ogrlinestring.cpp

用于读取TAB、MIF、SHP文件的类

    if( padfZ == NULL )
        Make2D();
    else
        Make3D();
    
/* -------------------------------------------------------------------- */
/*      Assign values.                                                  */
/* -------------------------------------------------------------------- */
    setNumPoints( nPointsIn );

    for( i = 0; i < nPointsIn; i++ )
    {
        paoPoints[i].x = padfX[i];
        paoPoints[i].y = padfY[i];
    }

    if( this->padfZ != NULL )
        memcpy( this->padfZ, padfZ, sizeof(double) * nPointsIn );
}

/************************************************************************/
/*                          getPoints()                                 */
/************************************************************************/

/**
 * Returns all points of line string.
 *
 * This method copies all points into user list. This list must be at
 * least sizeof(OGRRawPoint) * OGRGeometry::getNumPoints() byte in size.
 * It also copies all Z coordinates.
 *
 * There is no SFCOM analog to this method.
 *
 * @param paoPointsOut a buffer into which the points is written.
 * @param padfZ the Z values that go with the points (optional, may be NULL).
 */

void OGRLineString::getPoints( OGRRawPoint * paoPointsOut, double * padfZ ) const
{
    if ( ! paoPointsOut )
        return;
        
    memcpy( paoPointsOut, paoPoints, sizeof(OGRRawPoint) * nPointCount );

/* -------------------------------------------------------------------- */
/*      Check 2D/3D.                                                    */
/* -------------------------------------------------------------------- */
    if( padfZ )
    {
        if ( this->padfZ )
            memcpy( padfZ, this->padfZ, sizeof(double) * nPointCount );
        else
            memset( padfZ, 0, sizeof(double) * nPointCount );
    }
}


/************************************************************************/
/*                          addSubLineString()                          */
/************************************************************************/

/**
 * Add a segment of another linestring to this one.
 *
 * Adds the request range of vertices to the end of this line string
 * in an efficient manner.  If the nStartVertex is larger than the
 * nEndVertex then the vertices will be reversed as they are copied. 
 *
 * @param poOtherLine the other OGRLineString. 
 * @param nStartVertex the first vertex to copy, defaults to 0 to start
 * with the first vertex in the other linestring. 
 * @param nEndVertex the last vertex to copy, defaults to -1 indicating 
 * the last vertex of the other line string. 
 */

void OGRLineString::addSubLineString( const OGRLineString *poOtherLine, 
                                      int nStartVertex, int nEndVertex )

{
/* -------------------------------------------------------------------- */
/*      Do a bit of argument defaulting and validation.                 */
/* -------------------------------------------------------------------- */
    if( nEndVertex == -1 )
        nEndVertex = poOtherLine->getNumPoints() - 1;

    if( nStartVertex < 0 || nEndVertex < 0 
        || nStartVertex >= poOtherLine->getNumPoints() 
        || nEndVertex >= poOtherLine->getNumPoints() )
    {
        CPLAssert( FALSE );
        return;
    }

/* -------------------------------------------------------------------- */
/*      Grow this linestring to hold the additional points.             */
/* -------------------------------------------------------------------- */
    int nOldPoints = nPointCount;
    int nPointsToAdd = ABS(nEndVertex-nStartVertex) + 1;

    setNumPoints( nPointsToAdd + nOldPoints );

/* -------------------------------------------------------------------- */
/*      Copy the x/y points - forward copies use memcpy.                */
/* -------------------------------------------------------------------- */
    if( nEndVertex >= nStartVertex )
    {
        memcpy( paoPoints + nOldPoints, 
                poOtherLine->paoPoints + nStartVertex, 
                sizeof(OGRRawPoint) * nPointsToAdd );
        if( poOtherLine->padfZ != NULL )
        {
            Make3D();
            memcpy( padfZ + nOldPoints, poOtherLine->padfZ + nStartVertex,
                    sizeof(double) * nPointsToAdd );
        }
    }
    
/* -------------------------------------------------------------------- */
/*      Copy the x/y points - reverse copies done double by double.     */
/* -------------------------------------------------------------------- */
    else
    {
        int i;

        for( i = 0; i < nPointsToAdd; i++ )
        {
            paoPoints[i+nOldPoints].x = 
                poOtherLine->paoPoints[nStartVertex-i].x;
            paoPoints[i+nOldPoints].y = 
                poOtherLine->paoPoints[nStartVertex-i].y;
        }

        if( poOtherLine->padfZ != NULL )
        {
            Make3D();

            for( i = 0; i < nPointsToAdd; i++ )
            {
                padfZ[i+nOldPoints] = poOtherLine->padfZ[nStartVertex-i];
            }
        }
    }
}

