dbfopen.c

ESRI SHAPE文件读/写源代码。SHAPE是GIS中的重要文件格式

int	DBFGetFieldCount( DBFHandle psDBF )

{
    return( psDBF->nFields );
}

/************************************************************************/
/*                         DBFGetRecordCount()                          */
/*                                                                      */
/*      Return the number of records in this table.                     */
/************************************************************************/

int	DBFGetRecordCount( DBFHandle psDBF )

{
    return( psDBF->nRecords );
}

/************************************************************************/
/*                          DBFGetFieldInfo()                           */
/*                                                                      */
/*      Return any requested information about the field.               */
/************************************************************************/

DBFFieldType DBFGetFieldInfo( DBFHandle psDBF, int iField, char * pszFieldName,
			      int * pnWidth, int * pnDecimals )

{
    if( iField < 0 || iField >= psDBF->nFields )
        return( FTInvalid );

    if( pnWidth != NULL )
        *pnWidth = psDBF->panFieldSize[iField];

    if( pnDecimals != NULL )
        *pnDecimals = psDBF->panFieldDecimals[iField];

    if( pszFieldName != NULL )
    {
	int	i;

	strncpy( pszFieldName, (char *) psDBF->pszHeader+iField*32, 11 );
	pszFieldName[11] = '\0';
	for( i = 10; i > 0 && pszFieldName[i] == ' '; i-- )
	    pszFieldName[i] = '\0';
    }

    if( psDBF->pachFieldType[iField] == 'N' 
        || psDBF->pachFieldType[iField] == 'F'
        || psDBF->pachFieldType[iField] == 'D' )
    {
	if( psDBF->panFieldDecimals[iField] > 0 )
	    return( FTDouble );
	else
	    return( FTInteger );
    }
    else
    {
	return( FTString );
    }
}

/************************************************************************/
/*                         DBFWriteAttribute()                          */
/*									*/
/*	Write an attribute record to the file.				*/
/************************************************************************/

static int DBFWriteAttribute(DBFHandle psDBF, int hEntity, int iField,
			     void * pValue )

{
    int	       	nRecordOffset, i, j;
    uchar	*pabyRec;
    char	szSField[40], szFormat[12];

/* -------------------------------------------------------------------- */
/*	Is this a valid record?						*/
/* -------------------------------------------------------------------- */
    if( hEntity < 0 || hEntity > psDBF->nRecords )
        return( FALSE );

    if( psDBF->bNoHeader )
        DBFWriteHeader(psDBF);

/* -------------------------------------------------------------------- */
/*      Is this a brand new record?                                     */
/* -------------------------------------------------------------------- */
    if( hEntity == psDBF->nRecords )
    {
	DBFFlushRecord( psDBF );

	psDBF->nRecords++;
	for( i = 0; i < psDBF->nRecordLength; i++ )
	    psDBF->pszCurrentRecord[i] = ' ';

	psDBF->nCurrentRecord = hEntity;
    }

/* -------------------------------------------------------------------- */
/*      Is this an existing record, but different than the last one     */
/*      we accessed?                                                    */
/* -------------------------------------------------------------------- */
    if( psDBF->nCurrentRecord != hEntity )
    {
	DBFFlushRecord( psDBF );

	nRecordOffset = psDBF->nRecordLength * hEntity + psDBF->nHeaderLength;

	fseek( psDBF->fp, nRecordOffset, 0 );
	fread( psDBF->pszCurrentRecord, psDBF->nRecordLength, 1, psDBF->fp );

	psDBF->nCurrentRecord = hEntity;
    }

    pabyRec = (uchar *) psDBF->pszCurrentRecord;

