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gdcmItem.h

/*=========================================================================

  Program: GDCM (Grassroots DICOM). A DICOM library
  Module:  $URL$

  Copyright (c) 2006-2009 Mathieu Malaterre
  All rights reserved.
  See Copyright.txt or http://gdcm.sourceforge.net/Copyright.html for details.

     This software is distributed WITHOUT ANY WARRANTY; without even
     the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
     PURPOSE.  See the above copyright notice for more information.

=========================================================================*/

#ifndef __gdcmItem_h
#define __gdcmItem_h

#include "gdcmDataElement.h"
#include "gdcmDataSet.h"
#include "gdcmParseException.h"
#include "gdcmSwapper.h"

#ifdef GDCM_SUPPORT_BROKEN_IMPLEMENTATION
#include "gdcmByteSwapFilter.h"
#endif

namespace gdcm
{

class DataSet;
/**
 * \brief Class to represent an Item
 * A component of the value of a Data Element that is of Value Representation Sequence of Items.
 * An Item contains a Data Set .
 * See PS 3.5 7.5.1 Item Encoding Rules
 * Each Item of a Data Element of VR SQ shall be encoded as a DICOM Standart Data
 * Element with a specific Data Element Tag of Value (FFFE,E000). The Item Tag is
 * followed by a 4 byte Item Length field encoded in one of the following two ways
 * Explicit/ Implicit
 * \note
 * ITEM: A component of the Value of a Data Element that is of Value
 * Representation Sequence of Items. An Item contains a Data Set.
 */
00045 class GDCM_EXPORT Item : public DataElement
{
public:
  Item() : DataElement(Tag(0xfffe, 0xe000), 0xFFFFFFFF), NestedDataSet() {}
  friend std::ostream& operator<< (std::ostream &os, const Item &val);

00051   void Clear() {
    NestedDataSet.Clear();
    }

  template <typename TDE>
  VL GetLength() const;

  void InsertDataElement(const DataElement & de) {
    NestedDataSet.Insert(de);
    // Update the length
    if( !IsUndefinedLength() )
      {
      assert( 0 && "InsertDataElement" );
      //ValueLengthField += de.GetLength();
      }
    }
  const DataElement& GetDataElement(const Tag& t) const
    {
    return NestedDataSet.GetDataElement(t);
    }

  // Completely defines it with the nested dataset
  // destroy anything present
  void SetNestedDataSet(const DataSet& nested)
    {
    NestedDataSet = nested;
    }
  // Return a const ref to the Nested Data Set
  const DataSet &GetNestedDataSet() const
    {
    return NestedDataSet;
    }
  DataSet &GetNestedDataSet()
    {
    return NestedDataSet;
    }

  //Value const & GetValue() const { return *NestedDataSet; }

  Item(Item const &val):DataElement(val)
    {
    NestedDataSet = val.NestedDataSet;
    }

  template <typename TDE, typename TSwap>
  std::istream &Read(std::istream &is) {
    // Superclass
    {
        DataSet &nested = NestedDataSet;
        nested.Clear();
        assert( nested.IsEmpty() );
    }
    if( !TagField.Read<TSwap>(is) )
      {
      throw Exception("Should not happen (item)");
      return is;
      }
#ifdef GDCM_SUPPORT_BROKEN_IMPLEMENTATION
    // MR_Philips_Intera_SwitchIndianess_noLgtSQItem_in_trueLgtSeq.dcm
    if( TagField == Tag(0xfeff, 0x00e0)
      || TagField == Tag(0xfeff, 0xdde0) )
      {
      gdcmWarningMacro( "ByteSwaping Private SQ: " << TagField );
      // Invert previously read TagField since wrong endianess:
      TagField = Tag( SwapperDoOp::Swap( TagField.GetGroup() ), SwapperDoOp::Swap( TagField.GetElement() ) );
      assert ( TagField == Tag(0xfffe, 0xe000)
        || TagField == Tag(0xfffe, 0xe0dd) );

