Source Code 1994 March/Source_Code_CD-ROM_Walnut_Creek_March_1994.iso/compsrcs/misc/volume36/chiaro/part12

Text File | 1993-03-25 | 55.2 KB | 1,637 lines

Newsgroups: comp.sources.misc
From: [e-mail] (James W. Birdsall)
Subject: v36i082:  chiaro - Image Utilities, Part12/18
Message-ID: <[e-mail]>
X-Md4-Signature: 9695f50e3725082a8f6fa0cb9b14d584
Date: Fri, 26 Mar 1993 20:28:31 GMT
Approved: [e-mail]

Submitted-by: [e-mail] (James W. Birdsall)
Posting-number: Volume 36, Issue 82
Archive-name: chiaro/part12
Environment: UNIX, Sun, DECstation, 3B1

#! /bin/sh
# This is a shell archive.  Remove anything before this line, then feed it
# into a shell via "sh file" or similar.  To overwrite existing files,
# type "sh file -c".
# Contents:  src/bmp.c src/gifcheck.1
# Wrapped by kent@sparky on Thu Mar 25 11:20:05 1993
PATH=/bin:/usr/bin:/usr/ucb:/usr/local/bin:/usr/lbin ; export PATH
echo If this archive is complete, you will see the following message:
echo '          "shar: End of archive 12 (of 18)."'
if test -f 'src/bmp.c' -a "${1}" != "-c" ; then
  echo shar: Will not clobber existing file \"'src/bmp.c'\"
else
  echo shar: Extracting \"'src/bmp.c'\" \(19928 characters\)
  sed "s/^X//" >'src/bmp.c' <<'END_OF_FILE'
X/***************************************************************************
X*   BMP.C                                                                  *
X*   MODULE:  BMP                                                           *
X*   OS:      UNIX                                                          *
X*                                                                          *
X*   Copyright (c) 1993 James W. Birdsall. All Rights Reserved.             *
X*                                                                          *
X*   $Id: bmp.c,v 1.2 1993/03/02 00:52:42 jwbirdsa Exp $
X*                                                                          *
X*   This file contains functions to process BMP format files.              *
X*   Functions:                                                             *
X*      bmp_verify    - checks filename to see if it is an BMP file         *
X*      bmp_getheader - extracts header data from BMP file                  *
X*                                                                          *
X*      bmp_errstring - converts error code into message                    *
X*                                                                          *
X***************************************************************************/
X
X#include "config.h"
X
X/*
X** system includes <>
X*/
X
X#include <stdio.h>
X#ifndef NO_STR_INC
X#ifdef STRING_PLURAL
X#include <strings.h>
X#else
X#include <string.h>
X#endif
X#endif
X
X
X/*
X** custom includes ""
X*/
X
X#include "depend.h"
X#include "formats.h"
X#include "bmp.h"
X
X
X/*
X** local #defines
X*/
X
X/*
X** misc: copyright strings, version macros, etc.
X*/
X
X/*
X** typedefs
X*/
X
X/*
X** global variables
X*/
X
X/*
X** static globals
X*/
X
Xstatic char CONST rcsid[] = "$Id: bmp.c,v 1.2 1993/03/02 00:52:42 jwbirdsa Exp $";
X
X
X/*
X** function prototypes
X*/
X
X#ifdef NO_STR_INC
Xextern char *strrchr();
Xextern int strcmp();
X#endif
X
X
X/*
X** functions
X*/
X
X
X/***************************************************************************
X*   FUNCTION:    bmp_verify                                                *
X*                                                                          *
X*   DESCRIPTION:                                                           *
X*                                                                          *
X*       Verifies that a file is an BMP file by checking filename against   *
X*       list of extensions. Reads BMP magic number from start of file.     *
X*                                                                          *
X*   ENTRY:                                                                 *
X*                                                                          *
X*       filename - name of file to be verified                             *
X*       version  - pointer to unsigned long in which format/version value  *
X*                  is returned                                             *
X*       exts     - array of string pointers, list of extensions for BMP    *
X*                  files                                                   *
X*                                                                          *
X*   EXIT:                                                                  *
X*                                                                          *
X*       Returns an error/status code.                                      *
X*                                                                          *
X*   CONSTRAINTS/SIDE EFFECTS:                                              *
X*                                                                          *
X***************************************************************************/
XULONG
X#ifdef __STDC__
Xbmp_verify(char *filename, ULONG *version, char **exts)
X#else
Xbmp_verify(filename, version, exts)
Xchar *filename;
XULONG *version;
Xchar **exts;
X#endif
X{
X    char *extptr;
X    int loop;
X    int magic;
X    FILE *bmpfile;
X    char buffer[4];
X    ULONG infolen;
X    ULONG retval;
X
X    /* Search for '.' marking extension. */
X
X    extptr = strrchr(filename, '.');
X    if (NULL == extptr)
X    {
X        /* No extension, cannot classify. */
X
X        *version = BMP_NOT;
X        return 0;
X    }
X    extptr++;
X
X    /* Now we have the extension, check against list. */
X
X    for (loop = 0; exts[loop] != NULL; loop++)
X    {
X        /* Case-sensitive string compare. */
X
X        if (strcmp(extptr, exts[loop]) == 0)
X        {
X            /* Match, so break out of loop. */
X
X            break;
X        }
X    }
X
X    /* Check exit from loop. */
X
X    if (NULL == exts[loop])
X    {
X        /* No match, return. */
X
X        *version = BMP_NOT;
X        return 0;
X    }
X
X    /* Extension is valid for type BMP, so process accordingly. */
X
X    if ((bmpfile = fopen(filename, FOPEN_READ_BINARY)) == (FILE *) NULL)
X    {
X        return BMP_FILEERR_E;
X    }
X
X    /* Read magic number. */
X
X    if ((magic = fgetc(bmpfile)) == EOF)
X    {
X        *version = BMP_NOT;
X        retval = (feof(bmpfile) ? ST_SUCCESS : BMP_FILEERR_E);
X        fclose(bmpfile);
X        return retval;
X    }
X    if (2 == magic)
X    {
X        *version = BMP_WIN2;
X    }
X    else if ('B' == magic)
X    {
X        /* Read more magic number. */
X
X        if (((magic = fgetc(bmpfile)) == EOF) || (magic != 'M'))
X        {
X            *version = BMP_NOT;
X            retval = (feof(bmpfile) ? ST_SUCCESS : BMP_FILEERR_E);
X            fclose(bmpfile);
X            return retval;
X        }
X
X        if (fseek(bmpfile, (long) BMP_HDR_INFOLEN_OFF, SEEK_SET))
X        {
X            *version = BMP_NOT;
X            fclose(bmpfile);
X            return BMP_FILEERR_E;
X        }
X
X        if (fread(buffer, sizeof(char), 4, bmpfile) != 4)
X        {
X            *version = BMP_NOT;
X            retval = (feof(bmpfile) ? ST_SUCCESS : BMP_FILEERR_E);
X            fclose(bmpfile);
X            return retval;
X        }
X
X        if ((infolen = CONSTRUCT_I_ULONG(buffer)) >= MKLONG(65536))
X        {
X            *version = BMP_NOT;
X            return (fclose(bmpfile) ? BMP_FILEERR_E : ST_SUCCESS);
X        }
X        switch ((int)(infolen))
X        {
X            case BMP_HDR11_INFOLEN_VAL:
X                *version = BMP_OS2_11;
X                break;
X
X            case BMP_HDR3_INFOLEN_VAL:
X                *version = BMP_WIN3;
X                break;
X
X            case BMP_HDR20_INFOLEN_VAL:
X                *version = BMP_OS2_20;
X                break;
X
X            default:
X                *version = (((infolen > BMP_HDR3_INFOLEN_VAL) &&
X                             (infolen < BMP_HDR20_INFOLEN_VAL)) ?
