| .TH MACROS 3 "11 April 1990" |
| .SH NAME |
| IM_IMAGE_ADDR, IM_IMAGE_SIZEOF_ELEMENT, IM_IMAGE_SIZEOF_PEL, |
| IM_IMAGE_SIZEOF_LINE, IM_IMAGE_N_ELEMENTS \- |
| macros for images |
| .SH SYNOPSIS |
| .B #include <vips/vips.h> |
| |
| int IM_IMAGE_SIZEOF_ELEMENT( im ) |
| .br |
| IMAGE *im; |
| |
| int IM_IMAGE_SIZEOF_PEL( im ) |
| .br |
| IMAGE *im; |
| |
| int IM_IMAGE_SIZEOF_LINE( im ) |
| .br |
| IMAGE *im; |
| |
| int IM_IMAGE_N_ELEMENTS( im ) |
| .br |
| IMAGE *im; |
| |
| char *IM_IMAGE_ADDR( im, x, y ) |
| .br |
| IMAGE *im; |
| .br |
| int x; |
| .br |
| int y; |
| |
| .SH 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. |
| .SH COPYRIGHT |
| National Gallery, 1993 |
| .SH SEE ALSO |
| IM_REGION_ADDR(3), im_malloc(3), im_open_local(3). |
| .SH AUTHOR |
| J. Cupitt \- 23/7/93 |
