mirror of https://github.com/GNOME/gimp.git
83 lines
2.0 KiB
C
83 lines
2.0 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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* 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 "base-types.h"
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#include "pixel-region.h"
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#include "threshold.h"
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void
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threshold (Threshold *tr,
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PixelRegion *srcPR,
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PixelRegion *destPR)
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{
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const guchar *src, *s;
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guchar *dest, *d;
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gboolean has_alpha;
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gint alpha;
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gint w, h, b;
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gint value;
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h = srcPR->h;
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src = srcPR->data;
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dest = destPR->data;
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has_alpha = (srcPR->bytes == 2 || srcPR->bytes == 4);
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alpha = has_alpha ? srcPR->bytes - 1 : srcPR->bytes;
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while (h--)
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{
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w = srcPR->w;
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s = src;
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d = dest;
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while (w--)
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{
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if (tr->color)
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{
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value = MAX (s[RED_PIX], s[GREEN_PIX]);
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value = MAX (value, s[BLUE_PIX]);
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value = (value >= tr->low_threshold &&
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value <= tr->high_threshold ) ? 255 : 0;
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}
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else
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{
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value = (s[GRAY_PIX] >= tr->low_threshold &&
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s[GRAY_PIX] <= tr->high_threshold) ? 255 : 0;
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}
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for (b = 0; b < alpha; b++)
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d[b] = value;
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if (has_alpha)
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d[alpha] = s[alpha];
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s += srcPR->bytes;
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d += destPR->bytes;
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}
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src += srcPR->rowstride;
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dest += destPR->rowstride;
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}
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}
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