X                            BMP_OS2_20 : BMP_NOT);
X                break;
X        }
X    }
X
X    /* Close file. */
X
X    if (fclose(bmpfile))
X    {
X        return BMP_FILEERR_E;
X    }
X
X    /* Return OK. */
X
X    return 0;
X} /* end of bmp_verify() */
X
X
X/***************************************************************************
X*   FUNCTION:    bmp_getheader                                             *
X*                                                                          *
X*   DESCRIPTION:                                                           *
X*                                                                          *
X*       Assumes that file is an BMP file. Reads header from file, extracts *
X*       data into BMP_HDR structure.                                       *
X*                                                                          *
X*   ENTRY:                                                                 *
X*                                                                          *
X*       infile  - file to be processed                                     *
X*       results - pointer to BMP_HDR structure in which data from header   *
X*                 is returned                                              *
X*                                                                          *
X*   EXIT:                                                                  *
X*                                                                          *
X*       Returns an error/status code.                                      *
X*                                                                          *
X*   CONSTRAINTS/SIDE EFFECTS:                                              *
X*                                                                          *
X*       Leaves file pointing to beginning of image data.                   *
X*                                                                          *
X***************************************************************************/
XULONG
X#ifdef __STDC__
Xbmp_getheader(FILE *infile, BMP_HDR *results)
X#else
Xbmp_getheader(infile, results)
XFILE *infile;
XBMP_HDR *results;
X#endif
X{
X    UCHAR rawhdr[BMP_HDR20_LEN];
X    int validbytes;
X    ULONG infolen;
X
X    /* Make sure we're at beginning of file. */
X
X    if (fseek(infile, 0L, SEEK_SET))
X    {
X        return BMP_FILEERR_E;
X    }
X
X    /* Read raw bytes into buffer. */
X
X    if ((validbytes = fread(rawhdr, sizeof(UCHAR), BMP_HDR20_LEN, infile)) <
X        BMP_HDR2_LEN)
X    {
X        return (feof(infile) ? BMP_UNEOF_E : BMP_FILEERR_E);
X    }
X
X    /* Extract version from raw header. */
X
X    if (2 == *(rawhdr + BMP_HDR2_MAGIC_OFF))
X    {
X        /* Is a WIN2 BMP, very different. */
X
X        results->version = BMP_WIN2;
X    }
X    else if (('B' == *(rawhdr + BMP_HDR_MAGIC_OFF)) &&
X             ('M' == *(rawhdr + BMP_HDR_MAGIC_OFF + 1)) &&
X             (validbytes >= BMP_HDR11_LEN))
X    {
X        /* Is one of the OS2 or WIN3 BMPs. */
X
X        switch (infolen = CONSTRUCT_I_ULONG(rawhdr + BMP_HDR_INFOLEN_OFF))
X        {
X            case BMP_HDR11_INFOLEN_VAL:
X                results->version = BMP_OS2_11;
X                break;
X
X            case BMP_HDR3_INFOLEN_VAL:
X                results->version = BMP_WIN3;
X                break;
X
X            case BMP_HDR20_INFOLEN_VAL:
X                results->version = BMP_OS2_20;
X                break;
X
X            default:
X                results->version = (((infolen > BMP_HDR3_INFOLEN_VAL) &&
X                                     (infolen < BMP_HDR20_INFOLEN_VAL)) ?
X                                    BMP_OS2_20 : BMP_NOT);
X                break;
X        }
X        if (BMP_NOT == results->version)
X        {
X            return BMP_NOTBMP_E;
X        }
X    }
X    else
X    {
X        results->version = BMP_NOT;
X        return BMP_NOTBMP_E;
X    }
X
X    switch (FORMAT_VERS(results->version))
X    {
X        case FORMAT_VERS(BMP_WIN2):
X            results->imwid = (ULONG)CONSTRUCT_I_UINT(rawhdr+BMP_HDR2_IMWID_OFF);
X            results->imhi = (ULONG)CONSTRUCT_I_UINT(rawhdr + BMP_HDR2_IMHI_OFF);
X            results->planes = CONSTRUCT_I_UINT(rawhdr + BMP_HDR2_PLANES_OFF);
X            results->pixbits = CONSTRUCT_I_UINT(rawhdr + BMP_HDR2_BITS_OFF);
X            results->dataoffset = 16;
X            if ((results->more = ((VOID *) malloc(sizeof(BMP_H2)))) != NULL)
X            {
X                ((BMP_H2 *) results->more)->discardable =
X                                          (int)(*(rawhdr + BMP_HDR2_DISC_OFF));
X            }
X            break;
X
X        case FORMAT_VERS(BMP_OS2_11):
X            results->imwid = (ULONG)
X                             CONSTRUCT_I_UINT(rawhdr+BMP_HDR11_IMWID_OFF);
X            results->imhi = (ULONG)
X                            CONSTRUCT_I_UINT(rawhdr + BMP_HDR11_IMHI_OFF);
X            results->planes = CONSTRUCT_I_UINT(rawhdr + BMP_HDR11_PLANES_OFF);
X            results->pixbits = CONSTRUCT_I_UINT(rawhdr + BMP_HDR11_BITS_OFF);
X            results->dataoffset = CONSTRUCT_I_ULONG(rawhdr + BMP_HDR_HLEN_OFF);
X            if ((results->more = ((VOID *) malloc(sizeof(BMP_H11)))) != NULL)
X            {
X                ((BMP_H11 *) results->more)->filesize =
X                                 CONSTRUCT_I_ULONG(rawhdr + BMP_HDR_FSIZE_OFF);
X            }
X            break;
X
X        case FORMAT_VERS(BMP_WIN3):
X            results->imwid = (ULONG)CONSTRUCT_I_UINT(rawhdr+BMP_HDR3_IMWID_OFF);
X            results->imhi = (ULONG)CONSTRUCT_I_UINT(rawhdr + BMP_HDR3_IMHI_OFF);
X            results->planes = CONSTRUCT_I_UINT(rawhdr + BMP_HDR3_PLANES_OFF);
X            results->pixbits = CONSTRUCT_I_UINT(rawhdr + BMP_HDR3_BITS_OFF);
X            results->dataoffset = CONSTRUCT_I_ULONG(rawhdr + BMP_HDR_HLEN_OFF);
X            if ((results->more = ((VOID *) malloc(sizeof(BMP_H3)))) != NULL)
X            {
X                BMP_H3 *more = (BMP_H3 *) results->more;
X
X                more->more.filesize =
X                                 CONSTRUCT_I_ULONG(rawhdr + BMP_HDR_FSIZE_OFF);
X                more->compression =
X                                 CONSTRUCT_I_ULONG(rawhdr + BMP_HDR3_COMPR_OFF);
X                more->compsize = CONSTRUCT_I_ULONG(rawhdr + BMP_HDR3_CSIZE_OFF);
X                more->xres = CONSTRUCT_I_ULONG(rawhdr + BMP_HDR3_XRES_OFF);
X                more->yres = CONSTRUCT_I_ULONG(rawhdr + BMP_HDR3_YRES_OFF);
X                more->clrused =CONSTRUCT_I_ULONG(rawhdr + BMP_HDR3_CLRUSED_OFF);
X                more->clrimp = CONSTRUCT_I_ULONG(rawhdr + BMP_HDR3_CLRIMP_OFF);
X            }
X            break;
X
X        case FORMAT_VERS(BMP_OS2_20):
X            results->imwid = (ULONG)CONSTRUCT_I_UINT(rawhdr+BMP_HDR3_IMWID_OFF);
X            results->imhi = (ULONG)CONSTRUCT_I_UINT(rawhdr + BMP_HDR3_IMHI_OFF);
X            results->planes = CONSTRUCT_I_UINT(rawhdr + BMP_HDR3_PLANES_OFF);
X            results->pixbits = CONSTRUCT_I_UINT(rawhdr + BMP_HDR3_BITS_OFF);
X            results->dataoffset = CONSTRUCT_I_ULONG(rawhdr + BMP_HDR_HLEN_OFF);
X            if ((results->more = ((VOID *) malloc(sizeof(BMP_H20)))) != NULL)
X            {
X                BMP_H20 *more = (BMP_H20 *) results->more;
X
X                more->more.more.filesize =
X                                 CONSTRUCT_I_ULONG(rawhdr + BMP_HDR_FSIZE_OFF);
X
X                /*
X                ** At last! A real use for fall-through in a switch.
