libvips/libsrc/iofuncs/im_wrapmany.c

/* Wrap-up a buffer processing function as a PIO VIPS function.
 *
 * Given a NULL-terminated list of input images all of the same size, an
 * output image and a buffer processing function, make a PIO image processing
 * operation.
 *
 * 	int im_wrapmany( IMAGE **in, IMAGE *out, 
 *		im_wrapmany_fn fn, void *a, void *b )
 *
 * where im_wrapmany_fn has type:
 *
 *	process_buffer( void **in, void *out, int n,
 *		void *a, void *b )
 *
 * in is a NULL-terminated array of input buffers, out is an output buffer, n 
 * is the number of pixels (note! not band-elements) and a and b are extra 
 * arguments carried for the function
 *
 * Modified:
 * 1/8/95 JC
 *	- buffer functions now get their own copies of the input pointer
 *	  array
 * 28/7/97 JC
 *	- amazing error ... only worked if ir and or had same valid
 */

/*

    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 <vips/vips.h>

#ifdef WITH_DMALLOC
#include <dmalloc.h>
#endif /*WITH_DMALLOC*/

typedef struct {
	im_wrapmany_fn fn;	/* Function we call */ 
	void *a, *b;		/* User values for function */
} UserBundle;

/* Maximum number of input images -- why not?
 */
#define IM_MAX_INPUT_IMAGES (64)

/* Convert a REGION.
 */
static int
process_region( REGION *or, void *seq, void *a, void *b )
{
	REGION **ir = (REGION **) seq;
	UserBundle *bun = (UserBundle *) b;

	PEL *p[IM_MAX_INPUT_IMAGES], *q;
	int i, y;

	/* Prepare all input regions and make buffer pointers.
	 */
	for( i = 0; ir[i]; i++ ) {
		if( im_prepare( ir[i], &or->valid ) ) 
			return( -1 );
		p[i] = (PEL *) IM_REGION_ADDR( ir[i], 
			or->valid.left, or->valid.top );
	}
	p[i] = NULL;
	q = (PEL *) IM_REGION_ADDR( or, or->valid.left, or->valid.top );

	/* Convert linewise.
	 */
	for( y = 0; y < or->valid.height; y++ ) {
		PEL *p1[IM_MAX_INPUT_IMAGES];

		/* Make a copy of p[] which the buffer function can mess up if
		 * it wants.
		 */
		for( i = 0; ir[i]; i++ )
			p1[i] = p[i];

		/* Bizarre double-cast stops a bogus gcc 4.1 compiler warning.
		 */
		bun->fn( (void **) ((void *)p1), q, 
			or->valid.width, bun->a, bun->b );

		/* Move pointers on.
		 */
		for( i = 0; ir[i]; i++ )
			p[i] += IM_REGION_LSKIP( ir[i] );
		q += IM_REGION_LSKIP( or );
	}

	return( 0 );
}

/* Make a copy of an array of input images.
 */
static IMAGE **
dupims( IMAGE *out, IMAGE **in )
{
	IMAGE **new;
	int i, n;

	/* Count input images.
	 */
	for( n = 0; in[n]; n++ )
		;

	/* Allocate new array.
	 */
	if( !(new = IM_ARRAY( out, n + 1, IMAGE * )) )
		return( NULL );
	
	/* Copy.
	 */
	for( i = 0; i < n; i++ )
		new[i] = in[i];
	new[n] = NULL;

	return( new );
}

/* Wrap up as a partial.
 */
int
im_wrapmany( IMAGE **in, IMAGE *out, im_wrapmany_fn fn, void *a, void *b )
{
	UserBundle *bun = IM_NEW( out, UserBundle );
	int i, n;

	/* Count input images.
	 */
	for( n = 0; in[n]; n++ )
		;
	if( n >= IM_MAX_INPUT_IMAGES - 1 ) {
		im_error( "im_wrapmany", _( "too many input images" ) );
		return( -1 );
	}

	/* Save args.
	 */
	if( !bun || !(in = dupims( out, in )) )
		return( -1 );
	bun->fn = fn;
	bun->a = a;
	bun->b = b;

	/* Check descriptors --- make sure that our caller has done this
	 * correctly.
	 */
	for( i = 0; i < n; i++ ) {
		if( in[i]->Xsize != out->Xsize || in[i]->Ysize != out->Ysize ) {
			im_error( "im_wrapmany", 
				_( "descriptors differ in size" ) );
			return( -1 );
		}

		/* Check io style.
		 */
		if( im_piocheck( in[i], out ) )
			return( -1 );
	}
	
	/* Hint demand style. Being a buffer processor, we are happiest with
	 * thin strips.
	 */
        if( im_demand_hint_array( out, IM_THINSTRIP, in ) )
                return( -1 );

	/* Generate!
	 */
	if( im_generate( out,
		im_start_many, process_region, im_stop_many, in, bun ) )
		return( -1 );

	return( 0 );
}