1 /****************************************************************************
2
3 gifsponge.c - skeleton file for generic GIF `sponge' program
4
5 Slurp a GIF into core, operate on it, spew it out again. Most of the
6 junk above `int main' isn't needed for the skeleton, but is likely to
7 be for what you'll do with it.
8
9 If you compile this, it will turn into an expensive GIF copying routine;
10 stdin to stdout with no changes and minimal validation. Well, it's a
11 decent test of DGifSlurp() and EGifSpew(), anyway.
12
13 Note: due to the vicissitudes of Lempel-Ziv compression, the output of this
14 copier may not be bitwise identical to its input. This can happen if you
15 copy an image from a much more (or much *less*) memory-limited system; your
16 compression may use more (or fewer) bits. The uncompressed rasters should,
17 however, be identical (you can check this with gifbuild -d).
18
19 SPDX-License-Identifier: MIT
20
21 ****************************************************************************/
22
23 #include <fcntl.h>
24 #include <stdio.h>
25 #include <stdlib.h>
26 #include <string.h>
27
28 #include "getarg.h"
29 #include "gif_lib.h"
30
31 #define PROGRAM_NAME "gifsponge"
32
main(int argc,char ** argv)33 int main(int argc, char **argv) {
34 int i, ErrorCode;
35 GifFileType *GifFileIn, *GifFileOut = (GifFileType *)NULL;
36
37 if ((GifFileIn = DGifOpenFileHandle(0, &ErrorCode)) == NULL) {
38 PrintGifError(ErrorCode);
39 exit(EXIT_FAILURE);
40 }
41 if (DGifSlurp(GifFileIn) == GIF_ERROR) {
42 PrintGifError(GifFileIn->Error);
43 exit(EXIT_FAILURE);
44 }
45 if ((GifFileOut = EGifOpenFileHandle(1, &ErrorCode)) == NULL) {
46 PrintGifError(ErrorCode);
47 exit(EXIT_FAILURE);
48 }
49
50 /*
51 * Your operations on in-core structures go here.
52 * This code just copies the header and each image from the incoming
53 * file.
54 */
55 GifFileOut->SWidth = GifFileIn->SWidth;
56 GifFileOut->SHeight = GifFileIn->SHeight;
57 GifFileOut->SColorResolution = GifFileIn->SColorResolution;
58 GifFileOut->SBackGroundColor = GifFileIn->SBackGroundColor;
59 if (GifFileIn->SColorMap) {
60 GifFileOut->SColorMap =
61 GifMakeMapObject(GifFileIn->SColorMap->ColorCount,
62 GifFileIn->SColorMap->Colors);
63 } else {
64 GifFileOut->SColorMap = NULL;
65 }
66
67 for (i = 0; i < GifFileIn->ImageCount; i++) {
68 (void)GifMakeSavedImage(GifFileOut, &GifFileIn->SavedImages[i]);
69 }
70
71 /*
72 * Note: don't do DGifCloseFile early, as this will
73 * deallocate all the memory containing the GIF data!
74 *
75 * Further note: EGifSpew() doesn't try to validity-check any of this
76 * data; it's *your* responsibility to keep your changes consistent.
77 * Caveat hacker!
78 */
79 if (EGifSpew(GifFileOut) == GIF_ERROR) {
80 PrintGifError(GifFileOut->Error);
81 }
82
83 if (DGifCloseFile(GifFileIn, &ErrorCode) == GIF_ERROR) {
84 PrintGifError(ErrorCode);
85 }
86
87 return 0;
88 }
89
90 /* end */
91