ogrpolygon.cpp

用于读取TAB、MIF、SHP文件的类

/************************************************************************/
/*                              addRing()                               */
/************************************************************************/

/**
 * Add a ring to a polygon.
 *
 * If the polygon has no external ring (it is empty) this will be used as
 * the external ring, otherwise it is used as an internal ring.  The passed
 * OGRLinearRing remains the responsibility of the caller (an internal copy
 * is made).
 *
 * This method has no SFCOM analog.
 *
 * @param poNewRing ring to be added to the polygon.
 */

void OGRPolygon::addRing( OGRLinearRing * poNewRing )

{
    papoRings = (OGRLinearRing **) OGRRealloc( papoRings,
                                               sizeof(void*) * (nRingCount+1));

    papoRings[nRingCount] = new OGRLinearRing( poNewRing );

    nRingCount++;

    if( poNewRing->getCoordinateDimension() == 3 )
        nCoordDimension = 3;
}

/************************************************************************/
/*                          addRingDirectly()                           */
/************************************************************************/

/**
 * Add a ring to a polygon.
 *
 * If the polygon has no external ring (it is empty) this will be used as
 * the external ring, otherwise it is used as an internal ring.  Ownership
 * of the passed ring is assumed by the OGRPolygon, but otherwise this
 * method operates the same as OGRPolygon::AddRing().
 *
 * This method has no SFCOM analog.
 *
 * @param poNewRing ring to be added to the polygon.
 */

void OGRPolygon::addRingDirectly( OGRLinearRing * poNewRing )

{
    papoRings = (OGRLinearRing **) OGRRealloc( papoRings,
                                               sizeof(void*) * (nRingCount+1));

    papoRings[nRingCount] = poNewRing;

    nRingCount++;


    if( poNewRing->getCoordinateDimension() == 3 )
        nCoordDimension = 3;
}

/************************************************************************/
/*                              WkbSize()                               */
/*                                                                      */
/*      Return the size of this object in well known binary             */
/*      representation including the byte order, and type information.  */
/************************************************************************/

int OGRPolygon::WkbSize() const

{
    int         nSize = 9;
    int         b3D = getCoordinateDimension() == 3;

    for( int i = 0; i < nRingCount; i++ )
    {
        nSize += papoRings[i]->_WkbSize( b3D );
    }

    return nSize;
}

/************************************************************************/
/*                           importFromWkb()                            */
/*                                                                      */
/*      Initialize from serialized stream in well known binary          */
/*      format.                                                         */
/************************************************************************/

OGRErr OGRPolygon::importFromWkb( unsigned char * pabyData,
                                  int nSize )

{
    OGRwkbByteOrder     eByteOrder;
    int                 nDataOffset, b3D;
    
    if( nSize < 21 && nSize != -1 )
        return OGRERR_NOT_ENOUGH_DATA;

/* -------------------------------------------------------------------- */
/*      Get the byte order byte.                                        */
/* -------------------------------------------------------------------- */
    eByteOrder = DB2_V72_FIX_BYTE_ORDER((OGRwkbByteOrder) *pabyData);
    CPLAssert( eByteOrder == wkbXDR || eByteOrder == wkbNDR );

/* -------------------------------------------------------------------- */
/*      Get the geometry feature type.  For now we assume that          */
/*      geometry type is between 0 and 255 so we only have to fetch     */
/*      one byte.                                                       */
/* -------------------------------------------------------------------- */
#ifdef DEBUG
    OGRwkbGeometryType eGeometryType;
    
    if( eByteOrder == wkbNDR )
        eGeometryType = (OGRwkbGeometryType) pabyData[1];
    else
        eGeometryType = (OGRwkbGeometryType) pabyData[4];

    CPLAssert( eGeometryType == wkbPolygon );
#endif    

    if( eByteOrder == wkbNDR )
        b3D = pabyData[4] & 0x80 || pabyData[2] & 0x80;
    else
        b3D = pabyData[1] & 0x80 || pabyData[3] & 0x80;

    if( b3D )
        nCoordDimension = 3;
    else
        nCoordDimension = 2;

