read_sfa.c

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/*!
   \file lib/vector/Vlib/read_sfa.c
 
   \brief Vector library - reading features - simple feature access
 
   Higher level functions for reading/writing/manipulating vectors.
 
   See read_ogr.c (OGR interface) and read_pg.c (PostGIS interface)
   for implementation issues.
 
   (C) 2011-2012 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 Martin Landa <landa.martin gmail.com>
 */
 
#include <grass/vector.h>
#include <grass/glocale.h>
 
/*!
   \brief Reads feature from OGR/PostGIS layer on topological level.
 
   This function implements random access on level 2.
 
   Note: Topology must be built at level >= GV_BUILD_BASE
 
   \param Map pointer to Map_info structure
   \param[out] line_p container used to store line points within
   (pointer to line_pnts struct)
   \param[out] line_c container used to store line categories within
   (pointer to line_cats struct)
   \param line feature id (starts at 1)
 
   \return feature type
   \return -2 no more features
   \return -1 on failure
 */
int V2_read_line_sfa(struct Map_info *Map, struct line_pnts *line_p,
                     struct line_cats *line_c, int line)
{
    int type;
    struct P_line *Line;
 
    G_debug(4, "V2_read_line_sfa() line = %d", line);
 
    if (line < 1 || line > Map->plus.n_lines) {
        G_warning(_("Attempt to access feature with invalid id (%d)"), line);
        return -1;
    }
 
    Line = Map->plus.Line[line];
    if (Line == NULL) {
        G_warning(_("Attempt to access dead feature %d"), line);
        return -1;
    }
 
    if (Line->type == GV_CENTROID) {
        /* read centroid for topo */
        if (line_p != NULL) {
            int i, found;
            struct bound_box box;
            struct boxlist list;
            struct P_topo_c *topo = (struct P_topo_c *)Line->topo;
 
            G_debug(4, "Centroid: area = %d", topo->area);
            Vect_reset_line(line_p);
 
            if (topo->area > 0 && topo->area <= Map->plus.n_areas) {
                /* get area bbox */
                Vect_get_area_box(Map, topo->area, &box);
                /* search in spatial index for centroid with area bbox */
                dig_init_boxlist(&list, TRUE);
                Vect_select_lines_by_box(Map, &box, Line->type, &list);
 
                found = -1;
                for (i = 0; i < list.n_values; i++) {
                    if (list.id[i] == line) {
                        found = i;
                        break;
                    }
                }
 
                if (found > -1) {
                    Vect_append_point(line_p, list.box[found].E,
                                      list.box[found].N, 0.0);
                }
                else {
                    G_warning(
                        _("Unable to construct centroid for area %d. Skipped."),
                        topo->area);
                }
            }
            else {
                G_warning(_("Centroid %d: invalid area %d"), line, topo->area);
            }
        }
 
        if (line_c != NULL) {
            /* cat = fid and offset = fid for centroid */
            Vect_reset_cats(line_c);
            Vect_cat_set(line_c, 1, (int)Line->offset);
        }
 
        return GV_CENTROID;
    }
 
    if (!line_p && !line_c)
        return Line->type;
 
    if (Map->format == GV_FORMAT_POSTGIS)
        type = V1_read_line_pg(Map, line_p, line_c, Line->offset);
    else
        type = V1_read_line_ogr(Map, line_p, line_c, Line->offset);
 
    if (type != Line->type) {
        G_warning(_("Unexpected feature type (%d) - should be (%d)"), type,
                  Line->type);
        return -1;
    }
 
    return type;
}