93 lines
2.7 KiB
C
93 lines
2.7 KiB
C
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/*- pngtopng
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*
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* COPYRIGHT: Written by John Cunningham Bowler, 2011.
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* To the extent possible under law, the author has waived all copyright and
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* related or neighboring rights to this work. This work is published from:
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* United States.
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*
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* Read a PNG and write it out in a fixed format, using the 'simplified API'
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* that was introduced in libpng-1.6.0.
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*
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* This sample code is just the code from the top of 'example.c' with some error
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* handling added. See example.c for more comments.
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*/
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#include <stddef.h>
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#include <stdlib.h>
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#include <string.h>
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#include <stdio.h>
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/* Normally use <png.h> here to get the installed libpng, but this is done to
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* ensure the code picks up the local libpng implementation:
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*/
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#include "../../png.h"
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int main(int argc, const char **argv)
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{
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int result = 1;
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if (argc == 3)
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{
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png_image image;
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/* Only the image structure version number needs to be set. */
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memset(&image, 0, sizeof image);
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image.version = PNG_IMAGE_VERSION;
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if (png_image_begin_read_from_file(&image, argv[1]))
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{
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png_bytep buffer;
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/* Change this to try different formats! If you set a colormap format
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* then you must also supply a colormap below.
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*/
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image.format = PNG_FORMAT_RGBA;
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buffer = malloc(PNG_IMAGE_SIZE(image));
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if (buffer != NULL)
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{
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if (png_image_finish_read(&image, NULL/*background*/, buffer,
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0/*row_stride*/, NULL/*colormap for PNG_FORMAT_FLAG_COLORMAP */))
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{
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if (png_image_write_to_file(&image, argv[2],
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0/*convert_to_8bit*/, buffer, 0/*row_stride*/,
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NULL/*colormap*/))
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result = 0;
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else
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fprintf(stderr, "pngtopng: write %s: %s\n", argv[2],
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image.message);
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free(buffer);
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}
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else
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{
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fprintf(stderr, "pngtopng: read %s: %s\n", argv[1],
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image.message);
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/* This is the only place where a 'free' is required; libpng does
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* the cleanup on error and success, but in this case we couldn't
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* complete the read because of running out of memory.
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*/
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png_image_free(&image);
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}
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}
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else
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fprintf(stderr, "pngtopng: out of memory: %lu bytes\n",
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(unsigned long)PNG_IMAGE_SIZE(image));
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}
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else
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/* Failed to read the first argument: */
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fprintf(stderr, "pngtopng: %s: %s\n", argv[1], image.message);
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}
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else
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/* Wrong number of arguments */
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fprintf(stderr, "pngtopng: usage: pngtopng input-file output-file\n");
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return result;
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}
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