/* -------------------------------------------------------------------- */
/*      Do we already have some rings?                                  */
/* -------------------------------------------------------------------- */
    if( nRingCount != 0 )
    {
        for( int iRing = 0; iRing < nRingCount; iRing++ )
            delete papoRings[iRing];

        OGRFree( papoRings );
        papoRings = NULL;
    }
    
/* -------------------------------------------------------------------- */
/*      Get the ring count.                                             */
/* -------------------------------------------------------------------- */
    memcpy( &nRingCount, pabyData + 5, 4 );
    
    if( OGR_SWAP( eByteOrder ) )
        nRingCount = CPL_SWAP32(nRingCount);

    papoRings = (OGRLinearRing **) OGRMalloc(sizeof(void*) * nRingCount);

    nDataOffset = 9;
    if( nSize != -1 )
        nSize -= nDataOffset;

/* -------------------------------------------------------------------- */
/*      Get the rings.                                                  */
/* -------------------------------------------------------------------- */
    for( int iRing = 0; iRing < nRingCount; iRing++ )
    {
        OGRErr  eErr;
        
        papoRings[iRing] = new OGRLinearRing();
        eErr = papoRings[iRing]->_importFromWkb( eByteOrder, b3D,
                                                 pabyData + nDataOffset,
                                                 nSize );
        if( eErr != OGRERR_NONE )
        {
            nRingCount = iRing;
            return eErr;
        }

        if( nSize != -1 )
            nSize -= papoRings[iRing]->_WkbSize( b3D );

        nDataOffset += papoRings[iRing]->_WkbSize( b3D );
    }
    
    return OGRERR_NONE;
}

/************************************************************************/
/*                            exportToWkb()                             */
/*                                                                      */
/*      Build a well known binary representation of this object.        */
/************************************************************************/

OGRErr  OGRPolygon::exportToWkb( OGRwkbByteOrder eByteOrder,
                                 unsigned char * pabyData ) const

{
    int         nOffset;
    int         b3D = getCoordinateDimension() == 3;
    
/* -------------------------------------------------------------------- */
/*      Set the byte order.                                             */
/* -------------------------------------------------------------------- */
    pabyData[0] = DB2_V72_UNFIX_BYTE_ORDER((unsigned char) eByteOrder);

/* -------------------------------------------------------------------- */
/*      Set the geometry feature type.                                  */
/* -------------------------------------------------------------------- */
    GUInt32 nGType = getGeometryType();
    
    if( eByteOrder == wkbNDR )
        nGType = CPL_LSBWORD32( nGType );
    else
        nGType = CPL_MSBWORD32( nGType );

    memcpy( pabyData + 1, &nGType, 4 );
    
/* -------------------------------------------------------------------- */
/*      Copy in the raw data.                                           */
/* -------------------------------------------------------------------- */
    if( OGR_SWAP( eByteOrder ) )
    {
        int     nCount;

        nCount = CPL_SWAP32( nRingCount );
        memcpy( pabyData+5, &nCount, 4 );
    }
    else
    {
        memcpy( pabyData+5, &nRingCount, 4 );
    }
    
    nOffset = 9;
    
/* ==================================================================== */
/*      Serialize each of the rings.                                    */
/* ==================================================================== */
    for( int iRing = 0; iRing < nRingCount; iRing++ )
    {
        papoRings[iRing]->_exportToWkb( eByteOrder, b3D,
                                        pabyData + nOffset );

        nOffset += papoRings[iRing]->_WkbSize(b3D);
    }
    
    return OGRERR_NONE;
}

/************************************************************************/
/*                           importFromWkt()                            */
/*                                                                      */
/*      Instantiate from well known text format.  Currently this is     */
/*      `POLYGON ((x y, x y, ...),(x y, ...),...)'.                     */
/************************************************************************/

