ogr_srs_esri.cpp

mitab,读取MapInfo的地图文件

    if( papszDatumMapping != apszDefaultDatumMapping )
    {
        CSLDestroy( papszDatumMapping );
        papszDatumMapping = NULL;
    }
}
CPL_C_END

/************************************************************************/
/*                       InitDatumMappingTable()                        */
/************************************************************************/

static void InitDatumMappingTable()

{
    if( papszDatumMapping != NULL )
        return;

/* -------------------------------------------------------------------- */
/*      Try to open the datum.csv file.                                 */
/* -------------------------------------------------------------------- */
    const char  *pszFilename = CSVFilename("gdal_datum.csv");
    FILE * fp = VSIFOpen( pszFilename, "rb" );

/* -------------------------------------------------------------------- */
/*      Use simple default set if we can't find the file.               */
/* -------------------------------------------------------------------- */
    if( fp == NULL )
    {
        papszDatumMapping = apszDefaultDatumMapping;
        return;
    }

/* -------------------------------------------------------------------- */
/*      Figure out what fields we are interested in.                    */
/* -------------------------------------------------------------------- */
    char **papszFieldNames = CSVReadParseLine( fp );
    int  nDatumCodeField = CSLFindString( papszFieldNames, "DATUM_CODE" );
    int  nEPSGNameField = CSLFindString( papszFieldNames, "DATUM_NAME" );
    int  nESRINameField = CSLFindString( papszFieldNames, "ESRI_DATUM_NAME" );

    CSLDestroy( papszFieldNames );

    if( nDatumCodeField == -1 || nEPSGNameField == -1 || nESRINameField == -1 )
    {
        CPLError( CE_Failure, CPLE_AppDefined, 
                  "Failed to find required field in gdal_datum.csv in InitDatumMappingTable(), using default table setup." );
        
        papszDatumMapping = apszDefaultDatumMapping;
        return;
    }
    
/* -------------------------------------------------------------------- */
/*      Read each line, adding a detail line for each.                  */
/* -------------------------------------------------------------------- */
    int nMappingCount = 0;
    const int nMaxDatumMappings = 1000;
    char **papszFields;
    papszDatumMapping = (char **)CPLCalloc(sizeof(char*),nMaxDatumMappings*3);

    for( papszFields = CSVReadParseLine( fp );
         papszFields != NULL;
         papszFields = CSVReadParseLine( fp ) )
    {
        int nFieldCount = CSLCount(papszFields);

        CPLAssert( nMappingCount+1 < nMaxDatumMappings );

        if( MAX(nEPSGNameField,MAX(nDatumCodeField,nESRINameField)) 
            < nFieldCount 
            && nMaxDatumMappings > nMappingCount+1 )
        {
            papszDatumMapping[nMappingCount*3+0] = 
                CPLStrdup( papszFields[nDatumCodeField] );
            papszDatumMapping[nMappingCount*3+1] = 
                CPLStrdup( papszFields[nESRINameField] );
            papszDatumMapping[nMappingCount*3+2] = 
                CPLStrdup( papszFields[nEPSGNameField] );
            OGREPSGDatumNameMassage( &(papszDatumMapping[nMappingCount*3+2]) );

            nMappingCount++;
        }
        CSLDestroy( papszFields );
    }

    VSIFClose( fp );

    papszDatumMapping[nMappingCount*3+0] = NULL;
    papszDatumMapping[nMappingCount*3+1] = NULL;
    papszDatumMapping[nMappingCount*3+2] = NULL;
}


/************************************************************************/
/*                         OSRImportFromESRI()                          */
/************************************************************************/

OGRErr OSRImportFromESRI( OGRSpatialReferenceH hSRS, char **papszPrj )

{
    return ((OGRSpatialReference *) hSRS)->importFromESRI( papszPrj );
}

/************************************************************************/
/*                              OSR_GDV()                               */
/*                                                                      */
/*      Fetch a particular parameter out of the parameter list, or      */
/*      the indicated default if it isn't available.  This is a         */
/*      helper function for importFromESRI().                           */
/************************************************************************/

static double OSR_GDV( char **papszNV, const char * pszField, 
                       double dfDefaultValue )

{
    int         iLine;

    if( papszNV == NULL || papszNV[0] == NULL )
        return dfDefaultValue;

    if( EQUALN(pszField,"PARAM_",6) )
    {
        int     nOffset;

        for( iLine = 0; 
             papszNV[iLine] != NULL && !EQUALN(papszNV[iLine],"Paramet",7);
             iLine++ ) {}

        for( nOffset=atoi(pszField+6); 
             papszNV[iLine] != NULL && nOffset > 0; 
             iLine++ ) 
        {
            if( strlen(papszNV[iLine]) > 0 )
                nOffset--;
        }
        
        while( papszNV[iLine] != NULL && strlen(papszNV[iLine]) == 0 ) 
            iLine++;

        if( papszNV[iLine] != NULL )
        {
            char        **papszTokens, *pszLine = papszNV[iLine];
            double      dfValue;
            
            int         i;
            
            // Trim comments.
            for( i=0; pszLine[i] != '\0'; i++ )
            {
                if( pszLine[i] == '/' && pszLine[i+1] == '*' )
                    pszLine[i] = '\0';
            }

            papszTokens = CSLTokenizeString(papszNV[iLine]);
            if( CSLCount(papszTokens) == 3 )
            {
                dfValue = ABS(atof(papszTokens[0]))
                    + atof(papszTokens[1]) / 60.0
                    + atof(papszTokens[2]) / 3600.0;

                if( atof(papszTokens[0]) < 0.0 )
                    dfValue *= -1;
            }
            else if( CSLCount(papszTokens) > 0 )
                dfValue = atof(papszTokens[0]);
            else
                dfValue = dfDefaultValue;

