webgif.cpp

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/* Bring in the gd library functions */
#include "gd.h"

/* Bring in standard I/O and string manipulation functions */
#include <stdio.h>
#include <string.h>

int main(int argc, char **argv)
{
        FILE *in;
        FILE *out;
        char outFn[20];
        int useStdinStdout=0;

        /* Declare our image pointer */
        gdImagePtr im = 0;
        int i;
       /* We'll clear 'no' once we know the user has made a
                reasonable request. */
        int no = 1;
        /* We'll set 'write' once we know the user's request
                requires that the image be written back to disk. */
        int write = 0;
        /* C programs always get at least one argument; we want at
                least one more (the image), more in practice. */
        if (argc < 2 || !strcmp(argv[1], "--help")) {
                no = 1; 
                goto usage;
        }

        /* The last argument should be the image. Open the file. */
        if (strcmp("-", argv[argc-1])==0) { /* - is synonymous with STDIN */
          useStdinStdout = 1;
          in = stdin;
        } else {
          in = fopen(argv[argc-1], "rb");       
        }
        if (!in) {
                fprintf(stderr,
                        "Error: can't open file %s.\n", argv[argc-1]);
                exit(1);
        }
        /* Now load the image. */       
        im = gdImageCreateFromGif(in);
        fclose(in);
        /* If the load failed, it must not be a GIF file. */
        if (!im) {
                fprintf(stderr,
                        "Error: %s is not a valid gif file.\n", argv[argc-1]);
                exit(1);        
        }
        /* Consider each argument in turn. */
        for (i=1; (i < (argc-1)); i++) {
                /* -i turns on and off interlacing. */
                if (!strcmp(argv[i], "--help")) { 
                  /* Every program should use this for help! :) */
                  no = 1;
                  goto usage;
                } else if (!strcmp(argv[i], "-i")) {
                        if (i == (argc-2)) {
                                fprintf(stderr, 
                                "Error: -i specified without y or n.\n");
                                no = 1;
                                goto usage;
                        }
                        if (!strcmp(argv[i+1], "y")) {
                                /* Set interlace. */
                                gdImageInterlace(im, 1);
                        } else if (!strcmp(argv[i+1], "n")) {
                                /* Clear interlace. */
                                gdImageInterlace(im, 0);
                        } else {
                                fprintf(stderr,
                                "Error: -i specified without y or n.\n");
                                no = 1;
                                goto usage;
                        }
                        i++;
                        no = 0;
                        write = 1;
                } else if (!strcmp(argv[i], "-t")) {
                        /* Set transparent index (or none). */
                        int index;
                        if (i == (argc-2)) {
                                fprintf(stderr,
                "Error: -t specified without a color table index.\n");
                                no = 1;
                                goto usage;
                        }
                        if (!strcmp(argv[i+1], "none")) {
                                /* -1 means not transparent. */
                                gdImageColorTransparent(im, -1);
                        } else {
                                /* OK, get an integer and set the index. */
                                index = atoi(argv[i+1]);
                                gdImageColorTransparent(im, index);
                        }
                        i++;
                        write = 1;
                        no = 0;
                } else if (!strcmp(argv[i], "-l")) {
                        /* List the colors in the color table. */
                        int j;
                        /* Tabs used below. */
                        printf("Index   Red     Green   Blue\n");
                        for (j=0; (j < gdImageColorsTotal(im)); j++) {
                                /* Use access macros to learn colors. */
                                printf("%d      %d      %d      %d\n",
                                        j, 
                                        gdImageRed(im, j),
                                        gdImageGreen(im, j),
                                        gdImageBlue(im, j));
                        }
                        no = 0;
                } else if (!strcmp(argv[i], "-d")) {
                        /* Output dimensions, etc. */
                        int t;
                        printf("Width: %d Height: %d Colors: %d\n",
                                gdImageSX(im), gdImageSY(im),
                                gdImageColorsTotal(im));
                        t = gdImageGetTransparent(im);
                        if (t != (-1)) {
                                printf("Transparent index: %d\n", t);
                        } else {
                                /* -1 means the image is not transparent. */
                                printf("Transparent index: none\n");
                        }
                        if (gdImageGetInterlaced(im)) {
                                printf("Interlaced: yes\n");    
                        } else {
                                printf("Interlaced: no\n");     
                        }
                        no = 0;
                } else {
                        fprintf(stderr, "Unknown argument: %s\n", argv[i]);
                        break;  
                }
        }
usage:
        if (no) {
                /* If the command failed, output an explanation. */
                fprintf(stderr, 
"Usage: webgif [-i y|n ] [-l] [-t index|off ] [-d] gifname.gif\n"

"  -i [y|n]   Turns on/off interlace\n"
"  -l         Prints the table of color indexes\n"
"  -t [index] Set the transparent color to the specified index (0-255 or none)\n"
"  -d         Reports the dimensions and other characteristics of the image.\n"
"\n"
"If you specify '-' as the input file, stdin/stdout will be used input/output.\n"
);
        } 
        if (write) {
          if (useStdinStdout) {
            out = stdout;
          } else {
            /* Open a temporary file. */

            /* "temp.tmp" is not good temporary filename. */
            sprintf(outFn, "webgif.tmp%d", getpid());
            out = fopen(outFn, "wb"); 

            if (!out) {
              fprintf(stderr,
                      "Unable to write to %s -- exiting\n", outFn);
              exit(1);
            }
          }

          /* Write the new gif. */
          gdImageGif(im, out);

          if (!useStdinStdout) {
            fclose(out);
            /* Erase the old gif. */
            unlink(argv[argc-1]);
            /* Rename the new to the old. */
            if (rename(outFn, argv[argc-1])!=0) {
              perror("rename");
              exit(1);
            }
          }
        }
        /* Delete the image from memory. */
        if (im) {
                gdImageDestroy(im);
        }
        /* All's well that ends well. */
        return 0;
}

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