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/* shrink with a box filter
*
* 30/10/15
* - from shrink.c (now renamed as shrink2.c)
* - split to h and v shrinks for a large memory saving
* - now handles complex
* 15/8/16
* - more accurate resize
* - rename xshrink -> hshrink for greater consistency
*/
/*
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., 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301 USA
*/
/*
These files are distributed with VIPS - http://www.vips.ecs.soton.ac.uk
*/
/*
#define DEBUG
*/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif /*HAVE_CONFIG_H*/
#include <vips/intl.h>
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <vips/vips.h>
#include <vips/debug.h>
#include <vips/internal.h>
#include "presample.h"
typedef struct _VipsShrink {
VipsResample parent_instance;
double hshrink; /* Shrink factors */
double vshrink;
} VipsShrink;
typedef VipsResampleClass VipsShrinkClass;
G_DEFINE_TYPE( VipsShrink, vips_shrink, VIPS_TYPE_RESAMPLE );
static int
vips_shrink_build( VipsObject *object )
{
VipsResample *resample = VIPS_RESAMPLE( object );
VipsShrink *shrink = (VipsShrink *) object;
VipsImage **t = (VipsImage **)
vips_object_local_array( object, 3 );
int hshrink_int;
int vshrink_int;
if( VIPS_OBJECT_CLASS( vips_shrink_parent_class )->build( object ) )
return( -1 );
hshrink_int = (int) shrink->hshrink;
vshrink_int = (int) shrink->vshrink;
if( hshrink_int != shrink->hshrink ||
vshrink_int != shrink->vshrink ) {
/* Shrink by int factors, affine to final size.
*/
double xresidual = hshrink_int / shrink->hshrink;
double yresidual = vshrink_int / shrink->vshrink;
if( vips_shrinkv( resample->in, &t[0], vshrink_int, NULL ) ||
vips_shrinkh( t[0], &t[1], hshrink_int, NULL ) )
return( -1 );
if( vips_affine( t[1], &t[2],
xresidual, 0.0, 0.0, yresidual, NULL ) ||
vips_image_write( t[2], resample->out ) )
return( -1 );
}
else {
if( vips_shrinkv( resample->in, &t[0], shrink->vshrink, NULL ) ||
vips_shrinkh( t[0], &t[1], shrink->hshrink, NULL ) ||
vips_image_write( t[1], resample->out ) )
return( -1 );
}
return( 0 );
}
static void
vips_shrink_class_init( VipsShrinkClass *class )
{
GObjectClass *gobject_class = G_OBJECT_CLASS( class );
VipsObjectClass *vobject_class = VIPS_OBJECT_CLASS( class );
VipsOperationClass *operation_class = VIPS_OPERATION_CLASS( class );
VIPS_DEBUG_MSG( "vips_shrink_class_init\n" );
gobject_class->set_property = vips_object_set_property;
gobject_class->get_property = vips_object_get_property;
vobject_class->nickname = "shrink";
vobject_class->description = _( "shrink an image" );
vobject_class->build = vips_shrink_build;
operation_class->flags = VIPS_OPERATION_SEQUENTIAL_UNBUFFERED;
VIPS_ARG_DOUBLE( class, "vshrink", 9,
_( "Vshrink" ),
_( "Vertical shrink factor" ),
VIPS_ARGUMENT_REQUIRED_INPUT,
G_STRUCT_OFFSET( VipsShrink, vshrink ),
1.0, 1000000.0, 1.0 );
VIPS_ARG_DOUBLE( class, "hshrink", 8,
_( "Hshrink" ),
_( "Horizontal shrink factor" ),
VIPS_ARGUMENT_REQUIRED_INPUT,
G_STRUCT_OFFSET( VipsShrink, hshrink ),
1.0, 1000000.0, 1.0 );
/* The old names .. now use h and v everywhere.
*/
VIPS_ARG_DOUBLE( class, "xshrink", 8,
_( "Xshrink" ),
_( "Horizontal shrink factor" ),
VIPS_ARGUMENT_REQUIRED_INPUT | VIPS_ARGUMENT_DEPRECATED,
G_STRUCT_OFFSET( VipsShrink, hshrink ),
1.0, 1000000.0, 1.0 );
VIPS_ARG_DOUBLE( class, "yshrink", 9,
_( "Yshrink" ),
_( "Vertical shrink factor" ),
VIPS_ARGUMENT_REQUIRED_INPUT | VIPS_ARGUMENT_DEPRECATED,
G_STRUCT_OFFSET( VipsShrink, vshrink ),
1.0, 1000000.0, 1.0 );
}
static void
vips_shrink_init( VipsShrink *shrink )
{
}
/**
* vips_shrink:
* @in: input image
* @out: output image
* @hshrink: horizontal shrink
* @vshrink: vertical shrink
* @...: %NULL-terminated list of optional named arguments
*
* Shrink @in by a pair of factors with a simple box filter. For non-integer
* factors, vips_shrink() will first shrink by the integer part with a box
* filter, then use vips_affine() plus bilinear interpolation to shrink by the
* remaining fractional part.
*
* This is a very low-level operation: see vips_resize() for a more
* convenient way to resize images.
*
* This operation does not change xres or yres. The image resolution needs to
* be updated by the application.
*
* See also: vips_resize(), vips_affine().
*
* Returns: 0 on success, -1 on error
*/
int
vips_shrink( VipsImage *in, VipsImage **out,
double hshrink, double vshrink, ... )
{
va_list ap;
int result;
va_start( ap, vshrink );
result = vips_call_split( "shrink", ap, in, out, hshrink, vshrink );
va_end( ap );
return( result );
}
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