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gimp/app/core/gimp-transform-utils.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-utils.h"
void
gimp_transform_get_rotate_center (gint x,
gint y,
gint width,
gint height,
gboolean auto_center,
gdouble *center_x,
gdouble *center_y)
{
g_return_if_fail (center_x != NULL);
g_return_if_fail (center_y != NULL);
if (auto_center)
{
*center_x = (gdouble) x + (gdouble) width / 2.0;
*center_y = (gdouble) y + (gdouble) height / 2.0;
}
}
void
gimp_transform_get_flip_axis (gint x,
gint y,
gint width,
gint height,
GimpOrientationType flip_type,
gboolean auto_center,
gdouble *axis)
{
g_return_if_fail (axis != NULL);
if (auto_center)
{
switch (flip_type)
{
case GIMP_ORIENTATION_HORIZONTAL:
*axis = ((gdouble) x + (gdouble) width / 2.0);
break;
case GIMP_ORIENTATION_VERTICAL:
*axis = ((gdouble) y + (gdouble) height / 2.0);
break;
default:
g_return_if_reached ();
break;
}
}
}
void
gimp_transform_matrix_flip (GimpMatrix3 *matrix,
GimpOrientationType flip_type,
gdouble axis)
{
g_return_if_fail (matrix != NULL);
switch (flip_type)
{
case GIMP_ORIENTATION_HORIZONTAL:
gimp_matrix3_translate (matrix, - axis, 0.0);
gimp_matrix3_scale (matrix, -1.0, 1.0);
gimp_matrix3_translate (matrix, axis, 0.0);
break;
case GIMP_ORIENTATION_VERTICAL:
gimp_matrix3_translate (matrix, 0.0, - axis);
gimp_matrix3_scale (matrix, 1.0, -1.0);
gimp_matrix3_translate (matrix, 0.0, axis);
break;
case GIMP_ORIENTATION_UNKNOWN:
break;
}
}
void
gimp_transform_matrix_flip_free (GimpMatrix3 *matrix,
gdouble x1,
gdouble y1,
gdouble x2,
gdouble y2)
{
gdouble angle;
g_return_if_fail (matrix != NULL);
angle = atan2 (y2 - y1, x2 - x1);
gimp_matrix3_identity (matrix);
gimp_matrix3_translate (matrix, -x1, -y1);
gimp_matrix3_rotate (matrix, -angle);
gimp_matrix3_scale (matrix, 1.0, -1.0);
gimp_matrix3_rotate (matrix, angle);
gimp_matrix3_translate (matrix, x1, y1);
}
void
gimp_transform_matrix_rotate (GimpMatrix3 *matrix,
GimpRotationType rotate_type,
gdouble center_x,
gdouble center_y)
{
gdouble angle = 0;
switch (rotate_type)
{
case GIMP_ROTATE_90:
angle = G_PI_2;
break;
case GIMP_ROTATE_180:
angle = G_PI;
break;
case GIMP_ROTATE_270:
angle = - G_PI_2;
break;
}
gimp_transform_matrix_rotate_center (matrix, center_x, center_y, angle);
}
void
gimp_transform_matrix_rotate_rect (GimpMatrix3 *matrix,
gint x,
gint y,
gint width,
gint height,
gdouble angle)
{
gdouble center_x;
gdouble center_y;
g_return_if_fail (matrix != NULL);
center_x = (gdouble) x + (gdouble) width / 2.0;
center_y = (gdouble) y + (gdouble) height / 2.0;
gimp_matrix3_translate (matrix, -center_x, -center_y);
gimp_matrix3_rotate (matrix, angle);
gimp_matrix3_translate (matrix, +center_x, +center_y);
}
void
gimp_transform_matrix_rotate_center (GimpMatrix3 *matrix,
gdouble center_x,
gdouble center_y,
gdouble angle)
{
g_return_if_fail (matrix != NULL);
gimp_matrix3_translate (matrix, -center_x, -center_y);
gimp_matrix3_rotate (matrix, angle);
gimp_matrix3_translate (matrix, +center_x, +center_y);
}
void
gimp_transform_matrix_scale (GimpMatrix3 *matrix,
gint x,
gint y,
gint width,
gint height,
gdouble t_x,
gdouble t_y,
gdouble t_width,
gdouble t_height)
{
gdouble scale_x = 1.0;
gdouble scale_y = 1.0;
g_return_if_fail (matrix != NULL);
