ddfrecord.cpp

国际海图标准S-57格式数据读取源码VC

 * @return The value of the subfield, or zero if it failed for some reason.
 */

double DDFRecord::GetFloatSubfield( const char * pszField, int iFieldIndex,
                                 const char * pszSubfield, int iSubfieldIndex,
                                    int * pnSuccess )

{
    DDFField    *poField;
    int         nDummyErr;

    if( pnSuccess == NULL )
        pnSuccess = &nDummyErr;

    *pnSuccess = FALSE;
            
/* -------------------------------------------------------------------- */
/*      Fetch the field. If this fails, return zero.                    */
/* -------------------------------------------------------------------- */
    poField = FindField( pszField, iFieldIndex );
    if( poField == NULL )
        return 0;

/* -------------------------------------------------------------------- */
/*      Get the subfield definition                                     */
/* -------------------------------------------------------------------- */
    DDFSubfieldDefn     *poSFDefn;

    poSFDefn = poField->GetFieldDefn()->FindSubfieldDefn( pszSubfield );
    if( poSFDefn == NULL )
        return 0;

/* -------------------------------------------------------------------- */
/*      Get a pointer to the data.                                      */
/* -------------------------------------------------------------------- */
    int         nBytesRemaining;
    
    const char *pachData = poField->GetSubfieldData(poSFDefn,
                                                    &nBytesRemaining,
                                                    iSubfieldIndex);

/* -------------------------------------------------------------------- */
/*      Return the extracted value.                                     */
/* -------------------------------------------------------------------- */
    *pnSuccess = TRUE;

    return( poSFDefn->ExtractFloatData( pachData, nBytesRemaining, NULL ) );
}

/************************************************************************/
/*                         GetStringSubfield()                          */
/************************************************************************/

/**
 * Fetch value of a subfield as a string.  This is a convenience
 * function for fetching a subfield of a field within this record.
 *
 * @param pszField The name of the field containing the subfield.
 * @param iFieldIndex The instance of this field within the record.  Use
 * zero for the first instance of this field.
 * @param pszSubfield The name of the subfield within the selected field.
 * @param iSubfieldIndex The instance of this subfield within the record.
 * Use zero for the first instance.
 * @param pnSuccess Pointer to an int which will be set to TRUE if the fetch
 * succeeds, or FALSE if it fails.  Use NULL if you don't want to check
 * success.
 * @return The value of the subfield, or NULL if it failed for some reason.
 * The returned pointer is to internal data and should not be modified or
 * freed by the application.
 */

const char *
DDFRecord::GetStringSubfield( const char * pszField, int iFieldIndex,
                              const char * pszSubfield, int iSubfieldIndex,
                              int * pnSuccess )

{
    DDFField    *poField;
    int         nDummyErr;

    if( pnSuccess == NULL )
        pnSuccess = &nDummyErr;

    *pnSuccess = FALSE;
            
/* -------------------------------------------------------------------- */
/*      Fetch the field. If this fails, return zero.                    */
/* -------------------------------------------------------------------- */
    poField = FindField( pszField, iFieldIndex );
    if( poField == NULL )
        return NULL;

/* -------------------------------------------------------------------- */
/*      Get the subfield definition                                     */
/* -------------------------------------------------------------------- */
    DDFSubfieldDefn     *poSFDefn;

    poSFDefn = poField->GetFieldDefn()->FindSubfieldDefn( pszSubfield );
    if( poSFDefn == NULL )
        return NULL;

/* -------------------------------------------------------------------- */
/*      Get a pointer to the data.                                      */
/* -------------------------------------------------------------------- */
    int         nBytesRemaining;
    
    const char *pachData = poField->GetSubfieldData(poSFDefn,
                                                    &nBytesRemaining,
                                                    iSubfieldIndex);

/* -------------------------------------------------------------------- */
/*      Return the extracted value.                                     */
/* -------------------------------------------------------------------- */
    *pnSuccess = TRUE;

    return( poSFDefn->ExtractStringData( pachData, nBytesRemaining, NULL ) );
}

/************************************************************************/
/*                               Clone()                                */
/************************************************************************/

/**
 * Make a copy of a record.
 *
 * This method is used to make a copy of a record that will become (mostly)
 * the properly of application.  However, it is automatically destroyed if
 * the DDFModule it was created relative to is destroyed, as it's field
 * and subfield definitions relate to that DDFModule.  However, it does
 * persist even when the record returned by DDFModule::ReadRecord() is
 * invalidated, such as when reading a new record.  This allows an application
 * to cache whole DDFRecords.
 *
 * @return A new copy of the DDFRecord.  This can be delete'd by the
 * application when no longer needed, otherwise it will be cleaned up when
 * the DDFModule it relates to is destroyed or closed.
 */

DDFRecord * DDFRecord::Clone()

