NAME

       xlito     -    Append/Delete/Show    a    Trailing    Option    string    in    a    file.
       (XLoadImageTrailingOptions)

SYNOPSIS

       xlito [option] [string] files ...

DESCRIPTION

       xlito (XLoadImageTrailingOptions) is a utility that provides a file format independent way
       of marking image files with the appropriate options to display correctly.  It does this by
       appending to a file, a string specified by the user. The string is marked with some  magic
       numbers so that it can be extracted by a program that knows what to look for. Since almost
       all image files have some sort of image dimension information in the  file,  the  programs
       that  load  or manipulate these files generally do not look beyond the point at which they
       have read the complete image, so trailing information is safely be  hidden.  If  appending
       this information causes trouble with other utilities, it can simply be deleted.

       Appropriate  version of xloadimage (ie. xli 1.00) will recognise these trailing options at
       the end of the image files, and will treat the embedded string as if it were a sequence of
       command  line  Image Options.  Any Global Options will be ignored, and unlike command line
       image Options, Trailing Options are never propagated to other images.

       Old versions of xloadimage (3.01 or less) can be made forward compatible by using  the  -x
       option  to  pull  the trailing options out of the image files, and put them on the command
       line where xloadimage can see them.

OPTIONS

       The default behavior is to display the trailing option strings (if any) of  the  files  on
       the argument line.  The following options change the behavior of xlito:

       -c option_string file_name ...
               This  adds  or changes the embedded string to option_string.  The string will have
               to be quoted if it is composed of more than one word.

       -d file_name ...
               Delete any embedded trailing option strings in the given files.

       -x file_name ...
               Process the files and create a command line string suitable for use by xloadimage.
               Arguments starting with - are echoed, arguments not starting with - are treated as
               files and any trailing options strings are echoed followed by the file  name.  The
               xloadimage option -name is treated correctly.

EXAMPLES

       If  fred.gif  has  the  wrong aspect ratio, then it might need viewing with the xloadimage
       options:

            xloadimage -yzoom 130 fred.gif

       This option can then be appended to the file by:

            xlito -c "-yzoom 130" fred.gif

       and from then on some new versions of xloadimage will get the appropriate options from the
       image file itself. Old versions of xloadimage can be made to work by using:

            xloadimage `xlito -x fred.gif`

       This can be made transparent by using a script containing something like:

            xloadimage `xlito -x $∗`

       The script could be called xli for instance.

       The options can be deleted with:

            xlito -d fred.gif

AUTHOR

       Graeme Gill
       Labtam Australia
       graeme@labtam.oz.au

MAINTAINER

       smar@reptiles.org

COMPATIBILITY WITH IMAGE FILES

       Some image files are actually ascii files that are used in other contexts.  X Bitmap files
       are an example. They are formatted as 'C' style  #defines  and  an  initialised  array  of
       characters,  so  that  they  can  be included in 'C' source code.  Adding trailing options
       would therefore render the file unusable with a compiler, since it will get a syntax error
       on  the  railing  option  string and the magic numbers. The solution to this is that xlito
       will ignore a certain amount (a few hundred bytes) after the trailing options, and uses  a
       padding  of  20 bytes before the trailing options. These two areas will be maintained when
       changing an existing trailing option. In the case of an X bitmap then, the solution is  to
       edit the file and place the embedded string in some 'C' comments:

       eg: say the file starts as:
       #define tt_width 4
       #define tt_height 4
       static char tt_bits[] = {
          0x08, 0x02, 0x04, 0x01};

       and you add a trailing options:
       #define tt_width 4
       #define tt_height 4
       static char tt_bits[] = {
          0x08, 0x02, 0x04, 0x01};
       01234567890123456789XXX xloadimage trailing options XXX0007"-smooth"0007XXX
       xloadimage trailing options XXX

       Then the trailing options can be commented out:
       #define tt_width 4
       #define tt_height 4
       static char tt_bits[] = {
          0x08, 0x02, 0x04, 0x01};
       /∗234567890123456789XXX xloadimage trailing options XXX0007"-smooth"0007XXX
       xloadimage trailing options XXX ∗/

BUGS

       xlito  doesn't  cope  with  compressed files. A files will need uncompressing, the options
       added, and then compressing again.

                                            7 Jul 1993                                   XLITO(1)