vector/Vlib/read.c File Reference

Vector library - read features. More...

#include <sys/types.h>
#include <grass/vector.h>
#include <grass/glocale.h>

Include dependency graph for vector/Vlib/read.c:

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...

Detailed Description

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.

Author

Original author CERL, probably Dave Gerdes or Mike Higgins.

Update to GRASS 5.7 Radim Blazek and David D. Gray.

Update to GRASS 7 Martin Landa <landa.martin gmail.com>

Definition in file vector/Vlib/read.c.

Function Documentation

Vect_area_alive()

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

Parameters

Map	pointer to Map_info structure
area	area id

Returns

1 area alive

0 area is dead or index is out of range

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().

Vect_get_line_offset()

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().

Parameters

Map	pointer to Map_info structure
line	feature id

Returns

feature offset

-1 on error

Definition at line 295 of file vector/Vlib/read.c.

Vect_get_next_line_id()

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().

Parameters

Map	pointer to Map_info struct

Returns

feature id

-1 on error

Definition at line 88 of file vector/Vlib/read.c.

References _, G_debug(), G_warning(), Map_info::next_line, and VECT_OPEN.

Vect_isle_alive()

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

Parameters

Map	pointer to Map_info structure
isle	isle id

Returns

1 isle alive

0 isle is dead or index is out of range

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.

Vect_line_alive()

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

Parameters

Map	pointer to Map_info structure
line	feature id

Returns

1 feature alive

0 feature is dead or index is out of range

Definition at line 197 of file vector/Vlib/read.c.

Vect_node_alive()

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

Parameters

Map	pointer to Map_info structure
node	node id

Returns

1 node alive

0 node is dead or index is out of range

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.

Vect_read_line()

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.

Parameters

	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)

Returns

feature type

-1 on failure

-2 nothing to read

Definition at line 160 of file vector/Vlib/read.c.

Referenced by NetA_initialise_varray(), and Vect_get_area_cats().

Vect_read_next_line()

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.

Parameters

	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)

Returns

feature type (GV_POINT, GV_LINE, ...)

-1 on error

-2 nothing to read

Definition at line 121 of file vector/Vlib/read.c.

References _, G_debug(), G_warning(), Map_info::next_line, and VECT_OPEN.