NAME¶
img-gif - Img, Graphics Interchange Format (gif)
SYNOPSIS¶
package require
Tk
package require
img::gif ?1.4?
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 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>