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

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/* GIMP - The GNU 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 3 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, see <http://www.gnu.org/licenses/>.
*/
#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 EPSILON 0.00000001
#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
{
Point a, b, c, d;
gdouble area;
gdouble aspect;
} Rectangle;
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,
gdouble aspect,
gint *x1,
gint *y1,
gint *x2,
gint *y2);
static void add_rectangle (Point points[4],
Rectangle *r,
Point a,
Point b,
Point c,
Point d);
static gboolean intersect (Point a,
Point b,
Point c,
Point d,
Point *i);
static gboolean intersect_x (Point a,
Point b,
Point c,
Point *i);
static gboolean intersect_y (Point a,
Point b,
Point c,
Point *i);
static gboolean in_poly (Point points[4],
Point p);
static gboolean point_on_border (Point points[4],
Point p);
static void find_two_point_rectangle (Rectangle *r,
Point points[4],
gint p);
static void find_three_point_rectangle_corner (Rectangle *r,
Point points[4],
gint p);
static void find_three_point_rectangle (Rectangle *r,
Point points[4],
gint p);
static void find_three_point_rectangle_triangle (Rectangle *r,
Point points[4],
gint p);
static void find_maximum_aspect_rectangle (Rectangle *r,
Point points[4],
gint p);
/*
* 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 clipping then just return the original rectangle */
if (resize == GIMP_TRANSFORM_RESIZE_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");
/* since there is no sensible way to deal with this, just do the same as
* with GIMP_TRANSFORM_RESIZE_CLIP: return
*/
return;
}
switch (resize)
{
case GIMP_TRANSFORM_RESIZE_ADJUST:
/* return smallest rectangle (with sides parallel to x- and y-axis)
* that surrounds the new points */
gimp_transform_resize_adjust (dx1, dy1, dx2, dy2, dx3, dy3, dx4, dy4,
x1, y1, x2, y2);
break;
case GIMP_TRANSFORM_RESIZE_CROP:
gimp_transform_resize_crop (dx1, dy1, dx2, dy2, dx3, dy3, dx4, dy4,
0.0,
x1, y1, x2, y2);
break;
case GIMP_TRANSFORM_RESIZE_CROP_WITH_ASPECT:
gimp_transform_resize_crop (dx1, dy1, dx2, dy2, dx3, dy3, dx4, dy4,
((gdouble) u2 - u1) / (v2 - v1),
x1, y1, x2, y2);
break;
case GIMP_TRANSFORM_RESIZE_CLIP:
/* Remove warning about not handling all enum values. We handle
* this case in the beginning of the function
*/
break;
}
/* ensure that resulting rectangle has at least area 1 */
if (*x1 == *x2)
(*x2)++;
if (*y1 == *y2)
(*y2)++;
}
/* this calculates the smallest rectangle (with sides parallel to x- and
* y-axis) that contains the points d1 to d4
*/
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
gimp_transform_resize_crop (gdouble dx1,
gdouble dy1,
