ogrspatialreference.cpp

用于读取TAB、MIF、SHP文件的类

            && poChild->GetChildCount() >= 2 )
        {
            if( ppszName != NULL )
                *ppszName = (char *) poChild->GetChild(0)->GetValue();
            
            return atof( poChild->GetChild(1)->GetValue() );
        }
    }

    return 1.0;
}

/************************************************************************/
/*                         OSRGetLinearUnits()                          */
/************************************************************************/

double OSRGetLinearUnits( OGRSpatialReferenceH hSRS, char ** ppszName )
    
{
    return ((OGRSpatialReference *) hSRS)->GetLinearUnits( ppszName );
}

/************************************************************************/
/*                          GetPrimeMeridian()                          */
/************************************************************************/

/**
 * Fetch prime meridian info.
 *
 * Returns the offset of the prime meridian from greenwich in degrees,
 * and the prime meridian name (if requested).   If no PRIMEM value exists
 * in the coordinate system definition a value of "Greenwich" and an
 * offset of 0.0 is assumed.
 *
 * If the prime meridian name is returned, the pointer is to an internal
 * copy of the name. It should not be freed, altered or depended on after
 * the next OGR call.
 *
 * This method is the same as the C function OSRGetPrimeMeridian().
 *
 * @param ppszName return location for prime meridian name.  If NULL, name
 * is not returned.
 *
 * @return the offset to the GEOGCS prime meridian from greenwich in decimal
 * degrees.
 */

double OGRSpatialReference::GetPrimeMeridian( char **ppszName ) const 

{
    const OGR_SRSNode *poPRIMEM = GetAttrNode( "PRIMEM" );

    if( poPRIMEM != NULL && poPRIMEM->GetChildCount() >= 2 
        && atof(poPRIMEM->GetChild(1)->GetValue()) != 0.0 )
    {
        if( ppszName != NULL )
            *ppszName = (char *) poPRIMEM->GetChild(0)->GetValue();
        return atof(poPRIMEM->GetChild(1)->GetValue());
    }
    
    if( ppszName != NULL )
        *ppszName = SRS_PM_GREENWICH;

    return 0.0;
}

/************************************************************************/
/*                        OSRGetPrimeMeridian()                         */
/************************************************************************/

double OSRGetPrimeMeridian( OGRSpatialReferenceH hSRS, char **ppszName )

{
    return ((OGRSpatialReference *) hSRS)->GetPrimeMeridian( ppszName );
}

/************************************************************************/
/*                             SetGeogCS()                              */
/************************************************************************/

/**
 * Set geographic coordinate system. 
 *
 * This method is used to set the datum, ellipsoid, prime meridian and
 * angular units for a geographic coordinate system.  It can be used on it's
 * own to establish a geographic spatial reference, or applied to a 
 * projected coordinate system to establish the underlying geographic 
 * coordinate system. 
 *
 * This method does the same as the C function OSRSetGeogCS(). 
 *
 * @param pszGeogName user visible name for the geographic coordinate system
 * (not to serve as a key).
 * 
 * @param pszDatumName key name for this datum.  The OpenGIS specification 
 * lists some known values, and otherwise EPSG datum names with a standard
 * transformation are considered legal keys. 
 * 
 * @param pszSpheroidName user visible spheroid name (not to serve as a key)
 *
 * @param dfSemiMajor the semi major axis of the spheroid.
 * 
 * @param dfInvFlattening the inverse flattening for the spheroid.
 * This can be computed from the semi minor axis as 
 * 1/f = 1.0 / (1.0 - semiminor/semimajor).
 *
 * @param pszPMName the name of the prime merdidian (not to serve as a key)
 * If this is NULL a default value of "Greenwich" will be used. 
 * 
 * @param dfPMOffset the longitude of greenwich relative to this prime
 * meridian.
 *
 * @param pszAngularUnits the angular units name (see ogr_srs_api.h for some
 * standard names).  If NULL a value of "degrees" will be assumed. 
 * 
 * @param dfConvertToRadians value to multiply angular units by to transform
 * them to radians.  A value of SRS_UL_DEGREE_CONV will be used if
 * pszAngularUnits is NULL.
 *
 * @return OGRERR_NONE on success.
 */

