192 lines
4.9 KiB
C
192 lines
4.9 KiB
C
/* shrink with a box filter
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*
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* 30/10/15
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* - from shrink.c (now renamed as shrink2.c)
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* - split to h and v shrinks for a large memory saving
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* - now handles complex
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*/
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/*
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This file is part of VIPS.
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VIPS is free software; you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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02110-1301 USA
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*/
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/*
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These files are distributed with VIPS - http://www.vips.ecs.soton.ac.uk
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*/
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/*
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#define DEBUG
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*/
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#ifdef HAVE_CONFIG_H
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#include <config.h>
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#endif /*HAVE_CONFIG_H*/
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#include <vips/intl.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <math.h>
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#include <vips/vips.h>
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#include <vips/debug.h>
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#include <vips/internal.h>
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#include "presample.h"
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typedef struct _VipsShrink {
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VipsResample parent_instance;
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double xshrink; /* Shrink factors */
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double yshrink;
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} VipsShrink;
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typedef VipsResampleClass VipsShrinkClass;
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G_DEFINE_TYPE( VipsShrink, vips_shrink, VIPS_TYPE_RESAMPLE );
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static int
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vips_shrink_build( VipsObject *object )
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{
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VipsObjectClass *class = VIPS_OBJECT_GET_CLASS( object );
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VipsResample *resample = VIPS_RESAMPLE( object );
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VipsShrink *shrink = (VipsShrink *) object;
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VipsImage **t = (VipsImage **)
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vips_object_local_array( object, 3 );
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int xshrink_int;
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int yshrink_int;
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if( VIPS_OBJECT_CLASS( vips_shrink_parent_class )->build( object ) )
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return( -1 );
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xshrink_int = (int) shrink->xshrink;
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yshrink_int = (int) shrink->yshrink;
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if( xshrink_int != shrink->xshrink ||
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yshrink_int != shrink->yshrink ) {
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/* Shrink by int factors, affine to final size.
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*/
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int target_width = resample->in->Xsize / shrink->xshrink;
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int target_height = resample->in->Ysize / shrink->yshrink;
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double xresidual;
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double yresidual;
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if( vips_shrinkv( resample->in, &t[0], yshrink_int, NULL ) ||
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vips_shrinkh( t[0], &t[1], xshrink_int, NULL ) )
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return( -1 );
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xresidual = target_width / t[1]->Xsize;
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yresidual = target_height / t[1]->Ysize;
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if( vips_affine( t[1], &t[2],
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xresidual, 0, 0, yresidual, NULL ) ||
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vips_image_write( t[2], resample->out ) )
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return( -1 );
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}
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else {
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if( vips_shrinkv( resample->in, &t[0], shrink->yshrink, NULL ) ||
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vips_shrinkh( t[0], &t[1], shrink->xshrink, NULL ) ||
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vips_image_write( t[1], resample->out ) )
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return( -1 );
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}
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return( 0 );
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}
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static void
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vips_shrink_class_init( VipsShrinkClass *class )
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{
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GObjectClass *gobject_class = G_OBJECT_CLASS( class );
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VipsObjectClass *vobject_class = VIPS_OBJECT_CLASS( class );
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VipsOperationClass *operation_class = VIPS_OPERATION_CLASS( class );
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VIPS_DEBUG_MSG( "vips_shrink_class_init\n" );
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gobject_class->set_property = vips_object_set_property;
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gobject_class->get_property = vips_object_get_property;
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vobject_class->nickname = "shrink";
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vobject_class->description = _( "shrink an image" );
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vobject_class->build = vips_shrink_build;
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operation_class->flags = VIPS_OPERATION_SEQUENTIAL_UNBUFFERED;
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VIPS_ARG_DOUBLE( class, "xshrink", 8,
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_( "Xshrink" ),
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_( "Horizontal shrink factor" ),
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VIPS_ARGUMENT_REQUIRED_INPUT,
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G_STRUCT_OFFSET( VipsShrink, xshrink ),
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1.0, 1000000.0, 1.0 );
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VIPS_ARG_DOUBLE( class, "yshrink", 9,
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_( "Yshrink" ),
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_( "Vertical shrink factor" ),
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VIPS_ARGUMENT_REQUIRED_INPUT,
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G_STRUCT_OFFSET( VipsShrink, yshrink ),
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1.0, 1000000.0, 1.0 );
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}
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static void
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vips_shrink_init( VipsShrink *shrink )
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{
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}
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/**
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* vips_shrink:
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* @in: input image
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* @out: output image
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* @xshrink: horizontal shrink
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* @yshrink: vertical shrink
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* @...: %NULL-terminated list of optional named arguments
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*
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* Shrink @in by a pair of factors with a simple box filter. For non-integer
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* factors, vips_shrink() will first shrink by the integer part with a box
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* filter, then use vips_affine() plus bilinear interpolation to shrink by the
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* remaining fractional part.
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*
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* This is a very low-level operation: see vips_resize() for a more
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* convenient way to resize images.
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*
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* This operation does not change xres or yres. The image resolution needs to
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* be updated by the application.
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*
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* See also: vips_resize(), vips_affine().
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*
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* Returns: 0 on success, -1 on error
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*/
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int
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vips_shrink( VipsImage *in, VipsImage **out,
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double xshrink, double yshrink, ... )
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{
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va_list ap;
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int result;
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va_start( ap, yshrink );
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result = vips_call_split( "shrink", ap, in, out, xshrink, yshrink );
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va_end( ap );
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return( result );
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}
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