gdouble dx2,
gdouble dy2,
gdouble dx3,
gdouble dy3,
gdouble dx4,
gdouble dy4,
gdouble aspect,
gint *x1,
gint *y1,
gint *x2,
gint *y2)
{
Point points[4];
Rectangle r;
Point t,a;
gint i, j;
gint min;
/* 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;
/* find lowest, rightmost corner of surrounding rectangle */
a.x = 0;
a.y = 0;
for (i = 0; i < 4; i++)
{
if (points[i].x < a.x)
a.x = points[i].x;
if (points[i].y < a.y)
a.y = points[i].y;
}
/* and translate all the points to the first quadrant */
for (i = 0; i < 4; i++)
{
points[i].x += (-a.x) * 2;
points[i].y += (-a.y) * 2;
}
/* find the convex hull using Jarvis's March as the points are passed
* in different orders due to gimp_matrix3_transform_point()
*/
min = 0;
for (i = 0; i < 4; i++)
{
if (points[i].y < points[min].y)
min = i;
}
t = points[0];
points[0] = points[min];
points[min] = t;
for (i = 1; i < 4; i++)
{
gdouble theta, theta_m = 2.0 * G_PI;
gdouble theta_v = 0;
min = 3;
for (j = i; j < 4; j++)
{
gdouble sy = points[j].y - points[i - 1].y;
gdouble sx = points[j].x - points[i - 1].x;
theta = atan2 (sy, sx);
if ((theta < theta_m) &&
((theta > theta_v) || ((theta == theta_v) && (sx > 0))))
{
theta_m = theta;
min = j;
}
}
theta_v = theta_m;
t = points[i];
points[i] = points[min];
points[min] = t;
}
/* reverse the order of points */
t = points[0];
points[0] = points[3];
points[3] = t;
t = points[1];
points[1] = points[2];
points[2] = t;
r.a.x = r.a.y = r.b.x = r.b.y = r.c.x = r.c.y = r.d.x = r.d.y = r.area = 0;
r.aspect = aspect;
if (aspect != 0)
{
for (i = 0; i < 4; i++)
find_maximum_aspect_rectangle (&r, points, i);
}
else
{
for (i = 0; i < 4; i++)
{
find_three_point_rectangle (&r, points, i);
find_three_point_rectangle_corner (&r, points, i);
find_two_point_rectangle (&r, points, i);
find_three_point_rectangle_triangle (&r, points, i);
}
}
if (r.area == 0)
{
/* saveguard if something went wrong, adjust and give warning */
gimp_transform_resize_adjust (dx1, dy1, dx2, dy2, dx3, dy3, dx4, dy4,
x1, y1, x2, y2);
g_warning ("no rectangle found by algorith, no cropping done");
return;
}
else
{
/* round and translate the calculated points back */
*x1 = floor (r.a.x + 0.5);
*y1 = floor (r.a.y + 0.5);
*x2 = ceil (r.c.x - 0.5);
*y2 = ceil (r.c.y - 0.5);
*x1 = *x1 - ((-a.x) * 2);
*y1 = *y1 - ((-a.y) * 2);
*x2 = *x2 - ((-a.x) * 2);
*y2 = *y2 - ((-a.y) * 2);
return;
}
}
static void
find_three_point_rectangle (Rectangle *r,
Point points[4],
gint p)
{
Point a = points[p % 4]; /* 0 1 2 3 */
Point b = points[(p + 1) % 4]; /* 1 2 3 0 */
Point c = points[(p + 2) % 4]; /* 2 3 0 1 */
Point d = points[(p + 3) % 4]; /* 3 0 1 2 */
Point i1; /* intersection point */
Point i2; /* intersection point */
Point i3; /* intersection point */
if (intersect_x (b, c, a, &i1) &&
intersect_y (c, d, i1, &i2) &&
