ogrgmldatasource.cpp

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

/*      This method is used to update boundedby info for a              */
/*      dataset, and insert schema descriptions depending on            */
/*      selection options in effect.                                    */
/************************************************************************/

void OGRGMLDataSource::InsertHeader()

{
    FILE        *fpSchema;
    int         nSchemaStart;

    if( fpOutput == NULL || fpOutput == stdout )
        return;

/* -------------------------------------------------------------------- */
/*      Do we want to write the schema within the GML instance doc      */
/*      or to a separate file?  For now we only support external.       */
/* -------------------------------------------------------------------- */
    const char *pszSchemaURI = CSLFetchNameValue(papszCreateOptions,
                                                 "XSISCHEMAURI");
    const char *pszSchemaOpt = CSLFetchNameValue( papszCreateOptions, 
                                                  "XSISCHEMA" );

    if( pszSchemaURI != NULL )
        return;

    if( pszSchemaOpt == NULL || EQUAL(pszSchemaOpt,"EXTERNAL") )
    {
        const char *pszXSDFilename = CPLResetExtension( pszName, "xsd" );

        fpSchema = VSIFOpen( pszXSDFilename, "wt" );
        if( fpSchema == NULL )
        {
            CPLError( CE_Failure, CPLE_OpenFailed, 
                      "Failed to open file %.500s for schema output.", 
                      pszXSDFilename );
            return;
        }
        fprintf( fpSchema, "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n" );
    }
    else if( EQUAL(pszSchemaOpt,"INTERNAL") )
    {
        nSchemaStart = VSIFTell( fpOutput );
        fpSchema = fpOutput;
    }
    else                                                               
        return;

/* ==================================================================== */
/*      Write the schema section at the end of the file.  Once          */
/*      complete, we will read it back in, and then move the whole      */
/*      file "down" enough to insert the schema at the beginning.       */
/* ==================================================================== */

/* -------------------------------------------------------------------- */
/*      Emit the start of the schema section.                           */
/* -------------------------------------------------------------------- */
    const char *pszTargetNameSpace = "http://ogr.maptools.org/";
    const char *pszPrefix = "ogr";

    VSIFPrintf( fpSchema, 
                "<xs:schema targetNamespace=\"%s\" xmlns:%s=\"%s\" xmlns:xs=\"http://www.w3.org/2001/XMLSchema\" xmlns:gml=\"http://www.opengis.net/gml\" elementFormDefault=\"qualified\" version=\"1.0\">\n", 
                pszTargetNameSpace, pszPrefix, pszTargetNameSpace );
    
    VSIFPrintf( fpSchema, 
                "<xs:import namespace=\"http://www.opengis.net/gml\" schemaLocation=\"http://schemas.opengeospatial.net/gml/2.1.2/feature.xsd\"/>" );

/* -------------------------------------------------------------------- */
/*      Define the FeatureCollection                                    */
/* -------------------------------------------------------------------- */
    VSIFPrintf( fpSchema, 
                "<xs:element name=\"FeatureCollection\" type=\"%s:FeatureCollectionType\" substitutionGroup=\"gml:_FeatureCollection\"/>\n", 
                pszPrefix );

    VSIFPrintf( 
        fpSchema, 
        "<xs:complexType name=\"FeatureCollectionType\">\n"
        "  <xs:complexContent>\n"
        "    <xs:extension base=\"gml:AbstractFeatureCollectionType\">\n"
        "      <xs:attribute name=\"lockId\" type=\"xs:string\" use=\"optional\"/>\n"
        "      <xs:attribute name=\"scope\" type=\"xs:string\" use=\"optional\"/>\n"
        "    </xs:extension>\n"
        "  </xs:complexContent>\n"
        "</xs:complexType>\n" );

/* ==================================================================== */
/*      Define the schema for each layer.                               */
/* ==================================================================== */
    int iLayer;

    for( iLayer = 0; iLayer < GetLayerCount(); iLayer++ )
    {
        OGRFeatureDefn *poFDefn = GetLayer(iLayer)->GetLayerDefn();
        
/* -------------------------------------------------------------------- */
/*      Emit initial stuff for a feature type.                          */
/* -------------------------------------------------------------------- */
        VSIFPrintf( 
            fpSchema,
            "<xs:element name=\"%s\" type=\"%s:%s_Type\" substitutionGroup=\"gml:_Feature\"/>\n",
            poFDefn->GetName(), pszPrefix, poFDefn->GetName() );

        VSIFPrintf( 
            fpSchema, 
            "<xs:complexType name=\"%s_Type\">\n"
            "  <xs:complexContent>\n"
            "    <xs:extension base=\"gml:AbstractFeatureType\">\n"
            "      <xs:sequence>\n",
            poFDefn->GetName() );

/* -------------------------------------------------------------------- */
/*      Define the geometry attribute.  For now I always use the        */
/*      generic geometry type, but eventually we should express         */
/*      particulars if available.                                       */
/* -------------------------------------------------------------------- */
        VSIFPrintf( 
            fpSchema,
            "<xs:element name=\"geometryProperty\" type=\"gml:geometryPropertyType\" nillable=\"true\" minOccurs=\"1\" maxOccurs=\"1\"/>\n" );
            
/* -------------------------------------------------------------------- */
/*      Emit each of the attributes.                                    */
/* -------------------------------------------------------------------- */
        for( int iField = 0; iField < poFDefn->GetFieldCount(); iField++ )
        {
            OGRFieldDefn *poFieldDefn = poFDefn->GetFieldDefn(iField);

            if( poFieldDefn->GetType() == OFTInteger )
            {
                int nWidth;

                if( poFieldDefn->GetWidth() > 0 )
                    nWidth = poFieldDefn->GetWidth();
                else
                    nWidth = 16;

