ddfmodule.cpp

国际海图标准S-57格式数据读取源码VC

/* -------------------------------------------------------------------- */
/*      Create the file on disk.                                        */
/* -------------------------------------------------------------------- */
    fpDDF = VSIFOpen( pszFilename, "wb+" );
    if( fpDDF == NULL )
    {
        CPLError( CE_Failure, CPLE_OpenFailed, 
                  "Failed to create file %s, check path and permissions.",
                  pszFilename );
        return FALSE;
    }
    
    bReadOnly = FALSE;

/* -------------------------------------------------------------------- */
/*      Prepare all the field definition information.                   */
/* -------------------------------------------------------------------- */
    int iField;

    _fieldControlLength = 9;
    _recLength = 24 
        + nFieldDefnCount * (_sizeFieldLength+_sizeFieldPos+_sizeFieldTag) 
        + 1;
    
    _fieldAreaStart = _recLength;

    for( iField=0; iField < nFieldDefnCount; iField++ )
    {
        int nLength;

        papoFieldDefns[iField]->GenerateDDREntry( NULL, &nLength );
        _recLength += nLength;
    }

/* -------------------------------------------------------------------- */
/*      Setup 24 byte leader.                                           */
/* -------------------------------------------------------------------- */
    char achLeader[25];

    sprintf( achLeader+0, "%05d", (int) _recLength );
    achLeader[5] = _interchangeLevel;
    achLeader[6] = _leaderIden;
    achLeader[7] = _inlineCodeExtensionIndicator;
    achLeader[8] = _versionNumber;
    achLeader[9] = _appIndicator;
    sprintf( achLeader+10, "%02d", (int) _fieldControlLength );
    sprintf( achLeader+12, "%05d", (int) _fieldAreaStart );
    strncpy( achLeader+17, _extendedCharSet, 3 );
    sprintf( achLeader+20, "%1d", (int) _sizeFieldLength );
    sprintf( achLeader+21, "%1d", (int) _sizeFieldPos );
    achLeader[22] = '0';
    sprintf( achLeader+23, "%1d", (int) _sizeFieldTag );
    VSIFWrite( achLeader, 24, 1, fpDDF );

/* -------------------------------------------------------------------- */
/*      Write out directory entries.                                    */
/* -------------------------------------------------------------------- */
    int nOffset = 0;
    for( iField=0; iField < nFieldDefnCount; iField++ )
    {
        char achDirEntry[12];
        int nLength;

        papoFieldDefns[iField]->GenerateDDREntry( NULL, &nLength );

        strcpy( achDirEntry, papoFieldDefns[iField]->GetName() );
        sprintf( achDirEntry + _sizeFieldTag, "%03d", nLength );
        sprintf( achDirEntry + _sizeFieldTag + _sizeFieldLength, 
                 "%04d", nOffset );
        nOffset += nLength;

        VSIFWrite( achDirEntry, 11, 1, fpDDF );
    }

    char chUT = DDF_FIELD_TERMINATOR;
    VSIFWrite( &chUT, 1, 1, fpDDF );

/* -------------------------------------------------------------------- */
/*      Write out the field descriptions themselves.                    */
/* -------------------------------------------------------------------- */
    for( iField=0; iField < nFieldDefnCount; iField++ )
    {
        char *pachData;
        int nLength;

        papoFieldDefns[iField]->GenerateDDREntry( &pachData, &nLength );
        VSIFWrite( pachData, nLength, 1, fpDDF );
        CPLFree( pachData );
    }
    
    return TRUE;
}

/************************************************************************/
/*                                Dump()                                */
/************************************************************************/

/**
 * Write out module info to debugging file.
 *
 * A variety of information about the module is written to the debugging
 * file.  This includes all the field and subfield definitions read from
 * the header. 
 *
 * @param fp The standard io file handle to write to.  ie. stderr.
 */

void DDFModule::Dump( FILE * fp )

{
    fprintf( fp, "DDFModule:\n" );
    fprintf( fp, "    _recLength = %ld\n", _recLength );
    fprintf( fp, "    _interchangeLevel = %c\n", _interchangeLevel );
    fprintf( fp, "    _leaderIden = %c\n", _leaderIden );
    fprintf( fp, "    _inlineCodeExtensionIndicator = %c\n",
             _inlineCodeExtensionIndicator );
    fprintf( fp, "    _versionNumber = %c\n", _versionNumber );
    fprintf( fp, "    _appIndicator = %c\n", _appIndicator );
    fprintf( fp, "    _extendedCharSet = `%s'\n", _extendedCharSet );
    fprintf( fp, "    _fieldControlLength = %d\n", _fieldControlLength );
    fprintf( fp, "    _fieldAreaStart = %ld\n", _fieldAreaStart );
    fprintf( fp, "    _sizeFieldLength = %ld\n", _sizeFieldLength );
    fprintf( fp, "    _sizeFieldPos = %ld\n", _sizeFieldPos );
    fprintf( fp, "    _sizeFieldTag = %ld\n", _sizeFieldTag );

    for( int i = 0; i < nFieldDefnCount; i++ )
    {
        papoFieldDefns[i]->Dump( fp );
    }
}

/************************************************************************/
/*                           FindFieldDefn()                            */
/************************************************************************/

