vector/Vlib/select.c

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/*!
   \file lib/vector/Vlib/select.c
 
   \brief Vector library - spatial index
 
   Higher level functions for a custom spatial index.
 
   (C) 2001-2009 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 Radim Blazek
 */
 
#include <stdlib.h>
#include <unistd.h>
#include <sys/stat.h>
#include <string.h>
#include <grass/vector.h>
#include <grass/glocale.h>
 
/*!
   \brief Initialize spatial index structure
 
   \param si pointer to spatial index structure
 
   \return void
 */
void Vect_spatial_index_init(struct spatial_index *si, int with_z)
{
    G_debug(1, "Vect_spatial_index_init()");
 
    si->si_tree = RTreeCreateTree(-1, 0, 2 + (with_z != 0));
}
 
/*!
   \brief Destroy existing spatial index
 
   Vect_spatial_index_init() must be call before new use.
 
   \param si pointer to spatial index structure
 
   \return void
 */
void Vect_spatial_index_destroy(struct spatial_index *si)
{
    G_debug(1, "Vect_spatial_index_destroy()");
 
    RTreeDestroyTree(si->si_tree);
}
 
/*!
   \brief Add a new item to spatial index structure
 
   \param[in,out] si pointer to spatial index structure
   \param id item identifier
   \param box pointer to item bounding box
 
   \return void
 */
void Vect_spatial_index_add_item(struct spatial_index *si, int id,
                                 const struct bound_box *box)
{
    static struct RTree_Rect rect;
    static int rect_init = 0;
 
    if (!rect_init) {
        rect.boundary = G_malloc(si->si_tree->nsides_alloc * sizeof(RectReal));
        rect_init = si->si_tree->nsides_alloc;
    }
 
    G_debug(3, "Vect_spatial_index_add_item(): id = %d", id);
 
    rect.boundary[0] = box->W;
    rect.boundary[1] = box->S;
    rect.boundary[2] = box->B;
    rect.boundary[3] = box->E;
    rect.boundary[4] = box->N;
    rect.boundary[5] = box->T;
    RTreeInsertRect(&rect, id, si->si_tree);
}
 
/*!
   \brief Delete item from spatial index structure
 
   \param[in,out] si pointer to spatial index structure
   \param id item identifier
 
   \return void
 */
void Vect_spatial_index_del_item(struct spatial_index *si, int id,
                                 const struct bound_box *box)
{
    int ret;
    static struct RTree_Rect rect;
    static int rect_init = 0;
 
    if (!rect_init) {
        rect.boundary = G_malloc(si->si_tree->nsides_alloc * sizeof(RectReal));
        rect_init = si->si_tree->nsides_alloc;
    }
 
    G_debug(3, "Vect_spatial_index_del_item(): id = %d", id);
 
    rect.boundary[0] = box->W;
    rect.boundary[1] = box->S;
    rect.boundary[2] = box->B;
    rect.boundary[3] = box->E;
    rect.boundary[4] = box->N;
    rect.boundary[5] = box->T;
 
    ret = RTreeDeleteRect(&rect, id, si->si_tree);
 
    if (ret)
        G_fatal_error(_("Unable to delete item %d from spatial index"), id);
}
 
/************************* SELECT BY BOX *********************************/
/* This function is called by  RTreeSearch() to add selected item to the list */
static int _add_item(int id, const struct RTree_Rect *rect UNUSED,
                     struct ilist *list)
{
    G_ilist_add(list, id);
    return 1;
}
 
/*!
   \brief Select items by bounding box to list
 
   \param si pointer to spatial index structure
   \param box bounding box
   \param[out] list pointer to list where selected items are stored
 
   \return number of selected items
 */
int Vect_spatial_index_select(const struct spatial_index *si,
                              const struct bound_box *box, struct ilist *list)
{
    static struct RTree_Rect rect;
    static int rect_init = 0;
 
    if (!rect_init) {
        rect.boundary = G_malloc(si->si_tree->nsides_alloc * sizeof(RectReal));
        rect_init = si->si_tree->nsides_alloc;
    }
 
    Vect_reset_list(list);
 
    rect.boundary[0] = box->W;
    rect.boundary[1] = box->S;
    rect.boundary[2] = box->B;
    rect.boundary[3] = box->E;
    rect.boundary[4] = box->N;
    rect.boundary[5] = box->T;
    RTreeSearch(si->si_tree, &rect, (SearchHitCallback *)_add_item, list);
 
    G_debug(3, "Vect_spatial_index_select(): %d items selected",
            list->n_values);
 
    return list->n_values;
}