X                ** The header of an OS/2 2.0 bitmap may be truncated anywhere
X                ** after the bits per pixel field. So we zero out all fields
X                ** in the structure and use fall-through to collect whatever
X                ** ones are present.
X                */
X
X                more->more.compression = 0;
X                more->more.compsize = 0;
X                more->more.xres = 0;
X                more->more.yres = 0;
X                more->more.clrused = 0;
X                more->more.clrimp = 0;
X                more->resunits = 0;
X                more->origin = 0;
X                more->halfalg = 0;
X                more->half1 = 0;
X                more->half2 = 0;
X                more->clrencode = 0;
X                more->appdata = 0;
X
X                switch (infolen + BMP_HDR_INFOLEN_OFF)
X                {
X                    case BMP_HDR20_APPDATA_OFF:
X                        more->appdata =
X                              CONSTRUCT_I_ULONG(rawhdr + BMP_HDR20_APPDATA_OFF);
X                    case BMP_HDR20_CLRENC_OFF:
X                        more->clrencode =
X                               CONSTRUCT_I_ULONG(rawhdr + BMP_HDR20_CLRENC_OFF);
X                    case BMP_HDR20_HALF2_OFF:
X                        more->half2 =
X                               CONSTRUCT_I_ULONG(rawhdr + BMP_HDR20_HALF2_OFF);
X                    case BMP_HDR20_HALF1_OFF:
X                        more->half1 =
X                               CONSTRUCT_I_ULONG(rawhdr + BMP_HDR20_HALF1_OFF);
X                    case BMP_HDR20_HALFALG_OFF:
X                        more->halfalg =
X                               CONSTRUCT_I_UINT(rawhdr + BMP_HDR20_HALFALG_OFF);
X                    case BMP_HDR20_ORIENT_OFF:
X                        more->origin =
X                               CONSTRUCT_I_UINT(rawhdr + BMP_HDR20_ORIENT_OFF);
X                    case BMP_HDR20_RESUNITS_OFF:
X                        more->resunits =
X                              CONSTRUCT_I_UINT(rawhdr + BMP_HDR20_RESUNITS_OFF);
X                    case BMP_HDR3_CLRIMP_OFF:
X                        more->more.clrimp =
X                               CONSTRUCT_I_ULONG(rawhdr + BMP_HDR3_CLRIMP_OFF);
X                    case BMP_HDR3_CLRUSED_OFF:
X                        more->more.clrused =
X                               CONSTRUCT_I_ULONG(rawhdr + BMP_HDR3_CLRUSED_OFF);
X                    case BMP_HDR3_YRES_OFF:
X                        more->more.yres =
X                               CONSTRUCT_I_ULONG(rawhdr + BMP_HDR3_YRES_OFF);
X                    case BMP_HDR3_XRES_OFF:
X                        more->more.xres =
X                               CONSTRUCT_I_ULONG(rawhdr + BMP_HDR3_XRES_OFF);
X                    case BMP_HDR3_CSIZE_OFF:
X                        more->more.compsize =
X                               CONSTRUCT_I_ULONG(rawhdr + BMP_HDR3_CSIZE_OFF);
X                    case BMP_HDR3_COMPR_OFF:
X                        more->more.compression =
X                               CONSTRUCT_I_ULONG(rawhdr + BMP_HDR3_COMPR_OFF);
X                        break;
X
X                    default:
X                        /* Something very bad has happened. */
X
X                        results->version = BMP_NOT;
X                        return BMP_NOTBMP_E;
X                        break;
X                }
X            }
X            break;
X
X        default:
X            /* Something very bad has happened. */
X
X            results->version = BMP_NOT;
X            return BMP_NOTBMP_E;
X            break;
X    }
X
X    /* Set file to point to start of colormap or data. */
X
X    if (fseek(infile,
X              ((BMP_WIN2 == results->version) ?
X               16L : (long)(infolen + BMP_HDR_INFOLEN_OFF)), SEEK_SET))
X    {
X        return BMP_FILEERR_E;
X    }
X
X    /* Return OK. */
X
X    return 0;
X} /* end of bmp_getheader() */
X
X
X/***************************************************************************
X*   FUNCTION: bmp_errstring                                                *
X*                                                                          *
X*   DESCRIPTION:                                                           *
X*                                                                          *
X*      Returns a string corresponding to an error code.                    *
X*                                                                          *
X*   ENTRY:                                                                 *
X*                                                                          *
X*      errcode - error code to be translated                               *
X*                                                                          *
X*   EXIT:                                                                  *
X*                                                                          *
X*      Returns a pointer to the appropriate string, or NULL if there is    *
X*      no appropriate string.                                              *
X*                                                                          *
X*   CONSTRAINTS/SIDE EFFECTS:                                              *
X*                                                                          *
X***************************************************************************/
Xchar *
X#ifdef __STDC__
Xbmp_errstring(ULONG errcode)
X#else
Xbmp_errstring(errcode)
XULONG errcode;
X#endif
X{
X    char *temp;
X
X    /* If error code not from this module, return NULL. */
X
X    if ((errcode & ST_MOD_MASK) != BMP_MODULE)
X    {
X        return NULL;
X    }
X
X    /* Process by code. */
X
X    switch (ERRSEV(errcode))
X    {
X        case ERRSEV(BMP_NOTBMP_E):
X            temp = "File is not a BMP format file.";
X            break;
X        case ERRSEV(BMP_FILEERR_E):
X            temp = "Error accessing file.";
X            break;
X        case ERRSEV(BMP_UNEOF_E):
X            temp = "Unexpected End of File";
X            break;
X
X        default:
X            temp = NULL;
X            break;
X    }
X
X    return temp;
X} /* end of bmp_errstring() */
X
END_OF_FILE
  if test 19928 -ne `wc -c <'src/bmp.c'`; then
    echo shar: \"'src/bmp.c'\" unpacked with wrong size!
