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.\" whirlgif.1

.\"

.\" The Graphics Interchange Format (c) is the Copyright property of

.\" Compuserve Incorporated.  GIF(sm) is a Service Mark property of

.\" Compuserve Incorporated.

.\"

.TH WHIRLGIF 1 "February 1999"

.AT 3

.SH NAME

whirlgif \- reads a series of GIF87a or

GIF89a files, and produces

one single GIF89a file composed of those images.

.SH SYNOPSIS

.B whirlgif

.RI [ "global-options" ]

.RI [ "file-options " { GIFfile "|\fB-i\fP " incfile "}] ..."

.sp

The

.I global-options

are one or more of:

.br

.in +5

.B  \-v

.br

.BI \-trans " index"

.br

.BR \-background " {\fIcolor\fP|\fIindex\fP}"

.br

.B \-time

.I delay

.br

.B \-globmap

.br

.B \-minimize

.br

.B \-o

.I outfile

.br

.B \-loop

.RI [ count ]

.br

.B \-comment

.I comment

.br

.B \-disp

.I method

.in -5

.sp

The

.I file-options

are one or more of:

.br

.in +5

.B \-off

.I x:y-pair

.br

.BR \-trans " {\fIcolor\fP|\fIindex\fP}"

.br

.B \-time

.I delay

.br

.B \-disp

.I method

.sp

.SH DESCRIPTION

When

.I Whirlgif

processes a series of GIF files,

the first file defines the so called screen size and the background

color of the resulting GIF.  The background color may be changed by an

option.

.sp

The input files may be in either GIF87a or GIF89a format.  If a GIF

file contains more than one image, only the first image is read.  To

help saving bandwidth on the internet, there are options for forcing

all GIFs in the series to use the same color map and to create

sub-GIFs which only give the difference between one image and the next.

.PP

.SH OPTIONS

.PP

.TP

.B \-v

Verbose mode.  Output is written to the error out file.

This is a global option and must be given before any

.IR GIFfile s.

.TP

\fB\-trans\fP \fIindex\fP|\fIcolor\fP

Set the color identified with

.I index

or the color code

.BI # xxxxxx \fR,\fP

where

.I xxxxxx

is a hex

.B RGB

index to be transparent.

When this option is used as a

.IR file-option ,

its setting is valid for all subsequent

.IR GIFfile s,

until it is used again.

.TP

\fB\-background\fP index

Set the color identified with its

.I index

to be the background color, possibly

overriding the background color defined in the first

.IR GIFfile .

This is a global option and must be given before any

.IR GIFfile s.

.TP

\fB\-time\fP \fIdelay\fP

Defines inter\-frame timing in units of 1/100 second.  Whenever a value of

\fIdelay\fP is set by means of the \fB\-time\fP option, this value will

be valid for the following

.IR GIFfile s

until a new value is set.

.TP

\fB\-globmap\fP

Use the color map of the first

.I GIFfile

as the global color map throughout

the

.IR outfile .

If the color maps of subsequent

.IR GIFfile s

contain

colors that are not in the global color map, the nearest colors in a

3 dimensional RGB space will be chosen.

This is a global option and must be given before any

.IR GIFfile s.

.TP

\fB\-minimize\fP

Only the smallest rectangles covering the difference between two

.IR GIFfile s

will be output.  All

.IR GIFfile s

must be of the same size and have the same offset.

This is tested, and may result in an error message.

This is a global option and must be given before any

.IR GIFfile s.

.sp

As a side effect, the \fB\-minimize\fP

option forces the same (global)color map to be used throughout the

.IR outfile .

.TP

\fB\-o\fP outfile

Write the results to

.I outfile

This is a global option and must be given before any

.IR GIFfile s.

.TP

\fB\-loop\fP [\fIcount\fP]

Add the Netscape 'loop' extension.  If count is omitted, 0 (zero) is

assumed.

This is a global option and must be given before any

.IR GIFfile s.

.TP

.B "\-comment \fIcomment\fP"

Define a \fBComment Extension\fP block

within the resulting GIF file.

This block will be written at the end of the file.

A comment block can be at most 254 characters long, including line

shifts.

It may be used for copyright notices.

This is a global option and must be given before any

.IR GIFfile s.