      if( !ValueLengthField.Read<SwapperDoOp>(is) )
        {
        assert(0 && "Should not happen");
        return is;
        }
      // Self
      // Some file written by GDCM 1.0 we writting 0xFFFFFFFF instead of 0x0
      if( TagField == Tag(0xfffe,0xe0dd) )
        {
        if( ValueLengthField )
          {
          gdcmErrorMacro( "ValueLengthField is not 0" );
          }
        }
      //else if( ValueLengthField == 0 )
      //  {
      //  //assert( TagField == Tag( 0xfffe, 0xe0dd) );
      //  if( TagField != Tag( 0xfffe, 0xe0dd) )
      //    {
      //    gdcmErrorMacro( "SQ: " << TagField << " has a length of 0" );
      //    }
      //  }
      else if( ValueLengthField.IsUndefined() )
        {
        DataSet &nested = NestedDataSet;
        nested.Clear();
        assert( nested.IsEmpty() );
        std::streampos start = is.tellg();
        try
          {
          nested.template ReadNested<TDE,SwapperDoOp>(is);
          ByteSwapFilter bsf(nested);
          bsf.ByteSwap();
          }
        catch(ParseException &pe)
          {
          (void)pe;
          // MR_Philips_Intera_PrivateSequenceExplicitVR_in_SQ_2001_e05f_item_wrong_lgt_use_NOSHADOWSEQ.dcm
          // You have to byteswap the length but not the tag...sigh
          gdcmWarningMacro( "Attempt to read nested Item without byteswapping the Value Length." );
          start -= is.tellg();
          assert( start < 0 );
          is.seekg( start, std::ios::cur );
          nested.Clear();
          nested.template ReadNested<TDE,SwapperNoOp>(is);
          ByteSwapFilter bsf(nested);
          // Tag are read in big endian, need to byteswap them back...
          bsf.SetByteSwapTag(true);
          bsf.ByteSwap();
          }
        catch(Exception &e)
          {
          // MR_Philips_Intera_No_PrivateSequenceImplicitVR.dcm
          throw e;
          }
        catch(...)
          {
          assert(0);
          }
        }
      else /* if( ValueLengthField.IsUndefined() ) */
        {
        DataSet &nested = NestedDataSet;
        nested.Clear();
        assert( nested.IsEmpty() );
        nested.template ReadWithLength<TDE,SwapperDoOp>(is, ValueLengthField);
        ByteSwapFilter bsf(nested);
        bsf.ByteSwap();
        }
      return is;
      }
    // http://groups.google.com/group/comp.protocols.dicom/msg/c07efcf5e759fc83
    // Bug_Philips_ItemTag_3F3F.dcm
    if( TagField == Tag(0x3f3f, 0x3f00) )
      {
      //TagField = Tag(0xfffe, 0xe000);
      }
#endif
    if( TagField != Tag(0xfffe, 0xe000) && TagField != Tag(0xfffe, 0xe0dd) )
      {
      gdcmDebugMacro( "Invalid Item, found tag: " << TagField);
      throw Exception( "Not a valid Item" );
      }
    assert( TagField == Tag(0xfffe, 0xe000) || TagField == Tag(0xfffe, 0xe0dd) );

    if( !ValueLengthField.Read<TSwap>(is) )
      {
      assert(0 && "Should not happen");
      return is;
      }
    // Self
    if( TagField == Tag(0xfffe,0xe0dd) )
      {
      // Some file written by GDCM 1.0 were written with 0xFFFFFFFF instead of 0x0
      if( ValueLengthField )
        {
        gdcmDebugMacro( "ValueLengthField is not 0 but " << ValueLengthField );
        }
      }
    else if( ValueLengthField.IsUndefined() )
      {
      DataSet &nested = NestedDataSet;
      nested.Clear();
      assert( nested.IsEmpty() );
      nested.template ReadNested<TDE,TSwap>(is);
      }
    else /* if( ValueLengthField.IsUndefined() ) */
      {
      assert( !ValueLengthField.IsUndefined() );
      DataSet &nested = NestedDataSet;
      nested.Clear();
      assert( nested.IsEmpty() );
      nested.template ReadWithLength<TDE,TSwap>(is, ValueLengthField);
      }

    return is;
  }

  template <typename TDE, typename TSwap>
  const std::ostream &Write(std::ostream &os) const {
#ifdef GDCM_SUPPORT_BROKEN_IMPLEMENTATION
    if( TagField == Tag(0x3f3f,0x3f00) && false )
      {
      Tag t(0xfffe, 0xe000);
      t.Write<TSwap>(os);
      }
    else
#endif
      {
      assert ( TagField == Tag(0xfffe, 0xe000)
        || TagField == Tag(0xfffe, 0xe0dd) );
      // Not sure how this happen
      if( TagField == Tag(0xfffe, 0xe0dd) )
        {
        gdcmWarningMacro( "SegDelItem found in defined length Sequence" );
        assert( ValueLengthField == 0 );
        assert( NestedDataSet.Size() == 0 );
        }
      if( !TagField.Write<TSwap>(os) )
        {
        assert(0 && "Should not happen");
        return os;
        }
      }
    if( ValueLengthField.IsUndefined() )
      {
      if( !ValueLengthField.Write<TSwap>(os) )
        {
        assert(0 && "Should not happen");
        return os;
        }
      }
    else
      {
      VL dummy = NestedDataSet.GetLength<TDE>();
      //assert( ValueLengthField == dummy );
      if( !dummy.Write<TSwap>(os) )
        {
        assert(0 && "Should not happen");
        return os;
        }
      }
    // Self
    NestedDataSet.Write<TDE,TSwap>(os);
    if( ValueLengthField.IsUndefined() )
      {
      const Tag itemDelItem(0xfffe,0xe00d);
      itemDelItem.Write<TSwap>(os);
      VL zero = 0;
      zero.Write<TSwap>(os);
      }

    return os;
  }

/*
There are three special SQ related Data Elements that are not ruled by the VR encoding rules conveyed
by the Transfer Syntax. They shall be encoded as Implicit VR. These special Data Elements are Item
(FFFE,E000), Item Delimitation Item (FFFE,E00D), and Sequence Delimitation Item (FFFE,E0DD).
However, the Data Set within the Value Field of the Data Element Item (FFFE,E000) shall be encoded
according to the rules conveyed by the Transfer Syntax.
*/
  bool FindDataElement(const Tag &t) const {
    return NestedDataSet.FindDataElement( t );
  }

private:
  /* NESTED DATA SET  a Data Set contained within a Data Element of an other Data Set.
   * May be nested recursively.
   * Only Data Elements with VR = SQ  may, themselves, contain Data Sets
   */
  DataSet NestedDataSet;
};
//-----------------------------------------------------------------------------
inline std::ostream& operator<<(std::ostream& os, const Item &val)
{
  os << val.TagField;
  os << "\t" << val.ValueLengthField << "\n";
  val.NestedDataSet.Print( os, "\t" );

  return os;
}


} // end namespace gdcm

#include "gdcmItem.txx"

#endif //__gdcmItem_h

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