ogrpolygon.cpp

mitab,读取MapInfo的地图文件

        nCumulativeLength += strlen(papszRings[iRing] + 11);

        nNonEmptyRings++;
    }
    
/* -------------------------------------------------------------------- */
/*      If we have no valid rings, return POLYGON EMPTY.                */
/* -------------------------------------------------------------------- */
    if( nNonEmptyRings == 0 )
    {
        CPLFree( papszRings );
        *ppszDstText = CPLStrdup("POLYGON EMPTY");
        return OGRERR_NONE;
    }

/* -------------------------------------------------------------------- */
/*      Allocate exactly the right amount of space for the              */
/*      aggregated string.                                              */
/* -------------------------------------------------------------------- */
    *ppszDstText = (char *) VSIMalloc(nCumulativeLength + nNonEmptyRings + 11);

    if( *ppszDstText == NULL )
        return OGRERR_NOT_ENOUGH_MEMORY;

/* -------------------------------------------------------------------- */
/*      Build up the string, freeing temporary strings as we go.        */
/* -------------------------------------------------------------------- */
    strcpy( *ppszDstText, "POLYGON (" );

    for( iRing = 0; iRing < nRingCount; iRing++ )
    {                                                           
        if( papszRings[iRing] == NULL )
            continue;

        if( iRing > 0 )
            strcat( *ppszDstText, "," );
        
        strcat( *ppszDstText, papszRings[iRing] + 11 );
        VSIFree( papszRings[iRing] );
    }

    strcat( *ppszDstText, ")" );

    CPLFree( papszRings );

    return OGRERR_NONE;
}

/************************************************************************/
/*                              Centroid()                              */
/************************************************************************/

/**
 * Compute the polygon centroid.
 *
 * The centroid location is applied to the passed in OGRPoint object.
 *
 * @return OGRERR_NONE on success or OGRERR_FAILURE on error.
 */

int OGRPolygon::Centroid( OGRPoint *poPoint ) const

{
    if( poPoint == NULL )
        return OGRERR_FAILURE;

#ifndef HAVE_GEOS
    // notdef ... not implemented yet.
    
    return OGRERR_FAILURE;

#else

    GEOSGeom hThisGeosGeom = NULL;
    GEOSGeom hOtherGeosGeom = NULL;
    
    hThisGeosGeom = exportToGEOS();

    if( hThisGeosGeom != NULL )
    {
    	hOtherGeosGeom = GEOSGetCentroid( hThisGeosGeom );
        OGRPoint *poCentroid = (OGRPoint *) 
            OGRGeometryFactory::createFromGEOS( hOtherGeosGeom );

        GEOSGeom_destroy( hThisGeosGeom );
        GEOSGeom_destroy( hOtherGeosGeom );

        if( poPoint == NULL 
            || wkbFlatten(poPoint->getGeometryType()) != wkbPoint )
            return OGRERR_FAILURE;

	poPoint->setX( poCentroid->getX() );
	poPoint->setY( poCentroid->getY() );

        delete poCentroid;

    	return OGRERR_NONE;
    }
    else
    {
    	return OGRERR_FAILURE;
    }

#endif /* HAVE_GEOS */
}

/************************************************************************/
/*                           OGR_G_Centroid()                           */
/************************************************************************/

int OGR_G_Centroid( OGRGeometryH hPolygon, OGRGeometryH hCentroidPoint )

{
    OGRPolygon *poPoly = ((OGRPolygon *) hPolygon);
    OGRPoint *poCentroid = ((OGRPoint *) hCentroidPoint);
    
    if( poCentroid == NULL )
        return OGRERR_FAILURE;

    if( wkbFlatten(poCentroid->getGeometryType()) != wkbPoint )
    {
        CPLError( CE_Failure, CPLE_AppDefined, 
                  "Passed wrong geometry type as centroid argument." );
        return OGRERR_FAILURE;
    }

    if( wkbFlatten(poPoly->getGeometryType()) != wkbPolygon )
    {
        CPLError( CE_Failure, CPLE_AppDefined, 
                  "Invoked Centroid() on non-Polygon." );
        return OGRERR_FAILURE;
    }
                            
    return poPoly->Centroid( poCentroid );
}


/************************************************************************/
/*                           PointOnSurface()                           */
/************************************************************************/

int OGRPolygon::PointOnSurface( OGRPoint * ) const

{
    // notdef ... not implemented yet.
    
