Geografic-Information-System/lib/vector/Vlib/constraint.c

/*!
   \file constraint.c

   \brief Vector library - constraints

   Higher level functions for reading/writing/manipulating vectors.

   These routines can affect the read_next_line funtions
   by restricting what they return.
   They are applied on a per map basis.

   These do not affect the lower level direct read functions.

   Normally, All 'Alive' lines will be returned unless overridden
   by this function.   You can specified all the types you are interested
   in  (by oring their types together).  You can use this to say 
   exclude Area type lines.

   By default all DEAD lines are ignored by the read_next_line () functions
   This too can be overridden by including their types.

   Refer to  dig_defines for the line type Defines

   All lines can be forced to be read by setting type = -1

   (C) 2001-2008 by the GRASS Development Team

   This program is free software under the 
   GNU General Public License (>=v2). 
   Read the file COPYING that comes with GRASS
   for details.

   \author Original author CERL, probably Dave Gerdes or Mike Higgins.
   Update to GRASS 5.7 Radim Blazek and David D. Gray.

   \date 2001-2008
 */

#include <grass/Vect.h>
#include <grass/gis.h>

/*!
   \brief Set constraint region

   \param Map vector map
   \param n,s,e,w,t,b north, south, east, west, top, bottom coordinates

   \return 0 on success
   \return -1 on error
 */
int
Vect_set_constraint_region(struct Map_info *Map,
			   double n, double s, double e, double w, double t,
			   double b)
{
    if (n <= s)
	return (-1);
    if (e <= w)
	return (-1);

    Map->Constraint_region_flag = 1;
    Map->Constraint_N = n;
    Map->Constraint_S = s;
    Map->Constraint_E = e;
    Map->Constraint_W = w;
    Map->Constraint_T = t;
    Map->Constraint_B = b;
    Map->proj = G_projection();

    return (0);
}

/*!
   \brief Get constraint box

   \param Map vector map
   \param Box bounding box

   \return 0 on success
 */
int Vect_get_constraint_box(struct Map_info *Map, BOUND_BOX * Box)
{
    Box->N = Map->Constraint_N;
    Box->S = Map->Constraint_S;
    Box->E = Map->Constraint_E;
    Box->W = Map->Constraint_W;
    Box->T = Map->Constraint_T;
    Box->B = Map->Constraint_B;

    return 0;
}

/*!
   \brief Set constraint type

   \param Map vector map
   \param type constraint type

   \return 0 on success
 */
int Vect_set_constraint_type(struct Map_info *Map, int type)
{
    Map->Constraint_type = type;
    Map->Constraint_type_flag = 1;

    return 0;
}

/*!
   \brief Remove constraints

   \param Map vector map

   \return 0 on success
 */
int Vect_remove_constraints(struct Map_info *Map)
{
    Map->Constraint_region_flag = 0;
    Map->Constraint_type_flag = 0;

    return 0;
}