mirror of https://github.com/GNOME/gimp.git
162 lines
4.2 KiB
C
162 lines
4.2 KiB
C
/* The GIMP -- an image manipulation program
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* Copyright (C) 1995 Spencer Kimball and Peter Mattis
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*
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* gimpcoords.c
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* Copyright (C) 2002 Simon Budig <simon@gimp.org>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU 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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*
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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 General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*/
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#include "config.h"
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#include <glib-object.h>
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#include "core-types.h"
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#include "gimpcoords.h"
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#define INPUT_RESOLUTION 256
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/* amul * a + bmul * b = ret_val */
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void
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gimp_coords_mix (const gdouble amul,
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const GimpCoords *a,
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const gdouble bmul,
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const GimpCoords *b,
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GimpCoords *ret_val)
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{
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if (b)
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{
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ret_val->x = amul * a->x + bmul * b->x ;
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ret_val->y = amul * a->y + bmul * b->y ;
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ret_val->pressure = amul * a->pressure + bmul * b->pressure ;
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ret_val->xtilt = amul * a->xtilt + bmul * b->xtilt ;
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ret_val->ytilt = amul * a->ytilt + bmul * b->ytilt ;
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ret_val->wheel = amul * a->wheel + bmul * b->wheel ;
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}
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else
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{
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ret_val->x = amul * a->x;
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ret_val->y = amul * a->y;
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ret_val->pressure = amul * a->pressure;
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ret_val->xtilt = amul * a->xtilt;
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ret_val->ytilt = amul * a->ytilt;
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ret_val->wheel = amul * a->wheel;
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}
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}
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/* (a+b)/2 = ret_average */
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void
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gimp_coords_average (const GimpCoords *a,
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const GimpCoords *b,
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GimpCoords *ret_average)
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{
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gimp_coords_mix (0.5, a, 0.5, b, ret_average);
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}
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/* a + b = ret_add */
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void
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gimp_coords_add (const GimpCoords *a,
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const GimpCoords *b,
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GimpCoords *ret_add)
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{
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gimp_coords_mix (1.0, a, 1.0, b, ret_add);
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}
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/* a - b = ret_difference */
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void
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gimp_coords_difference (const GimpCoords *a,
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const GimpCoords *b,
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GimpCoords *ret_difference)
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{
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gimp_coords_mix (1.0, a, -1.0, b, ret_difference);
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}
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/* a * f = ret_product */
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void
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gimp_coords_scale (const gdouble f,
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const GimpCoords *a,
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GimpCoords *ret_product)
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{
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gimp_coords_mix (f, a, 0.0, NULL, ret_product);
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}
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/* local helper for measuring the scalarproduct of two gimpcoords. */
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gdouble
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gimp_coords_scalarprod (const GimpCoords *a,
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const GimpCoords *b)
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{
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return (a->x * b->x +
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a->y * b->y +
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a->pressure * b->pressure +
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a->xtilt * b->xtilt +
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a->ytilt * b->ytilt +
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a->wheel * b->wheel );
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}
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/*
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* The "lenght" of the gimpcoord.
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* Applies a metric that increases the weight on the
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* pressure/xtilt/ytilt/wheel to ensure proper interpolation
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*/
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gdouble
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gimp_coords_length_squared (const GimpCoords *a)
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{
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GimpCoords upscaled_a;
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upscaled_a.x = a->x;
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upscaled_a.y = a->y;
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upscaled_a.pressure = a->pressure * INPUT_RESOLUTION;
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upscaled_a.xtilt = a->xtilt * INPUT_RESOLUTION;
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upscaled_a.ytilt = a->ytilt * INPUT_RESOLUTION;
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upscaled_a.wheel = a->wheel * INPUT_RESOLUTION;
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return gimp_coords_scalarprod (&upscaled_a, &upscaled_a);
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}
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gdouble
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gimp_coords_length (const GimpCoords *a)
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{
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return sqrt (gimp_coords_length_squared (a));
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}
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gboolean
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gimp_coords_equal (const GimpCoords *a,
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const GimpCoords *b)
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{
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return ( a->x == b->x &&
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a->y == b->y &&
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a->pressure == b->pressure &&
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a->xtilt == b->xtilt &&
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a->ytilt == b->ytilt &&
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a->wheel == b->wheel);
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}
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