  fi
  # end of 'src/bmp.c'
fi
if test -f 'src/gifcheck.1' -a "${1}" != "-c" ; then
  echo shar: Will not clobber existing file \"'src/gifcheck.1'\"
else
  echo shar: Extracting \"'src/gifcheck.1'\" \(32803 characters\)
  sed "s/^X//" >'src/gifcheck.1' <<'END_OF_FILE'
X.\"
X.\" $Id: gifcheck.1,v 1.3 1993/03/13 02:58:49 jwbirdsa Exp $
X.\"
X.TH GIFCHECK 1 "$Date: 1993/03/13 02:58:49 $
X.PD 1
X.SH NAME
Xgifcheck \- GIF file analysis and verification
X.SH SYNOPSIS
X.B gifcheck
X[
X.B \-v
X][
X.B \-H
X][
X.B \-c
X][
X.B \-dn
X][
X.B \-en
X][
X.B \-b
X][
X.B \-r
X][
X.B \-\-
X][
X.B \-l
X][
X.B \-f
X][
X.B \-h
X] target [ target... ]
X.br
X.SH DESCRIPTION
X.I Gifcheck
Xperforms complete analysis and verification of GIF-format images
Xand displays the information it finds. It can also be used in shell scripts
Xto determine whether GIF files are valid, and if they need to be passed
Xthrough the
X.I gifstrip
Xprogram to remove excess characters.
X.SH TARGETS
XA target is a filename or directory. Multiple targets may be specified on
Xthe command line. If a target is a directory, all files in that directory
Xwill be processed. If no targets are specified on the command line, a usage
Xmessage will be printed.
X.SH OPTIONS
XOptions may not be combined. In the case of the
X.B \-dn
Xand
X.B \-en
Xoptions, there cannot be a space between the option and the argument to the
Xoption.
X.TP
X.B \-v
XOutput is in a more verbose format. No additional data is displayed.
X.TP
X.B \-H
XPlain Text Extensions and Comment Extensions are displayed in hex dump
Xformat instead of as text.
X.TP
X.B \-c
XAll color tables in the file are dumped as decimal RGB triplets of the form
XRRR/GGG/BBB.
X.TP
X.B \-dn
XSets display warning level (see DIAGNOSTICS below for an explanation of the
Xtypes):
X.RS 10
X.PP
X.nf
X-d0             display anomalies and violations
X-d1 (default)   display anomalies, violations,
X                 and fascinatings
X-d2             display all (anomalies, violations,
X                 fascinatings, nitpicks)
X.fi
X.RE
X.TP
X.B \-en
XSet exit warning level, at which processing of an image is stopped and
X.I gifcheck
Xskips to the next image (see DIAGNOSTICS below for an explanation of the
Xtypes):
X.RS 10
X.PP
X.nf
X-e0             skip on anomalies only
X-e1 (default)   skip on anomalies and violations
X-e2             skip on anomalies, violations,
X                 and fascinatings
X.fi
X.RE
X.TP
X.B \-b
XOperate in batch mode. All output is suppressed. This option should be
Xfirst on the command line or other options may generate output before this
Xoption is found. When in batch mode,
X.I gifcheck
Xadjusts its status return to reflect the results of processing. The status
Xmay be:
X.RS 10
X.PP
X.nf
X0     the file is GIF format and did not need
X       stripping
X1     file is not GIF format
X2     an unexpected EOF was encountered
X       (usually indicates a corrupt file)
X3     any other error
X4     file is GIF format and needs stripping
X5     file is GIF format and needs to be
X       stripped with the -m option
X.fi
X.RE
X.RS 5
X.PP
XNote that the status reflects the result of only the last file processed.
XTherefore, in batch mode only one file should be specified on the command
Xline.
X.RE
X.TP
X.B \-r
XRedirects error messages to stderr.
X.TP
X.B \-\-
XRead targets from stdin. The list of targets must have only one target per
Xline. Targets which are directories will be expanded as usual, but
Xwildcards will not be expanded. Targets on the command line will be
Xignored.
XFor use with the
X.B \-f
Xoption of
X.I
Xchils.
X.TP
X.B \-l
XDisables check for excess characters at the beginning of the file. By
Xdefault,
X.I gifcheck
Xwill search through a file looking for the GIF signature if the file does
Xnot begin with that signature. This option will disable that search.
X.TP
X.B \-f
XDisables image decompression. This can be a slow process for large files.
XHowever, an image cannot be completely verified if it is not decompressed,
Xand some information can only be obtained by decompressing the image data.
X.TP
X.B \-p
XIf
X.I gifcheck
Xwas compiled with the PROGRESS_IND option enabled, it will by default print
Xa progress indicator when decompressing an image. This option turns off the
Xprogress indicator. Note that this option is not valid if
X.I gifcheck
Xwas not complied with the PROGRESS_IND option enabled. Check the help
X(-h) to see if this option is listed and hence valid.
X.TP
X.B \-h
XPrints a usage message. No files are processed and all other options are
Xignored.
X.SH OUTPUT
X.I Gifcheck
Xrecognizes eight different types of blocks within a GIF file: file headers,
Ximages, and five types of extension block: generic extensions, Graphic
XControl Extensions, Plain Text Extensions, Comment Extensions, and
XApplication Extensions (the last four are found only in GIF89a-format
Xfiles).
X.PP
XData from each type of block is output in a different format, which may
Xchange according to the settings of the output format options. The various
Xdisplays are explained below.
X.RS 3
X.SS "FILE HEADER"
XThe default file header display, with no options, looks like this:
X.RS 3
X.PP
X.nf
XProcessing junk2/devil.gif...
XFILE junk2/devil.gif   GIF87a      11209 bytes
X   logical screen:    640 x   480
X   8 bits per color available on source
XGLOBAL COLOR TABLE:
X   6 bits (64 colors)   bg index 0 (000/000/000)
X   59 unique colors.
X.fi
X.RE
X.PP
XThe first line gives the filename, in case an error is encountered
Ximmediately. The second line repeats the filename and displays the
Xformat and filesize. The third line gives the size, in pixels, of the
Xlogical screen on which all images in the file will be displayed. The
Xfourth line displays how many bits per color (R,G,B) were available on
Xthe machine on which the file was created. This value is frequently set
Xincorrectly and may generally be ignored.
X.PP
XThe global color table, if present, has a subsection to itself. The
Xsixth line indicates how large the global color table is. It also
Xdisplays the background color index and the RGB value corresponding to
Xthat index. While the background color index is actually part of the
Xfile header proper, it is meaningless unless a global color table is
Xpresent, so it is displayed in the global color table section. If the
Xfile is a GIF89a-format image, this line also indicates whether the
Xglobal color table is sorted. Finally, the seventh line indicates how
Xmany unique colors are present in the global color table.
X.PP
XIf no global color table is present, a line stating this is displayed
Xinstead.
X.PP
XIf the
X.B \-v
Xoption is in effect, the file header display looks like this:
X.RS 3
X.PP
X.nf
XProcessing junk2/devil.gif...
XFILE junk2/devil.gif is GIF version GIF87a:
X   file size (bytes):    11209
X   logical screen size (pixels, width x height):   640 x   480
X   8 bits per color available on source
X   This file has a global color table.
XGLOBAL COLOR TABLE:
X   6 bits per index for a table size of 64
X   background index 0, RGB value 000/000/000
X   59 unique colors.
