the pixel data either in memory or in file,
        // so just retrieve the color model from the given dataset
        result = dataset->findAndGetOFString(DCM_PhotometricInterpretation, decompressedColorModel);
        if (result == EC_TagNotFound)
        {
          DCMDATA_WARN("DcmPixelData: Mandatory element PhotometricInterpretation " << DCM_PhotometricInterpretation << " is missing");
          result = EC_MissingAttribute;
        }
        else if (result.bad())
        {
          DCMDATA_WARN("DcmPixelData: Cannot retrieve value of element PhotometricInterpretation " << DCM_PhotometricInterpretation << ": " << result.text());
        }
        else if (decompressedColorModel.empty())
        {
          DCMDATA_WARN("DcmPixelData: No value for mandatory element PhotometricInterpretation " << DCM_PhotometricInterpretation);
          result = EC_MissingValue;
        }
    } else {
        // we only have a compressed version of the pixel data.
        // Identify a codec for determining the color model.
        result = DcmCodecList::determineDecompressedColorModel(
          (*original)->repType, (*original)->repParam, (*original)->pixSeq,
          dataset, decompressedColorModel);
      }
    }
    return result;
}

OFBool DcmPixelData::writeUnencapsulated(const E_TransferSyntax xfer)
{
    // There are three cases under which a dataset is written out
    // unencapsulated:
    //
    // - It was already read unencapsulated (handled via alwaysUnencapsulated)
    // - We were told to do so (handled via alwaysUnencapsulated)
    // - This is not the pixel data element on the main level and it exists
    //   unencapsulated.

    if (alwaysUnencapsulated)
        return OFTrue;
    if (DcmXfer(xfer).isEncapsulated()) {
        DcmRepresentationListIterator found;
        OFCondition cond = findConformingEncapsulatedRepresentation(xfer, NULL, found);
        if (cond.good()) {
            // We found a suitable encapsulated representation, so encapsulate
            // this element in the output.
            return OFFalse;
        }
    }

    return existUnencapsulated && isNested();
}


OFCondition DcmPixelData::writeJson(STD_NAMESPACE ostream &out,
                                             DcmJsonFormat &format)
{

    // check if we have an empty uncompressed value field.
    // We never encode that as BulkDataURI.
    OFBool emptyValue = OFFalse;
    if ((current == repListEnd) && existUnencapsulated && (getLengthField() == 0))
    {
      emptyValue = OFTrue;
    }

    // now check if the pixel data will be written as
    // BulkDataURI, which is possible for both uncompressed
    // and encapsulated pixel data.
    OFString value;
    if ((! emptyValue) && format.asBulkDataURI(getTag(), value))
    {
        /* write JSON Opener */
        writeJsonOpener(out, format);

        /* return defined BulkDataURI */
        format.printBulkDataURIPrefix(out);
        DcmJsonFormat::printString(out, value);

        /* write JSON Closer */
        writeJsonCloser(out, format);
        return EC_Normal;
    }

    // No bulk data URI, we're supposed to write as InlineBinary.
    // This is only defined for uncompressed data, not for any of the
    // encapsulated encodings.

    // check the current pixel data representation
    if ((current == repListEnd) && existUnencapsulated)
    {
      // current pixel data representation is uncompressed (and available).

      /* write JSON Opener */
      writeJsonOpener(out, format);

      /* for an empty value field, we do not need to do anything */
      if (getLengthField() > 0)
      {
         /* encode binary data as Base64 */
         format.printInlineBinaryPrefix(out);
         out << "\"";
         /* adjust byte order to little endian */
         Uint8 *byteValues = OFstatic_cast(Uint8 *, getValue(EBO_LittleEndian));
         OFStandard::encodeBase64(out, byteValues, OFstatic_cast(size_t, getLengthField()));
         out << "\"";
      }
      /* write JSON Closer */
      writeJsonCloser(out, format);
      return EC_Normal;
    }

    /* write JSON Opener and Closer, because otherwise the output is not valid JSON */
    writeJsonOpener(out, format);
    writeJsonCloser(out, format);

    // pixel data is encapsulated, return error
    return EC_CannotWriteJsonInlineBinary;
}