libvips/libsrc/resample/transform.c

243 lines
6.0 KiB
C

/* affine transforms
*/
/*
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
*/
/*
*/
#define DEBUG
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif /*HAVE_CONFIG_H*/
#include <vips/intl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include <limits.h>
#include <vips/vips.h>
#include <vips/internal.h>
#include <vips/transform.h>
#ifdef WITH_DMALLOC
#include <dmalloc.h>
#endif /*WITH_DMALLOC*/
/* Calculate the inverse transformation.
*/
int
im__transform_calc_inverse( Transformation *trn )
{
DOUBLEMASK *msk, *msk2;
if( !(msk = im_create_dmaskv( "boink", 2, 2,
trn->a, trn->b, trn->c, trn->d )) )
return( -1 );
if( !(msk2 = im_matinv( msk, "boink2" )) ) {
(void) im_free_dmask( msk );
return( -1 );
}
trn->ia = msk2->coeff[0];
trn->ib = msk2->coeff[1];
trn->ic = msk2->coeff[2];
trn->id = msk2->coeff[3];
(void) im_free_dmask( msk );
(void) im_free_dmask( msk2 );
return( 0 );
}
/* Init a Transform.
*/
void
im__transform_init( Transformation *trn )
{
trn->oarea.left = 0;
trn->oarea.top = 0;
trn->oarea.width = -1;
trn->oarea.height = -1;
trn->iarea.left = 0;
trn->iarea.top = 0;
trn->iarea.width = -1;
trn->iarea.height = -1;
trn->a = 1.0; /* Identity transform */
trn->b = 0.0;
trn->c = 0.0;
trn->d = 1.0;
trn->dx = 0.0;
trn->dy = 0.0;
(void) im__transform_calc_inverse( trn );
}
/* Test for transform is identity function.
*/
int
im__transform_isidentity( const Transformation *trn )
{
if( trn->a == 1.0 && trn->b == 0.0 && trn->c == 0.0 &&
trn->d == 1.0 && trn->dx == 0.0 && trn->dy == 0.0 )
return( 1 );
else
return( 0 );
}
/* Combine two transformations. out can be one of the ins.
*/
int
im__transform_add( const Transformation *in1, const Transformation *in2,
Transformation *out )
{
out->a = in1->a * in2->a + in1->c * in2->b;
out->b = in1->b * in2->a + in1->d * in2->b;
out->c = in1->a * in2->c + in1->c * in2->d;
out->d = in1->b * in2->c + in1->d * in2->d;
out->dx = in1->dx * in2->a + in1->dy * in2->b + in2->dx;
out->dy = in1->dx * in2->c + in1->dy * in2->d + in2->dy;
if( im__transform_calc_inverse( out ) )
return( -1 );
return( 0 );
}
void
im__transform_print( const Transformation *trn )
{
printf( "im__transform_print:\n" );
printf( " iarea: left=%d, top=%d, width=%d, height=%d\n",
trn->iarea.left,
trn->iarea.top,
trn->iarea.width,
trn->iarea.height );
printf( " oarea: left=%d, top=%d, width=%d, height=%d\n",
trn->oarea.left,
trn->oarea.top,
trn->oarea.width,
trn->oarea.height );
printf( " mat: a=%g, b=%g, c=%g, d=%g\n",
trn->a, trn->b, trn->c, trn->d );
printf( " off: dx=%g, dy=%g\n",
trn->dx, trn->dy );
}
/* Map a pixel coordinate through the transform.
*/
void
im__transform_forward_point( const Transformation *trn,
const double x, const double y, /* In input space */
double *ox, double *oy ) /* In output space */
{
*ox = trn->a * x + trn->b * y + trn->dx;
*oy = trn->c * x + trn->d * y + trn->dy;
}
/* Map a pixel coordinate through the inverse transform.
*/
void
im__transform_invert_point( const Transformation *trn,
const double x, const double y, /* In output space */
double *ox, double *oy ) /* In input space */
{
double mx = x - trn->dx;
double my = y - trn->dy;
*ox = trn->ia * mx + trn->ib * my;
*oy = trn->ic * mx + trn->id * my;
}
typedef void (*transform_fn)( const Transformation *,
const double, const double, double*, double* );
/* Transform a rect using a point transformer.
*/
static void
transform_rect( const Transformation *trn, transform_fn transform,
const Rect *in, /* In input space */
Rect *out ) /* In output space */
{
double x1, y1; /* Map corners */
double x2, y2;
double x3, y3;
double x4, y4;
double left, right, top, bottom;
/* Map input Rect.
*/
transform( trn, in->left, in->top, &x1, &y1 );
transform( trn, in->left, IM_RECT_BOTTOM( in ), &x3, &y3 );
transform( trn, IM_RECT_RIGHT( in ), in->top, &x2, &y2 );
transform( trn, IM_RECT_RIGHT( in ), IM_RECT_BOTTOM( in ), &x4, &y4 );
/* Find bounding box for these four corners. Round-to-nearest to try
* to stop rounding errors growing images.
*/
left = IM_MIN( x1, IM_MIN( x2, IM_MIN( x3, x4 ) ) );
right = IM_MAX( x1, IM_MAX( x2, IM_MAX( x3, x4 ) ) );
top = IM_MIN( y1, IM_MIN( y2, IM_MIN( y3, y4 ) ) );
bottom = IM_MAX( y1, IM_MAX( y2, IM_MAX( y3, y4 ) ) );
out->left = IM_RINT( left );
out->top = IM_RINT( top );
out->width = IM_RINT( right - left );
out->height = IM_RINT( bottom - top );
}
/* Given an area in the input image, calculate the bounding box for those
* pixels in the output image.
*/
void
im__transform_forward_rect( const Transformation *trn,
const Rect *in, /* In input space */
Rect *out ) /* In output space */
{
transform_rect( trn, im__transform_forward_point, in, out );
}
/* Given an area in the output image, calculate the bounding box for the
* corresponding pixels in the input image.
*/
void
im__transform_invert_rect( const Transformation *trn,
const Rect *in, /* In output space */
Rect *out ) /* In input space */
{
transform_rect( trn, im__transform_invert_point, in, out );
}
/* Set output area of trn so that it just holds all of our input pels.
*/
void
im__transform_set_area( Transformation *trn )
{
im__transform_forward_rect( trn, &trn->iarea, &trn->oarea );
}