    return OGRERR_FAILURE;
}



/************************************************************************/
/*                            getEnvelope()                             */
/************************************************************************/
 
void OGRPolygon::getEnvelope( OGREnvelope * psEnvelope ) const

{
    OGREnvelope         oRingEnv;
    
    if( nRingCount == 0 )
        return;

    papoRings[0]->getEnvelope( psEnvelope );

    for( int iRing = 1; iRing < nRingCount; iRing++ )
    {
        papoRings[iRing]->getEnvelope( &oRingEnv );

        if( psEnvelope->MinX > oRingEnv.MinX )
            psEnvelope->MinX = oRingEnv.MinX;
        if( psEnvelope->MinY > oRingEnv.MinY )
            psEnvelope->MinY = oRingEnv.MinY;
        if( psEnvelope->MaxX < oRingEnv.MaxX )
            psEnvelope->MaxX = oRingEnv.MaxX;
        if( psEnvelope->MaxY < oRingEnv.MaxY )
            psEnvelope->MaxY = oRingEnv.MaxY;
    }
}

/************************************************************************/
/*                               Equal()                                */
/************************************************************************/

OGRBoolean OGRPolygon::Equals( OGRGeometry * poOther ) const

{
    OGRPolygon *poOPoly = (OGRPolygon *) poOther;

    if( poOPoly == this )
        return TRUE;
    
    if( poOther->getGeometryType() != getGeometryType() )
        return FALSE;

    if( getNumInteriorRings() != poOPoly->getNumInteriorRings() )
        return FALSE;

    if( !getExteriorRing()->Equals( poOPoly->getExteriorRing() ) )
        return FALSE;
    
    // we should eventually test the SRS.

    for( int iRing = 0; iRing < getNumInteriorRings(); iRing++ )
    {
        if( !getInteriorRing(iRing)->Equals(poOPoly->getInteriorRing(iRing)) )
            return FALSE;
    }

    return TRUE;
}

/************************************************************************/
/*                             transform()                              */
/************************************************************************/

OGRErr OGRPolygon::transform( OGRCoordinateTransformation *poCT )

{
#ifdef DISABLE_OGRGEOM_TRANSFORM
    return OGRERR_FAILURE;
#else
    for( int iRing = 0; iRing < nRingCount; iRing++ )
    {
        OGRErr  eErr;

        eErr = papoRings[iRing]->transform( poCT );
        if( eErr != OGRERR_NONE )
        {
            if( iRing != 0 )
            {
                CPLDebug("OGR", 
                         "OGRPolygon::transform() failed for a ring other\n"
                         "than the first, meaning some rings are transformed\n"
                         "and some are not!\n" );

                return OGRERR_FAILURE;
            }

            return eErr;
        }
    }

    assignSpatialReference( poCT->GetTargetCS() );

    return OGRERR_NONE;
#endif
}

/************************************************************************/
/*                           IsPointOnSurface()                           */
/************************************************************************/

OGRBoolean OGRPolygon::IsPointOnSurface( const OGRPoint * pt) const
{
    if ( NULL == pt)
        return 0;

    for( int iRing = 0; iRing < nRingCount; iRing++ )
    {
        if ( papoRings[iRing]->isPointInRing(pt) )
        {
            return 1;
        }
    }

    return 0;
}

/************************************************************************/
/*                             closeRings()                             */
/************************************************************************/

void OGRPolygon::closeRings()

{
    for( int iRing = 0; iRing < nRingCount; iRing++ )
        papoRings[iRing]->closeRings();
}

/************************************************************************/
/*                              get_Area()                              */
/************************************************************************/

/**
 * Compute area of polygon.
 *
 * The area is computed as the area of the outer ring less the area of all
 * internal rings. 
 *
 * @return computed area.
 */

double OGRPolygon::get_Area() const

{
    double dfArea = 0.0;

    if( getExteriorRing() != NULL )
    {
        int iRing;

        dfArea = getExteriorRing()->get_Area();

        for( iRing = 0; iRing < getNumInteriorRings(); iRing++ )
            dfArea -= getInteriorRing( iRing )->get_Area();
    }

    return dfArea;
}

/************************************************************************/
/*                       setCoordinateDimension()                       */
/************************************************************************/

void OGRPolygon::setCoordinateDimension( int nNewDimension )

{
    for( int iRing = 0; iRing < nRingCount; iRing++ )
        papoRings[iRing]->setCoordinateDimension( nNewDimension );

    OGRGeometry::setCoordinateDimension( nNewDimension );
}