X.fi
X.RE
X.PP
XThe data displayed is the same, but more explanatory text is
Xincluded.
X.PP
XIf the
X.B \-c
Xoption is in effect, the file header display looks like this:
X.RS 3
X.PP
X.nf
XProcessing junk2/devil.gif...
XFILE junk2/devil.gif   GIF87a      11209 bytes
X   logical screen:    640 x   480
X   8 bits per color available on source
XGLOBAL COLOR TABLE:
X   6 bits (64 colors)   bg index 0 (000/000/000)
X   59 unique colors.
X   000/000/000   255/197/197   255/156/156   255/189/189   255/131/131
X   255/180/180   255/148/148   255/205/205   041/000/000   255/123/123
X   255/172/172   255/074/074   082/000/000   255/057/057   255/090/090
X   255/115/115   008/000/000   049/000/000   255/164/164   024/000/000
X   131/000/000   255/049/049   074/000/000   255/082/082   123/000/000
X   255/139/139   065/000/000   148/000/000   255/041/041   016/000/000
X   255/016/016   230/024/024   255/032/032   115/000/000   164/000/000
X   057/000/000   255/106/106   106/000/000   156/000/000   255/008/008
X   032/000/000   255/065/065   139/000/000   180/000/000   255/024/024
X   098/000/000   090/000/000   238/000/000   189/000/000   230/000/000
X   213/000/000   172/000/000   205/000/000   197/000/000   246/000/000
X   222/000/000   230/016/016   255/000/000   255/098/098   000/000/000
X   000/000/000   000/000/000   000/000/000   000/000/000
X.fi
X.RE
X.PP
XThe standard or verbose display is followed by a listing, in decimal,
Xof the raw RGB values found in the global color map.
X.SS IMAGE
XThe default image display, with no options, looks like this:
X.RS 3
X.PP
X.nf
XIMAGE 1:
X   size   640 x   480   corner     0,     0   sequentially
X   This image uses the global color table (no local color table).
X   IMAGE DATA FOR IMAGE 1:
X   code size 6 bits
X   Reached end of codes in block 42
X   totals: 7906 codes packed into 10948 bytes in 43 blocks
X        307200 pixels extracted
X        code table cleared 2 times
X        compressed data is 4% of the size of uncompressed image
X        59 colors referenced (59 unique)
X.fi
X.RE
X.PP
XEach image in the file is numbered by
X.I gifcheck
Xstarting at 1 and has
Xa section to itself. The first line gives the image number. The second
Xline indicates the size, in pixels, of the image; the location, in
Xpixels, of the upper left corner, and how the image is stored
X("sequentially" or "interlaced").
X.PP
XThe third line indicates whether there is a local color table, and
Xwhether the image uses the global or local color table. If there is a
Xlocal color table, the third line is followed by a color table display
Xsimilar to the one for global color tables, including a dump of
Xthe raw RGB values if the
X.B \-c
Xcolor dump option is in effect. Very few images have local color tables.
X.PP
XImage data is stored compressed, and the compressed data is further
Xbroken up into blocks (which are numbered by
X.I gifcheck
Xstarting at 0).
XThe fifth line indicates the minimum code size for the image. The sixth
Xline indicates the block in which the end-of-information (EOI) code was
Xencountered. The seventh line indicates the number of codes extracted,
Xthe number of bytes which those codes occupied, and how many blocks
Xthose bytes were divided into. The eighth line indicates how many pixels
Xwere generated when the codes were decompressed, and the ninth line
Xindicates how many times the table-clear code was encountered.
X.PP
XThe tenth line indicates the size of the compressed data as a
Xpercentage of the size of the uncompressed image. The size of the
Xcompressed data is the size of the data only, not including block
Xheaders, image headers, or any other non-image data, so the compression
Xratio is accurate. The size of the uncompressed image is calculated by
Xmultiplying the height and the width to get the total number of pixels
Xin the image, then multiplying by the number of bits required to
Xrepresent the global or local color table, depending on which one is
Xused by the image. Finally, the eleventh line indicates how many colors
Xwere referenced by the image data, and how many of the colors referenced
Xare unique.
X.PP
XIf the
X.B \-v
Xoption is in effect, the image display looks like this:
X.RS 3
X.PP
X.nf
XIMAGE 1:
X   image size (pixels, width x height):   640 x   480
X   image upper left corner (column, row):     0,     0
X   image is stored sequentially
X   This image uses the global color table (no local color table).
X   IMAGE DATA FOR IMAGE 1:
X   code size 6 bits
X   Reached end of codes in block 42
X   totals: 7906 codes packed into 10948 bytes in 43 blocks
X        307200 pixels extracted
X        code table cleared 2 times
X        compressed data is 4% of the size of uncompressed image
X        59 colors referenced (59 unique)
X.fi
X.RE
X.PP
XThe data displayed is the same, but more explanatory text is included.
X.PP
XIf the
X.B \-f
Xoption is in effect, the image display looks like this:
X.RS 3
X.PP
X.nf
XIMAGE 1:
X   size   640 x   480   corner     0,     0   sequentially
X   This image uses the global color table (no local color table).
X   IMAGE DATA FOR IMAGE 1:
X   code size 6 bits
X   totals: 10948 bytes in 43 blocks
X        compressed data is 4% of the size of uncompressed image
X.fi
X.RE
X.PP
XSince the compressed image data is not decompressed under this
Xoption, less information is available.
X.SS "GENERIC EXTENSIONS"
XIf the format is GIF87a, or the format is GIF89a but the type
Xidentifier is not one of the four dedicated types, the "generic
Xextension" format is used. It looks like this:
X.RS 3
X.PP
X.nf
XGENERIC EXTENSION BLOCK 1:
X   extension block type 255
X   BLOCK 0 (11 bytes):
XG 47    I 49    F 46    L 4C    I 49    T 54    E 45      20
X  20      20      20
X   BLOCK 1 (6 bytes):
X  01    ) 29    p 70      0E      02      00
X   totals: 17 bytes of data in 2 blocks
X.fi
X.RE
X.PP
XGeneric extension blocks are numbered sequentially by
X.I gifcheck
Xstarting at 1. The
Xfirst line indicates that it is a generic extension block and gives the
Xsequence number. The second line shows the type identifier value. The
Xnext lines display the data in hex dump format (generic extensions are
Xalways displayed in hex dump format, regardless of the setting of the
X.B \-H
Xoption). Each data block is numbered sequentially by
X.I gifcheck
Xstarting at 0. A line giving the data block number and the number of
Xbytes in the block is shown. Then the data bytes themselves are
Xdisplayed, eight per line. If the byte is a printable character, the
Xcharacter is printed, followed by the hex value of the byte; otherwise a
Xspace is printed, followed by the hex value. Finally, a totals line is
Xprinted, indicating the total number of data bytes and the total number
Xof data blocks.
X.PP
XThe
X.B \-v
Xoption has no effect on generic extension displays.
X.SS "GRAPHIC CONTROL EXTENSION"
XGraphic Control Extensions (GCEs) are one of the GIF89a dedicated
Xextension types. When encountered, they are displayed like this:
X.RS 3
X.PP
X.nf
XGRAPHIC CONTROL EXTENSION BLOCK 1:
X   Disposal method: 0 (none)
X   User input is not expected
X   Transparency enabled (index 3)
X   No delay time specified
X.fi
X.RE
X.PP
XGCEs are numbered sequentially (by
X.I gifcheck).
