GRASS GIS 8 Programmer's Manual  8.4.0dev(2024)-6da4f45b8e
bitmap.c File Reference
#include <stdio.h>
#include <stdlib.h>
#include <grass/linkm.h>
#include <grass/bitmap.h>
Include dependency graph for bitmap.c:

Go to the source code of this file.

Macros

#define BM_col_to_byte(x)   ((x) >> 3) /* x / 8 */
 
#define BM_col_to_bit(x)   ((x)&7) /* x % 8 */
 

Functions

struct BMBM_create (int x, int y)
 Create bitmap of dimension x/y and return structure token. More...
 
int BM_destroy (struct BM *map)
 Destroy bitmap and free all associated memory. More...
 
int BM_set_mode (int mode, int size)
 Specify the type of data structure to use for bitmap. 'mode' can be either BM_FLAT or BM_SPARSE: More...
 
int BM_set (struct BM *map, int x, int y, int val)
 Sets bitmap value to 'val' at location 'x' 'y'. More...
 
int BM_get (struct BM *map, int x, int y)
 Gets 'val' from the bitmap. More...
 
size_t BM_get_map_size (struct BM *map)
 Returns size in bytes that bitmap is taking up. More...
 
int BM_file_write (FILE *fp, struct BM *map)
 Write bitmap out to file. More...
 
struct BMBM_file_read (FILE *fp)
 Create map structure and load it from file. More...
 

Macro Definition Documentation

◆ BM_col_to_bit

#define BM_col_to_bit (   x)    ((x)&7) /* x % 8 */

Definition at line 41 of file bitmap.c.

◆ BM_col_to_byte

#define BM_col_to_byte (   x)    ((x) >> 3) /* x / 8 */

Definition at line 40 of file bitmap.c.

Function Documentation

◆ BM_create()

struct BM* BM_create ( int  x,
int  y 
)

Create bitmap of dimension x/y and return structure token.

Bitmap is initialized to all zeros

Parameters
xx dimension
yy dimension
Returns
pointer to struct BM
NULL on error

Definition at line 58 of file bitmap.c.

Referenced by gs_update_curmask(), gsbm_make_mask(), IL_create_bitmask(), and main().

◆ BM_destroy()

int BM_destroy ( struct BM map)

Destroy bitmap and free all associated memory.

Parameters
map
Returns
int returns 0

Definition at line 89 of file bitmap.c.

References BM_destroy_sparse(), BM::data, free(), and BM::sparse.

Referenced by gs_update_curmask().

◆ BM_file_read()

struct BM* BM_file_read ( FILE *  fp)

Create map structure and load it from file.

'fp' should previously been created by BM_file_write()

Returns struct BM * or NULL on error

Parameters
fp
Returns
struct BM

Definition at line 306 of file bitmap.c.

◆ BM_file_write()

int BM_file_write ( FILE *  fp,
struct BM map 
)

Write bitmap out to file.

Expects open file pointer 'fp' and existing map structure. Caller is responsible to open and close 'fp'.

Returns 0 or -1 on error

Parameters
fp
map
Returns
int

Definition at line 264 of file bitmap.c.

◆ BM_get()

int BM_get ( struct BM map,
int  x,
int  y 
)

Gets 'val' from the bitmap.

Returns 0 or 1 on success or -1 on error

Parameters
map
x
y
Returns
int

Definition at line 217 of file bitmap.c.

References BM_col_to_bit, BM_col_to_byte, BM_get_sparse(), BM::bytes, BM::cols, BM::data, BM::rows, BM::sparse, and x.

Referenced by calc_norm(), get_mapatt(), gs_masked(), gs_point_is_masked(), gsbm_make_mask(), gsd_wire_arrows(), gsd_wire_surf_const(), gsd_wire_surf_map(), IL_secpar_loop_2d(), and print_bm().

◆ BM_get_map_size()

size_t BM_get_map_size ( struct BM map)

Returns size in bytes that bitmap is taking up.

Parameters
map
Returns
int

Definition at line 241 of file bitmap.c.

References BM_get_map_size_sparse(), BM::bytes, BM::rows, and BM::sparse.

◆ BM_set()

int BM_set ( struct BM map,
int  x,
int  y,
int  val 
)

Sets bitmap value to 'val' at location 'x' 'y'.

Returns 0 on success

Parameters
map
x
y
val
Returns
int

Definition at line 185 of file bitmap.c.

References BM_col_to_bit, BM_col_to_byte, BM_set_sparse(), BM::bytes, BM::cols, BM::data, BM::rows, BM::sparse, and x.

Referenced by gs_update_curmask(), gsbm_make_mask(), IL_create_bitmask(), and main().

◆ BM_set_mode()

int BM_set_mode ( int  mode,
int  size 
)

Specify the type of data structure to use for bitmap. 'mode' can be either BM_FLAT or BM_SPARSE:

BM_FLAT is a basic packed bitmap - eight values stored per byte thus creating a 1:8 compression over using char arrays and a 1:32 compression over using CELL arrays.

BM_SPARSE is a linked array of values. This is much more efficient for large, very sparse arrays. It is slower to access, especially for writing, but can save several orders of magnitude of memory on large bitmaps.

NOTE: At this time 'size' must be passed a value of 1

returns 0 on success or -1 on error

Parameters
mode
size
Returns
int

Definition at line 147 of file bitmap.c.