intersect_x (d, a, i2, &i3))
add_rectangle (points, r, i3, i3, i1, i1);
if (intersect_y (b, c, a, &i1) &&
intersect_x (c, d, i1, &i2) &&
intersect_y (d, a, i2, &i3))
add_rectangle (points, r, i3, i3, i1, i1);
if (intersect_x (d, c, a, &i1) &&
intersect_y (c, b, i1, &i2) &&
intersect_x (b, a, i2, &i3))
add_rectangle (points, r, i3, i3, i1, i1);
if (intersect_y (d, c, a, &i1) &&
intersect_x (c, b, i1, &i2) &&
intersect_y (b, a, i2, &i3))
add_rectangle (points, r, i3, i3, i1, i1);
}
static void
find_three_point_rectangle_corner (Rectangle *r,
Point points[4],
gint p)
{
Point a = points[p % 4]; /* 0 1 2 3 */
Point b = points[(p + 1) % 4]; /* 1 2 3 0 */
Point c = points[(p + 2) % 4]; /* 2 3 0 2 */
Point d = points[(p + 3) % 4]; /* 3 0 2 1 */
Point i1; /* intersection point */
Point i2; /* intersection point */
if (intersect_x (b, c, a , &i1) &&
intersect_y (c, d, i1, &i2))
add_rectangle (points, r, a, a, i1, i2);
if (intersect_y (b, c, a , &i1) &&
intersect_x (c, d, i1, &i2))
add_rectangle (points, r, a, a, i1, i2);
if (intersect_x (c, d, a , &i1) &&
intersect_y (b, c, i1, &i2))
add_rectangle (points, r, a, a, i1, i2);
if (intersect_y (c, d, a , &i1) &&
intersect_x (b, c, i1, &i2))
add_rectangle (points, r, a, a, i1, i2);
}
static void
find_two_point_rectangle (Rectangle *r,
Point points[4],
gint p)
{
Point a = points[ p % 4]; /* 0 1 2 3 */
Point b = points[(p + 1) % 4]; /* 1 2 3 0 */
Point c = points[(p + 2) % 4]; /* 2 3 0 1 */
Point d = points[(p + 3) % 4]; /* 3 0 1 2 */
Point i1; /* intersection point */
Point i2; /* intersection point */
Point mid; /* Mid point */
add_rectangle (points, r, a, a, c, c);
add_rectangle (points, r, b, b, d, d);
if (intersect_x (c, b, a, &i1) &&
intersect_y (c, b, a, &i2))
{
mid.x = ( i1.x + i2.x ) / 2.0;
mid.y = ( i1.y + i2.y ) / 2.0;
add_rectangle (points, r, a, a, mid, mid);
}
}
static void
find_three_point_rectangle_triangle (Rectangle *r,
Point points[4],
gint p)
{
Point a = points[p % 4]; /* 0 1 2 3 */
Point b = points[(p + 1) % 4]; /* 1 2 3 0 */
Point c = points[(p + 2) % 4]; /* 2 3 0 1 */
Point d = points[(p + 3) % 4]; /* 3 0 1 2 */
Point i1; /* intersection point */
Point i2; /* intersection point */
Point mid;
mid.x = (a.x + b.x) / 2.0;
mid.y = (a.y + b.y) / 2.0;
if (intersect_x (b, c, mid, &i1) &&
intersect_y (a, d, mid, &i2))
add_rectangle (points, r, mid, mid, i1, i2);
if (intersect_y (b, c, mid, &i1) &&
intersect_x (a, d, mid, &i2))
add_rectangle (points, r, mid, mid, i1, i2);
if (intersect_x (a, d, mid, &i1) &&
intersect_y (b, c, mid, &i2))
add_rectangle (points, r, mid, mid, i1, i2);
if (intersect_y (a, d, mid, &i1) &&
intersect_x (b, c, mid, &i2))
add_rectangle (points, r, mid, mid, i1, i2);
}
static void
find_maximum_aspect_rectangle (Rectangle *r,
Point points[4],
gint p)
{
