1<?xml version="1.0" encoding="UTF-8"?> 2<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>gifbuild</title><meta name="generator" content="DocBook XSL Stylesheets V1.79.1" /></head><body><div class="refentry"><a id="gifbuild.1"></a><div class="titlepage"></div><div class="refnamediv"><a id="name"></a><h2>Name</h2><p>gifbuild — dump GIF data in a textual format, or undump it to a GIF</p></div><div class="refsynopsisdiv"><a id="synopsis"></a><h2>Synopsis</h2><div class="cmdsynopsis"><p><code class="command">gifbuild</code> [-v] [-a] [-d] [-t <em class="replaceable"><code>translation-table</code></em>] [-h] [<em class="replaceable"><code>gif-file</code></em>]</p></div></div><div class="refsect1"><a id="idm23"></a><h2>Options</h2><p>A program to convert a series of editable text GIF icon specifications and 3named GIF files into a multi-image GIF, usable as a graphic resource file. 4It can also dump existing GIFs in this format. When dumping a GIF, 5certain sanity checks are performed which may result in a warning 6emitted to standard error.</p><p>If no GIF file is given, gifbuild will try to read a text input 7from stdin.</p></div><div class="refsect1"><a id="idm27"></a><h2>Specification Syntax</h2><p>Here is a syntax summary in informal BNF. The token `NL' represents a 8required newline.</p><pre class="programlisting"> 9<gif-spec> ::= <header-block> <image-block>... 10 11<header-block> ::= <header-declaration>... 12 13<header-declaration ::= 14 | screen width <digits> NL 15 | screen height <digits> NL 16 | screen colors <digits> NL 17 | screen background <digits> NL 18 | pixel aspect byte <digits> NL 19 | screen map <color-table> NL 20 21<color-table> ::= <color-declaration>... end NL 22 23<color-declaration> ::= rgb <digits> <digits> <digits> [ is <key>] NL 24 | sort flag {on|off} NL 25 26<image-block> ::= include <file-name> NL 27 | image NL 28 <image-declaration>... 29 <raster-picture> 30 [ <extension> ] 31 32<image-declarations> ::= image top <digits> NL 33 | image left <digits> NL 34 | image interlaced NL 35 | image map <color-table> NL 36 | image bits <digits> by <digits> [hex|ascii] NL <raster-block> 37 38<extension> := <comment> NL <extension-block> NL end NL 39 | <plaintext> NL <extension-block> NL end NL 40 | graphics control NL <GCB-part> NL end NL 41 | netscape loop <digits> NL 42 | extension <hex-digits> NL <extension-block> NL end NL 43 44<GCB-part> ::= disposal mode <digits> NL 45 | user input flag {on|off} NL 46 | delay <digits> NL 47 | transparent index <digits> NL 48 49</pre><p>If the data types of the <span class="quote">“<span class="quote">screen height</span>”</span>, 50<span class="quote">“<span class="quote">screen width</span>”</span>, <span class="quote">“<span class="quote">screen background</span>”</span>, 51<span class="quote">“<span class="quote">image top</span>”</span>, and <span class="quote">“<span class="quote">image left</span>”</span> declarations 52aren't obvious to you, what are you doing with this software?</p><p>The <span class="quote">“<span class="quote">pixel aspect byte</span>”</span> declaration sets an integer 53denominator for a fraction expressing the puxel aspect ratio. See the 54GIF standard for details; this field is actually long obsolete.</p><p>A color table declares color indices (in ascending order from 0) 55and may associate them with key characters (these associations are 56absent when the map is more than 94 colors lang and raster blocks 57using it must use hex pairs). These characters can later be used in 58raster blocks. As these must be printable and non-whitespace, you can 59only specify 94 colors per icon. Life is like that sometimes.</p><p>A color table declaration can also set the table's sort flag with 60"sort flag on" or "sort flag off" on any line before the end.