gmlreader.cpp

GIS系统支持库Geospatial Data Abstraction Library代码.GDAL is a translator library for raster geospatial dat

        return FALSE;

    if( m_poState->m_nPathLength > 0 )
        return FALSE;

    GMLFeatureClass *poClass = m_poState->m_poFeature->GetClass();

    if( !poClass->IsSchemaLocked() )
        return TRUE;

    for( int i = 0; i < poClass->GetPropertyCount(); i++ )
        if( EQUAL(poClass->GetProperty(i)->GetSrcElement(),pszElement) )
            return TRUE;

    return FALSE;
}

/************************************************************************/
/*                              PopState()                              */
/************************************************************************/

void GMLReader::PopState()

{
    if( m_poState != NULL )
    {
        if( m_poState->m_poFeature != NULL && m_poCompleteFeature == NULL )
        {
            m_poCompleteFeature = m_poState->m_poFeature;
            m_poState->m_poFeature = NULL;
        }

        GMLReadState *poParent;

        poParent = m_poState->m_poParentState;
        
        delete m_poState;
        m_poState = poParent;
    }
}

/************************************************************************/
/*                             PushState()                              */
/************************************************************************/

void GMLReader::PushState( GMLReadState *poState )

{
    poState->m_poParentState = m_poState;
    m_poState = poState;
}

/************************************************************************/
/*                              GetClass()                              */
/************************************************************************/

GMLFeatureClass *GMLReader::GetClass( int iClass ) const

{
    if( iClass < 0 || iClass >= m_nClassCount )
        return NULL;
    else
        return m_papoClass[iClass];
}

/************************************************************************/
/*                              GetClass()                              */
/************************************************************************/

GMLFeatureClass *GMLReader::GetClass( const char *pszName ) const

{
    for( int iClass = 0; iClass < m_nClassCount; iClass++ )
    {
        if( EQUAL(GetClass(iClass)->GetName(),pszName) )
            return GetClass(iClass);
    }

    return NULL;
}

/************************************************************************/
/*                              AddClass()                              */
/************************************************************************/

int GMLReader::AddClass( GMLFeatureClass *poNewClass )

{
    CPLAssert( GetClass( poNewClass->GetName() ) == NULL );

    m_nClassCount++;
    m_papoClass = (GMLFeatureClass **) 
        CPLRealloc( m_papoClass, sizeof(void*) * m_nClassCount );
    m_papoClass[m_nClassCount-1] = poNewClass;

    return m_nClassCount-1;
}

/************************************************************************/
/*                            ClearClasses()                            */
/************************************************************************/

void GMLReader::ClearClasses()

{
    for( int i = 0; i < m_nClassCount; i++ )
        delete m_papoClass[i];
    CPLFree( m_papoClass );

    m_nClassCount = 0;
    m_papoClass = NULL;
}

/************************************************************************/
/*                         SetFeatureProperty()                         */
/*                                                                      */
/*      Set the property value on the current feature, adding the       */
/*      property name to the GMLFeatureClass if required.               */
/*      Eventually this function may also "refine" the property         */
/*      type based on what is encountered.                              */
/************************************************************************/

void GMLReader::SetFeatureProperty( const char *pszElement, 
                                    const char *pszValue )

{
    GMLFeature *poFeature = GetState()->m_poFeature;

    CPLAssert( poFeature  != NULL );

/* -------------------------------------------------------------------- */
/*      Does this property exist in the feature class?  If not, add     */
/*      it.                                                             */
/* -------------------------------------------------------------------- */
    GMLFeatureClass *poClass = poFeature->GetClass();
    int      iProperty;

    for( iProperty=0; iProperty < poClass->GetPropertyCount(); iProperty++ )
    {
        if( EQUAL(poClass->GetProperty( iProperty )->GetSrcElement(),
                  pszElement ) )
            break;
    }
    
    if( iProperty == poClass->GetPropertyCount() )
    {
        if( poClass->IsSchemaLocked() )
        {
            CPLDebug("GML","Encountered property missing from class schema.");
            return;
        }

