NAME
IM_IMAGE_ADDR, IM_IMAGE_SIZEOF_ELEMENT, IM_IMAGE_SIZEOF_PEL,
IM_IMAGE_SIZEOF_LINE, IM_IMAGE_N_ELEMENTS - macros for images
SYNOPSIS
#include <vips/vips.h>
int IM_IMAGE_SIZEOF_ELEMENT( im )
IMAGE *im;
int IM_IMAGE_SIZEOF_PEL( im )
IMAGE *im;
int IM_IMAGE_SIZEOF_LINE( im )
IMAGE *im;
int IM_IMAGE_N_ELEMENTS( im )
IMAGE *im;
char *IM_IMAGE_ADDR( im, x, y )
IMAGE *im;
int x;
int y;
DESCRIPTION
These macros help to simplify address arithmetic for images.
returns sizeof( one band element ).
IM_IMAGE_SIZEOF_PEL(3) returns sizeof( one pel ).
IM_IMAGE_SIZEOF_LINE(3) returns sizeof( one horizontal line of pels ).
IM_IMAGE_N_ELEMENTS(3) returns the number of band elements across a
horizontal line.
IM_IMAGE_ADDR(3) returns a pointer to the pixel at position (x,y) in
the image. The point (x,y) should lie within the image.
If the macro DEBUG has been defined, then IM_IMAGE_ADDR(3) will also
perform bounds checking. If you ask for the address of a pel outside
the image, then IM_IMAGE_ADDR(3) will print an error message of the
form:
IM_IMAGE_ADDR: point out of bounds, file "test.c", line 18
(point x=50, y=0
should have been within Rect left=0, top=0, width=50, height=50)
and call abort(3).
DEBUG needs to be defined *before* vips.h is included. Either define
DEBUG with -D in your Makefile, or have a #define DEBUG right at the
top of your file.
COPYRIGHT
National Gallery, 1993
SEE ALSO
IM_REGION_ADDR(3), im_malloc(3), im_open_local(3).
AUTHOR
J. Cupitt - 23/7/93
11 April 1990 MACROS(3)