Point a = points[ p % 4]; /* 0 1 2 3 */
Point b = points[(p + 1) % 4]; /* 1 2 3 0 */
Point c = points[(p + 2) % 4]; /* 2 3 0 1 */
Point d = points[(p + 3) % 4]; /* 3 0 1 2 */
Point i1; /* intersection point */
Point i2; /* intersection point */
Point i3; /* intersection point */
if (intersect_x (b, c, a, &i1))
{
i2.x = i1.x + 1.0 * r->aspect;
i2.y = i1.y + 1.0;
if (intersect (d, a, i1, i2, &i3))
add_rectangle (points, r, i1, i3, i1, i3);
if (intersect (a, b, i1, i2, &i3))
add_rectangle (points, r, i1, i3, i1, i3);
if (intersect (c, d, i1, i2, &i3))
add_rectangle (points, r, i1, i3, i1, i3);
i2.x = i1.x - 1.0 * r->aspect;
i2.y = i1.y + 1.0;
if (intersect (d, a, i1, i2, &i3))
add_rectangle (points, r, i1, i3, i1, i3);
if (intersect (a, b, i1, i2, &i3))
add_rectangle (points, r, i1, i3, i1, i3);
if (intersect (c, d, i1, i2, &i3))
add_rectangle (points, r, i1, i3, i1, i3);
}
if (intersect_y (b, c, a, &i1))
{
i2.x = i1.x + 1.0 * r->aspect;
i2.y = i1.y + 1.0;
if (intersect (d, a, i1, i2, &i3))
add_rectangle (points, r, i1, i3, i1, i3);
if (intersect (a, b, i1, i2, &i3))
add_rectangle (points, r, i1, i3, i1, i3);
if (intersect (c, d, i1, i2, &i3))
add_rectangle (points, r, i1, i3, i1, i3);
i2.x = i1.x - 1.0 * r->aspect;
i2.y = i1.y + 1.0;
if (intersect (d, a, i1, i2, &i3))
add_rectangle (points, r, i1, i3, i1, i3);
if (intersect (a, b, i1, i2, &i3))
add_rectangle (points, r, i1, i3, i1, i3);
if (intersect (c, d, i1, i2, &i3))
add_rectangle (points, r, i1, i3, i1, i3);
}
if (intersect_x (c, d, a, &i1))
{
i2.x = i1.x + 1.0 * r->aspect;
i2.y = i1.y + 1.0;
if (intersect (d, a, i1, i2, &i3))
add_rectangle (points, r, i1, i3, i1, i3);
if (intersect (a, b, i1, i2, &i3))
add_rectangle (points, r, i1, i3, i1, i3);
if (intersect (b, c, i1, i2, &i3))
add_rectangle (points, r, i1, i3, i1, i3);
i2.x = i1.x - 1.0 * r->aspect;
i2.y = i1.y + 1.0;
if (intersect (d, a, i1, i2, &i3))
add_rectangle (points, r, i1, i3, i1, i3);
if (intersect (a, b, i1, i2, &i3))
add_rectangle (points, r, i1, i3, i1, i3);
if (intersect (b, c, i1, i2, &i3))
add_rectangle (points, r, i1, i3, i1, i3);
}
if (intersect_y (c, d, a, &i1))
{
i2.x = i1.x + 1.0 * r->aspect;
i2.y = i1.y + 1.0;
if (intersect (d, a, i1, i2, &i3))
add_rectangle (points, r, i1, i3, i1, i3);
if (intersect (a, b, i1, i2, &i3))
add_rectangle (points, r, i1, i3, i1, i3);
if (intersect (b, c, i1, i2, &i3))
add_rectangle (points, r, i1, i3, i1, i3);
i2.x = i1.x - 1.0 * r->aspect;
i2.y = i1.y + 1.0;
if (intersect (d, a, i1, i2, &i3))
add_rectangle (points, r, i1, i3, i1, i3);
if (intersect (a, b, i1, i2, &i3))
add_rectangle (points, r, i1, i3, i1, i3);
if (intersect (b, c, i1, i2, &i3))
add_rectangle (points, r, i1, i3, i1, i3);
}
}
/* check if point is inside the polygon "points", if point is on border
* its still inside.