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

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

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

/* -------------------------------------------------------------------- */
/*      Get the byte order byte.                                        */
/* -------------------------------------------------------------------- */
    eByteOrder = DB2_V72_FIX_BYTE_ORDER((OGRwkbByteOrder) *pabyData);
    assert( 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.                                                       */
/* -------------------------------------------------------------------- */
    OGRwkbGeometryType eGeometryType;
    int bIs3D = FALSE;
    int nBytesAvailable = nSize;

    if( eByteOrder == wkbNDR )
    {
        eGeometryType = (OGRwkbGeometryType) pabyData[1];
        bIs3D = pabyData[4] & 0x80 || pabyData[2] & 0x80;
    }
    else
    {
        eGeometryType = (OGRwkbGeometryType) pabyData[4];
        bIs3D = pabyData[1] & 0x80 || pabyData[3] & 0x80;
    }

    CPLAssert( eGeometryType == wkbLineString );

/* -------------------------------------------------------------------- */
/*      Get the vertex count.                                           */
/* -------------------------------------------------------------------- */
    int         nNewNumPoints;
    
    memcpy( &nNewNumPoints, pabyData + 5, 4 );
    
    if( OGR_SWAP( eByteOrder ) )
        nNewNumPoints = CPL_SWAP32(nNewNumPoints);
    
    /* Check if the wkb stream buffer is big enough to store
     * fetched number of points.
     * 16 or 24 - size of point structure
     */
    int nPointSize = (bIs3D ? 24 : 16);
    int nBufferMinSize = nPointSize * nNewNumPoints;

    if( nBufferMinSize > nBytesAvailable && nBytesAvailable > 0 )
    {
        CPLError( CE_Failure, CPLE_AppDefined,
                  "Length of input WKB is too small" );
        return OGRERR_NOT_ENOUGH_DATA;
    }

    setNumPoints( nNewNumPoints );
    
    if( bIs3D )
        Make3D();
    else
        Make2D();
    
/* -------------------------------------------------------------------- */
/*      Get the vertex.                                                 */
/* -------------------------------------------------------------------- */
    int i = 0;
    int nBytesToCopy = 0;
    
    if( bIs3D )
    {
        for( i = 0; i < nPointCount; i++ )
        {
            nBytesToCopy = 24;

            if( nBytesToCopy > nBytesAvailable && nBytesAvailable > 0 )
            {
                CPLError( CE_Failure, CPLE_AppDefined,
                          "WKB buffer with OGRLineString points is too small! \
                          \n\tWKB stream may be corrupted or it is EWKB stream which is not supported");
                return OGRERR_NOT_ENOUGH_DATA;
            }
            if ( nBytesAvailable > 0 )
                nBytesAvailable -= nBytesToCopy;

            memcpy( paoPoints + i, pabyData + 9 + i*24, 16 );
            memcpy( padfZ + i, pabyData + 9 + 16 + i*24, 8 );
        }
    }
    else
    {
        nBytesToCopy = 16 * nPointCount;

        if( nBytesToCopy > nBytesAvailable && nBytesAvailable > 0 )
        {
            CPLError( CE_Failure, CPLE_AppDefined,
                      "WKB buffer with OGRLineString points is too small! \
                      \n\tWKB stream may be corrupted or it is EWKB stream which is not supported");
            return OGRERR_NOT_ENOUGH_DATA;
        }


        memcpy( paoPoints, pabyData + 9, nBytesToCopy );
    }
    
/* -------------------------------------------------------------------- */
/*      Byte swap if needed.                                            */
/* -------------------------------------------------------------------- */
    if( OGR_SWAP( eByteOrder ) )
    {
        for( i = 0; i < nPointCount; i++ )
        {
            CPL_SWAPDOUBLE( &(paoPoints[i].x) );
            CPL_SWAPDOUBLE( &(paoPoints[i].y) );
        }

        if( bIs3D )
        {
            for( i = 0; i < nPointCount; i++ )
            {
                CPL_SWAPDOUBLE( padfZ + i );
            }
        }
    }
    
    return OGRERR_NONE;
}

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

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

{
/* -------------------------------------------------------------------- */
/*      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 data count.                                         */
/* -------------------------------------------------------------------- */
    memcpy( pabyData+5, &nPointCount, 4 );

/* -------------------------------------------------------------------- */
/*      Copy in the raw data.                                           */
/* -------------------------------------------------------------------- */
    int         i;
    
    if( getCoordinateDimension() == 3 )
    {
        for( i = 0; i < nPointCount; i++ )
        {
            memcpy( pabyData + 9 + 24*i, paoPoints+i, 16 );
            memcpy( pabyData + 9 + 16 + 24*i, padfZ+i, 8 );
        }
    }
    else
        memcpy( pabyData+9, paoPoints, 16 * nPointCount );

/* -------------------------------------------------------------------- */
/*      Swap if needed.                                                 */
/* -------------------------------------------------------------------- */
    if( OGR_SWAP( eByteOrder ) )
    {
        int     nCount;

        nCount = CPL_SWAP32( nPointCount );
        memcpy( pabyData+5, &nCount, 4 );

        for( i = getCoordinateDimension() * nPointCount - 1; i >= 0; i-- )
        {
            CPL_SWAP64PTR( pabyData + 9 + 8 * i );
        }
    }
    
    return OGRERR_NONE;
}

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

OGRErr OGRLineString::importFromWkt( char ** ppszInput )

{