mirror of https://github.com/GNOME/gimp.git
167 lines
3.2 KiB
C
167 lines
3.2 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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* 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 <glib.h>
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#include "brush_scale.h"
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MaskBuf *
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brush_scale_mask (MaskBuf *brush_mask,
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int dest_width,
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int dest_height)
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{
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MaskBuf *scale_brush;
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int src_width;
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int src_height;
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int value;
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int area;
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int i, j;
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int x, x0, y, y0;
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int dx, dx0, dy, dy0;
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int fx, fx0, fy, fy0;
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unsigned char *src, *dest;
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g_return_val_if_fail (brush_mask != NULL &&
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dest_width != 0 && dest_height != 0, NULL);
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src_width = brush_mask->width;
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src_height = brush_mask->height;
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scale_brush = mask_buf_new (dest_width, dest_height);
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g_return_val_if_fail (scale_brush != NULL, NULL);
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/* get the data */
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dest = mask_buf_data (scale_brush);
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src = mask_buf_data (brush_mask);
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fx = fx0 = (256.0 * src_width) / dest_width;
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fy = fy0 = (256.0 * src_height) / dest_height;
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area = fx0 * fy0;
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x = x0 = 0;
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y = y0 = 0;
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dx = dx0 = 0;
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dy = dy0 = 0;
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for (i=0; i<dest_height; i++)
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{
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for (j=0; j<dest_width; j++)
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{
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value = 0;
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fy = fy0;
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y = y0;
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dy = dy0;
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if (dy)
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{
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fx = fx0;
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x = x0;
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dx = dx0;
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if (dx)
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{
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value += dx * dy * src[x + src_width * y];
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x++;
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fx -= dx;
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dx = 0;
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}
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while (fx >= 256)
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{
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value += 256 * dy * src[x + src_width * y];
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x++;
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fx -= 256;
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}
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if (fx)
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{
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value += fx * dy * src[x + src_width * y];
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dx = 256 - fx;
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}
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y++;
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fy -= dy;
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dy = 0;
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}
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while (fy >= 256)
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{
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fx = fx0;
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x = x0;
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dx = dx0;
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if (dx)
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{
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value += dx * 256 * src[x + src_width * y];
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x++;
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fx -= dx;
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dx = 0;
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}
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while (fx >= 256)
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{
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value += 256 * 256 * src[x + src_width * y];
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x++;
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fx -= 256;
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}
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if (fx)
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{
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value += fx * 256 * src[x + src_width * y];
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dx = 256 - fx;
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}
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y++;
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fy -= 256;
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}
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if (fy)
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{
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fx = fx0;
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x = x0;
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dx = dx0;
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if (dx)
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{
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value += dx * fy * src[x + src_width * y];
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x++;
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fx -= dx;
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dx = 0;
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}
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while (fx >= 256)
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{
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value += 256 * fy * src[x + src_width * y];
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x++;
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fx -= 256;
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}
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if (fx)
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{
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value += fx * fy * src[x + src_width * y];
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dx = 256 - fx;
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}
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dy = 256 - fy;
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}
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*dest++ = MIN ((value / area), 255);
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x0 = x;
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dx0 = dx;
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}
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x0 = 0;
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dx0 = 0;
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y0 = y;
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dy0 = dy;
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}
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return scale_brush;
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}
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