{
    DDFRecord   *poNR;

    poNR = new DDFRecord( poModule );

    poNR->nReuseHeader = FALSE;
    poNR->nFieldOffset = nFieldOffset;
    
    poNR->nDataSize = nDataSize;
    poNR->pachData = (char *) CPLMalloc(nDataSize);
    memcpy( poNR->pachData, pachData, nDataSize );
    
    poNR->nFieldCount = nFieldCount;
    poNR->paoFields = new DDFField[nFieldCount];
    for( int i = 0; i < nFieldCount; i++ )
    {
        int     nOffset;

        nOffset = (paoFields[i].GetData() - pachData);
        poNR->paoFields[i].Initialize( paoFields[i].GetFieldDefn(),
                                       poNR->pachData + nOffset,
                                       paoFields[i].GetDataSize() );
    }
    
    poNR->bIsClone = TRUE;
    poModule->AddCloneRecord( poNR );

    return poNR;
}

/************************************************************************/
/*                              CloneOn()                               */
/************************************************************************/

/**
 * Recreate a record referencing another module.
 *
 * Works similarly to the DDFRecord::Clone() method, but creates the
 * new record with reference to a different DDFModule.  All DDFFieldDefn
 * references are transcribed onto the new module based on field names.
 * If any fields don't have a similarly named field on the target module
 * the operation will fail.  No validation of field types and properties
 * is done, but this operation is intended only to be used between 
 * modules with matching definitions of all affected fields. 
 *
 * The new record will be managed as a clone by the target module in
 * a manner similar to regular clones. 
 *
 * @param poTargetModule the module on which the record copy should be
 * created.
 *
 * @return NULL on failure or a pointer to the cloned record.
 */

DDFRecord *DDFRecord::CloneOn( DDFModule *poTargetModule )

{
/* -------------------------------------------------------------------- */
/*      Verify that all fields have a corresponding field definition    */
/*      on the target module.                                           */
/* -------------------------------------------------------------------- */
    int         i;

    for( i = 0; i < nFieldCount; i++ )
    {
        DDFFieldDefn    *poDefn = paoFields[i].GetFieldDefn();

        if( poTargetModule->FindFieldDefn( poDefn->GetName() ) == NULL )
            return NULL;
    }

/* -------------------------------------------------------------------- */
/*      Create a clone.                                                 */
/* -------------------------------------------------------------------- */
    DDFRecord   *poClone;

    poClone = Clone();

/* -------------------------------------------------------------------- */
/*      Update all internal information to reference other module.      */
/* -------------------------------------------------------------------- */
    for( i = 0; i < nFieldCount; i++ )
    {
        DDFField        *poField = poClone->paoFields+i;
        DDFFieldDefn    *poDefn;

        poDefn = poTargetModule->FindFieldDefn( 
            poField->GetFieldDefn()->GetName() );
        
        poField->Initialize( poDefn, poField->GetData(), 
                             poField->GetDataSize() );
    }

    poModule->RemoveCloneRecord( poClone );
    poClone->poModule = poTargetModule;
    poTargetModule->AddCloneRecord( poClone );

    return poClone;
}


/************************************************************************/
/*                            DeleteField()                             */
/************************************************************************/

/**
 * Delete a field instance from a record.
 *
 * Remove a field from this record, cleaning up the data            
 * portion and repacking the fields list.  We don't try to          
 * reallocate the data area of the record to be smaller.            
 *                                                                       
 * NOTE: This method doesn't actually remove the header             
 * information for this field from the record tag list yet.        
 * This should be added if the resulting record is even to be      
 * written back to disk!                                           
 *
 * @param poTarget the field instance on this record to delete.
 *
 * @return TRUE on success, or FALSE on failure.  Failure can occur if 
 * poTarget isn't really a field on this record.
 */

int DDFRecord::DeleteField( DDFField *poTarget )

{
    int         iTarget, i;

/* -------------------------------------------------------------------- */
/*      Find which field we are to delete.                              */
/* -------------------------------------------------------------------- */
    for( iTarget = 0; iTarget < nFieldCount; iTarget++ )
    {
        if( paoFields + iTarget == poTarget )
            break;
    }

    if( iTarget == nFieldCount )
        return FALSE;

/* -------------------------------------------------------------------- */
/*      Change the target fields data size to zero.  This takes care    */
/*      of repacking the data array, and updating all the following     */
/*      field data pointers.                                            */
/* -------------------------------------------------------------------- */
    ResizeField( poTarget, 0 );

/* -------------------------------------------------------------------- */
/*      remove the target field, moving down all the other fields       */
/*      one step in the field list.                                     */
/* -------------------------------------------------------------------- */
    for( i = iTarget; i < nFieldCount-1; i++ )
    {
        paoFields[i] = paoFields[i+1];
    }

    nFieldCount--;

    return TRUE;
}

/************************************************************************/
/*                            ResizeField()                             */
/************************************************************************/

/**
 * Alter field data size within record.
 *
 * This method will rearrange a DDFRecord altering the amount of space
 * reserved for one of the existing fields.  All following fields will
 * be shifted accordingly.  This includes updating the DDFField infos, 
 * and actually moving stuff within the data array after reallocating
 * to the desired size.
 *
 * @param poField the field to alter.
 * @param nNewDataSize the number of data bytes to be reserved for the field.
 *
 * @return TRUE on success or FALSE on failure. 
 */

int DDFRecord::ResizeField( DDFField *poField, int nNewDataSize )

{
    int         iTarget, i;
    int         nBytesToMove;

/* -------------------------------------------------------------------- */
/*      Find which field we are to resize.                              */
/* -------------------------------------------------------------------- */
    for( iTarget = 0; iTarget < nFieldCount; iTarget++ )
    {
        if( paoFields + iTarget == poField )
            break;