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MACROS

MACROS

Section: C Library Functions (3) Updated: 11 April 1990
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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.

IM_IMAGE_SIZEOF_ELEMENT(3) 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


 

Index

NAME
SYNOPSIS
DESCRIPTION
COPYRIGHT
SEE ALSO
AUTHOR

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Time: 21:48:20 GMT, April 16, 2011