108 lines
No EOL
3.2 KiB
C
108 lines
No EOL
3.2 KiB
C
#include <stdio.h>
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#include <stdlib.h>
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#include "png.h"
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/* The png_jmpbuf() macro, used in error handling, became available in
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* libpng version 1.0.6. If you want to be able to run your code with older
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* versions of libpng, you must define the macro yourself (but only if it
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* is not already defined by libpng!).
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*/
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#ifndef png_jmpbuf
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#define png_jmpbuf(png_ptr) ((png_ptr)->jmpbuf)
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#endif
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#define ERROR 1
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#define OK 0
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int read_png(char *file_name) /* We need to open the file */
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{
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png_structp png_ptr;
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png_infop info_ptr;
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unsigned int sig_read = 0;
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png_uint_32 width, height;
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int bit_depth, color_type, interlace_type;
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FILE *fp;
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if ((fp = fopen(file_name, "rb")) == NULL)
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return (ERROR);
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/* Create and initialize the png_struct with the desired error handler
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* functions. If you want to use the default stderr and longjump method,
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* you can supply NULL for the last three parameters. We also supply the
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* the compiler header file version, so that we know if the application
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* was compiled with a compatible version of the library. REQUIRED
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*/
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png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING,
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NULL, NULL, NULL);
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if (png_ptr == NULL)
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{
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fclose(fp);
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return (ERROR);
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}
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/* Allocate/initialize the memory for image information. REQUIRED. */
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info_ptr = png_create_info_struct(png_ptr);
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if (info_ptr == NULL)
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{
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fclose(fp);
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png_destroy_read_struct(&png_ptr, png_infopp_NULL, png_infopp_NULL);
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return (ERROR);
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}
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/* Set error handling if you are using the setjmp/longjmp method (this is
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* the normal method of doing things with libpng). REQUIRED unless you
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* set up your own error handlers in the png_create_read_struct() earlier.
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*/
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if (setjmp(png_jmpbuf(png_ptr)))
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{
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/* Free all of the memory associated with the png_ptr and info_ptr */
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png_destroy_read_struct(&png_ptr, &info_ptr, png_infopp_NULL);
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fclose(fp);
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/* If we get here, we had a problem reading the file */
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return (ERROR);
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}
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/* Set up the input control if you are using standard C streams */
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png_init_io(png_ptr, fp);
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/* If we have already read some of the signature */
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png_set_sig_bytes(png_ptr, sig_read);
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/*
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* If you have enough memory to read in the entire image at once,
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* and you need to specify only transforms that can be controlled
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* with one of the PNG_TRANSFORM_* bits (this presently excludes
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* dithering, filling, setting background, and doing gamma
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* adjustment), then you can read the entire image (including
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* pixels) into the info structure with this call:
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*/
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png_read_png(png_ptr, info_ptr, PNG_TRANSFORM_IDENTITY, png_voidp_NULL);
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/* clean up after the read, and free any memory allocated - REQUIRED */
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png_destroy_read_struct(&png_ptr, &info_ptr, png_infopp_NULL);
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/* close the file */
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fclose(fp);
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/* that's it */
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return (OK);
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}
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int main(int argc, char **argv)
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{
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if(argc < 2){
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fprintf(stderr, "Usage: %s <png>n", argv[0]);
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return EXIT_FAILURE;
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}
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if(read_png(argv[1]) != OK){
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fprintf(stderr, "Error reading pngn");
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return EXIT_FAILURE;
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}
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return 0;
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}
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// milw0rm.com [2004-08-13]
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