XThe first line
Xindicates that it is a GCE and gives the sequence number. The second
Xline shows the disposal method (which applies to the next graphic --
Xi.e. image or Plain Text Extension -- in the file). This can be: "none",
X"leave in place", "restore to background", or "restore to previous".
X.PP
XThe third line indicates whether user input is expected before the
Xnext graphic will be displayed. The fourth line indicates whether a
Xtransparency color index (which indicates that pixels of the given color
Xshould be rendered "transparent" -- i.e., not drawn) has been specified,
Xand if so, what the transparency index is. The last line indicates
Xwhether a delay time (delay before the next graphic is displayed) has
Xbeen specified, and if so what the delay value is.
X.PP
XThe
X.B \-v
Xoption has no effect on GCE displays.
X.SS "PLAIN TEXT EXTENSION"
XPlain Text Extensions (PTEs) are one of the GIF89a dedicated
Xextension types. When encountered, they are displayed like this:
X.RS 3
X.PP
X.nf
XPLAIN TEXT EXTENSION BLOCK 1:
X   char cell   8 x  28, grid  96( 12) x  28(  1) at     0,   112
X   Foreground color index 0 (RGB 016/016/014)
X   Background color index 3 (RGB 113/110/232)
X   START TEXT (12 characters):
X Cass Berry
X   END TEXT.
X.fi
X.RE
X.PP
XPTEs are numbered sequentially by
X.I gifcheck
Xstarting at 1. The first line
Xindicates that it is a PTE and gives the sequence number. The second
Xline shows: the size of the character cell, in pixels; the size of the
Xcharacter grid, in pixels and cells (cells in parentheses); and the
Xlocation of the upper left corner of the grid. The third line shows the
Xindex and RGB values of the foreground text color, and the fourth line
Xshows the same for the background color.
X.PP
XThe fifth line indicates the start of the text, and how many
Xcharacters of text are present. It is followed by the text itself, which
Xis in turn followed by an "END TEXT." marker on the next line.
X.PP
XIf the
X.B \-v
Xoption is in effect, PTEs are displayed like this:
X.RS 3
X.PP
X.nf
XPLAIN TEXT EXTENSION BLOCK 1:
X   Character cell grid upper left corner (column, row):     0,   112
X   Character cell size (pixels, width x height):   8 x  28
X   Character grid size (pixels, width x height):  96 x  28
X   Character grid size (chars, width x height):  12 x   1
X   Foreground color index 0 (RGB 016/016/014)
X   Background color index 3 (RGB 113/110/232)
X   START TEXT (12 characters):
X Cass Berry
X   END TEXT.
X.fi
X.RE
X.PP
XThe same information is displayed, but more explanatory text is included.
X.PP
XIf the
X.B \-H
Xoption is in effect, the text is displayed in hex dump format, like this:
X.RS 3
X.PP
X.nf
XPLAIN TEXT EXTENSION BLOCK 1:
X   char cell   8 x  28, grid  96( 12) x  28(  1) at     0,   112
X   Foreground color index 0 (RGB 016/016/014)
X   Background color index 3 (RGB 113/110/232)
X   START TEXT (12 characters):
X   LINE 1:
X  20    C 43    a 61    s 73    s 73      20    B 42    e 65
Xr 72    r 72    y 79      20
X   END TEXT.
X.fi
X.RE
X.PP
XInstead of simply displaying the text, each character is displayed
Xindividually, followed by its hex value.
X.SS "COMMENT EXTENSION"
XComment Extensions are one of the GIF89a dedicated extension types.
XWhen encountered, they are displayed like this:
X.RS 3
X.PP
X.nf
XCOMMENT EXTENSION BLOCK 1:
X   START TEXT (161 characters):
X+-------------------------------------------------+
X| Multi-image GIF89a created with CompuMake Tools |
X+-------------------------------------------------+
X
X   END TEXT.
X   0 unprintable characters.
X.fi
X.RE
X.PP
XComment Extensions are numbered sequentially by
X.I gifcheck
Xstarting at 1. The first
Xline indicates that it is a Comment Extension and gives the sequence
Xnumber. The second line indicates the start of the text and how many
Xcharacters of text are present. It is followed by the text itself, which
Xis in turn followed by an "END TEXT." marker on the next line. The last
Xline indicates how many unprintable characters were found in the text.
X.PP
XThe
X.B \-v
Xoption has no effect on Comment Extension displays.
X.PP
XIf the
X.B \-H
Xoption is in effect, the text is displayed in hex dump format, like this:
X.RS 3
X.PP
X.nf
XCOMMENT EXTENSION BLOCK 1:
X   START TEXT (161 characters):
X+ 2B    - 2D    - 2D    - 2D    - 2D    - 2D    - 2D    - 2D
X- 2D    - 2D    - 2D    - 2D    - 2D    - 2D    - 2D    - 2D
X- 2D    - 2D    - 2D    - 2D    - 2D    - 2D    - 2D    - 2D
X- 2D    - 2D    - 2D    - 2D    - 2D    - 2D    - 2D    - 2D
X- 2D    - 2D    - 2D    - 2D    - 2D    - 2D    - 2D    - 2D
X- 2D    - 2D    - 2D    - 2D    - 2D    - 2D    - 2D    - 2D
X- 2D    - 2D    + 2B      0D      0A    | 7C      20    M 4D
Xu 75    l 6C    t 74    i 69    - 2D    i 69    m 6D    a 61
Xg 67    e 65      20    G 47    I 49    F 46    8 38    9 39
Xa 61      20    c 63    r 72    e 65    a 61    t 74    e 65
Xd 64      20    w 77    i 69    t 74    h 68      20    C 43
Xo 6F    m 6D    p 70    u 75    M 4D    a 61    k 6B    e 65
X  20    T 54    o 6F    o 6F    l 6C    s 73      20    | 7C
X  0D      0A    + 2B    - 2D    - 2D    - 2D    - 2D    - 2D
X- 2D    - 2D    - 2D    - 2D    - 2D    - 2D    - 2D    - 2D
X- 2D    - 2D    - 2D    - 2D    - 2D    - 2D    - 2D    - 2D
X- 2D    - 2D    - 2D    - 2D    - 2D    - 2D    - 2D    - 2D
X- 2D    - 2D    - 2D    - 2D    - 2D    - 2D    - 2D    - 2D
X- 2D    - 2D    - 2D    - 2D    - 2D    - 2D    - 2D    - 2D
X- 2D    - 2D    - 2D    - 2D    + 2B      0D      0A      0D
X  0A
X   END TEXT.
X   0 unprintable characters.
X.fi
X.RE
X.PP
XInstead of simply displaying the text, each character is displayed
Xindividually, followed by its hex value.
X.SS "APPLICATION EXTENSION"
XApplication Extensions are one of the GIF89a dedicated extension
Xtypes. When encountered, they are displayed like this:
X.RS 3
X.PP
X.nf
XAPPLICATION EXTENSION BLOCK 1:
X   application identifier:
Xf 66    r 72    a 61    c 63    t 74    i 69    n 6E    t 74
X   application authentication code:
X0 30    0 30    1 31
X   246 bytes of application data.