/* -------------------------------------------------------------------- */
/*      Assign all the record fields.                                   */
/* -------------------------------------------------------------------- */
    switch( psDBF->pachFieldType[iField] )
    {
      case 'D':
      case 'N':
      case 'F':
	if( psDBF->panFieldDecimals[iField] == 0 )
	{
	    sprintf( szFormat, "%%%dd", psDBF->panFieldSize[iField] );
	    sprintf(szSField, szFormat, (int) *((double *) pValue) );
	    if( strlen(szSField) > psDBF->panFieldSize[iField] )
	        szSField[psDBF->panFieldSize[iField]] = '\0';

	    strncpy((char *) (pabyRec+psDBF->panFieldOffset[iField]),
		    szSField, strlen(szSField) );
	}
	else
	{
	    sprintf( szFormat, "%%%d.%df", 
		     psDBF->panFieldSize[iField],
		     psDBF->panFieldDecimals[iField] );
	    sprintf(szSField, szFormat, *((double *) pValue) );
	    if( strlen(szSField) > psDBF->panFieldSize[iField] )
	        szSField[psDBF->panFieldSize[iField]] = '\0';
	    strncpy((char *) (pabyRec+psDBF->panFieldOffset[iField]),
		    szSField, strlen(szSField) );
	}
	break;

      default:
	if( strlen((char *) pValue) > psDBF->panFieldSize[iField] )
	    j = psDBF->panFieldSize[iField];
	else
        {
            memset( pabyRec+psDBF->panFieldOffset[iField], ' ',
                    psDBF->panFieldSize[iField] );
	    j = strlen((char *) pValue);
        }

	strncpy((char *) (pabyRec+psDBF->panFieldOffset[iField]),
		(char *) pValue, j );
	break;
    }

    psDBF->bCurrentRecordModified = TRUE;
    psDBF->bUpdated = TRUE;

    return( TRUE );
}

/************************************************************************/
/*                      DBFWriteDoubleAttribute()                       */
/*                                                                      */
/*      Write a double attribute.                                       */
/************************************************************************/

int DBFWriteDoubleAttribute( DBFHandle psDBF, int iRecord, int iField,
			     double dValue )

{
    return( DBFWriteAttribute( psDBF, iRecord, iField, (void *) &dValue ) );
}

/************************************************************************/
/*                      DBFWriteIntegerAttribute()                      */
/*                                                                      */
/*      Write a integer attribute.                                      */
/************************************************************************/

int DBFWriteIntegerAttribute( DBFHandle psDBF, int iRecord, int iField,
			      int nValue )

{
    double	dValue = nValue;

    return( DBFWriteAttribute( psDBF, iRecord, iField, (void *) &dValue ) );
}

/************************************************************************/
/*                      DBFWriteStringAttribute()                       */
/*                                                                      */
/*      Write a string attribute.                                       */
/************************************************************************/

int DBFWriteStringAttribute( DBFHandle psDBF, int iRecord, int iField,
			     const char * pszValue )

{
    return( DBFWriteAttribute( psDBF, iRecord, iField, (void *) pszValue ) );
}

/************************************************************************/
/*                         DBFWriteTuple()                              */
/*									*/
/*	Write an attribute record to the file.				*/
/************************************************************************/

int DBFWriteTuple(DBFHandle psDBF, int hEntity, void * pRawTuple )

{
    int	       	nRecordOffset, i;
    uchar	*pabyRec;

/* -------------------------------------------------------------------- */
/*	Is this a valid record?						*/
/* -------------------------------------------------------------------- */
    if( hEntity < 0 || hEntity > psDBF->nRecords )
        return( FALSE );

    if( psDBF->bNoHeader )
        DBFWriteHeader(psDBF);

/* -------------------------------------------------------------------- */
/*      Is this a brand new record?                                     */
/* -------------------------------------------------------------------- */
    if( hEntity == psDBF->nRecords )
    {
	DBFFlushRecord( psDBF );

	psDBF->nRecords++;
	for( i = 0; i < psDBF->nRecordLength; i++ )
	    psDBF->pszCurrentRecord[i] = ' ';

	psDBF->nCurrentRecord = hEntity;
    }

/* -------------------------------------------------------------------- */
/*      Is this an existing record, but different than the last one     */
/*      we accessed?                                                    */
/* -------------------------------------------------------------------- */
    if( psDBF->nCurrentRecord != hEntity )
    {
	DBFFlushRecord( psDBF );

	nRecordOffset = psDBF->nRecordLength * hEntity + psDBF->nHeaderLength;

