img-gif(3tk)															      img-gif(3tk)

NAME

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

SYNOPSIS

       package require Tk

       package require img::gif  ?1.3?

       image create photo ?name? ?options?

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 com-
       pression 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 rea-
       sonably 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-gif, img-ico, img-intro, img-jpeg, img-pcx, img-pixmap, img-png, img-ppm, img-ps, img-sgi, img-sun,  img-tga,  img-tiff,  img-
       window, img-xbm, img-xpm

KEYWORDS

       gif, image handling, tk

COPYRIGHT

       Copyright (c) 1995-2003 Jan Nijtmans <nijtmans@users.sourceforge.com>

Img									1.3							      img-gif(3tk)