OGRErr OGRPolygon::importFromWkt( char ** ppszInput )

{
    char        szToken[OGR_WKT_TOKEN_MAX];
    const char  *pszInput = *ppszInput;
    int         iRing;

/* -------------------------------------------------------------------- */
/*      Clear existing rings.                                           */
/* -------------------------------------------------------------------- */
    if( nRingCount > 0 )
    {
        for( iRing = 0; iRing < nRingCount; iRing++ )
            delete papoRings[iRing];
        
        nRingCount = 0;
        CPLFree( papoRings );
    }

/* -------------------------------------------------------------------- */
/*      Read and verify the ``POLYGON'' keyword token.                  */
/* -------------------------------------------------------------------- */
    pszInput = OGRWktReadToken( pszInput, szToken );

    if( !EQUAL(szToken,"POLYGON") )
        return OGRERR_CORRUPT_DATA;

/* -------------------------------------------------------------------- */
/*      The next character should be a ( indicating the start of the    */
/*      list of rings.  We also need to support POLYGON EMPTY and       */
/*      POLYGON(EMPTY).                                                 */
/* -------------------------------------------------------------------- */
    pszInput = OGRWktReadToken( pszInput, szToken );

    if( EQUAL(szToken,"EMPTY") )
    {
        *ppszInput = (char *) pszInput;
        return OGRERR_NONE;
    }

    if( szToken[0] != '(' )
        return OGRERR_CORRUPT_DATA;

    OGRWktReadToken( pszInput, szToken );
    if( EQUAL(szToken,"EMPTY") )
    {
        pszInput = OGRWktReadToken( pszInput, szToken );
        pszInput = OGRWktReadToken( pszInput, szToken );
        
        *ppszInput = (char *) pszInput;

        if( !EQUAL(szToken,")") )
            return OGRERR_CORRUPT_DATA;
        else
            return OGRERR_NONE;
    }

/* ==================================================================== */
/*      Read each ring in turn.  Note that we try to reuse the same     */
/*      point list buffer from ring to ring to cut down on              */
/*      allocate/deallocate overhead.                                   */
/* ==================================================================== */
    OGRRawPoint *paoPoints = NULL;
    int         nMaxPoints = 0, nMaxRings = 0;
    double      *padfZ = NULL;

    nCoordDimension = 2;
    
    do
    {
        int     nPoints = 0;

/* -------------------------------------------------------------------- */
/*      Read points for one ring from input.                            */
/* -------------------------------------------------------------------- */
        pszInput = OGRWktReadPoints( pszInput, &paoPoints, &padfZ, &nMaxPoints,
                                     &nPoints );

        if( pszInput == NULL )
        {
            CPLFree( paoPoints );
            return OGRERR_CORRUPT_DATA;
        }
        
/* -------------------------------------------------------------------- */
/*      Do we need to grow the ring array?                              */
/* -------------------------------------------------------------------- */
        if( nRingCount == nMaxRings )
        {
            nMaxRings = nMaxRings * 2 + 1;
            papoRings = (OGRLinearRing **)
                CPLRealloc(papoRings, nMaxRings * sizeof(OGRLinearRing*));
        }

/* -------------------------------------------------------------------- */
/*      Create the new ring, and assign to ring list.                   */
/* -------------------------------------------------------------------- */
        papoRings[nRingCount] = new OGRLinearRing();
        papoRings[nRingCount]->setPoints( nPoints, paoPoints, padfZ );

        nRingCount++;

        if( padfZ )
            nCoordDimension = 3;

/* -------------------------------------------------------------------- */
/*      Read the delimeter following the ring.                          */
/* -------------------------------------------------------------------- */
        
        pszInput = OGRWktReadToken( pszInput, szToken );
    } while( szToken[0] == ',' );

/* -------------------------------------------------------------------- */
/*      freak if we don't get a closing bracket.                        */
/* -------------------------------------------------------------------- */