                VSIFPrintf( fpSchema, 
                            "    <xs:element name=\"%s\" nillable=\"true\" minOccurs=\"0\" maxOccurs=\"1\">\n"
                            "      <xs:simpleType>\n"
                            "        <xs:restriction base=\"xs:integer\">\n"
                            "          <xs:totalDigits value=\"%d\"/>\n"
                            "        </xs:restriction>\n"
                            "      </xs:simpleType>\n"
                            "    </xs:element>\n",
                            poFieldDefn->GetNameRef(), nWidth );
            }
            else if( poFieldDefn->GetType() == OFTReal )
            {
                int nWidth, nDecimals;

                if( poFieldDefn->GetPrecision() == 0 )
                    nDecimals = 16;
                else
                    nDecimals = poFieldDefn->GetPrecision();

                if( poFieldDefn->GetWidth() > 0 )
                    nWidth = poFieldDefn->GetWidth();
                else
                    nWidth = 33;

                VSIFPrintf( fpSchema, 
                            "    <xs:element name=\"%s\" nillable=\"true\" minOccurs=\"0\" maxOccurs=\"1\">\n"
                            "      <xs:simpleType>\n"
                            "        <xs:restriction base=\"xs:decimal\">\n"
                            "          <xs:totalDigits value=\"%d\"/>\n"
                            "          <xs:fractionDigits value=\"%d\"/>\n"
                            "        </xs:restriction>\n"
                            "      </xs:simpleType>\n"
                            "    </xs:element>\n",
                            poFieldDefn->GetNameRef(), nWidth, nDecimals );
            }
            else if( poFieldDefn->GetType() == OFTString )
            {
                char szMaxLength[48];

                if( poFieldDefn->GetWidth() == 0 )
                    sprintf( szMaxLength, "unbounded" );
                else
                    sprintf( szMaxLength, "%d", poFieldDefn->GetWidth() );

                VSIFPrintf( fpSchema, 
                            "    <xs:element name=\"%s\" nillable=\"true\" minOccurs=\"0\" maxOccurs=\"1\">\n"
                            "      <xs:simpleType>\n"
                            "        <xs:restriction base=\"xs:string\">\n"
                            "          <xs:maxLength value=\"%s\"/>\n"
                            "        </xs:restriction>\n"
                            "      </xs:simpleType>\n"
                            "    </xs:element>\n",
                            poFieldDefn->GetNameRef(), szMaxLength );
            }
            else
            {
                /* TODO */
            }
        } /* next field */

/* -------------------------------------------------------------------- */
/*      Finish off feature type.                                        */
/* -------------------------------------------------------------------- */
        VSIFPrintf( fpSchema, 
                    "      </xs:sequence>\n"
                    "    </xs:extension>\n"
                    "  </xs:complexContent>\n"
                    "</xs:complexType>\n" );
    } /* next layer */

    VSIFPrintf( fpSchema, "</xs:schema>\n" );

/* ==================================================================== */
/*      Move schema to the start of the file.                           */
/* ==================================================================== */
    if( fpSchema == fpOutput )
    {
/* -------------------------------------------------------------------- */
/*      Read the schema into memory.                                    */
/* -------------------------------------------------------------------- */
        int nSchemaSize = VSIFTell( fpOutput ) - nSchemaStart;
        char *pszSchema = (char *) CPLMalloc(nSchemaSize+1);
    
        VSIFSeek( fpOutput, nSchemaStart, SEEK_SET );

        VSIFRead( pszSchema, 1, nSchemaSize, fpOutput );
        pszSchema[nSchemaSize] = '\0';
    
/* -------------------------------------------------------------------- */
/*      Move file data down by "schema size" bytes from after <?xml>    */
/*      header so we have room insert the schema.  Move in pretty       */
/*      big chunks.                                                     */
/* -------------------------------------------------------------------- */
        int nChunkSize = MIN(nSchemaStart-nSchemaInsertLocation,250000);
        char *pszChunk = (char *) CPLMalloc(nChunkSize);
        int nEndOfUnmovedData = nSchemaStart;

        for( nEndOfUnmovedData = nSchemaStart;
             nEndOfUnmovedData > nSchemaInsertLocation; )
        {
            int nBytesToMove = 
                MIN(nChunkSize, nEndOfUnmovedData - nSchemaInsertLocation );

            VSIFSeek( fpOutput, nEndOfUnmovedData - nBytesToMove, SEEK_SET );
            VSIFRead( pszChunk, 1, nBytesToMove, fpOutput );
            VSIFSeek( fpOutput, nEndOfUnmovedData - nBytesToMove + nSchemaSize, 
                      SEEK_SET );
            VSIFWrite( pszChunk, 1, nBytesToMove, fpOutput );
        
            nEndOfUnmovedData -= nBytesToMove;
        }

        CPLFree( pszChunk );

/* -------------------------------------------------------------------- */
/*      Write the schema in the opened slot.                            */
/* -------------------------------------------------------------------- */
        VSIFSeek( fpOutput, nSchemaInsertLocation, SEEK_SET );
        VSIFWrite( pszSchema, 1, nSchemaSize, fpOutput );

        VSIFSeek( fpOutput, 0, SEEK_END );

        nBoundedByLocation += nSchemaSize;
    }
/* -------------------------------------------------------------------- */
/*      Close external schema files.                                    */
/* -------------------------------------------------------------------- */
    else
        VSIFClose( fpSchema );
}