        GMLPropertyDefn *poPDefn = new GMLPropertyDefn(pszElement,pszElement);

        if( EQUAL(CPLGetConfigOption( "GML_FIELDTYPES", ""), "ALWAYS_STRING") )
            poPDefn->SetType( GMLPT_String );

        poClass->AddProperty( poPDefn );

    }

/* -------------------------------------------------------------------- */
/*      Set the property                                                */
/* -------------------------------------------------------------------- */
    poFeature->SetProperty( iProperty, pszValue );

/* -------------------------------------------------------------------- */
/*      Do we need to update the property type?                         */
/* -------------------------------------------------------------------- */
    if( !poClass->IsSchemaLocked() )
        poClass->GetProperty( iProperty )->AnalysePropertyValue(pszValue);
}

/************************************************************************/
/*                            LoadClasses()                             */
/************************************************************************/

int GMLReader::LoadClasses( const char *pszFile )

{
    // Add logic later to determine reasonable default schema file. 
    if( pszFile == NULL )
        return FALSE;

/* -------------------------------------------------------------------- */
/*      Load the raw XML file.                                          */
/* -------------------------------------------------------------------- */
    FILE       *fp;
    int         nLength;
    char        *pszWholeText;

    fp = VSIFOpen( pszFile, "rb" );

    if( fp == NULL )
    {
        CPLError( CE_Failure, CPLE_OpenFailed, 
                  "Failed to open file %s.", pszFile );
        return FALSE;
    }

    VSIFSeek( fp, 0, SEEK_END );
    nLength = VSIFTell( fp );
    VSIFSeek( fp, 0, SEEK_SET );

    pszWholeText = (char *) VSIMalloc(nLength+1);
    if( pszWholeText == NULL )
    {
        CPLError( CE_Failure, CPLE_AppDefined, 
                  "Failed to allocate %d byte buffer for %s,\n"
                  "is this really a GMLFeatureClassList file?",
                  nLength, pszFile );
        VSIFClose( fp );
        return FALSE;
    }
    
    if( VSIFRead( pszWholeText, nLength, 1, fp ) != 1 )
    {
        VSIFree( pszWholeText );
        VSIFClose( fp );
        CPLError( CE_Failure, CPLE_AppDefined, 
                  "Read failed on %s.", pszFile );
        return FALSE;
    }
    pszWholeText[nLength] = '\0';

    VSIFClose( fp );

    if( strstr( pszWholeText, "<GMLFeatureClassList>" ) == NULL )
    {
        VSIFree( pszWholeText );
        CPLError( CE_Failure, CPLE_AppDefined, 
                  "File %s does not contain a GMLFeatureClassList tree.",
                  pszFile );
        return FALSE;
    }

/* -------------------------------------------------------------------- */
/*      Convert to XML parse tree.                                      */
/* -------------------------------------------------------------------- */
    CPLXMLNode *psRoot;

    psRoot = CPLParseXMLString( pszWholeText );
    VSIFree( pszWholeText );

    // We assume parser will report errors via CPL.
    if( psRoot == NULL )
        return FALSE;

    if( psRoot->eType != CXT_Element 
        || !EQUAL(psRoot->pszValue,"GMLFeatureClassList") )
    {
        CPLDestroyXMLNode(psRoot);
        CPLError( CE_Failure, CPLE_AppDefined, 
                  "File %s is not a GMLFeatureClassList document.",
                  pszFile );
        return FALSE;
    }

/* -------------------------------------------------------------------- */
/*      Extract feature classes for all definitions found.              */
/* -------------------------------------------------------------------- */
    CPLXMLNode *psThis;

    for( psThis = psRoot->psChild; psThis != NULL; psThis = psThis->psNext )
    {
        if( psThis->eType == CXT_Element 
            && EQUAL(psThis->pszValue,"GMLFeatureClass") )
        {
            GMLFeatureClass   *poClass;

            poClass = new GMLFeatureClass();

            if( !poClass->InitializeFromXML( psThis ) )
            {
                delete poClass;
                CPLDestroyXMLNode( psRoot );
                return FALSE;
            }

            poClass->SetSchemaLocked( TRUE );

            AddClass( poClass );
        }
    }

    CPLDestroyXMLNode( psRoot );
    