</p><p>An <span class="quote">“<span class="quote">ascii</span>”</span> raster block is just a block of key 61characters (used for a color map of 94 or fewer colors). A 62<span class="quote">“<span class="quote">hex</span>”</span> raster block uses hex digit pairs instead (used for 63a color map with more than 94 colors). The default is ASCII. It 64should be sized correctly for the <span class="quote">“<span class="quote">image bits</span>”</span> 65declaration that leads it. Raster blocks from interlaced GIFs are 66dumped with the lines in non-interlaced order.</p><p>The <span class="quote">“<span class="quote">comment</span>”</span>, <span class="quote">“<span class="quote">plaintext</span>”</span> or 67<span class="quote">“<span class="quote">ggraphics control</span>”</span> keywords lead defined GIF89 extension 68record data. The final GIF89 type, graphics control and application 69block, are not yet supported, but the code does recognize a Netscape 70loop block. You can also say <span class="quote">“<span class="quote">extension</span>”</span> followed by a 71hexadecimal record type. All of these extension declarations must be 72followed by an extension block, which is terminated by the keyword 73<span class="quote">“<span class="quote">end</span>”</span> on its own line.</p><p>An extension block is a series of text lines, each interpreted 74as a string of bytes to fill an extension block (the terminating 75newline is stripped). Text may include standard C-style octal and hex 76escapes preceded by a backslash.</p><p>A graphics control block declaration creates a graphics control 77extension block; for the field semantics see the GIF89 standard, part 7823.</p><p>A netscape loop declaration creates an application extension 79block containing a NETSCAPE 2.0 animation loop control with a 80specified repeat count (repeat count 0 means loop forever). This must 81be immediately after the header declaration. These loop blocks are 82interpreted by the Netscape/Mozilla/Firefox line of browsers.</p><p>All <digits> tokens are interpreted as decimal numerals; 83<hex-digits> tokens are interpreted as two hex digits (a byte). All 84coordinates are zero-origin with the top left corner (0,0). Range 85checking is weak and signedness checking nonexistent; caveat 86hacker!</p><p>In general, the amount of whitespace and order of declarations within a 87header or image block is not significant, except that a raster picture 88must immediately follow its <span class="quote">“<span class="quote">image bits</span>”</span> bits declaration.</p><p>The <span class="quote">“<span class="quote">include</span>”</span> declaration includes a named GIF as 89the next image. The global color maps of included GIFs are merged 90with the base table defined by any <span class="quote">“<span class="quote">screen color</span>”</span> 91declaration. All images of an included multi-image GIF will be 92included in order.</p><p>Comments (preceded with <span class="quote">“<span class="quote">#</span>”</span>) will be ignored.</p></div><div class="refsect1"><a id="idm62"></a><h2>Options</h2><div class="variablelist"><dl class="variablelist"><dt><span class="term">-v</span></dt><dd><p>Verbose mode (show progress). 93Enables printout of running scan lines.</p></dd><dt><span class="term">-d</span></dt><dd><p> Dump the input GIF file(s) into the text form described 94above.</p></dd><dt><span class="term">-t</span></dt><dd><p>Specify name characters to use when dumping raster blocks. Only 95valid with -d option.</p></dd><dt><span class="term">-h</span></dt><dd><p>Print one line of command line help, similar to Usage 96above.</p></dd></dl></div></div><div class="refsect1"><a id="idm81"></a><h2>Bugs</h2><p>Error checking is rudimentary.</p></div><div class="refsect1"><a id="idm84"></a><h2>Example:</h2><p>A sample icon file called <code class="filename">sample.ico</code> is 97included in the pic directory of the GIFLIB source 98distribution.</p></div><div class="refsect1"><a id="idm88"></a><h2>Author</h2><p>Eric S. Raymond <code class="email"><<a class="email" href="mailto:esr@thyrsus.com">esr@thyrsus.com</a>></code></p></div></div></body></html>