OGRErr
OGRSpatialReference::SetGeogCS( const char * pszGeogName,
                                const char * pszDatumName,
                                const char * pszSpheroidName,
                                double dfSemiMajor, double dfInvFlattening,
                                const char * pszPMName, double dfPMOffset,
                                const char * pszAngularUnits,
                                double dfConvertToRadians )

{
    bNormInfoSet = FALSE;

/* -------------------------------------------------------------------- */
/*      Do we already have a GEOGCS?  If so, blow it away so it can     */
/*      be properly replaced.                                           */
/* -------------------------------------------------------------------- */
    if( GetAttrNode( "GEOGCS" ) != NULL )
    {
        OGR_SRSNode *poPROJCS;

        if( EQUAL(GetRoot()->GetValue(),"GEOGCS") )
            Clear();
        else if( (poPROJCS = GetAttrNode( "PROJCS" )) != NULL
                 && poPROJCS->FindChild( "GEOGCS" ) != -1 )
            poPROJCS->DestroyChild( poPROJCS->FindChild( "GEOGCS" ) );
        else
            return OGRERR_FAILURE;
    }

/* -------------------------------------------------------------------- */
/*      Set defaults for various parameters.                            */
/* -------------------------------------------------------------------- */
    if( pszGeogName == NULL )
        pszGeogName = "unnamed";

    if( pszPMName == NULL )
        pszPMName = SRS_PM_GREENWICH;

    if( pszDatumName == NULL )
        pszDatumName = "unknown";

    if( pszSpheroidName == NULL )
        pszSpheroidName = "unnamed";

    if( pszAngularUnits == NULL )
    {
        pszAngularUnits = SRS_UA_DEGREE;
        dfConvertToRadians = atof(SRS_UA_DEGREE_CONV);
    }

/* -------------------------------------------------------------------- */
/*      Build the GEOGCS object.                                        */
/* -------------------------------------------------------------------- */
    char                szValue[128];
    OGR_SRSNode         *poGeogCS, *poSpheroid, *poDatum, *poPM, *poUnits;

    poGeogCS = new OGR_SRSNode( "GEOGCS" );
    poGeogCS->AddChild( new OGR_SRSNode( pszGeogName ) );
    
/* -------------------------------------------------------------------- */
/*      Setup the spheroid.                                             */
/* -------------------------------------------------------------------- */
    poSpheroid = new OGR_SRSNode( "SPHEROID" );
    poSpheroid->AddChild( new OGR_SRSNode( pszSpheroidName ) );

    OGRPrintDouble( szValue, dfSemiMajor );
    poSpheroid->AddChild( new OGR_SRSNode(szValue) );

    OGRPrintDouble( szValue, dfInvFlattening );
    poSpheroid->AddChild( new OGR_SRSNode(szValue) );

/* -------------------------------------------------------------------- */
/*      Setup the Datum.                                                */
/* -------------------------------------------------------------------- */
    poDatum = new OGR_SRSNode( "DATUM" );
    poDatum->AddChild( new OGR_SRSNode(pszDatumName) );
    poDatum->AddChild( poSpheroid );

/* -------------------------------------------------------------------- */
/*      Setup the prime meridian.                                       */
/* -------------------------------------------------------------------- */
    if( dfPMOffset == 0.0 )
        strcpy( szValue, "0" );
    else
        OGRPrintDouble( szValue, dfPMOffset );
    
    poPM = new OGR_SRSNode( "PRIMEM" );
    poPM->AddChild( new OGR_SRSNode( pszPMName ) );
    poPM->AddChild( new OGR_SRSNode( szValue ) );

/* -------------------------------------------------------------------- */
/*      Setup the rotational units.                                     */
/* -------------------------------------------------------------------- */
    OGRPrintDouble( szValue, dfConvertToRadians );
    
    poUnits = new OGR_SRSNode( "UNIT" );
    poUnits->AddChild( new OGR_SRSNode(pszAngularUnits) );
    poUnits->AddChild( new OGR_SRSNode(szValue) );
    
