NAME

       img-gif - Img, Graphics Interchange Format (gif)

SYNOPSIS

       package require Tk

       package require img::gif  ?1.4?

       image create photo ?name? ?options?

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DESCRIPTION

       The  package  img::gif is a sub-package of Img. It can be loaded as a part of the complete
       Img support, via package require Img, or on its own, via package require img::gif.

       Like all packages of Img it does not provide new commands, but  extends  the  existing  Tk
       command  image  so  that  it  supports  files  containing  raster  images  in the Graphics
       Interchange Format (gif). More specifically img::gif extends Tk's photo image type.

       The name of the  new  format  handler  is  gif.   This  handler  provides  new  additional
       configuration options. See section GIF OPTIONS for more detailed explanations.

       All of the above means that in a call like

       image create photo ?name? ?options?

       [1]    Image data in gif format (options -data and -file) is detected automatically.

       [2]    The format name gif is recognized by the option -format.  In addition the value for
              the option is treated as list and may contain any of the special options listed  in
              section GIF OPTIONS.

GIF OPTIONS

       The  handler provides two options, one for reading from a GIF image, the other influencing
       the writing of such.

       -index n
              This option is for reading from GIF files containing more than one image  (animated
              GIF's,  GIF  movies.  When  specified  it will read the n'th image in the data. The
              first image is at index 0 and will be read by default, i.e. when the option is  not
              specified.

       -interlaced bool
              If  the  value  of  this  option is set to true the image will be written using the
              interlaced sub-format of GIF. The default is to write  non-interlaced  files.  This
              option is not implemented yet.

IMAGE COMPRESSION

       Instead  of  LZW the run-length encoding of Hutchison Avenue Software Corporation is used,
       also known as miGIF compression. The miGIF compression routines do not, strictly speaking,
       generate  files  conforming  to  the  GIF spec, since the image data is not LZW-compressed
       (this is the point: in order to avoid transgression  of  the  Unisys  patent  on  the  LZW
       algorithm.)   However,   miGIF  generates  data  streams  that  any  reasonably  sane  LZW
       decompresser will decompress to what we want.

TRANSPARENCY

       If you want to write images to disk which contain transparency  information  (e.g.  GIF89)
       you need at least Tk 8.3.

SEE ALSO

       img-bmp,  img-dted,  img-gif,  img-ico, img-intro, img-jpeg, img-pcx, img-pixmap, img-png,
       img-ppm, img-ps, img-raw, img-sgi, img-sun, img-tga, img-tiff, img-window,  img-xbm,  img-
       xpm

KEYWORDS

       gif, image handling, tk

COPYRIGHT

       Copyright (c) 1995-2009 Jan Nijtmans <nijtmans@users.sourceforge.net>