GRASS GIS 8 Programmer's Manual
8.2.2dev(2023)-3d2c704037
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Vector library - read features. More...
Go to the source code of this file.
Functions | |
int | Vect_get_next_line_id (const struct Map_info *Map) |
Get line id for sequential reading. More... | |
int | Vect_read_next_line (const struct Map_info *Map, struct line_pnts *line_p, struct line_cats *line_c) |
Read next vector feature. More... | |
int | Vect_read_line (const struct Map_info *Map, struct line_pnts *line_p, struct line_cats *line_c, int line) |
Read vector feature (topological level required) More... | |
int | Vect_line_alive (const struct Map_info *Map, int line) |
Check if feature is alive or dead (topological level required) More... | |
int | Vect_node_alive (const struct Map_info *Map, int node) |
Check if node is alive or dead (topological level required) More... | |
int | Vect_area_alive (const struct Map_info *Map, int area) |
Check if area is alive or dead (topological level required) More... | |
int | Vect_isle_alive (const struct Map_info *Map, int isle) |
Check if isle is alive or dead (topological level required) More... | |
off_t | Vect_get_line_offset (const struct Map_info *Map, int line) |
Get feature offset (topological level required) More... | |
Vector library - read features.
Higher level functions for reading/writing/manipulating vectors.
(C) 2001-2009, 2011-2013 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.
Definition in file vector/Vlib/read.c.
int Vect_area_alive | ( | const struct Map_info * | Map, |
int | area | ||
) |
Check if area is alive or dead (topological level required)
Note: Topology must be built at level >= GV_BUILD_AREAS
Map | pointer to Map_info structure |
area | area id |
Definition at line 245 of file vector/Vlib/read.c.
References _, Plus_head::Area, G_warning(), Plus_head::n_areas, NULL, and Map_info::plus.
Referenced by vector2perimeters(), and Vedit_delete_areas_cat().
off_t Vect_get_line_offset | ( | const struct Map_info * | Map, |
int | line | ||
) |
Get feature offset (topological level required)
Note: Topology must be built at level >= GV_BUILD_BASE
Used for Vect_restore_line().
Map | pointer to Map_info structure |
line | feature id |
Definition at line 295 of file vector/Vlib/read.c.
int Vect_get_next_line_id | ( | const struct Map_info * | Map | ) |
Get line id for sequential reading.
This function returns id of feature which has been read by calling Vect_read_next_line().
Map | pointer to Map_info struct |
Definition at line 88 of file vector/Vlib/read.c.
References _, G_debug(), G_warning(), Map_info::next_line, and VECT_OPEN.
int Vect_isle_alive | ( | const struct Map_info * | Map, |
int | isle | ||
) |
Check if isle is alive or dead (topological level required)
Note: Topology must be built at level >= GV_BUILD_AREAS
Map | pointer to Map_info structure |
isle | isle id |
Definition at line 269 of file vector/Vlib/read.c.
References _, G_warning(), Plus_head::Isle, Plus_head::n_isles, NULL, and Map_info::plus.
int Vect_line_alive | ( | const struct Map_info * | Map, |
int | line | ||
) |
Check if feature is alive or dead (topological level required)
Note: Topology must be built at level >= GV_BUILD_BASE
Map | pointer to Map_info structure |
line | feature id |
Definition at line 197 of file vector/Vlib/read.c.
int Vect_node_alive | ( | const struct Map_info * | Map, |
int | node | ||
) |
Check if node is alive or dead (topological level required)
Note: Topology must be built at level >= GV_BUILD_BASE
Map | pointer to Map_info structure |
node | node id |
Definition at line 221 of file vector/Vlib/read.c.
References _, G_warning(), Plus_head::n_nodes, Plus_head::Node, NULL, and Map_info::plus.
int Vect_read_line | ( | const struct Map_info * | Map, |
struct line_pnts * | line_p, | ||
struct line_cats * | line_c, | ||
int | line | ||
) |
Read vector feature (topological level required)
This function implements random access. Constraits are ignored.
Note: Topology must be built at level >= GV_BUILD_BASE
A warning is printed on failure.
Map | pointer to vector map | |
[out] | line_p | feature geometry (pointer to line_pnts struct) |
[out] | line_c | feature categories (pointer to line_cats struct) |
line | feature id (starts at 1) |
Definition at line 160 of file vector/Vlib/read.c.
Referenced by NetA_initialise_varray(), and Vect_get_area_cats().
int Vect_read_next_line | ( | const struct Map_info * | Map, |
struct line_pnts * | line_p, | ||
struct line_cats * | line_c | ||
) |
Read next vector feature.
This function implements sequential access, constraints are reflected, see Vect_set_constraint_region(), Vect_set_constraint_type(), or Vect_set_constraint_field() for details.
Use Vect_rewind() to reset reading. Topological level is not required.
A warning is printed on failure.
Map | pointer Map_info struct | |
[out] | line_p | feature geometry (pointer to line_pnts struct) |
[out] | line_c | feature categories (pointer to line_cats struct) |
Definition at line 121 of file vector/Vlib/read.c.
References _, G_debug(), G_warning(), Map_info::next_line, and VECT_OPEN.