ogr_api.cpp

mitab,读取MapInfo的地图文件

/************************************************************************/
/*                           OGR_G_AddPoint()                           */
/************************************************************************/
/**
 * Add a point to a geometry (line string or point).
 *
 * The vertex count of the line string is increased by one, and assigned from
 * the passed location value.
 *
 * @param hGeom handle to the geometry to add a point to.
 * @param dfX x coordinate of point to add.
 * @param dfY y coordinate of point to add.
 */

void OGR_G_AddPoint_2D( OGRGeometryH hGeom, 
                        double dfX, double dfY )

{
    switch( wkbFlatten(((OGRGeometry *) hGeom)->getGeometryType()) )
    {
      case wkbPoint:
      {
          ((OGRPoint *) hGeom)->setX( dfX );
          ((OGRPoint *) hGeom)->setY( dfY );
      }
      break;

      case wkbLineString:
        ((OGRLineString *) hGeom)->addPoint( dfX, dfY );
        break;

      default:
        CPLAssert( FALSE );
        break;
    }
}

/************************************************************************/
/*                       OGR_G_GetGeometryCount()                       */
/************************************************************************/
/**
 * Fetch the number of elements in a geometry.
 *
 * @param hGeom geometry from which to get the number of elements.
 * @return the number of elements.
 */

int OGR_G_GetGeometryCount( OGRGeometryH hGeom )

{
    switch( wkbFlatten(((OGRGeometry *) hGeom)->getGeometryType()) )
    {
      case wkbPolygon:
        if( ((OGRPolygon *)hGeom)->getExteriorRing() == NULL )
            return 0;
        else
            return ((OGRPolygon *)hGeom)->getNumInteriorRings() + 1;

      case wkbMultiPoint:
      case wkbMultiLineString:
      case wkbMultiPolygon:
      case wkbGeometryCollection:
        return ((OGRGeometryCollection *)hGeom)->getNumGeometries();

      default:
        return 0;
    }
}

/************************************************************************/
/*                        OGR_G_GetGeometryRef()                        */
/************************************************************************/

/**
 * Fetch geometry from a geometry container.
 *
 * This function returns an handle to a geometry within the container.
 * The returned geometry remains owned by the container, and should not be
 * modified.  The handle is only valid untill the next change to the
 * geometry container.  Use OGR_G_Clone() to make a copy.
 *
 * This function relates to the SFCOM 
 * IGeometryCollection::get_Geometry() method.
 *
 * This function is the same as the CPP method 
 * OGRGeometryCollection::getGeometryRef().
 *
 * @param hGeom handle to the geometry container from which to get a 
 * geometry from.
 * @param iSubGeom the index of the geometry to fetch, between 0 and
 *          getNumGeometries() - 1.
 * @return handle to the requested geometry.
 */

OGRGeometryH OGR_G_GetGeometryRef( OGRGeometryH hGeom, int iSubGeom )

{
    switch( wkbFlatten(((OGRGeometry *) hGeom)->getGeometryType()) )
    {
      case wkbPolygon:
        if( iSubGeom == 0 )
            return (OGRGeometryH) 
                ((OGRPolygon *)hGeom)->getExteriorRing();
        else
            return (OGRGeometryH) 
                ((OGRPolygon *)hGeom)->getInteriorRing(iSubGeom-1);

      case wkbMultiPoint:
      case wkbMultiLineString:
      case wkbMultiPolygon:
      case wkbGeometryCollection:
        return (OGRGeometryH) 
            ((OGRGeometryCollection *)hGeom)->getGeometryRef( iSubGeom );

      default:
        return 0;
    }
}

/************************************************************************/
/*                         OGR_G_AddGeometry()                          */
/************************************************************************/

/**
 * Add a geometry to a geometry container.
 *
 * Some subclasses of OGRGeometryCollection restrict the types of geometry
 * that can be added, and may return an error.  The passed geometry is cloned
 * to make an internal copy.
 *
 * There is no SFCOM analog to this method.
 *
 * This function is the same as the CPP method 
 * OGRGeometryCollection::addGeometry.
 *
 * @param hGeom existing geometry container.
 * @param hNewSubGeom geometry to add to the container.
 *
 * @return OGRERR_NONE if successful, or OGRERR_UNSUPPORTED_GEOMETRY_TYPE if
 * the geometry type is illegal for the type of existing geometry.
 */

OGRErr OGR_G_AddGeometry( OGRGeometryH hGeom, OGRGeometryH hNewSubGeom )