/* -------------------------------------------------------------------- */
/*      Complete the GeogCS                                             */
/* -------------------------------------------------------------------- */
    poGeogCS->AddChild( poDatum );
    poGeogCS->AddChild( poPM );
    poGeogCS->AddChild( poUnits );

/* -------------------------------------------------------------------- */
/*      Attach below the PROJCS if there is one, or make this the root. */
/* -------------------------------------------------------------------- */
    if( GetRoot() != NULL && EQUAL(GetRoot()->GetValue(),"PROJCS") )
        poRoot->InsertChild( poGeogCS, 1 );
    else
        SetRoot( poGeogCS );

    return OGRERR_NONE;
}

/************************************************************************/
/*                            OSRSetGeogCS()                            */
/************************************************************************/

OGRErr OSRSetGeogCS( OGRSpatialReferenceH hSRS,
                     const char * pszGeogName,
                     const char * pszDatumName,
                     const char * pszSpheroidName,
                     double dfSemiMajor, double dfInvFlattening,
                     const char * pszPMName, double dfPMOffset,
                     const char * pszAngularUnits,
                     double dfConvertToRadians )

{
    return ((OGRSpatialReference *) hSRS)->SetGeogCS( 
        pszGeogName, pszDatumName, 
        pszSpheroidName, dfSemiMajor, dfInvFlattening, 
        pszPMName, dfPMOffset, pszAngularUnits, dfConvertToRadians );
                                                      
}

/************************************************************************/
/*                         SetWellKnownGeogCS()                         */
/************************************************************************/

/**
 * Set a GeogCS based on well known name.
 *
 * This may be called on an empty OGRSpatialReference to make a geographic
 * coordinate system, or on something with an existing PROJCS node to 
 * set the underlying geographic coordinate system of a projected coordinate
 * system. 
 *
 * The following well known text values are currently supported:
 * <ul>
 * <li> "WGS84": same as "EPSG:4326" but has no dependence on EPSG data files.
 * <li> "WGS72": same as "EPSG:4322" but has no dependence on EPSG data files.
 * <li> "NAD27": same as "EPSG:4267" but has no dependence on EPSG data files.
 * <li> "NAD83": same as "EPSG:4269" but has no dependence on EPSG data files.
 * <li> "EPSG:n": same as doing an ImportFromEPSG(n).
 * </ul>
 * 
 * @param pszName name of well known geographic coordinate system.
 * @return OGRERR_NONE on success, or OGRERR_FAILURE if the name isn't
 * recognised, the target object is already initialized, or an EPSG value
 * can't be successfully looked up.
 */ 

OGRErr OGRSpatialReference::SetWellKnownGeogCS( const char * pszName )

{
    OGRSpatialReference   oSRS2;
    OGRErr eErr;

/* -------------------------------------------------------------------- */
/*      Check for EPSG authority numbers.                               */
/* -------------------------------------------------------------------- */
    if( EQUALN(pszName, "EPSG:",5) )
    {
        eErr = oSRS2.importFromEPSG( atoi(pszName+5) );
        if( eErr != OGRERR_NONE )
            return eErr;

        if( !oSRS2.IsGeographic() )
            return OGRERR_FAILURE;

        return CopyGeogCSFrom( &oSRS2 );
    }

/* -------------------------------------------------------------------- */
/*      Check for simple names.                                         */
/* -------------------------------------------------------------------- */
    char         *pszWKT = NULL;

    if( EQUAL(pszName, "WGS84") || EQUAL(pszName,"CRS84") )
        pszWKT = "GEOGCS[\"WGS 84\",DATUM[\"WGS_1984\",SPHEROID[\"WGS 84\",6378137,298.257223563,AUTHORITY[\"EPSG\",\"7030\"]],TOWGS84[0,0,0,0,0,0,0],AUTHORITY[\"EPSG\",\"6326\"]],PRIMEM[\"Greenwich\",0,AUTHORITY[\"EPSG\",\"8901\"]],UNIT[\"degree\",0.0174532925199433,AUTHORITY[\"EPSG\",\"9108\"]],AXIS[\"Lat\",NORTH],AXIS[\"Long\",EAST],AUTHORITY[\"EPSG\",\"4326\"]]";

