#include <stdio.h>
#include <stdlib.h>
#include "png.h"
/* The png_jmpbuf() macro, used in error handling, became available in
* libpng version 1.0.6. If you want to be able to run your code with older
* versions of libpng, you must define the macro yourself (but only if it
* is not already defined by libpng!).
*/
#ifndef png_jmpbuf
#define png_jmpbuf(png_ptr) ((png_ptr)->jmpbuf)
#endif
#define ERROR 1
#define OK 0
int read_png(char *file_name) /* We need to open the file */
{
png_structp png_ptr;
png_infop info_ptr;
unsigned int sig_read = 0;
png_uint_32 width, height;
int bit_depth, color_type, interlace_type;
FILE *fp;
if ((fp = fopen(file_name, "rb")) == NULL)
return (ERROR);
/* Create and initialize the png_struct with the desired error handler
* functions. If you want to use the default stderr and longjump method,
* you can supply NULL for the last three parameters. We also supply the
* the compiler header file version, so that we know if the application
* was compiled with a compatible version of the library. REQUIRED
*/
png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING,
NULL, NULL, NULL);
if (png_ptr == NULL)
{
fclose(fp);
return (ERROR);
}
/* Allocate/initialize the memory for image information. REQUIRED. */
info_ptr = png_create_info_struct(png_ptr);
if (info_ptr == NULL)
{
fclose(fp);
png_destroy_read_struct(&png_ptr, png_infopp_NULL, png_infopp_NULL);
return (ERROR);
}
/* Set error handling if you are using the setjmp/longjmp method (this is
* the normal method of doing things with libpng). REQUIRED unless you
* set up your own error handlers in the png_create_read_struct() earlier.
*/
if (setjmp(png_jmpbuf(png_ptr)))
{
/* Free all of the memory associated with the png_ptr and info_ptr */
png_destroy_read_struct(&png_ptr, &info_ptr, png_infopp_NULL);
fclose(fp);
/* If we get here, we had a problem reading the file */
return (ERROR);
}
/* Set up the input control if you are using standard C streams */
png_init_io(png_ptr, fp);
/* If we have already read some of the signature */
png_set_sig_bytes(png_ptr, sig_read);
/*
* If you have enough memory to read in the entire image at once,
* and you need to specify only transforms that can be controlled
* with one of the PNG_TRANSFORM_* bits (this presently excludes
* dithering, filling, setting background, and doing gamma
* adjustment), then you can read the entire image (including
* pixels) into the info structure with this call:
*/
png_read_png(png_ptr, info_ptr, PNG_TRANSFORM_IDENTITY, png_voidp_NULL);
/* clean up after the read, and free any memory allocated - REQUIRED */
png_destroy_read_struct(&png_ptr, &info_ptr, png_infopp_NULL);
/* close the file */
fclose(fp);
/* that's it */
return (OK);
}
int main(int argc, char **argv)
{
if(argc < 2){
fprintf(stderr, "Usage: %s <png>n", argv[0]);
return EXIT_FAILURE;
}
if(read_png(argv[1]) != OK){
fprintf(stderr, "Error reading pngn");
return EXIT_FAILURE;
}
return 0;
}
// milw0rm.com [2004-08-13]