{
    switch( wkbFlatten(((OGRGeometry *) hGeom)->getGeometryType()) )
    {
      case wkbPolygon:
      {
          OGRLinearRing *poRing = (OGRLinearRing *) hNewSubGeom;

          if( poRing->WkbSize() != 0 
              || wkbFlatten(poRing->getGeometryType()) != wkbLineString )
              return OGRERR_UNSUPPORTED_GEOMETRY_TYPE;
          else
          {
              ((OGRPolygon *)hGeom)->addRing( poRing );
              return OGRERR_NONE;
          }
      }

      case wkbMultiPoint:
      case wkbMultiLineString:
      case wkbMultiPolygon:
      case wkbGeometryCollection:
        return ((OGRGeometryCollection *)hGeom)->addGeometry( 
            (OGRGeometry *) hNewSubGeom );

      default:
        return OGRERR_UNSUPPORTED_OPERATION;
    }
}

/************************************************************************/
/*                     OGR_G_AddGeometryDirectly()                      */
/************************************************************************/
/**
 * Add a geometry directly to an existing geometry container.
 *
 * Some subclasses of OGRGeometryCollection restrict the types of geometry
 * that can be added, and may return an error.  Ownership of the passed
 * geometry is taken by the container rather than cloning as addGeometry()
 * does.
 *
 * This function is the same as the CPP method 
 * OGRGeometryCollection::addGeometryDirectly.
 *
 * There is no SFCOM analog to this method.
 *
 * @param hGeom existing geometry.
 * @param hNewSubGeom geometry to add to the existing geometry.
 *
 * @return OGRERR_NONE if successful, or OGRERR_UNSUPPORTED_GEOMETRY_TYPE if
 * the geometry type is illegal for the type of geometry container.
 */

OGRErr OGR_G_AddGeometryDirectly( OGRGeometryH hGeom, 
                                  OGRGeometryH hNewSubGeom )

{
    switch( wkbFlatten(((OGRGeometry *) hGeom)->getGeometryType()) )
    {
      case wkbPolygon:
      {
          OGRLinearRing *poRing = (OGRLinearRing *) hNewSubGeom;

          if( poRing->WkbSize() != 0 
              || wkbFlatten(poRing->getGeometryType()) != wkbLineString )
              return OGRERR_UNSUPPORTED_GEOMETRY_TYPE;
          else
          {
              ((OGRPolygon *)hGeom)->addRingDirectly( poRing );
              return OGRERR_NONE;
          }
      }

      case wkbMultiPoint:
      case wkbMultiLineString:
      case wkbMultiPolygon:
      case wkbGeometryCollection:
        return ((OGRGeometryCollection *)hGeom)->addGeometryDirectly( 
            (OGRGeometry *) hNewSubGeom );

      default:
        return OGRERR_UNSUPPORTED_OPERATION;
    }
}

/************************************************************************/
/*                        OGR_G_RemoveGeometry()                        */
/************************************************************************/

/**
 * Remove a geometry from an exiting geometry container.
 *
 * Removing a geometry will cause the geometry count to drop by one, and all
 * "higher" geometries will shuffle down one in index.
 *
 * There is no SFCOM analog to this method.
 *
 * This function is the same as the CPP method 
 * OGRGeometryCollection::removeGeometry().
 *
 * @param hGeom the existing geometry to delete from.
 * @param iGeom the index of the geometry to delete.  A value of -1 is a
 * special flag meaning that all geometries should be removed.
 *
 * @param bDelete if TRUE the geometry will be destroyed, otherwise it will
 * not.  The default is TRUE as the existing geometry is considered to own the
 * geometries in it. 
 *
 * @return OGRERR_NONE if successful, or OGRERR_FAILURE if the index is
 * out of range.
 */



OGRErr OGR_G_RemoveGeometry( OGRGeometryH hGeom, int iGeom, int bDelete )

{
    switch( wkbFlatten(((OGRGeometry *) hGeom)->getGeometryType()) )
    {
      case wkbPolygon:
      {
          CPLError( CE_Failure, CPLE_AppDefined, 
                    "OGR_G_RemoveGeometry() not supported on polygons yet." );
          return OGRERR_UNSUPPORTED_OPERATION;
      }

      case wkbMultiPoint:
      case wkbMultiLineString:
      case wkbMultiPolygon:
      case wkbGeometryCollection:
        return ((OGRGeometryCollection *)hGeom)->removeGeometry( iGeom,bDelete);

      default:
        return OGRERR_UNSUPPORTED_OPERATION;
    }
}

/************************************************************************/
/*                           OGR_G_GetArea()                            */
/************************************************************************/

/**
 * Compute geometry area.
 *
 * Computes the area for an OGRLinearRing, OGRPolygon or OGRMultiPolygon.
 * Undefined for all other geometry types (returns zero). 
 *
 * This function utilizes the C++ get_Area() methods such as
 * OGRPolygon::get_Area(). 
 *
 * @param hGeom the geometry to operate on. 
 * @return the area or 0.0 for unsupported geometry types.
 */

double OGR_G_GetArea( OGRGeometryH hGeom )

{
    double fArea = 0.0;

    switch( wkbFlatten(((OGRGeometry *) hGeom)->getGeometryType()) )
    {
      case wkbPolygon:
        fArea = ((OGRPolygon *) hGeom)->get_Area();
        break;

      case wkbMultiPolygon:
        fArea = ((OGRMultiPolygon *) hGeom)->get_Area();
        break;

      case wkbLinearRing:
      case wkbLineString:
        /* This test below is required to filter out wkbLineString geometries
         * not being of type of wkbLinearRing.
         */
        if( EQUAL( ((OGRGeometry*) hGeom)->getGeometryName(), "LINEARRING" ) )
        {
            fArea = ((OGRLinearRing *) hGeom)->get_Area();
        }
        break;

      default:
        CPLError( CE_Warning, CPLE_AppDefined,
                  "OGR_G_GetArea() called against non-surface geometry type." );

        fArea = 0.0;
    }

    return fArea;
}