    else if( EQUAL(pszName, "WGS72") )
        pszWKT = "GEOGCS[\"WGS 72\",DATUM[\"WGS_1972\",SPHEROID[\"WGS 72\",6378135,298.26,AUTHORITY[\"EPSG\",\"7043\"]],TOWGS84[0,0,4.5,0,0,0.554,0.2263],AUTHORITY[\"EPSG\",\"6322\"]],PRIMEM[\"Greenwich\",0,AUTHORITY[\"EPSG\",\"8901\"]],UNIT[\"degree\",0.0174532925199433,AUTHORITY[\"EPSG\",\"9108\"]],AXIS[\"Lat\",NORTH],AXIS[\"Long\",EAST],AUTHORITY[\"EPSG\",\"4322\"]]";

    else if( EQUAL(pszName, "NAD27") || EQUAL(pszName, "CRS27") )
        pszWKT = "GEOGCS[\"NAD27\",DATUM[\"North_American_Datum_1927\",SPHEROID[\"Clarke 1866\",6378206.4,294.978698213898,AUTHORITY[\"EPSG\",\"7008\"]],TOWGS84[-3,142,183,0,0,0,0],AUTHORITY[\"EPSG\",\"6267\"]],PRIMEM[\"Greenwich\",0,AUTHORITY[\"EPSG\",\"8901\"]],UNIT[\"degree\",0.0174532925199433,AUTHORITY[\"EPSG\",\"9108\"]],AXIS[\"Lat\",NORTH],AXIS[\"Long\",EAST],AUTHORITY[\"EPSG\",\"4267\"]]";
        
    else if( EQUAL(pszName, "NAD83") || EQUAL(pszName,"CRS83") )
        pszWKT = "GEOGCS[\"NAD83\",DATUM[\"North_American_Datum_1983\",SPHEROID[\"GRS 1980\",6378137,298.257222101,AUTHORITY[\"EPSG\",\"7019\"]],TOWGS84[0,0,0,0,0,0,0],AUTHORITY[\"EPSG\",\"6269\"]],PRIMEM[\"Greenwich\",0,AUTHORITY[\"EPSG\",\"8901\"]],UNIT[\"degree\",0.0174532925199433,AUTHORITY[\"EPSG\",\"9108\"]],AXIS[\"Lat\",NORTH],AXIS[\"Long\",EAST],AUTHORITY[\"EPSG\",\"4269\"]]";

    else
        return OGRERR_FAILURE;

/* -------------------------------------------------------------------- */
/*      Import the WKT                                                  */
/* -------------------------------------------------------------------- */
    eErr = oSRS2.importFromWkt( &pszWKT );
    if( eErr != OGRERR_NONE )
        return eErr;

/* -------------------------------------------------------------------- */
/*      Copy over.                                                      */
/* -------------------------------------------------------------------- */
    return CopyGeogCSFrom( &oSRS2 );
}

/************************************************************************/
/*                       OSRSetWellKnownGeogCS()                        */
/************************************************************************/

OGRErr OSRSetWellKnownGeogCS( OGRSpatialReferenceH hSRS, const char *pszName )

{
    return ((OGRSpatialReference *) hSRS)->SetWellKnownGeogCS( pszName );
}

/************************************************************************/
/*                           CopyGeogCSFrom()                           */
/************************************************************************/

/**
 * Copy GEOGCS from another OGRSpatialReference.
 *
 * The GEOGCS information is copied into this OGRSpatialReference from another.
 * If this object has a PROJCS root already, the GEOGCS is installed within
 * it, otherwise it is installed as the root.
 * 
 * @param poSrcSRS the spatial reference to copy the GEOGCS information from.
 * 
 * @return OGRERR_NONE on success or an error code.
 */


OGRErr OGRSpatialReference::CopyGeogCSFrom( 
    const OGRSpatialReference * poSrcSRS )

{
    const OGR_SRSNode  *poGeogCS = NULL;

    bNormInfoSet = FALSE;

/* -------------------------------------------------------------------- */