XF 46    r 72    a 61    c 63    t 74    a 61    l 6C      00
X  96      00      07      00      00      00      00    h 68
X  D8      FB      0C    @ 40      00      00      00      20
X  0B      FF      0C    @ 40      00      00      00      00
X  00      E9    I 49    ? 3F      00      00      00      00
X  F0    = 3D      89    ? 3F      00      00      00      00
X  00      00      00      00      00      00      00      00
X  00      00      00      00      00      00      00      00
X  00      00      00      00      1B      00      80      02
X  E0      01      00      01      04      00      00      00
X  00      00      00      00      00      00      00      00
X  00      00      00      00      00      00      00      00
X  00      00      00      00      00      00      FF      FF
X  01      00      01      00      00      00      00      00
X  00      00      00      00      00      00      00      00
X  00      00      00      00      E7      03      00      00
XZ 5A      00      09      01      00      00    x 78      00
X  8C      00    ( 28      00      00      00      02      00
Xn 6E      00      00      00      00      00      01      00
X  FF      FF      01      00      00      00      14      00
X  00      00      00      00      04      00      00      00
X  00      00      04      00    P 50      00    d 64      00
X  00      00      00      00      00      00      FF      FF
X  00      00      00    h 68      D8      FB      0C    @ 40
X  00      00      00      00      00      E9    I 49    ? 3F
Xg 67      00      04      00      06      01      00      00
X  00      00      00      00      00      00      D8      A7
X  00      00      00      06      02      03      00      00
X  00      00      00      00      00      00      00      00
X  00      00      00      00      00      00      00      00
X  01      00      00      00      00      00
X.fi
X.RE
X.PP
XApplication Extensions are numbered sequentially by
X.I gifcheck
Xstarting at 1. The
Xfirst line indicates that it is an Application Extension and gives the
Xsequence number. The second line introduces the eight-byte application
Xidentifier and is followed on the third line by the application
Xidentifier itself, in hex dump format. The fourth line introduces the
Xthree-byte application authentication code and is followed on the fifth
Xline by the application authentication code itself, in hex dump format.
XThe sixth line indicates how many bytes of application data are present,
Xand is followed by the application data itself in hex dump format. All
Xdata in Application Extensions is always displayed in hex dump format,
Xregardless of the setting of the
X.B \-H
Xoption.
X.PP
XThe
X.B \-v
Xoption has no effect on Application Extension displays.
X.SS TERMINATOR
XWhen the GIF terminator block is encountered,
X.I gifcheck
Xprints this line:
X.RS 3
X.PP
X.nf
XGIF TERMINATOR
X.fi
X.RE
X.SH DIAGNOSTICS
X.I Gifcheck
Xcan produce a variety of diagnostic messages. Some indicate
Xproblems within the GIF file. Others indicate malfunctions of
X.I gifcheck
Xor the computer. Messages beginning with "ANOMALY", "VIOLATION",
X"FASCINATING", and "NITPICK" indicate problems within the GIF file.
XMessages beginning "FATAL ERROR", "ERROR", or "WARNING" indicate
Xmalfunctions. Messages beginning "STRIP" indicate that the file should
Xbe processed by the
X.I gifstrip
Xprogram to remove excess characters.
X.RS 3
X.SS ANOMALIES
XAnomalies are radical violations of the GIF specification. Anomalies
Xmay be caused by massive corruption of the file, to the extent that
X.I gifcheck
Xcannot determine how to proceed with processing of the file, or
Xby individual values that make no sense. In either case, an image with
Xanomalies will probably be rejected by most GIF viewers. Anomalies are
Xalways displayed and always cause
X.I gifcheck
Xto skip immediately to the next file to be processed.
X.PP
XThe various anomalies that
X.I gifcheck
Xcan detect are explained below.
X.HP 9
XANOMALY: end of data reached before end of codes
X.RS 5
X.PD 0
X.PP
X.I gifcheck
Xreached the end of the packed image data
Xwithout encountering an End-of-Information code, which
Xsignals the end of the image.
X.RE
X.PD 1
X.HP 9
XANOMALY: decompression error in block xxx at offset yyy
X.RS 5
X.PD 0
X.PP
X.I gifcheck
Xfound a bad code in the packed image data. This
Xindicates that the file has been corrupted, and most
Xlikely the rest of the file is trash.
X.RE
X.PD 1
X.HP 9
XANOMALY: foreground color index off end of global color table
X.RS 5
X.PD 0
X.PP
XThe color index specified for the foreground in a GIF89a
XPlain Text Extension is invalid (PTEs always use the
Xglobal color table).
X.RE
X.PD 1
X.HP 9
XANOMALY: background color index off end of global color table
X.RS 5
X.PD 0
X.PP
XThe color index specified for the background in a GIF89a
XPlain Text Extension is invalid (PTEs always use the
Xglobal color table).
X.RE
X.PD 1
X.HP 9
XANOMALY: an undefined disposal method (x) is given
X.RS 5
X.PD 0
X.PP
XThe value in the disposal method of a Graphic Control
XExtension is undefined.
X.RE
X.PD 1
X.HP 9
XANOMALY: a ... cannot follow a ...
X.RS 5
X.PD 0
X.PP
XWhere "..." is a block type. The GIF89a specification
Xincludes a grammar which indicates which types of blocks
Xcan follow which other types of blocks (in the simpler
XGIF87a specification, there was no need). This grammar
Xhas been violated.
X.PD 1
X.RE
X.SS VIOLATIONS
XViolations are major violations of the GIF specification. Violations
Xmay be caused by corruption of the file or by individual values that
Xmake no sense. In either case, an image with violations may be rejected
Xby some viewers and displayed with difficulty by others. Violations are
Xalways displayed, and by default cause
X.I gifcheck
Xto skip immediately to the next file to be processed.
X.PP
XThe various violations that
X.I gifcheck
Xcan detect are explained below.
X.HP 11
XVIOLATION: image does not fit on logical screen
X.PD 0
X.RS 5
X.PP
XEither the size of the image given in the image header
Xis greater in one or both dimensions than the size of
Xthe logical screen given in the file header, or the
Xposition of the image given in the image header causes
Xparts of the image to extend beyond the boundaries of
Xthe logical screen.
X.RE
X.PD 1
X.HP 11
XVIOLATION: bad transparency index (x)
X.PD 0
X.RS 5
X.PP
XIf processing a Plain Text Extension, indicates that the
Xtransparency index specified by a preceeding Graphic
XControl Extension is off the end of the global color
Xtable (PTEs always use the global color table). If
Xprocessing an image, indicates that the transparency
Xindex is off the end of either the global or local color
Xtable, depending on which one the image uses.
X.RE
X.PD 1
X.HP 11
XVIOLATION: character grid does not fit on logical screen
X.PD 0
X.RS 5
X.PP
XEither the size of the character grid given in the Plain
XText Extension is greater in one or both dimensions than
Xthe size of the logical screen given in the file header,
Xor the position of the character grid causes parts of it
Xto extend beyond the boundaries of the logical screen.
X.RE
X.PD 1
X.HP 11
XVIOLATION: text is too long to fit into character grid
X.PD 0
X.RS 5
X.PP
XThe text given in the Plain Text Extension contains more
Xcharacters than there are character cells in the
Xcharacter grid.
X.RE
X.PD 1
X.HP 11
XVIOLATION: xxx garbage characters found between blocks
X.PD 0
X.RS 5
X.PP
XThere should be no garbage characters between blocks.
XWhile this can theoretically be solved by using the
X.I gifstrip
Xprogram, it probably indicates that the file
Xhas been corrupted.
