NAME
icon2gif - A program to convert a series of editable text GIF icon
specifications and named GIF files into a multi-image GIF, usable as a
graphic resource file. It can also dump existing GIFs in this format.
USAGE
icon2gif [-q] [-a] [-d] [t TranslationTable] [-h] gif-file...
If no gif-file is given, icon2gif will try to read a text input from
stdin.
Specification Syntax
Here is a syntax summary in informal BNF. The token ‘NL’ represents a
required newline.
<gif-spec> ::= <header-block> <image-block>...
<header-block> ::= <header-declaration>...
<header-declaration ::= | screen width <digits> NL | screen height
<digits> NL | screen colors <digits> NL | screen background <digits> NL
| screen map <color-table> NL
<color-table> ::= <color-declaration>... end NL
<color-declaration> ::= rgb <digits> <digits> <digits> is <key> NL
<image-block> ::= include <file-name> NL | image NL
<image-declaration>... <raster-picture> [ <extension> ]
<image-declarations> ::= image top <digits> NL | image left <digits> NL
| image interlaced NL | image map <color-table> NL | image bits
<digits> by <digits> NL <raster-block>
<extension> := <comment> NL <extension-block> NL end NL | <plaintext>
NL <extension-block> NL end NL | extension <hex-digits> NL
<extension-block> NL end NL
If the semantics of the ‘screen height’, ‘screen width’, ‘screen
background’, ‘image top’, ‘image left’ declarations aren’t obvious to
you, what are you doing with this software?
A color table declares color indices (in ascending order from 0) and
assiciates them with key characters. These characters can later be
used in raster blocks. As these must be printable and non-whitespace,
you can only specify 94 colors per icon. Life is like that sometimes.
A raster block is just a block of key characters. It should be sized
correctly for the ‘image bits’ declaration that leads it.
The ‘comment’ or ‘plaintext’ keywords lead defined GIF89 extension
record data (the other two GIF89 types, graphics control and
application block, are not yet supported). You can also say
‘extension’ followed by a hexadecimal record type. All of these
extension declarations must be followed by an extension block, which is
terminated by the keyword ‘end’ on its own line.
An extension block is a series of text lines, each interpreted as a
string of bytes to fill an argument block (the terminating newline is
stripped). Text may include standard C-style octal and hex escapes
preceded by a backslash.
All <digits> tokens are interpreted as decimal numerals; <hex-digits>
tokens are interpreted as two hex digits (a byte). All coordinates are
zero-origin with the top left corner (0,0). Range checking is weak and
signedness checking nonexistent; caveat hacker!
In general, the amount of whitespace and order of declarations within a
header or image block is not significant, except that a raster picture
must immediately follow its ‘image bits’ bits declaration.
The ‘include’ declaration includes a named GIF as the next image. The
global color maps of included GIFs are merged with the base table
defined by any ‘screen color’ declaration. All images of an included
multi-image GIF will be included in order.
Comments may be preceded with ‘#’ and will be ignored.
MEMORY REQUIRED
For the compilation mode, proportional to the size of the input file.
For dumping, proportional to the line size of the widest GIF.
OPTIONS
[-q]
Quiet mode. Defaults off on MSDOS, on under UNIX. Controls
printout of running scan lines. Use -q- to invert.
[-d]
Dump the input GIF file(s) into the text form described above.
[-t]
Specify name characters to use when dumping raster blocks.
Only valid with -d option.
[-h]
Print one line of command line help, similar to Usage above.
BUGS
Because there are only 94 characters unambiguously usable for raster
blocks, an attempt to dump a GIF with a larger color map will fail.
Error checking is rudimentary.
Example:
A sample icon file called ‘sample.ico’ is included in the pic
directory.
AUTHOR
Eric S. Raymond <esr@snark.thyrsus.com>
Man page created by T.Gridel <tgridel@free.fr>, originally written by
Eric S. Raymond <esr@thyrsus.com>
giflib-tools icon2gif(1)