*/
static gboolean
in_poly (Point points[4],
Point p)
{
Point p1, p2;
gint counter = 0;
gint i;
p1 = points[0];
for (i = 1; i <= 4; i++)
{
p2 = points[i % 4];
if (p.y > MIN (p1.y, p2.y))
{
if (p.y <= MAX (p1.y, p2.y))
{
if (p.x <= MAX (p1.x, p2.x))
{
if (p1.y != p2.y)
{
gdouble xinters = ((p.y - p1.y) * (p2.x - p1.x) /
(p2.y - p1.y) + p1.x);
if (p1.x == p2.x || p.x <= xinters)
counter++;
}
}
}
}
p1 = p2;
}
/* border check */
if (point_on_border (points, p))
return TRUE;
return (counter % 2 != 0);
}
/* check if the point p lies on the polygon "points"
*/
static gboolean
point_on_border (Point points[4],
Point p)
{
gint i;
for (i = 0; i <= 4; i++)
{
Point a = points[i % 4];
Point b = points[(i + 1) % 4];
gdouble a1 = (b.y - a.y);
gdouble b1 = (a.x - b.x);
gdouble c1 = a1 * a.x + b1 * a.y;
gdouble c2 = a1 * p.x + b1 * p.y;
if (ABS (c1 - c2) < EPSILON &&
MIN (a.x, b.x) <= p.x &&
MAX (a.x, b.x) >= p.x &&
MIN (a.y, b.y) <= p.y &&
MAX (a.y, b.y) >= p.y)
return TRUE;
}
return FALSE;
}
/* calculate the intersection point of the line a-b with the line c-d
* and write it to i, if existing.
*/
static gboolean
intersect (Point a,
Point b,
Point c,
Point d,
Point *i)
{
gdouble a1 = (b.y - a.y);
gdouble b1 = (a.x - b.x);
gdouble c1 = a1 * a.x + b1 * a.y;
gdouble a2 = (d.y - c.y);
gdouble b2 = (c.x - d.x);
gdouble c2 = a2 * c.x + b2 * c.y;
gdouble det = a1 * b2 - a2 * b1;
if (det == 0)
return FALSE;
i->x = (b2 * c1 - b1 * c2) / det;
i->y = (a1 * c2 - a2 * c1) / det;
return TRUE;
}
/* calculate the intersection point of the line a-b with the vertical line
* through c and write it to i, if existing.
*/
static gboolean
intersect_x (Point a,
Point b,
Point c,
Point *i)
{
Point d = c;
d.y += 1;
return intersect(a,b,c,d,i);
}
/* calculate the intersection point of the line a-b with the horizontal line
* through c and write it to i, if existing.
*/
static gboolean
intersect_y (Point a,
Point b,
Point c,
Point *i)
{
Point d = c;
d.x += 1;
return intersect(a,b,c,d,i);
}
/* this takes the smallest ortho-aligned (the sides of the rectangle are
* parallel to the x- and y-axis) rectangle fitting around the points a to d,
* checks if the whole rectangle is inside the polygon described by points and
* writes it to r if the area is bigger than the rectangle already stored in r.
*/
static void
add_rectangle (Point points[4],
Rectangle *r,
Point a,
Point b,
Point c,
Point d)
{
gdouble width;
gdouble height;
gdouble minx, maxx;
gdouble miny, maxy;
/* get the orthoaligned (the sides of the rectangle are parallel to the x-
* and y-axis) rectangle surrounding the points a to d.
*/
minx = MIN4 (a.x, b.x, c.x, d.x);
maxx = MAX4 (a.x, b.x, c.x, d.x);
miny = MIN4 (a.y, b.y, c.y, d.y);
maxy = MAX4 (a.y, b.y, c.y, d.y);
a.x = minx;
a.y = miny;
b.x = maxx;
b.y = miny;
c.x = maxx;
c.y = maxy;
d.x = minx;
d.y = maxy;
width = maxx - minx;
height = maxy - miny;
/* check if this rectangle is inside the polygon "points" */
if (in_poly (points, a) &&
in_poly (points, b) &&
in_poly (points, c) &&
in_poly (points, d))
{
gdouble area = width * height;
/* check if the new rectangle is larger (in terms of area)
* than the currently stored rectangle in r, if yes store
* new rectangle to r
*/
if (r->area <= area)
{
r->a.x = a.x;
r->a.y = a.y;
r->b.x = b.x;
r->b.y = b.y;
r->c.x = c.x;
r->c.y = c.y;
r->d.x = d.x;
r->d.y = d.y;
r->area = area;
}
}
}
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