libvips/libsrc/relational/im_ifthenelse.c

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/* @(#) Two images as input: must match in size and type. Build an output
* @(#) image choosing pixels from the left if a conditional image is
* @(#) non-zero and from the right otherwise.
* @(#)
* @(#) The conditional image can have n bands or 1 band. If n bands, then we
* @(#) choose from the two source images an element at a time. If 1 band,
* @(#) then choose from the source images a pixel at a time.
* @(#)
* @(#) int
* @(#) im_ifthenelse( c, a, b, out )
* @(#) IMAGE *c, *a, *b;
* @(#) IMAGE *out;
* @(#)
* @(#) Returns either 0 (success) or -1 (fail).
*
* Modified:
* 9/2/95 JC
* - partialed and ANSIfied
* 11/9/95 JC
* - return( 0 ) missing! oops
* 15/4/05
* - now just evals left/right if all zero/all one
* 7/10/06
* - set THINSTRIP
*/
/*
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 <vips/vips.h>
#ifdef WITH_DMALLOC
#include <dmalloc.h>
#endif /*WITH_DMALLOC*/
static int
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ifthenelse_gen( REGION *or, void *seq, void *client1, void *client2 )
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{
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REGION **ir = (REGION **) seq;
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Rect *r = &or->valid;
int le = r->left;
int to = r->top;
int bo = IM_RECT_BOTTOM(r);
IMAGE *c = ir[0]->im;
IMAGE *a = ir[1]->im;
int size, width;
int i, x, y, z;
int all0, alln0;
if( c->Bands == 1 ) {
/* Copying PEL-sized units with a one-band conditional.
*/
size = IM_IMAGE_SIZEOF_PEL( a );
width = r->width;
}
else {
/* Copying ELEMENT sized-units with an n-band conditional.
*/
size = IM_IMAGE_SIZEOF_ELEMENT( a );
width = r->width * a->Bands;
}
if( im_prepare( ir[0], r ) )
return( -1 );
/* Is the conditional all zero or all non-zero? We can avoid asking
* for one of the inputs to be calculated.
*/
all0 = *((PEL *) IM_REGION_ADDR( ir[0], le, to )) == 0;
alln0 = *((PEL *) IM_REGION_ADDR( ir[0], le, to )) != 0;
for( y = to; y < bo; y++ ) {
PEL *p = (PEL *) IM_REGION_ADDR( ir[0], le, y );
for( x = 0; x < width; x++ ) {
all0 &= p[x] == 0;
alln0 &= p[x] != 0;
}
if( !all0 && !alln0 )
break;
}
if( alln0 ) {
/* All non-zero. Point or at the then image.
*/
if( im_prepare( ir[1], r ) ||
im_region_region( or, ir[1], r, r->left, r->top ) )
return( -1 );
}
else if( all0 ) {
/* All zero. Point or at the else image.
*/
if( im_prepare( ir[2], r ) ||
im_region_region( or, ir[2], r, r->left, r->top ) )
return( -1 );
}
else {
/* Mix of set and clear ... ask for both then and else parts
* and interleave.
*/
if( im_prepare( ir[1], r ) || im_prepare( ir[2], r ) )
return( -1 );
for( y = to; y < bo; y++ ) {
PEL *cp = (PEL *) IM_REGION_ADDR( ir[0], le, y );
PEL *ap = (PEL *) IM_REGION_ADDR( ir[1], le, y );
PEL *bp = (PEL *) IM_REGION_ADDR( ir[2], le, y );
PEL *q = (PEL *) IM_REGION_ADDR( or, le, y );
for( x = 0, i = 0; i < width; i++, x += size ) {
if( cp[i] )
for( z = x; z < x + size; z++ )
q[z] = ap[z];
else
for( z = x; z < x + size; z++ )
q[z] = bp[z];
}
}
}
return( 0 );
}
/* if-then-else. Use IM_BANDFMT_UCHAR image to choose between two other images.
* Either: all same number of bands, or choice image is one band, others are
* n band.
*/
int
im_ifthenelse( IMAGE *c, IMAGE *a, IMAGE *b, IMAGE *out )
{
IMAGE **in;
/* Check args.
*/
if( a->Coding != IM_CODING_NONE && a->Coding != IM_CODING_LABQ ) {
im_error( "im_ifthenelse",
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"%s", _( "then image must be uncoded or labpack" ) );
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return( -1 );
}
if( b->Coding != IM_CODING_NONE && b->Coding != IM_CODING_LABQ ) {
im_error( "im_ifthenelse",
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"%s", _( "else image must be uncoded or labpack" ) );
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return( -1 );
}
if( c->Coding != IM_CODING_NONE ) {
im_error( "im_ifthenelse",
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"%s", _( "condition image must be uncoded" ) );
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return( -1 );
}
if( a->BandFmt != b->BandFmt ||
a->Bands != b->Bands ) {
im_error( "im_ifthenelse",
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"%s", _( "size and format of then and else "
"must match" ) );
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return( -1 );
}
if( c->BandFmt != IM_BANDFMT_UCHAR ) {
im_error( "im_ifthenelse",
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"%s", _( "conditional image must be uchar" ) );
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return( -1 );
}
if( c->Bands != 1 && c->Bands != a->Bands ) {
im_error( "im_ifthenelse",
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"%s", _( "conditional image must be one band or same "
"as then and else images" ) );
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return( -1 );
}
/* Make output image.
*/
if( im_demand_hint( out, IM_THINSTRIP, c, a, b, NULL ) ||
im_cp_descv( out, a, b, c, NULL ) ||
!(in = im_allocate_input_array( out, c, a, b, NULL )) ||
im_generate( out,
im_start_many, ifthenelse_gen, im_stop_many,
in, NULL ) )
return( -1 );
return( 0 );
}