    SetClassListLocked( TRUE );

    return TRUE;
}

/************************************************************************/
/*                            SaveClasses()                             */
/************************************************************************/

int GMLReader::SaveClasses( const char *pszFile )

{
    // Add logic later to determine reasonable default schema file. 
    if( pszFile == NULL )
        return FALSE;

/* -------------------------------------------------------------------- */
/*      Create in memory schema tree.                                   */
/* -------------------------------------------------------------------- */
    CPLXMLNode *psRoot;

    psRoot = CPLCreateXMLNode( NULL, CXT_Element, "GMLFeatureClassList" );

    for( int iClass = 0; iClass < GetClassCount(); iClass++ )
    {
        GMLFeatureClass *poClass = GetClass( iClass );
        
        CPLAddXMLChild( psRoot, poClass->SerializeToXML() );
    }

/* -------------------------------------------------------------------- */
/*      Serialize to disk.                                              */
/* -------------------------------------------------------------------- */
    FILE        *fp;
    int         bSuccess = TRUE;
    char        *pszWholeText = CPLSerializeXMLTree( psRoot );
    
    CPLDestroyXMLNode( psRoot );
 
    fp = VSIFOpen( pszFile, "wb" );
    
    if( fp == NULL )
        bSuccess = FALSE;
    else if( VSIFWrite( pszWholeText, strlen(pszWholeText), 1, fp ) != 1 )
        bSuccess = FALSE;
    else
        VSIFClose( fp );

    CPLFree( pszWholeText );

    return bSuccess;
}

/************************************************************************/
/*                          PrescanForSchema()                          */
/*                                                                      */
/*      For now we use a pretty dumb approach of just doing a normal    */
/*      scan of the whole file, building up the schema information.     */
/*      Eventually we hope to do a more efficient scan when just        */
/*      looking for schema information.                                 */
/************************************************************************/

int GMLReader::PrescanForSchema( int bGetExtents )

{
    GMLFeature  *poFeature;

    if( m_pszFilename == NULL )
        return FALSE;

    SetClassListLocked( FALSE );

    ClearClasses();
    if( !SetupParser() )
        return FALSE;

    while( (poFeature = NextFeature()) != NULL )
    {
        GMLFeatureClass *poClass = poFeature->GetClass();

        if( poClass->GetFeatureCount() == -1 )
            poClass->SetFeatureCount( 1 );
        else
            poClass->SetFeatureCount( poClass->GetFeatureCount() + 1 );

#ifdef SUPPORT_GEOMETRY
        if( bGetExtents )
        {
            OGRGeometry *poGeometry = NULL;

            if( poFeature->GetGeometry() != NULL 
                && strlen(poFeature->GetGeometry()) != 0 )
            {
                poGeometry = OGRGeometryFactory::createFromGML( 
                    poFeature->GetGeometry() );
            }

            if( poGeometry != NULL )
            {
                double  dfXMin, dfXMax, dfYMin, dfYMax;
                OGREnvelope sEnvelope;

                poGeometry->getEnvelope( &sEnvelope );
                delete poGeometry;
                if( poClass->GetExtents(&dfXMin, &dfXMax, &dfYMin, &dfYMax) )
                {
                    dfXMin = MIN(dfXMin,sEnvelope.MinX);
                    dfXMax = MAX(dfXMax,sEnvelope.MaxX);
                    dfYMin = MIN(dfYMin,sEnvelope.MinY);
                    dfYMax = MAX(dfYMax,sEnvelope.MaxY);
                }
                else
                {
                    dfXMin = sEnvelope.MinX;
                    dfXMax = sEnvelope.MaxX;
                    dfYMin = sEnvelope.MinY;
                    dfYMax = sEnvelope.MaxY;
                }

                poClass->SetExtents( dfXMin, dfXMax, dfYMin, dfYMax );
            }
#endif /* def SUPPORT_GEOMETRY */
        }
        
        delete poFeature;
    }

    CleanupParser();

    return GetClassCount() > 0;
}

/************************************************************************/
/*                            ResetReading()                            */
/************************************************************************/

void GMLReader::ResetReading()

{
    CleanupParser();
}

#endif /* HAVE_XERCES == 1 */