/**
 * Fetch the definition of the named field.
 *
 * This function will scan the DDFFieldDefn's on this module, to find
 * one with the indicated field name.
 *
 * @param pszFieldName The name of the field to search for.  The comparison is
 *                     case insensitive.
 *
 * @return A pointer to the request DDFFieldDefn object is returned, or NULL
 * if none matching the name are found.  The return object remains owned by
 * the DDFModule, and should not be deleted by application code.
 */

DDFFieldDefn *DDFModule::FindFieldDefn( const char *pszFieldName )

{
    int         i;
    
/* -------------------------------------------------------------------- */
/*      This pass tries to reduce the cost of comparing strings by      */
/*      first checking the first character, and by using strcmp()       */
/* -------------------------------------------------------------------- */
    for( i = 0; i < nFieldDefnCount; i++ )
    {
        const char *pszThisName = papoFieldDefns[i]->GetName();
        
        if( *pszThisName == *pszFieldName
            && strcmp( pszFieldName+1, pszThisName+1) == 0 )
            return papoFieldDefns[i];
    }

/* -------------------------------------------------------------------- */
/*      Now do a more general check.  Application code may not          */
/*      always use the correct name case.                               */
/* -------------------------------------------------------------------- */
    for( i = 0; i < nFieldDefnCount; i++ )
    {
        if( EQUAL(pszFieldName, papoFieldDefns[i]->GetName()) )
            return papoFieldDefns[i];
    }

    return NULL;
}

/************************************************************************/
/*                             ReadRecord()                             */
/*                                                                      */
/*      Read one record from the file, and return to the                */
/*      application.  The returned record is owned by the module,       */
/*      and is reused from call to call in order to preserve headers    */
/*      when they aren't being re-read from record to record.           */
/************************************************************************/

/**
 * Read one record from the file.
 *
 * @return A pointer to a DDFRecord object is returned, or NULL if a read
 * error, or end of file occurs.  The returned record is owned by the
 * module, and should not be deleted by the application.  The record is
 * only valid untill the next ReadRecord() at which point it is overwritten.
 */

DDFRecord *DDFModule::ReadRecord()

{
    if( poRecord == NULL )
        poRecord = new DDFRecord( this );

    if( poRecord->Read() )
        return poRecord;
    else
        return NULL;
}

/************************************************************************/
/*                              AddField()                              */
/************************************************************************/

/**
 * Add new field definition.
 *
 * Field definitions may only be added to DDFModules being used for 
 * writing, not those being used for reading.  Ownership of the 
 * DDFFieldDefn object is taken by the DDFModule.
 *
 * @param poNewFDefn definition to be added to the module. 
 */

void DDFModule::AddField( DDFFieldDefn *poNewFDefn )

{
    nFieldDefnCount++;
    papoFieldDefns = (DDFFieldDefn **) 
        CPLRealloc(papoFieldDefns, sizeof(void*)*nFieldDefnCount);
    papoFieldDefns[nFieldDefnCount-1] = poNewFDefn;
}

/************************************************************************/
/*                              GetField()                              */
/************************************************************************/

/**
 * Fetch a field definition by index.
 *
 * @param i (from 0 to GetFieldCount() - 1.
 * @return the returned field pointer or NULL if the index is out of range.
 */

DDFFieldDefn *DDFModule::GetField(int i)

{
    if( i < 0 || i >= nFieldDefnCount )
        return NULL;
    else
        return papoFieldDefns[i];
}
    
/************************************************************************/
/*                           AddCloneRecord()                           */
/*                                                                      */
/*      We want to keep track of cloned records, so we can clean        */
/*      them up when the module is destroyed.                           */
/************************************************************************/

void DDFModule::AddCloneRecord( DDFRecord * poRecord )

{
/* -------------------------------------------------------------------- */
/*      Do we need to grow the container array?                         */
/* -------------------------------------------------------------------- */
    if( nCloneCount == nMaxCloneCount )
    {
        nMaxCloneCount = nCloneCount*2 + 20;
        papoClones = (DDFRecord **) CPLRealloc(papoClones,
                                               nMaxCloneCount * sizeof(void*));
    }

/* -------------------------------------------------------------------- */
/*      Add to the list.                                                */
/* -------------------------------------------------------------------- */
    papoClones[nCloneCount++] = poRecord;
}

/************************************************************************/
/*                         RemoveCloneRecord()                          */
/************************************************************************/

void DDFModule::RemoveCloneRecord( DDFRecord * poRecord )

{
    int         i;
 
    for( i = 0; i < nCloneCount; i++ )
    {
        if( papoClones[i] == poRecord )
        {
            papoClones[i] = papoClones[nCloneCount-1];
            nCloneCount--;
            return;
        }
    }

    CPLAssert( FALSE );
}

/************************************************************************/
/*                               Rewind()                               */
/************************************************************************/

/**
 * Return to first record.
 * 
 * The next call to ReadRecord() will read the first data record in the file.
 *
 * @param nOffset the offset in the file to return to.  By default this is
 * -1, a special value indicating that reading should return to the first
 * data record.  Otherwise it is an absolute byte offset in the file.
 */

void DDFModule::Rewind( long nOffset )

{
    if( nOffset == -1 )
        nOffset = nFirstRecordOffset;

    if( fpDDF == NULL )
        return;
    
    VSIFSeek( fpDDF, nOffset, SEEK_SET );

    if( nOffset == nFirstRecordOffset && poRecord != NULL )
        poRecord->Clear();
        
}