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
abort_(const char * s,...)17 void 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
write_png_file(const char * file_name,char * pixels,int width,int height)26 void 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