| .TH IM_ITERATE 3 "30 October 1992" |
| .SH NAME |
| im_iterate \- PIO input from image |
| .SH SYNOPSIS |
| .B #include <vips/vips.h> |
| |
| int im_iterate( im, start_fn, scan_fn, stop_fn, a, b ) |
| .br |
| IMAGE *im; |
| .br |
| void *(*start_fn)(); |
| .br |
| int (*scan_fn)(); |
| .br |
| int (*stop_fn)(); |
| .br |
| void *a, *b; |
| |
| where, typically, |
| |
| void *start_fn( im, a, b ) |
| .br |
| IMAGE *im; |
| .br |
| void *a, *b; |
| |
| int scan_fn( or, seq, a, b ) |
| .br |
| REGION *or; |
| .br |
| void *seq; |
| .br |
| void *a, *b; |
| |
| int stop_fn( seq, a, b ) |
| .br |
| void *seq; |
| .br |
| void *a, *b; |
| .SH DESCRIPTION |
| im_iterate(3) is used for PIO image input. See `VIPS Library Programmers' |
| guide,' in the accompanying documentation, for an introduction to this |
| function. |
| |
| im_iterate(3) makes one or more regions on im, and starts one or more sequences |
| running over the image. im_iterate(3) guarantees that |
| |
| - scan_fn() will see each of the pels in im exactly once |
| - start_fn() and stop_fn() are both exclusive |
| |
| See the guide, the man page for im_generate(3), and the source to im_deviate(3) |
| for examples. |
| |
| On machines with SVR4 threads and several CPUs, im_generate(3) and |
| im_iterate(3) automatically parallelise programs. You can set the desired |
| concurrency level with the environment variable IM_CONCURRENCY, for example |
| |
| example% setenv IM_CONCURRENCY 2 |
| example% stats fred.v |
| |
| will run stats with enough concurrency to keep 2 CPUs fully occupied. |
| If IM_CONCURRENCY is not set, then it defaults to 1. |
| .SH RETURN VALUE |
| All functions return 0 on success and non-zero on error. |
| .SH SEE ALSO |
| im_generate(3). |
| .SH COPYRIGHT |
| National Gallery, 1993 |
| .SH AUTHOR |
| J. Cupitt \- 23/7/93 |
