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/* pngpack: lossless image compression for a series of screen shots
* Copyright (C) 2005-2010 Carsten Gnoerlich.
*
* 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,
* or direct your browser at http://www.gnu.org.
*/
#include <errno.h>
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "pngio.h"
#include "memory.h"
/*
* Thumbnail generation
*/
void SaveThumbnail(Image *pi, char *name, int thumb_size, char *thumb_dir)
{ Image *thumb;
char tname[strlen(thumb_dir)+strlen(name)+2];
double ratio, inv_ratio;
unsigned int size, *pixel;
int i,j;
/* sanity check */
if(pi->width < thumb_size && pi->height < thumb_size)
{ fprintf(stdout, "... NOT creating thumbnail because of image size (%dx%d)\n",
pi->width, pi->height);
return;
}
/* Create thumbnail copy from image */
thumb=malloc(sizeof(Image));
memcpy(thumb, pi, sizeof(Image));
if(thumb->width > thumb->height)
inv_ratio = (double)thumb->width/(double)thumb_size;
else inv_ratio = (double)thumb->height/(double)thumb_size;
ratio = 1.0/inv_ratio;
thumb->width = (int)((double)thumb->width*ratio+0.5);
thumb->height = (int)((double)thumb->height*ratio+0.5);
sprintf(tname, "%s/%s", thumb_dir, name);
fprintf(stdout, "... and %dx%d thumbnail %s\n", thumb->width, thumb->height, tname);
size = thumb->width * thumb->height;
thumb->bytesize = sizeof(unsigned int) * size;
thumb->image = malloc(thumb->bytesize);
if(!thumb->image) Stop("out of memory for image");
/*
* Decimate the image
*/
pixel = thumb->image;
for(i=0; i<thumb->height; i++)
for(j=0; j<thumb->width; j++)
{ double first_x = j*inv_ratio;
double first_y = i*inv_ratio;
double last_x = (j+1)*inv_ratio;
double last_y = (i+1)*inv_ratio;
double area = 0.0;
int x0 = floor(first_x);
int x1 = ceil(last_x);
int y0 = floor(first_y);
int y1 = ceil(last_y);
int x,y;
double c1,c2,c3,c4;
unsigned int ci1,ci2,ci3,ci4;
#if 0
printf("%d %d -> (%d %d) - (%d %d)\n", j,i, x0,y0, x1, y1);
printf("%f %f %f %f\n", first_x, first_y, last_x, last_y);
printf("%f %f\n", ratio, inv_ratio);
#endif
if(x1>=pi->width) x1=pi->width-1;
if(y1>=pi->height) y1=pi->height-1;
c1 = c2 = c3 = c4 = 0.0;
for(y=y0; y<=y1; y++)
{ double ysize = 1.0;
double size;
if(y<y0) ysize = 1.0-(y0-y);
if(y>y1) ysize = 1.0-(y-y1);
for(x=x0; x<=x1; x++)
{ int idx = x+y*pi->width;
size = ysize;
if(x<x0) size *= (1.0-(x0-x));
if(x>x1) size *= (1-0-(x-x1));
c1 += size * ((pi->image[idx]>>24)&0xff);
c2 += size * ((pi->image[idx]>>16)&0xff);
c3 += size * ((pi->image[idx]>> 8)&0xff);
c4 += size * ((pi->image[idx] )&0xff);
area += size;
}
}
ci1 = c1/area; ci2 = c2/area; ci3 = c3/area; ci4 = c4/area;
*pixel++ = (ci1<<24) | (ci2<<16) | (ci3<<8) | ci4;
}
SavePNG(thumb, tname);
free(thumb->image);
free(thumb);
}
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