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gimp/app/core/gimp-transform-resize.c

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/* The GIMP -- an image manipulation program
* Copyright (C) 1995-2001 Spencer Kimball, Peter Mattis, and others
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU 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 General Public License for more details.
*
* You should have received a copy of the GNU 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.
*/
#include "config.h"
#include <glib-object.h>
#include "libgimpmath/gimpmath.h"
#include "core-types.h"
#include "gimp-transform-resize.h"
#if defined (HAVE_FINITE)
#define FINITE(x) finite(x)
#elif defined (HAVE_ISFINITE)
#define FINITE(x) isfinite(x)
#elif defined (G_OS_WIN32)
#define FINITE(x) _finite(x)
#else
#error "no FINITE() implementation available?!"
#endif
#define MIN4(a,b,c,d) MIN(MIN((a),(b)),MIN((c),(d)))
#define MAX4(a,b,c,d) MAX(MAX((a),(b)),MAX((c),(d)))
typedef struct
{
gdouble x, y;
} Point;
typedef struct
{
gint xmin, xmax;
gint ymin, ymax;
gdouble m, b; /* y = mx + b */
gboolean top, right;
} Edge;
static void gimp_transform_resize_adjust (gdouble dx1,
gdouble dy1,
gdouble dx2,
gdouble dy2,
gdouble dx3,
gdouble dy3,
gdouble dx4,
gdouble dy4,
gint *x1,
gint *y1,
gint *x2,
gint *y2);
static void gimp_transform_resize_crop (gdouble dx1,
gdouble dy1,
gdouble dx2,
gdouble dy2,
gdouble dx3,
gdouble dy3,
gdouble dx4,
gdouble dy4,
gint *x1,
gint *y1,
gint *x2,
gint *y2);
/*
* This function wants to be passed the inverse transformation matrix!!
*/
void
gimp_transform_resize_boundary (const GimpMatrix3 *inv,
GimpTransformResize resize,
gint u1,
gint v1,
gint u2,
gint v2,
gint *x1,
gint *y1,
gint *x2,
gint *y2)
{
gdouble dx1, dx2, dx3, dx4;
gdouble dy1, dy2, dy3, dy4;
g_return_if_fail (inv != NULL);
/* initialize with the original boundary */
*x1 = u1;
*y1 = v1;
*x2 = u2;
*y2 = v2;
if (resize == GIMP_TRANSFORM_SIZE_CLIP)
return;
gimp_matrix3_transform_point (inv, u1, v1, &dx1, &dy1);
gimp_matrix3_transform_point (inv, u2, v1, &dx2, &dy2);
gimp_matrix3_transform_point (inv, u1, v2, &dx3, &dy3);
gimp_matrix3_transform_point (inv, u2, v2, &dx4, &dy4);
/* check if the transformation matrix is valid at all */
if (! FINITE (dx1) || ! FINITE (dy1) ||
! FINITE (dx2) || ! FINITE (dy2) ||
! FINITE (dx3) || ! FINITE (dy3) ||
! FINITE (dx4) || ! FINITE (dy4))
{
g_warning ("invalid transform matrix");
resize = GIMP_TRANSFORM_SIZE_CLIP;
}
switch (resize)
{
case GIMP_TRANSFORM_SIZE_ADJUST:
gimp_transform_resize_adjust (dx1, dy1, dx2, dy2, dx3, dy3, dx4, dy4,
x1, y1, x2, y2);
break;
case GIMP_TRANSFORM_SIZE_CLIP:
/* we are all done already */
break;
case GIMP_TRANSFORM_SIZE_CROP:
gimp_transform_resize_crop (dx1, dy1, dx2, dy2, dx3, dy3, dx4, dy4,
x1, y1, x2, y2);
break;
}
if (*x1 == *x2)
(*x2)++;
if (*y1 == *y2)
(*y2)++;
}
static void
gimp_transform_resize_adjust (gdouble dx1,
gdouble dy1,
gdouble dx2,
gdouble dy2,
gdouble dx3,
gdouble dy3,
gdouble dx4,
gdouble dy4,
gint *x1,
gint *y1,
gint *x2,
gint *y2)
{
*x1 = (gint) floor (MIN4 (dx1, dx2, dx3, dx4));
*y1 = (gint) floor (MIN4 (dy1, dy2, dy3, dy4));
*x2 = (gint) ceil (MAX4 (dx1, dx2, dx3, dx4));
*y2 = (gint) ceil (MAX4 (dy1, dy2, dy3, dy4));
}
static void
edge_init (Edge *edge,
const Point *p,
const Point *q)
{
edge->xmin = MIN (ceil (p->x), ceil (q->x));
