ogrct.cpp

在linux环境下

/**
 * Create transformation object.
 *
 * This is the same as the C function OCTNewCoordinateTransformation().
 *
 * The delete operator, or OCTDestroyCoordinateTransformation() should
 * be used to destroy transformation objects. 
 *
 * @param poSource source spatial reference system. 
 * @param poTarget target spatial reference system. 
 * @return NULL on failure or a ready to use transformation object.
 */

OGRCoordinateTransformation*
OGRCreateCoordinateTransformation( OGRSpatialReference *poSource, 
                                   OGRSpatialReference *poTarget )

{
    OGRProj4CT  *poCT;

    if( !LoadProjLibrary() )
    {
        CPLError( CE_Failure, CPLE_NotSupported, 
                  "Unable to load PROJ.4 library (%s), creation of\n"
                  "OGRCoordinateTransformation failed.",
                  LIBNAME );
        return NULL;
    }

    poCT = new OGRProj4CT();
    
    if( !poCT->Initialize( poSource, poTarget ) )
    {
        delete poCT;
        return NULL;
    }
    else
    {
        return poCT;
    }
}

/************************************************************************/
/*                   OCTNewCoordinateTransformation()                   */
/************************************************************************/

OGRCoordinateTransformationH OCTNewCoordinateTransformation(
    OGRSpatialReferenceH hSourceSRS, OGRSpatialReferenceH hTargetSRS )

{
    return (OGRCoordinateTransformationH) 
        OGRCreateCoordinateTransformation( 
            (OGRSpatialReference *) hSourceSRS,
            (OGRSpatialReference *) hTargetSRS );
}

/************************************************************************/
/*                             OGRProj4CT()                             */
/************************************************************************/

OGRProj4CT::OGRProj4CT()

{
    poSRSSource = NULL;
    poSRSTarget = NULL;
    psPJSource = NULL;
    psPJTarget = NULL;

    nErrorCount = 0;
}

/************************************************************************/
/*                            ~OGRProj4CT()                             */
/************************************************************************/

OGRProj4CT::~OGRProj4CT()

{
    if( poSRSSource != NULL )
        delete poSRSSource;

    if( poSRSTarget != NULL )
        delete poSRSTarget;

    if( psPJSource != NULL )
        pfn_pj_free( psPJSource );

    if( psPJTarget != NULL )
        pfn_pj_free( psPJTarget );
}

/************************************************************************/
/*                             Initialize()                             */
/************************************************************************/

int OGRProj4CT::Initialize( OGRSpatialReference * poSourceIn, 
                            OGRSpatialReference * poTargetIn )

{
    poSRSSource = poSourceIn->Clone();
    poSRSTarget = poTargetIn->Clone();

    bSourceLatLong = poSRSSource->IsGeographic();
    bTargetLatLong = poSRSTarget->IsGeographic();

/* -------------------------------------------------------------------- */
/*      Setup source and target translations to radians for lat/long    */
/*      systems.                                                        */
/* -------------------------------------------------------------------- */
    dfSourceToRadians = DEG_TO_RAD;
    dfSourceFromRadians = RAD_TO_DEG;

    if( bSourceLatLong )
    {
        OGR_SRSNode *poUNITS = poSRSSource->GetAttrNode( "GEOGCS|UNIT" );
        if( poUNITS && poUNITS->GetChildCount() >= 2 )
        {
            dfSourceToRadians = atof(poUNITS->GetChild(1)->GetValue());
            if( dfSourceToRadians == 0.0 )
                dfSourceToRadians = DEG_TO_RAD;
            else
                dfSourceFromRadians = 1 / dfSourceToRadians;
        }
    }

    dfTargetToRadians = DEG_TO_RAD;
    dfTargetFromRadians = RAD_TO_DEG;

    if( bTargetLatLong )
    {
        OGR_SRSNode *poUNITS = poSRSTarget->GetAttrNode( "GEOGCS|UNIT" );
        if( poUNITS && poUNITS->GetChildCount() >= 2 )
        {
            dfTargetToRadians = atof(poUNITS->GetChild(1)->GetValue());
            if( dfTargetToRadians == 0.0 )
                dfTargetToRadians = DEG_TO_RAD;
            else
                dfTargetFromRadians = 1 / dfTargetToRadians;
        }
    }


