libvips/libsrc/iofuncs/callback.c

172 lines
4.1 KiB
C

/* Close and generate callbacks.
*
* 1/7/93 JC
* 20/7/93 JC
* - eval callbacks added
* 16/8/94 JC
* - evalend callbacks added
* 16/1/04 JC
* - now always calls all callbacks, even if some fail
* 2/7/08
* - added invalidate callbacks
* 26/11/08
* - don't set im_error() on callback failed, that's the user's job
*/
/*
This file is part of VIPS.
VIPS is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
/*
These files are distributed with VIPS - http://www.vips.ecs.soton.ac.uk
*/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif /*HAVE_CONFIG_H*/
#include <vips/intl.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <vips/vips.h>
#ifdef WITH_DMALLOC
#include <dmalloc.h>
#endif /*WITH_DMALLOC*/
/* Callback struct. We attach a list of callbacks to images to be invoked when
* the image is closed. These do things like closing previous elements in a
* chain of operations, freeing client data, etc.
*/
typedef struct {
IMAGE *im; /* IMAGE we are attached to */
int (*fn)(); /* callback function */
void *a, *b; /* arguments to callback */
} VCallback;
/* Add a callback to an IMAGE. We can't use IM_NEW(), note! Freed eventually by
* im__close(), or by im_generate(), etc. for evalend callbacks.
*/
static int
add_callback( IMAGE *im, GSList **cblist, int (*fn)(), void *a, void *b )
{
VCallback *cbs;
if( !(cbs = IM_NEW( NULL, VCallback )) )
return( -1 );
cbs->fn = fn;
cbs->a = a;
cbs->b = b;
cbs->im = im;
*cblist = g_slist_prepend( *cblist, cbs );
return( 0 );
}
int
im_add_close_callback( IMAGE *im, int (*fn)(), void *a, void *b )
{
return( add_callback( im, &im->closefns, fn, a, b ) );
}
int
im_add_preclose_callback( IMAGE *im, int (*fn)(), void *a, void *b )
{
return( add_callback( im, &im->preclosefns, fn, a, b ) );
}
/* Add an eval callback to an IMAGE. You must call this after opening the
* image but before using it as an argument to an operation.
*/
int
im_add_eval_callback( IMAGE *im, int (*fn)(), void *a, void *b )
{
/* Mark this image as needing progress feedback. im__link_make()
* propogates this value to our children as we build a pipeline.
* im__handle_eval() looks up the IMAGE it should signal on.
*/
im->progress = im;
return( add_callback( im, &im->evalfns, fn, a, b ) );
}
int
im_add_evalend_callback( IMAGE *im, int (*fn)(), void *a, void *b )
{
return( add_callback( im, &im->evalendfns, fn, a, b ) );
}
int
im_add_evalstart_callback( IMAGE *im, int (*fn)(), void *a, void *b )
{
return( add_callback( im, &im->evalstartfns, fn, a, b ) );
}
int
im_add_invalidate_callback( IMAGE *im, int (*fn)(), void *a, void *b )
{
return( add_callback( im, &im->invalidatefns, fn, a, b ) );
}
/* Perform a user callback.
*/
static void *
call_callback( VCallback *cbs, int *result )
{
int res;
if( (res = cbs->fn( cbs->a, cbs->b )) ) {
/* We don't set im_error() here, that's the callback's
* responsibility.
*/
*result = res;
#ifdef DEBUG_IO
printf( "im__trigger_callbacks: user callback "
"failed for %s\n", cbs->im->filename );
#endif /*DEBUG_IO*/
}
return( NULL );
}
/* Perform a list of user callbacks.
*/
int
im__trigger_callbacks( GSList *cblist )
{
int result;
#ifdef DEBUG_IO
printf( "im__trigger_callbacks: calling %d user callbacks ..\n",
g_slist_length( cblist ) );
#endif /*DEBUG_IO*/
result = 0;
(void) im_slist_map2( cblist,
(VSListMap2Fn) call_callback, &result, NULL );
return( result );
}