edge->xmax = MAX (floor (p->x), floor (q->x));
edge->ymin = MIN (ceil (p->y), ceil (q->y));
edge->ymax = MAX (floor (p->y), floor (q->y));
edge->top = p->x > q->x;
edge->right = p->y > q->y;
edge->m = (q->y - p->y) / (q->x - p->x);
edge->b = p->y - edge->m * p->x;
}
static const Edge *
find_edge (const Edge *edges,
gint x,
gboolean top)
{
const Edge *emax = edges;
gint i;
for (i = 0; i < 4; i++)
{
const Edge *e = edges + i;
if (e->xmin == x && e->xmax != e->xmin &&
((e->top && top) || (!e->top && !top)))
emax = e;
}
return emax;
}
/* find largest pixel completely inside;
* look through all edges for intersection
*/
static gint
intersect_x (const Edge *edges,
gint y)
{
gdouble x0 = 0;
gdouble x1 = 0;
gint i;
for (i = 0; i < 4; i++)
if (edges[i].right && edges[i].ymin <= y && edges[i].ymax >= y)
{
x0 = (double) (y + 0.5 - edges[i].b) / edges[i].m;
x1 = (double) (y - 0.5 - edges[i].b) / edges[i].m;
}
return (gint) floor (MIN (x0, x1));
}
static gint
intersect_y (const Edge *edge,
gint xi)
{
gdouble yfirst = edge->m * (xi - 0.5) + edge->b;
gdouble ylast = edge->m * (xi + 0.5) + edge->b;
return (gint) floor (edge->top ? MAX (yfirst, ylast) : MIN (yfirst, ylast));
}
static void
gimp_transform_resize_crop (gdouble dx1,
gdouble dy1,
gdouble dx2,
gdouble dy2,
gdouble dx3,
gdouble dy3,
gdouble dx4,
gdouble dy4,
gint *x1,
gint *y1,
gint *x2,
gint *y2)
{
Point points[4];
Edge edges[4];
const Point *a;
const Point *b;
const Edge *top;
const Edge *bottom;
gint *px;
gint xmin, ymin;
gint xmax, ymax;
gint maxarea = 0;
gint xi, y;
gint i;
/* fill in the points array */
points[0].x = dx1;
points[0].y = dy1;
points[1].x = dx2;
points[1].y = dy2;
points[2].x = dx3;
points[2].y = dy3;
points[3].x = dx4;
points[3].y = dy4;
/* create an array of edges */
for (i = 0, a = points + 3, b = points; i < 4; i++, a = b, b++)
edge_init (edges + i, a, b);
/* determine the bounding box */
xmin = edges[0].xmin;
xmax = edges[0].xmax;
ymin = edges[0].ymin;
ymax = edges[0].ymax;
for (i = 1; i < 4; i++)
{
const Edge *edge = edges + i;
if (edge->xmin < xmin)
xmin = edge->xmin;
if (edge->xmax > xmax)
xmax = edge->xmax;
if (edge->ymin < ymin)
ymin = edge->ymin;
if (edge->ymax > ymax)
ymax = edge->ymax;
}
g_printerr ("%d, %d -> %d, %d\n", xmin, ymin, xmax, ymax);
px = g_new (gint, ymax - ymin + 1);
for (y = ymin, i = 0; y <= ymax; y++, i++)
px[i] = intersect_x (edges, y);
top = find_edge (edges, xmin, TRUE);
bottom = find_edge (edges, xmax, FALSE);
g_printerr ("top: %d, %d -> %d, %d\n",
top->xmin, top->ymin, top->xmax, top->ymax);
g_printerr ("bottom: %d, %d -> %d, %d\n",
bottom->xmin, bottom->ymin, bottom->xmax, bottom->ymax);
for (xi = xmin; xi < xmax; xi++)
{
gint ylo, yhi;
ymin = intersect_y (top, xi);
ymax = intersect_y (bottom, xi);
for (ylo = ymax; ylo >= ymin; ylo--)
{
for (yhi = ymin; yhi <= ymax; yhi++)
{
if (yhi > ylo)
{
gint xlo = px[ylo - ymin];
gint xhi = px[yhi - ymin];
gint width = MIN (xlo, xhi) - xi;
gint height = yhi - ylo;
gint area = width * height;
if (area > maxarea)
{
maxarea = area;
*x1 = xi;
*y1 = ylo;
*x2 = xi + width;
*y2 = ylo + height;
}
}
}
}
if (xi == top->xmax)
top = find_edge (edges, xi, TRUE);
if (xi == bottom->xmax)
bottom = find_edge (edges, xi, FALSE);
}
g_printerr ("%d, %d -> %d, %d\n", *x1, *y1, *x2, *y2);
g_free (px);
}
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