1// Copyright 2002-2010 Guillaume Cottenceau.
2// This software may be freely redistributed under the terms of
3// the X11 license.
4//
5// Function write_png_file taken slightly modified from
6// http://zarb.org/~gc/html/libpng.html
7
8#include <png.h>
9#include <stdarg.h>
10#include <stdio.h>
11
12#include <base/files/file_util.h>
13#include <gflags/gflags.h>
14
15#include "png_helper.h"
16
17void abort_(const char * s, ...) {
18  va_list args;
19  va_start(args, s);
20  vfprintf(stderr, s, args);
21  fprintf(stderr, "\n");
22  va_end(args);
23  abort();
24}
25
26void write_png_file(const char* file_name, char* pixels, int width, int height)
27{
28  int         x, y;
29  png_bytep  *row_pointers;
30  png_structp png_ptr;
31  png_infop   info_ptr;
32  png_byte    bit_depth = 8;  // 8 bits per channel RGBA
33  png_byte    color_type = 6; // RGBA
34
35  row_pointers = (png_bytep*) malloc(sizeof(png_bytep) * height);
36  char *p = pixels;
37  for (y=height-1; y>=0; y--) {
38    row_pointers[y] = (png_byte*) malloc(4*width);
39    for (x=0; x<width; x++) {
40      png_byte* pixel = &(row_pointers[y][x*4]);
41      pixel[0] = *p; p++; // R
42      pixel[1] = *p; p++; // G
43      pixel[2] = *p; p++; // B
44      pixel[3] = *p; p++; // A
45    }
46  }
47
48  /* create file */
49  FILE *fp = fopen(file_name, "wb");
50  if (!fp)
51    abort_("[write_png_file] File %s could not be opened for writing",
52           file_name);
53  /* initialize stuff */
54  png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
55  if (!png_ptr)
56    abort_("[write_png_file] png_create_write_struct failed");
57  info_ptr = png_create_info_struct(png_ptr);
58  if (!info_ptr)
59    abort_("[write_png_file] png_create_info_struct failed");
60  if (setjmp(png_jmpbuf(png_ptr)))
61    abort_("[write_png_file] Error during init_io");
62  png_init_io(png_ptr, fp);
63
64  /* write header */
65  if (setjmp(png_jmpbuf(png_ptr)))
66    abort_("[write_png_file] Error during writing header");
67  png_set_IHDR(png_ptr, info_ptr, width, height,
68               bit_depth, color_type, PNG_INTERLACE_NONE,
69               PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
70  png_write_info(png_ptr, info_ptr);
71
72  /* write bytes */
73  if (setjmp(png_jmpbuf(png_ptr)))
74    abort_("[write_png_file] Error during writing bytes");
75  png_write_image(png_ptr, row_pointers);
76
77  /* end write */
78  if (setjmp(png_jmpbuf(png_ptr)))
79    abort_("[write_png_file] Error during end of write");
80  png_write_end(png_ptr, NULL);
81
82  /* cleanup heap allocation */
83  for (y=0; y<height; y++)
84    free(row_pointers[y]);
85  free(row_pointers);
86
87  fclose(fp);
88
89  // Try to flush saved image to disk such that more data survives a hard crash.
90  system("/bin/sync");
91}
92