X.PD 1
X.RE
X.SS FASCINATINGS
XFascinatings are not always violations of the GIF specification.
XFascinatings are unusual conditions which most viewers can cope with, but
Xare still worthy of note. Fascinatings are displayed by default, and by
Xdefault do NOT cause
X.I gifcheck
Xto skip.
X.PP
XThe various fascinatings that
X.I gifcheck
Xcan detect are explained below.
X.HP 13
XFASCINATING: this file does not contain a global color table
X.PD 0
X.RS 5
X.PP
XThe GIF specification allows for files without global
Xcolor tables; they are to be displayed using the global
Xcolor table from a previous file, or a default table
Xchosen by the viewer if no previous global color table
Xis available. Files without global color tables are
Xextremely rare. This message is displayed when an image
Xwhich uses the global color table is encountered in a
Xfile which has none.
X.RE
X.PD 1
X.HP 13
XFASCINATING: xxx extra blocks on end of image
X.PD 0
X.RS 5
X.PP
XThe packed image data continued for one or more blocks
Xafter the block in which the End-of-Information (EOI)
Xcode was found. While this condition is suspicious, the
Xdata before the EOI decompressed correctly (otherwise an
XANOMALY would have occurred), so there's no concrete
Xevidence that the image is bad.
X.RE
X.PD 1
X.HP 13
XFASCINATING: too few pixels extracted (xxx lines found, yyy pixels missing)
X.PD 0
X.RS 5
X.PP
XWhen the End-of-Information code was encountered, too
Xfew pixels had been extracted to fill the image (e.g,
Xfor a 320 by 200 image, which should have 64,000 pixels,
Xonly 63,999 were extracted). Typically only one or two
Xare missing. Viewers seem to cope with this condition
XOK.
X.RE
X.PD 1
X.HP 13
XFASCINATING: too many pixels extracted (xxx extra)
X.PD 0
X.RS 5
X.PP
XWhen the End-of-Information code was encountered, more
Xpixels than necessary had been extracted (e.g., for a
X320 by 200 image, which should have 64,000 pixels,
X64,001 were extracted). Typically only one or two extras
Xare present. Viewers seem to cope with this condition
XOK.
X.RE
X.PD 1
X.HP 13
XFASCINATING: code table never cleared
X.PD 0
X.RS 5
X.PP
XWhile this is technically OK, it is recommended practice
Xto clear the decompression code table (via a clear code
Xin the compressed image data) immediately at the
Xbeginning of the image. If the code table was never
Xcleared, this initial clear never occurred.
X.RE
X.PD 1
X.HP 13
XFASCINATING: this file has no Global Color Table (GCT is used by PTE)
X.PD 0
X.RS 5
X.PP
XThe GIF specification allows for files without global
Xcolor tables; they are to be displayed using the global
Xcolor table from a previous file, or a default table
Xchosen by the viewer if no previous global color table
Xis available. Files without global color tables are
Xextremely rare. This message is displayed when a Plain
XText Extension (PTEs always use the global color table)
Xis encountered in a file which has no global color table.
X.RE
X.PD 1
X.HP 13
XFASCINATING: transparency index does not match either foreground or background
X.PD 0
X.RS 5
X.PP
XThis message is displayed when processing a Plain Text
XExtension and the transparency index specified by a
Xpreceeding Graphic Control Extension does not match
Xeither the foreground or the background color indices of
Xthe PTE. This renders the transparency index
Xmeaningless, since it only applies to the next graphic
X(image or PTE) following the GCE. Nothing is technically
Xwrong, but it's weird.
X.PD 1
X.RE
X.SS NITPICKS
XNitpicks are minor technical violations of the GIF specification.
XSome are very common, and they should not cause problems when viewing
Xthe file. Nitpicks are by default NOT displayed, and never cause
X.I gifcheck
Xto skip.
X.PP
XThe various nitpicks that
X.I gifcheck
Xcan detect are explained below.
XMost of these messages are self-explanatory, so no detailed explanation
Xis given.
X.HP 9
XNITPICK: byte 6 of the logical screen descriptor should be 0 for GIF87A
X.HP 9
XNITPICK: bit 3, byte 4 of logical screen descriptor should be 0 for GIF87A
X.HP 9
XNITPICK: bits 3 and 4, byte 9 of image descriptor should be 0
X.HP 9
XNITPICK: bit 5, byte 9 of image descriptor should be 0 for GIF87A
X.HP 9
XNITPICK: bits 5-7, byte 1 of graphic control extension should be 0
X.HP 9
XNITPICK: local color table size is nonzero
X.PD 0
X.RS 5
X.PP
XThe image does not have a local color table, but the
Xlocal color table size is nonzero.
X.PD 1
X.RE
X.HP 9
XNITPICK: character grid not an integral number of character cells wide
X.PD 0
X.RS 5
X.PP
XThe horizontal size of the character grid in a Plain
XText Extension is not evenly divisible by the horizontal
Xsize of a character cell.
X.PD 1
X.RE
X.HP 9
XNITPICK: character grid not an integral number of character cells high
X.PD 0
X.RS 5
X.PP
XThe vertical size of the character grid in a Plain Text
XExtension is not evenly divisible by the vertical size
Xof a character cell.
X.PD 1
X.RE
X.HP 9
XNITPICK: xxx unprintable characters in text
X.PD 0
X.RS 5
X.PP
XPlain Text Extensions are supposed to contain only
X"7-bit printable ASCII characters".
X.PD 1
X.RE
X.SS MISCELLANEOUS
X.I Gifcheck
Xcan also produce messages beginning with "FATAL ERROR",
X"ERROR", "WARNING", and "STRIP". The first three indicate malfunctions
Xof
X.I gifcheck
Xor the computer, and typically cause
X.I gifcheck
Xto exit
Ximmediately. Messages beginning with "STRIP" indicate that the file
Xshould be processed by the
X.I gifstrip
Xprogram to remove excess characters,
Xand are simply for the user's information. Processing of the file is not
Xaffected.
X.RE
X.SH COPYRIGHT
X.I Gifcheck
Xis copyright 1993 by James W. Birdsall, all rights reserved.
X.PP
XThe Graphics Interchange Format(c) is the Copyright property of CompuServe
XIncorporated. GIF(sm) is a Service Mark property of CompuServe
XIncorporated.
X.SH AUTHOR
XJames W. Birdsall
X.RS 3
X.nf
[e-mail]
Xuunet!uw-coco!amc-gw!picarefy!support
XCompuServe: 71261,1731
XGEnie: J.BIRDSALL2
X.fi
X.RE
X.SH "SEE ALSO"
Xchils(1),
Xgifstrip(1)
END_OF_FILE
  if test 32803 -ne `wc -c <'src/gifcheck.1'`; then
    echo shar: \"'src/gifcheck.1'\" unpacked with wrong size!
  fi
  # end of 'src/gifcheck.1'
fi
echo shar: End of archive 12 \(of 18\).
cp /dev/null ark12isdone
MISSING=""
for I in 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 ; do
    if test ! -f ark${I}isdone ; then
    MISSING="${MISSING} ${I}"
    fi
done
if test "${MISSING}" = "" ; then
    echo You have unpacked all 18 archives.
    rm -f ark[1-9]isdone ark[1-9][0-9]isdone
else
    echo You still must unpack the following archives:
    echo "        " ${MISSING}
fi
exit 0
exit 0 # Just in case...