gimp/app/brush_scale.c

167 lines
3.2 KiB
C

/* The GIMP -- an image manipulation program
* Copyright (C) 1995 Spencer Kimball and Peter Mattis
*
* 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 2 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, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
#include <glib.h>
#include "brush_scale.h"
MaskBuf *
brush_scale_mask (MaskBuf *brush_mask,
int dest_width,
int dest_height)
{
MaskBuf *scale_brush;
int src_width;
int src_height;
int value;
int area;
int i, j;
int x, x0, y, y0;
int dx, dx0, dy, dy0;
int fx, fx0, fy, fy0;
unsigned char *src, *dest;
g_return_val_if_fail (brush_mask != NULL &&
dest_width != 0 && dest_height != 0, NULL);
src_width = brush_mask->width;
src_height = brush_mask->height;
scale_brush = mask_buf_new (dest_width, dest_height);
g_return_val_if_fail (scale_brush != NULL, NULL);
/* get the data */
dest = mask_buf_data (scale_brush);
src = mask_buf_data (brush_mask);
fx = fx0 = (256.0 * src_width) / dest_width;
fy = fy0 = (256.0 * src_height) / dest_height;
area = fx0 * fy0;
x = x0 = 0;
y = y0 = 0;
dx = dx0 = 0;
dy = dy0 = 0;
for (i=0; i<dest_height; i++)
{
for (j=0; j<dest_width; j++)
{
value = 0;
fy = fy0;
y = y0;
dy = dy0;
if (dy)
{
fx = fx0;
x = x0;
dx = dx0;
if (dx)
{
value += dx * dy * src[x + src_width * y];
x++;
fx -= dx;
dx = 0;
}
while (fx >= 256)
{
value += 256 * dy * src[x + src_width * y];
x++;
fx -= 256;
}
if (fx)
{
value += fx * dy * src[x + src_width * y];
dx = 256 - fx;
}
y++;
fy -= dy;
dy = 0;
}
while (fy >= 256)
{
fx = fx0;
x = x0;
dx = dx0;
if (dx)
{
value += dx * 256 * src[x + src_width * y];
x++;
fx -= dx;
dx = 0;
}
while (fx >= 256)
{
value += 256 * 256 * src[x + src_width * y];
x++;
fx -= 256;
}
if (fx)
{
value += fx * 256 * src[x + src_width * y];
dx = 256 - fx;
}
y++;
fy -= 256;
}
if (fy)
{
fx = fx0;
x = x0;
dx = dx0;
if (dx)
{
value += dx * fy * src[x + src_width * y];
x++;
fx -= dx;
dx = 0;
}
while (fx >= 256)
{
value += 256 * fy * src[x + src_width * y];
x++;
fx -= 256;
}
if (fx)
{
value += fx * fy * src[x + src_width * y];
dx = 256 - fx;
}
dy = 256 - fy;
}
*dest++ = MIN ((value / area), 255);
x0 = x;
dx0 = dx;
}
x0 = 0;
dx0 = 0;
y0 = y;
dy0 = dy;
}
return scale_brush;
}