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// fill transparent areas of an image with nearby values
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// increases compressibility and enhances image quality
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// in the presence of naive interpolation algorithms.
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//----------------------------------------------------------
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//Copyright (C) 2006 Marc Lehmann <pcg@goof.com>
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//This program is free software; you can redistribute it and/or
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//modify it under the terms of the GNU Lesser General Public
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//License as published by the Free Software Foundation; either
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//version 2.1 of the License, or (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 GNU
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//Lesser General Public License for more details.
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//
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//You should have received a copy of the GNU Lesser General Public
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//License 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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#include <cstdio>
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#include <cstdlib>
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#include <cstring>
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#include <stdint.h>
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#include <endian.h>
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using namespace std;
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#if __BYTE_ORDER == __BIG_ENDIAN
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# define Rshift 24
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# define Gshift 16
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# define Bshift 8
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# define Ashift 0
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#else
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# define Rshift 0
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# define Gshift 8
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# define Bshift 16
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# define Ashift 24
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#endif
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#define Cmask 0xffUL
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#define Amask (Cmask << Ashift)
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typedef uint32_t pixel;
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inline void gather (pixel *img, char *flag, int x, int y, int w, int h, int &c, int &r, int &g, int &b)
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{
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if (x < 0 || x >= w)
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return;
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if (y < 0 || y >= h)
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return;
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int p = img [y * w + x];
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int weight = (p >> Ashift) & Cmask;
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if (!weight)
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weight = !!flag [y * w + x];
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if (!weight)
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return;
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c += weight;
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r += ((p >> Rshift) & Cmask) * weight;
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g += ((p >> Gshift) & Cmask) * weight;
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b += ((p >> Bshift) & Cmask) * weight;
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}
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void filla (pixel *img, int w, int h)
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{
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char *flag = (char *)calloc (w * h, 1);
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char *flag2 = (char *)calloc (w * h, 1);
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pixel *dst = new pixel [w * h];
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for (int iter = 3; --iter; )
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{
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for (int x = 0; x < w; x++)
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for (int y = 0; y < h; y++)
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{
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int o = y * w + x;
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if ((img [o] & Amask) || flag [o])
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dst [o] = img [o];
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else
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{
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int weight = 0, r = 0, g = 0, b = 0;
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gather (img, flag, x - 1, y - 1, w, h, weight, r, g, b);
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gather (img, flag, x , y - 1, w, h, weight, r, g, b);
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gather (img, flag, x + 1, y - 1, w, h, weight, r, g, b);
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gather (img, flag, x - 1, y , w, h, weight, r, g, b);
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gather (img, flag, x + 1, y , w, h, weight, r, g, b);
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gather (img, flag, x - 1, y + 1, w, h, weight, r, g, b);
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gather (img, flag, x , y + 1, w, h, weight, r, g, b);
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gather (img, flag, x + 1, y + 1, w, h, weight, r, g, b);
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if (weight)
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{
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flag2 [o] = 1;
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dst [o] = ((r + weight / 2) / weight) << Rshift
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| ((g + weight / 2) / weight) << Gshift
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| ((b + weight / 2) / weight) << Bshift;
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}
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else
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dst [o] = img [o]; // not yet here
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}
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}
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memcpy (img, dst, w * h * sizeof (pixel));
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memcpy (flag, flag2, w * h);
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}
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for (int o = w * h; o--; )
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if (!(img [o] & Amask || flag [o]))
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img [o] = 0;
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free (dst);
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free (flag);
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free (flag2);
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}
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int main (int argc, char* argv[])
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{
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if (argc <= 2)
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{
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printf("\nUsage: filla w h <input.rgba >output.rgba\n");
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printf("input file must be 32 bit rgba w*h.\n");
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return 1;
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}
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int w = atoi (argv [1]);
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int h = atoi (argv [2]);
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int size = w * h * sizeof (pixel);
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pixel *img = (pixel *)new unsigned char [size];
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if (fread (img, size, 1, stdin) != 1)
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{
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perror ("unable to read input file\n");
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exit (1);
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}
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filla (img, w, h);
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if (fwrite (img, size, 1, stdout) != 1)
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{
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perror ("unable to read output file\n");
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exit (1);
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}
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return 0;
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}
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