/* -------------------------------------------------------------------- */
/*      Establish PROJ.4 handle for source if projection.               */
/* -------------------------------------------------------------------- */
    char        *pszProj4Defn;

    if( poSRSSource->exportToProj4( &pszProj4Defn ) != OGRERR_NONE )
        return FALSE;

    psPJSource = pfn_pj_init_plus( pszProj4Defn );
    
    if( psPJSource == NULL )
    {
        if( pfn_pj_get_errno_ref != NULL
            && pfn_pj_strerrno != NULL )
        {
            int *p_pj_errno = pfn_pj_get_errno_ref();

            CPLError( CE_Failure, CPLE_NotSupported, 
                      "Failed to initialize PROJ.4 with `%s'.\n%s", 
                      pszProj4Defn, pfn_pj_strerrno(*p_pj_errno) );
        }
        else
        {
            CPLError( CE_Failure, CPLE_NotSupported, 
                      "Failed to initialize PROJ.4 with `%s'.\n", 
                      pszProj4Defn );
        }
    }
    
    CPLFree( pszProj4Defn );
    
    if( psPJSource == NULL )
        return FALSE;

/* -------------------------------------------------------------------- */
/*      Establish PROJ.4 handle for target if projection.               */
/* -------------------------------------------------------------------- */
    if( poSRSTarget->exportToProj4( &pszProj4Defn ) != OGRERR_NONE )
        return FALSE;

    psPJTarget = pfn_pj_init_plus( pszProj4Defn );
    
    if( psPJTarget == NULL )
        CPLError( CE_Failure, CPLE_NotSupported, 
                  "Failed to initialize PROJ.4 with `%s'.", 
                  pszProj4Defn );
    
    CPLFree( pszProj4Defn );
    
    if( psPJTarget == NULL )
        return FALSE;

    return TRUE;
}

/************************************************************************/
/*                            GetSourceCS()                             */
/************************************************************************/

OGRSpatialReference *OGRProj4CT::GetSourceCS()

{
    return poSRSSource;
}

/************************************************************************/
/*                            GetTargetCS()                             */
/************************************************************************/

OGRSpatialReference *OGRProj4CT::GetTargetCS()

{
    return poSRSTarget;
}

/************************************************************************/
/*                             Transform()                              */
/************************************************************************/

int OGRProj4CT::Transform( int nCount, double *x, double *y, double *z )

{
    int   err, i;

/* -------------------------------------------------------------------- */
/*      Potentially transform to radians.                               */
/* -------------------------------------------------------------------- */
    if( bSourceLatLong )
    {
        for( i = 0; i < nCount; i++ )
        {
            x[i] *= dfSourceToRadians;
            y[i] *= dfSourceToRadians;
        }
    }

/* -------------------------------------------------------------------- */
/*      Do the transformation using PROJ.4.                             */
/* -------------------------------------------------------------------- */
    err = pfn_pj_transform( psPJSource, psPJTarget, nCount, 1, x, y, z );

/* -------------------------------------------------------------------- */
/*      Try to report an error through CPL.  Get proj.4 error string    */
/*      if possible.  Try to avoid reporting thousands of error         */
/*      ... supress further error reporting on this OGRProj4CT if we    */
/*      have already reported 20 errors.                                */
/* -------------------------------------------------------------------- */
    if( err != 0 )
    {
        if( ++nErrorCount < 20 )
        {
            const char *pszError = NULL;
            if( pfn_pj_strerrno != NULL )
                pszError = pfn_pj_strerrno( err );
            
            if( pszError == NULL )
                CPLError( CE_Failure, CPLE_AppDefined, 
                          "Reprojection failed, err = %d", 
                          err );
            else
                CPLError( CE_Failure, CPLE_AppDefined, "%s", pszError );
        }
        else if( nErrorCount == 20 )
        {
            CPLError( CE_Failure, CPLE_AppDefined, 
                      "Reprojection failed, err = %d, further errors will be supressed on the transform object.", 
                      err );
        }

        return FALSE;
    }

/* -------------------------------------------------------------------- */
/*      Potentially transform back to degrees.                          */
/* -------------------------------------------------------------------- */
    if( bTargetLatLong )
    {
        for( i = 0; i < nCount; i++ )
        {
            x[i] *= dfTargetFromRadians;
            y[i] *= dfTargetFromRadians;
        }
    }

    return TRUE;
}

/************************************************************************/
/*                            OCTTransform()                            */
/************************************************************************/

int OCTTransform( OGRCoordinateTransformationH hTransform,
                  int nCount, double *x, double *y, double *z )

{
    return ((OGRCoordinateTransformation*) hTransform)->
        Transform( nCount, x, y,z );
}