	fseek( psDBF->fp, nRecordOffset, 0 );
	fread( psDBF->pszCurrentRecord, psDBF->nRecordLength, 1, psDBF->fp );

	psDBF->nCurrentRecord = hEntity;
    }

    pabyRec = (uchar *) psDBF->pszCurrentRecord;

    memcpy ( pabyRec, pRawTuple,  psDBF->nRecordLength );

    psDBF->bCurrentRecordModified = TRUE;
    psDBF->bUpdated = TRUE;

    return( TRUE );
}

/************************************************************************/
/*                          DBFReadTuple()                              */
/*                                                                      */
/*      Read one of the attribute fields of a record.                   */
/************************************************************************/

const char *DBFReadTuple(DBFHandle psDBF, int hEntity )

{
    int	       	nRecordOffset;
    uchar	*pabyRec;
    static char	*pReturnTuple = NULL;

    static int	nTupleLen = 0;

/* -------------------------------------------------------------------- */
/*	Have we read the record?					*/
/* -------------------------------------------------------------------- */
    if( hEntity < 0 || hEntity >= psDBF->nRecords )
        return( NULL );

    if( psDBF->nCurrentRecord != hEntity )
    {
	DBFFlushRecord( psDBF );

	nRecordOffset = psDBF->nRecordLength * hEntity + psDBF->nHeaderLength;

	fseek( psDBF->fp, nRecordOffset, 0 );
	fread( psDBF->pszCurrentRecord, psDBF->nRecordLength, 1, psDBF->fp );

	psDBF->nCurrentRecord = hEntity;
    }

    pabyRec = (uchar *) psDBF->pszCurrentRecord;

    if ( nTupleLen < psDBF->nRecordLength) {
      nTupleLen = psDBF->nRecordLength;
      pReturnTuple = (char *) SfRealloc(pReturnTuple, psDBF->nRecordLength);
    }
    
    memcpy ( pReturnTuple, pabyRec, psDBF->nRecordLength );
        
    return( pReturnTuple );
}

/************************************************************************/
/*                          DBFCloneEmpty()                              */
/*                                                                      */
/*      Read one of the attribute fields of a record.                   */
/************************************************************************/

DBFHandle DBFCloneEmpty(DBFHandle psDBF, const char * pszFilename ) 
{
    DBFHandle	newDBF;

   newDBF = DBFCreate ( pszFilename );
   if ( newDBF == NULL ) return ( NULL ); 
   
   newDBF->pszHeader = (void *) malloc ( 32 * psDBF->nFields );
   memcpy ( newDBF->pszHeader, psDBF->pszHeader, 32 * psDBF->nFields );
   
   newDBF->nFields = psDBF->nFields;
   newDBF->nRecordLength = psDBF->nRecordLength;
   newDBF->nHeaderLength = psDBF->nHeaderLength;
    
   newDBF->panFieldOffset = (void *) malloc ( sizeof(int) * psDBF->nFields ); 
   memcpy ( newDBF->panFieldOffset, psDBF->panFieldOffset, sizeof(int) * psDBF->nFields );
   newDBF->panFieldSize = (void *) malloc ( sizeof(int) * psDBF->nFields );
   memcpy ( newDBF->panFieldSize, psDBF->panFieldSize, sizeof(int) * psDBF->nFields );
   newDBF->panFieldDecimals = (void *) malloc ( sizeof(int) * psDBF->nFields );
   memcpy ( newDBF->panFieldDecimals, psDBF->panFieldDecimals, sizeof(int) * psDBF->nFields );
   newDBF->pachFieldType = (void *) malloc ( sizeof(int) * psDBF->nFields );
   memcpy ( newDBF->pachFieldType, psDBF->pachFieldType, sizeof(int) * psDBF->nFields );

   newDBF->bNoHeader = TRUE;
   newDBF->bUpdated = TRUE;
   
   DBFWriteHeader ( newDBF );
   DBFClose ( newDBF );
   
   newDBF = DBFOpen ( pszFilename, "rb+" );

   return ( newDBF );
}