            CSLDestroy( papszTokens );

            return dfValue;
        }
        else
            return dfDefaultValue;
    }
    else
    {
        for( iLine = 0; 
             papszNV[iLine] != NULL && 
                 !EQUALN(papszNV[iLine],pszField,strlen(pszField));
             iLine++ ) {}

        if( papszNV[iLine] == NULL )
            return dfDefaultValue;
        else
            return atof( papszNV[iLine] + strlen(pszField) );
    }
}

/************************************************************************/
/*                              OSR_GDS()                               */
/************************************************************************/

static const char*OSR_GDS( char **papszNV, const char * pszField, 
                           const char *pszDefaultValue )

{
    int         iLine;

    if( papszNV == NULL || papszNV[0] == NULL )
        return pszDefaultValue;

    for( iLine = 0; 
         papszNV[iLine] != NULL && 
             !EQUALN(papszNV[iLine],pszField,strlen(pszField));
         iLine++ ) {}

    if( papszNV[iLine] == NULL )
        return pszDefaultValue;
    else
    {
        static char     szResult[80];
        char    **papszTokens;
        
        papszTokens = CSLTokenizeString(papszNV[iLine]);

        if( CSLCount(papszTokens) > 1 )
            strncpy( szResult, papszTokens[1], sizeof(szResult));
        else
            strncpy( szResult, pszDefaultValue, sizeof(szResult));
        
        CSLDestroy( papszTokens );
        return szResult;
    }
}

/************************************************************************/
/*                          importFromESRI()                            */
/************************************************************************/

/**
 * Import coordinate system from ESRI .prj format(s).
 *
 * This function will read the text loaded from an ESRI .prj file, and
 * translate it into an OGRSpatialReference definition.  This should support
 * many (but by no means all) old style (Arc/Info 7.x) .prj files, as well
 * as the newer pseudo-OGC WKT .prj files.  Note that new style .prj files
 * are in OGC WKT format, but require some manipulation to correct datum
 * names, and units on some projection parameters.  This is addressed within
 * importFromESRI() by an automatical call to morphFromESRI(). 
 *
 * Currently only GEOGRAPHIC, UTM, STATEPLANE, GREATBRITIAN_GRID, ALBERS, 
 * EQUIDISTANT_CONIC, and TRANSVERSE (mercator) projections are supported
 * from old style files. 
 *
 * At this time there is no equivelent exportToESRI() method.  Writing old
 * style .prj files is not supported by OGRSpatialReference. However the
 * morphToESRI() and exportToWkt() methods can be used to generate output
 * suitable to write to new style (Arc 8) .prj files. 
 *
 * This function is the equilvelent of the C function OSRImportFromESRI().
 *
 * @param papszPrj NULL terminated list of strings containing the definition.
 *
 * @return OGRERR_NONE on success or an error code in case of failure. 
 */

OGRErr OGRSpatialReference::importFromESRI( char **papszPrj )

{
    if( papszPrj == NULL || papszPrj[0] == NULL )
        return OGRERR_CORRUPT_DATA;

/* -------------------------------------------------------------------- */
/*      ArcGIS and related products now use a varient of Well Known     */
/*      Text.  Try to recognise this and ingest it.  WKT is usually     */
/*      all on one line, but we will accept multi-line formats and      */
/*      concatenate.                                                    */
/* -------------------------------------------------------------------- */
    if( EQUALN(papszPrj[0],"GEOGCS",6)
        || EQUALN(papszPrj[0],"PROJCS",6)
        || EQUALN(papszPrj[0],"LOCAL_CS",8) )
    {
        char    *pszWKT, *pszWKT2;
        OGRErr  eErr;
        int     i;

        pszWKT = CPLStrdup(papszPrj[0]);
        for( i = 1; papszPrj[i] != NULL; i++ )
        {
            pszWKT = (char *) 
                CPLRealloc(pszWKT,strlen(pszWKT)+strlen(papszPrj[i])+1);
            strcat( pszWKT, papszPrj[i] );
        }
        pszWKT2 = pszWKT;
        eErr = importFromWkt( &pszWKT2 );
        CPLFree( pszWKT );

        if( eErr == OGRERR_NONE )
            eErr = morphFromESRI();
        return eErr;
    }

/* -------------------------------------------------------------------- */
/*      Operate on the basis of the projection name.                    */
/* -------------------------------------------------------------------- */
    const char *pszProj = OSR_GDS( papszPrj, "Projection", NULL );

    if( pszProj == NULL )
    {
        CPLDebug( "OGR_ESRI", "Can't find Projection\n" );
        return OGRERR_CORRUPT_DATA;
    }

    else if( EQUAL(pszProj,"GEOGRAPHIC") )
    {
    }
    
    else if( EQUAL(pszProj,"utm") )
    {
        if( (int) OSR_GDV( papszPrj, "zone", 0.0 ) != 0 )
        {
            double      dfYShift = OSR_GDV( papszPrj, "Yshift", 0.0 );

            SetUTM( (int) OSR_GDV( papszPrj, "zone", 0.0 ),
                    dfYShift == 0.0 );
        }
        else
        {
            double      dfCentralMeridian, dfRefLat;
            int         nZone;

            dfCentralMeridian = OSR_GDV( papszPrj, "PARAM_1", 0.0 );
            dfRefLat = OSR_GDV( papszPrj, "PARAM_2", 0.0 );

            nZone = (int) ((dfCentralMeridian+183) / 6.0 + 0.0000001);
            SetUTM( nZone, dfRefLat >= 0.0 );
        }
    }