.TP

\fB\-disp\fP \fImethod\fP

Sets the image 'disposal' method.  When this option is used as a

.IR file-option ,

its setting is valid for all subsequent

.IR GIFfile s,

until it is used again.  The methods may be one of

the keywords:

.sp

.in +5

.ti -5

.B none

No disposal specified.

.sp

.ti -5

.B back

Restore to background color.

Fill the image's space with the background color.

.sp

.ti -5

.B prev

Restore to previous, restores the screen area

to what was there before.  Netscape has a problem with this option.

.sp

.ti -5

.B not

Do not dispose.  The default, the next image will overlay this one.

.sp

.in -5

.TP

\fB\-i\fP incfile

Read a list of names from

.I incfile

.TP

.B "\-off \fIx:y-pair\fP"

Sets the position of the next

.I GIFfile

or the set of

.IR GIFfile s

in an

.IR incfile .

.sp

The \fIx:y-pair\fP consists of two integers, separated by one

character which cannot be part of a number.  A colon, ':' is preferred.

The two integers define the position of the upper left corner of the

next image within the 'screen' of the resulting GIF.

The integers are added to a possible offset within the next

.IR GIFfile .

One or both may be negative.

Negative numbers will re-position an image upwards

and/or to the left within its own 'screen'.

The 'screen' of a GIF is the term used in the GIF definitions for the

area, a GIF covers.

.SH TIPS

.PP

If you don't specify an output file, the GIF will be sent to stdout.

This is a good thing if you're using whirlgif in a CGI script,

but could cause problems if you run from a terminal and forget to

redirect stdout.

.sp

The output file (if any) and the loop option

.B MUST

be specified before any GIF images.

.sp

You can specify several delay statements on the command line to change

the delay between images in the middle of an animation, e.g.

.sp

.ti -5

whirlgif \-time 25 a.gif b.gif c.gif \-time 100 d.gif \-time 25 e.gif f.gif

.sp

Usually, the bacground color is defined by the first

.IR GIFfile ,

and often it is index number zero (0).

If you are animating with a transparent color,

a good method is usually to use the same color as the background.

.sp

It is possible, but may cause problems for some programs, to specify

several transparency statements on the command line.

.sp

The size of the resulting GIF and the global color map is

defined by the first

.IR GIFfile .

If you have a large background GIF and have several smaller GIFs, you

may make some kind of a bulletin board by a command of the following form:

.sp

.ti -5

whirlgif large.gif -off 77:44 small1.gif -off 22:99 small2.giff ...

.sp

You may build in some timing between the small GIFs.

.SH LIMITATIONS

.PP

The loop 'count' is ineffective because Netspcape always loops infinitely.

.SH BUGS

.PP

.I Whirlgif

should be able to specify delay and offset in an 'incfile' list (see next bug).

.sp

Does not handle filenames starting with a \- (hypen), except in 'incfile'.

.SH TODO

.PP

.ti +2

\- Make a graphic interface.  Perhaps by re-implementing the

algorithms in Java(tm).

.sp

.ti +2

\- option for other choices of unification methods for colormaps.

The nearest point in the 3 dimensional RGB color space may not be

the best choice.

.sp

.ti +2

\- define extension block in order to have frame lists.

.sp

.ti +2

\- define single-letter options and use

.IR getopt (3)

like most UNIX programs.

.SH AVAILABILITY

.PP

This program is available via the

archive for comp.soruces.unix

.B http://sources.isc.org/

(and also via http://www.danbbs.dk/~dino/whirlgif/ ).

.SH AUTHORs

.PP

V3.00 \- 3.04 Hans Dinsen-Hansen <dino@danbbs.dk>

.br

Based on

Whirlgif V2.02 by Kevin Kadow <kadokev@msg.net>

.br

.ti +5

& Hans Dinsen-Hansen <dino@danbbs.dk>

.br

which is again based on 'txtmerge' written by:

.br

Mark Podlipec <podlipec@BayNetworks.com> 

.br

Man Page by Mintak Ng <mintak@hitak.com>

.br

.ti +5

& Hans Dinsen-Hansen <dino@danbbs.dk>

.sp

.SH COPYRIGHT NOTICES

.PP

The Graphics Interchange Format (c) is the Copyright property of

Compuserve Incorporated.  GIF(sm) is a Service Mark property of

Compuserve Incorporated.

.sp

See other Copyright notices in the accompanying texts.