| 1 | /*- pngtopng
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| 2 | *
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| 3 | * COPYRIGHT: Written by John Cunningham Bowler, 2011, 2017.
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| 4 | * To the extent possible under law, the author has waived all copyright and
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| 5 | * related or neighboring rights to this work. This work is published from:
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| 6 | * United States.
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| 7 | *
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| 8 | * Read a PNG and write it out in a fixed format, using the 'simplified API'
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| 9 | * that was introduced in libpng-1.6.0.
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| 10 | *
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| 11 | * This sample code is just the code from the top of 'example.c' with some error
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| 12 | * handling added. See example.c for more comments.
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| 13 | */
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| 14 | #include <stddef.h>
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| 15 | #include <stdlib.h>
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| 16 | #include <string.h>
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| 17 | #include <stdio.h>
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| 18 |
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| 19 | /* Normally use <png.h> here to get the installed libpng, but this is done to
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| 20 | * ensure the code picks up the local libpng implementation:
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| 21 | */
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| 22 | #include "../../png.h"
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| 23 | #if defined(PNG_SIMPLIFIED_READ_SUPPORTED) && \
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| 24 | defined(PNG_SIMPLIFIED_WRITE_SUPPORTED)
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| 25 |
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| 26 | int main(int argc, const char **argv)
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| 27 | {
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| 28 | int result = 1;
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| 29 |
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| 30 | if (argc == 3)
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| 31 | {
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| 32 | png_image image;
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| 33 |
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| 34 | /* Only the image structure version number needs to be set. */
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| 35 | memset(&image, 0, sizeof image);
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| 36 | image.version = PNG_IMAGE_VERSION;
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| 37 |
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| 38 | if (png_image_begin_read_from_file(&image, argv[1]))
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| 39 | {
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| 40 | png_bytep buffer;
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| 41 |
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| 42 | /* Change this to try different formats! If you set a colormap format
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| 43 | * then you must also supply a colormap below.
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| 44 | */
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| 45 | image.format = PNG_FORMAT_RGBA;
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| 46 |
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| 47 | buffer = malloc(PNG_IMAGE_SIZE(image));
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| 48 |
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| 49 | if (buffer != NULL)
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| 50 | {
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| 51 | if (png_image_finish_read(&image, NULL/*background*/, buffer,
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| 52 | 0/*row_stride*/, NULL/*colormap for PNG_FORMAT_FLAG_COLORMAP */))
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| 53 | {
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| 54 | if (png_image_write_to_file(&image, argv[2],
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| 55 | 0/*convert_to_8bit*/, buffer, 0/*row_stride*/,
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| 56 | NULL/*colormap*/))
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| 57 | result = 0;
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| 58 |
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| 59 | else
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| 60 | fprintf(stderr, "pngtopng: write %s: %s\n", argv[2],
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| 61 | image.message);
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| 62 | }
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| 63 |
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| 64 | else
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| 65 | fprintf(stderr, "pngtopng: read %s: %s\n", argv[1],
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| 66 | image.message);
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| 67 |
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| 68 | free(buffer);
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| 69 | }
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| 70 |
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| 71 | else
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| 72 | {
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| 73 | fprintf(stderr, "pngtopng: out of memory: %lu bytes\n",
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| 74 | (unsigned long)PNG_IMAGE_SIZE(image));
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| 75 |
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| 76 | /* This is the only place where a 'free' is required; libpng does
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| 77 | * the cleanup on error and success, but in this case we couldn't
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| 78 | * complete the read because of running out of memory and so libpng
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| 79 | * has not got to the point where it can do cleanup.
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| 80 | */
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| 81 | png_image_free(&image);
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| 82 | }
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| 83 | }
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| 84 |
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| 85 | else
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| 86 | /* Failed to read the first argument: */
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| 87 | fprintf(stderr, "pngtopng: %s: %s\n", argv[1], image.message);
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| 88 | }
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| 89 |
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| 90 | else
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| 91 | /* Wrong number of arguments */
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| 92 | fprintf(stderr, "pngtopng: usage: pngtopng input-file output-file\n");
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| 93 |
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| 94 | return result;
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| 95 | }
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| 96 | #endif /* READ && WRITE */
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