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| #include <png.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
FILE *fp;
png_structp png_ptr;
png_infop info_ptr, end_info;
png_byte magic[8];
png_byte custom_chunk[5] = { 116, 73, 77, 69, (png_byte)'\0' }; // tIME
png_byte unused_chunks[]=
{
104, 73, 83, 84, (png_byte) '\0', /* hIST */
105, 84, 88, 116, (png_byte) '\0', /* iTXt */
112, 67, 65, 76, (png_byte) '\0', /* pCAL */
115, 67, 65, 76, (png_byte) '\0', /* sCAL */
115, 80, 76, 84, (png_byte) '\0', /* sPLT */
'I', 'D', 'A', 'T', (png_byte) '\0'
};
void readPNG(char *file);
void read_chunk_custom(png_structp ptr, png_unknown_chunkp chunk);
int main(int argc, char **argv);
void read_chunk_custom(png_structp ptr, png_unknown_chunkp chunk) {
printf("Reading custom chunk @ %p\n", chunk->data);
FILE *out = fopen("./out.jpg", "wb");
if (!out) {
fprintf(stderr, "Cannot write the chunk to ouput.\n");
return;
}
fwrite(chunk->data, 1, sizeof(chunk->data), out);
fclose(out);
return;
}
void readPNG(char *file) {
printf("read: %s\n", file);
fp = fopen(file, "rb");
if (!fp) {
fprintf(stderr, "Cannot open %s.\n", file);
return;
}
fread(magic, 1, sizeof(magic), fp);
if (!png_check_sig(magic, sizeof(magic))) {
fprintf(stderr, "error: %s isn't a valid PNG file.\n", file);
return;
}
//fseek(fp, 0, SEEK_SET);
png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
if (!png_ptr) {
fprintf(stderr, "Cannot create read struct.\n");
return;
}
info_ptr = png_create_info_struct(png_ptr);
if (!info_ptr) {
png_destroy_read_struct(&png_ptr, (png_infopp)NULL, (png_infopp)NULL);
fprintf(stderr, "Cannot create info struct.\n");
return;
}
end_info = png_create_info_struct(png_ptr);
if (!end_info)
{
png_destroy_read_struct(&png_ptr, &info_ptr, (png_infopp)NULL);
fprintf(stderr, "Cannot create end info struct.\n");
return;
}
if (setjmp(png_jmpbuf(png_ptr))) {
fprintf(stderr, "Error: fatal.\n");
return;
}
png_init_io(png_ptr, fp);
png_set_sig_bytes(png_ptr, sizeof(magic));
png_read_info(png_ptr, info_ptr);
png_read_update_info (png_ptr, info_ptr);
int width = png_get_image_width(png_ptr, info_ptr),
height = png_get_image_height(png_ptr, info_ptr);
printf("Image %i x %i\n", width, height);
/* ignore all unknown chunks: */
png_set_keep_unknown_chunks(png_ptr, 1, NULL, 0);
/* except for our custom chunk: */
png_set_keep_unknown_chunks(png_ptr, 2, custom_chunk, sizeof(custom_chunk)/5);
/* also ignore unused known chunks: */
png_set_keep_unknown_chunks(png_ptr, 1, unused_chunks, sizeof(unused_chunks)/5);
png_set_read_user_chunk_fn(png_ptr, NULL, (png_user_chunk_ptr)read_chunk_custom);
//png_set_keep_unknown_chunks(png_ptr, PNG_HANDLE_CHUNK_ALWAYS, custom_chunk, sizeof(custom_chunk)/5);
// Renvoie une erreur CRC si décommenter !
//png_read_end(png_ptr, end_info);
png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
fclose(fp);
}
int main(int argc, char **argv) {
if (strcmp(argv[1], "-r") || strcmp(argv[1], "--read")) {
readPNG(argv[2]);
}
return 0;
} |
