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GIFBUILD(1)		     GIFLIB Documentation		   GIFBUILD(1)

       gifbuild	- dump GIF data	in a textual format, or	undump it to a GIF

       gifbuild	[-v] [-a] [-d] [-t translation-table] [-h] [gif-file]

       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. When
       dumping a GIF, certain sanity checks are	performed which	may result in
       a warning emitted to standard error.

       If no GIF file is given,	gifbuild will try to read a text input from

       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
		     | pixel aspect byte <digits> NL
		     | screen map <color-table>	NL

	   <color-table> ::= <color-declaration>... end	NL

	   <color-declaration> ::= rgb <digits>	<digits> <digits> [ is <key>] NL
			   | sort flag {on|off}	NL

	   <image-block> ::= include <file-name> NL
		     | image NL
			  [ <extension>	]

	   <image-declarations>	::= image top <digits> NL
			  | image left <digits>	NL
			  | image interlaced NL
			  | image map <color-table> NL
			  | image bits <digits>	by <digits> [hex|ascii]	NL <raster-block>

	   <extension> := <comment> NL <extension-block> NL end	NL
		     | <plaintext> NL <extension-block>	NL end NL
			   | graphics control NL <GCB-part> NL end NL
			   | netscape loop  <digits> NL
		     | extension <hex-digits> NL <extension-block> NL end NL

	   <GCB-part> ::= disposal mode	<digits> NL
			   | user input	flag {on|off} NL
			   | delay <digits> NL
			   | transparent index <digits>	NL

       If the data types of the	"screen	height", "screen width", "screen
       background", "image top", and "image left" declarations aren't obvious
       to you, what are	you doing with this software?

       The "pixel aspect byte" declaration sets	an integer denominator for a
       fraction	expressing the puxel aspect ratio. See the GIF standard	for
       details;	this field is actually long obsolete.

       A color table declares color indices (in	ascending order	from 0)	and
       may associate them with key characters (these associations are absent
       when the	map is more than 94 colors lang	and raster blocks using	it
       must use	hex pairs). 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 color table declaration can also set the table's sort flag with "sort
       flag on"	or "sort flag off" on any line before the end.

       An "ascii" raster block is just a block of key characters (used for a
       color map of 94 or fewer	colors). A "hex" raster	block uses hex digit
       pairs instead (used for a color map with	more than 94 colors). The
       default is ASCII. It should be sized correctly for the "image bits"
       declaration that	leads it. Raster blocks	from interlaced	GIFs are
       dumped with the lines in	non-interlaced order.

       The "comment", "plaintext" or "ggraphics	control" keywords lead defined
       GIF89 extension record data. The	final GIF89 type, graphics control and
       application block, are not yet supported, but the code does recognize a
       Netscape	loop block. 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 extension block (the terminating newline is
       stripped). Text may include standard C-style octal and hex escapes
       preceded	by a backslash.

       A graphics control block	declaration creates a graphics control
       extension block;	for the	field semantics	see the	GIF89 standard,	part

       A netscape loop declaration creates an application extension block
       containing a NETSCAPE 2.0 animation loop	control	with a specified
       repeat count (repeat count 0 means loop forever). This must be
       immediately after the header declaration. These loop blocks are
       interpreted by the Netscape/Mozilla/Firefox line	of browsers.

       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	(preceded with "#") will be ignored.

	   Verbose mode	(show progress). Enables printout of running scan

	   Dump	the input GIF file(s) into the text form described above.

	   Specify name	characters to use when dumping raster blocks. Only
	   valid with -d option.

	   Print one line of command line help,	similar	to Usage above.

       Error checking is rudimentary.

       A sample	icon file called sample.ico is included	in the pic directory
       of the GIFLIB source distribution.

       Eric S. Raymond <>

GIFLIB				  2 May	2012			   GIFBUILD(1)


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