Allink  v0.1
ReadWritePng.cpp
1 /*
2  * Copyright 2002-2008 Guillaume Cottenceau.
3  *
4  * This software may be freely redistributed under the terms
5  * of the X11 license.
6  *
7  */
8 
9 #include <unistd.h>
10 #include <stdlib.h>
11 #include <stdio.h>
12 #include <string.h>
13 #include <stdarg.h>
14 
15 #define PNG_DEBUG 3
16 #include <png.h>
17 
18 void abort_(const char * s, ...)
19 {
20  va_list args;
21  va_start(args, s);
22  vfprintf(stderr, s, args);
23  fprintf(stderr, "\n");
24  va_end(args);
25  abort();
26 }
27 
28 int x, y;
29 
30 png_byte color_type;
31 png_byte bit_depth;
32 
33 png_structp png_ptr;
34 png_infop info_ptr;
35 int number_of_passes;
36 png_bytep * row_pointers;
37 int width, height;
38 
39 void read_png_file(char* file_name)
40 {
41  png_byte header[8]; // 8 is the maximum size that can be checked
42 
43  /* open file and test for it being a png */
44  FILE *fp = fopen(file_name, "rb");
45  if (!fp)
46  abort_("[read_png_file] File %s could not be opened for reading", file_name);
47  fread(header, 1, 8, fp);
48  if (png_sig_cmp(header, 0, 8))
49  abort_("[read_png_file] File %s is not recognized as a PNG file", file_name);
50 
51 
52  /* initialize stuff */
53  png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
54 
55  if (!png_ptr)
56  abort_("[read_png_file] png_create_read_struct failed");
57 
58  info_ptr = png_create_info_struct(png_ptr);
59  if (!info_ptr)
60  abort_("[read_png_file] png_create_info_struct failed");
61 
62  if (setjmp(png_jmpbuf(png_ptr)))
63  abort_("[read_png_file] Error during init_io");
64 
65  png_init_io(png_ptr, fp);
66  png_set_sig_bytes(png_ptr, 8);
67 
68  png_read_info(png_ptr, info_ptr);
69 
70  width = info_ptr->width;
71  height = info_ptr->height;
72  color_type = info_ptr->color_type;
73  bit_depth = info_ptr->bit_depth;
74 
75  number_of_passes = png_set_interlace_handling(png_ptr);
76  png_read_update_info(png_ptr, info_ptr);
77 
78  printf("%d %d %d %d\n",width,height,color_type,bit_depth);
79  /* read file */
80  if (setjmp(png_jmpbuf(png_ptr)))
81  abort_("[read_png_file] Error during read_image");
82 
83  row_pointers = (png_bytep*) malloc(sizeof(png_bytep) * height);
84  for (y=0; y<height; y++)
85  row_pointers[y] = (png_byte*) malloc(info_ptr->rowbytes);
86 
87  png_read_image(png_ptr, row_pointers);
88 
89  fclose(fp);
90 }
91 
92 
93 void write_png_file(char* file_name,png_bytep * row_pointers,int ImWidth,int ImHeight)
94 {
95  /* create file */
96  FILE *fp = fopen(file_name, "wb");
97  if (!fp)
98  abort_("[write_png_file] File %s could not be opened for writing", file_name);
99 
100 
101  /* initialize stuff */
102  png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
103 
104  if (!png_ptr)
105  abort_("[write_png_file] png_create_write_struct failed");
106 
107  info_ptr = png_create_info_struct(png_ptr);
108  if (!info_ptr)
109  abort_("[write_png_file] png_create_info_struct failed");
110 
111  if (setjmp(png_jmpbuf(png_ptr)))
112  abort_("[write_png_file] Error during init_io");
113 
114  png_init_io(png_ptr, fp);
115 
116 
117  /* write header */
118  if (setjmp(png_jmpbuf(png_ptr)))
119  abort_("[write_png_file] Error during writing header");
120 
121  png_set_IHDR(png_ptr, info_ptr, ImWidth, ImHeight,
122  bit_depth, color_type, PNG_INTERLACE_NONE,
123  PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
124 
125  png_write_info(png_ptr, info_ptr);
126 
127 
128  /* write bytes */
129  if (setjmp(png_jmpbuf(png_ptr)))
130  abort_("[write_png_file] Error during writing bytes");
131 
132  png_write_image(png_ptr, row_pointers);
133 
134 
135  /* end write */
136  if (setjmp(png_jmpbuf(png_ptr)))
137  abort_("[write_png_file] Error during end of write");
138 
139  png_write_end(png_ptr, NULL);
140 
141  /* cleanup heap allocation */
142  for (y=0; y<ImHeight; y++)
143  free(row_pointers[y]);
144  free(row_pointers);
145 
146  fclose(fp);
147 }
148 
149 
150 void process_file(int height,int width)
151 {
152  if (info_ptr->color_type != PNG_COLOR_TYPE_RGBA)
153  abort_("[process_file] color_type of input file must be PNG_COLOR_TYPE_RGBA (is %d)", info_ptr->color_type);
154 
155  for (y=0; y<height; y++) {
156  png_byte* row = row_pointers[y];
157  for (x=0; x<width; x++) {
158  png_byte* ptr = &(row[x*4]);
159  //printf("Pixel at position [ %d - %d ] has the following RGBA values: %d - %d - %d - %d\n",x, y, ptr[0], ptr[1], ptr[2], ptr[3]);
160 
161  /* set red value to 0 and green value to the blue one */
162  ptr[0] = 0;
163  ptr[1] = ptr[2];
164  }
165  }
166 
167 }
168 
169 
170 int main(int argc, char **argv)
171 {
172  if (argc != 3)
173  abort_("Usage: program_name <file_in> <file_out>");
174 
175  read_png_file(argv[1]);
176  process_file(width,height);
177  write_png_file(argv[2],row_pointers,width,height);
178 
179  return 0;
180 }