if (width > 0)
scale_x = t_width / (gdouble) width;
if (height > 0)
scale_y = t_height / (gdouble) height;
gimp_matrix3_identity (matrix);
gimp_matrix3_translate (matrix, -x, -y);
gimp_matrix3_scale (matrix, scale_x, scale_y);
gimp_matrix3_translate (matrix, t_x, t_y);
}
void
gimp_transform_matrix_shear (GimpMatrix3 *matrix,
gint x,
gint y,
gint width,
gint height,
GimpOrientationType orientation,
gdouble amount)
{
gdouble center_x;
gdouble center_y;
g_return_if_fail (matrix != NULL);
if (width == 0)
width = 1;
if (height == 0)
height = 1;
center_x = (gdouble) x + (gdouble) width / 2.0;
center_y = (gdouble) y + (gdouble) height / 2.0;
gimp_matrix3_identity (matrix);
gimp_matrix3_translate (matrix, -center_x, -center_y);
if (orientation == GIMP_ORIENTATION_HORIZONTAL)
gimp_matrix3_xshear (matrix, amount / height);
else
gimp_matrix3_yshear (matrix, amount / width);
gimp_matrix3_translate (matrix, +center_x, +center_y);
}
void
gimp_transform_matrix_perspective (GimpMatrix3 *matrix,
gint x,
gint y,
gint width,
gint height,
gdouble t_x1,
gdouble t_y1,
gdouble t_x2,
gdouble t_y2,
gdouble t_x3,
gdouble t_y3,
gdouble t_x4,
gdouble t_y4)
{
GimpMatrix3 trafo;
gdouble scalex;
gdouble scaley;
g_return_if_fail (matrix != NULL);
scalex = scaley = 1.0;
if (width > 0)
scalex = 1.0 / (gdouble) width;
if (height > 0)
scaley = 1.0 / (gdouble) height;
gimp_matrix3_translate (matrix, -x, -y);
gimp_matrix3_scale (matrix, scalex, scaley);
/* Determine the perspective transform that maps from
* the unit cube to the transformed coordinates
*/
{
gdouble dx1, dx2, dx3, dy1, dy2, dy3;
dx1 = t_x2 - t_x4;
dx2 = t_x3 - t_x4;
dx3 = t_x1 - t_x2 + t_x4 - t_x3;
dy1 = t_y2 - t_y4;
dy2 = t_y3 - t_y4;
dy3 = t_y1 - t_y2 + t_y4 - t_y3;
/* Is the mapping affine? */
if ((dx3 == 0.0) && (dy3 == 0.0))
{
trafo.coeff[0][0] = t_x2 - t_x1;
trafo.coeff[0][1] = t_x4 - t_x2;
trafo.coeff[0][2] = t_x1;
trafo.coeff[1][0] = t_y2 - t_y1;
trafo.coeff[1][1] = t_y4 - t_y2;
trafo.coeff[1][2] = t_y1;
trafo.coeff[2][0] = 0.0;
trafo.coeff[2][1] = 0.0;
}
else
{
gdouble det1, det2;
det1 = dx3 * dy2 - dy3 * dx2;
det2 = dx1 * dy2 - dy1 * dx2;
trafo.coeff[2][0] = (det2 == 0.0) ? 1.0 : det1 / det2;
det1 = dx1 * dy3 - dy1 * dx3;
trafo.coeff[2][1] = (det2 == 0.0) ? 1.0 : det1 / det2;
trafo.coeff[0][0] = t_x2 - t_x1 + trafo.coeff[2][0] * t_x2;
trafo.coeff[0][1] = t_x3 - t_x1 + trafo.coeff[2][1] * t_x3;
trafo.coeff[0][2] = t_x1;
trafo.coeff[1][0] = t_y2 - t_y1 + trafo.coeff[2][0] * t_y2;
trafo.coeff[1][1] = t_y3 - t_y1 + trafo.coeff[2][1] * t_y3;
trafo.coeff[1][2] = t_y1;
}
trafo.coeff[2][2] = 1.0;
}
gimp_matrix3_mult (&trafo, matrix);
}
gboolean
gimp_transform_polygon_is_convex (gdouble x1,
gdouble y1,
gdouble x2,
gdouble y2,
gdouble x3,
gdouble y3,
gdouble x4,
gdouble y4)
{
gdouble z1, z2, z3, z4;
/* We test if the transformed polygon is convex. if z1 and z2 have
* the same sign as well as z3 and z4 the polygon is convex.
*/
z1 = ((x2 - x1) * (y4 - y1) -
(x4 - x1) * (y2 - y1));
z2 = ((x4 - x1) * (y3 - y1) -
(x3 - x1) * (y4 - y1));
z3 = ((x4 - x2) * (y3 - y2) -
(x3 - x2) * (y4 - y2));
z4 = ((x3 - x2) * (y1 - y2) -
(x1 - x2) * (y3 - y2));
return (z1 * z2 > 0) && (z3 * z4 > 0);
}
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