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https://github.com/sigmasternchen/php-doc-en
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git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@128942 c90b9560-bf6c-de11-be94-00142212c4b1
221 lines
6.9 KiB
XML
221 lines
6.9 KiB
XML
<?xml version="1.0" encoding="iso-8859-1"?>
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<!-- $Revision: 1.17 $ -->
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<reference id="ref.image">
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<title>Image functions</title>
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<titleabbrev>Image</titleabbrev>
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<partintro>
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<section id="image.intro">
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&reftitle.intro;
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<para>
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PHP is not limited to creating just HTML output. It can also be
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used to create and manipulate image files in a variety of different
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image formats, including gif, png, jpg, wbmp, and xpm. Even more
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convenient, PHP can output image streams directly to a browser. You
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will need to compile PHP with the GD library of image functions for
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this to work. GD and PHP may also require other libraries, depending
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on which image formats you want to work with.
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</para>
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<para>
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You can use the image functions in PHP to get the size of
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<acronym>JPEG</acronym>, <acronym>GIF</acronym>,
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<acronym>PNG</acronym>, <acronym>SWF</acronym>,
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<acronym>TIFF</acronym> and <acronym>JPEG2000</acronym> images.
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</para>
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<para>
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<note>
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<simpara>
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Read requirements section about how to expand image capabilities
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to read, write and modify images and to read meta data of pictures
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taken by digital cameras.
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</simpara>
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</note>
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</para>
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</section>
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<section id="image.requirements">
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&reftitle.required;
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<para>
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If you have the <acronym>GD</acronym> library (available at <ulink
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url="&url.gd;">&url.gd;</ulink>) you will also be able to create
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and manipulate images.
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</para>
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<para>
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The format of images you are able to manipulate depend on the
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version of <acronym>GD</acronym> you install, and any other libraries
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<acronym>GD</acronym> might need to access those image formats.
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Versions of <acronym>GD</acronym> older than gd-1.6
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support GIF format images, and do not support PNG, where versions
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greater than gd-1.6 support PNG, not GIF.
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<note>
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<simpara>
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Since PHP 4.3 there is a bundled version of the GD lib. This bundled
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version has some additional features like alpha blending, and should
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be used in preference to the external library
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since it's codebase is better maintained and more stable.
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</simpara>
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</note>
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</para>
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<para>
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You may wish to enhance GD to handle more image formats.
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<table>
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<title>Supported image formats</title>
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<tgroup cols="3">
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<thead>
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<row>
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<entry>Image format</entry>
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<entry>Library to download</entry>
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<entry>Notes</entry>
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</row>
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</thead>
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<tbody>
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<row>
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<entry><literal>gif</literal></entry>
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<entry></entry>
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<entry>
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Only supported in GD versions older than gd-1.6. <emphasis>Read-only
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</emphasis> GIF support is available with PHP 4.3.0 and the bundled
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GD-library.
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</entry>
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</row>
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<row>
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<entry><literal>jpeg-6b</literal></entry>
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<entry><ulink url="&url.jpeg;">&url.jpeg;</ulink></entry>
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<entry></entry>
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</row>
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<row>
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<entry><literal>png</literal></entry>
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<entry><ulink url="&url.libpng;">&url.libpng;</ulink></entry>
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<entry>
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Only supported in GD versions greater than gd-1.6.
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</entry>
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</row>
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<row>
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<entry><literal>xpm</literal></entry>
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<entry><ulink url="&url.libxpm;">&url.libxpm;</ulink></entry>
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<entry>
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It's likely you have this library already available, if your system
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has an installed X-Environment.
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</entry>
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</row>
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</tbody>
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</tgroup>
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</table>
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</para>
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<para>
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You may wish to enhance GD to deal with different fonts. The following
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font libraries are supported:
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<table>
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<title>Supported font libraries</title>
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<tgroup cols="3">
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<thead>
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<row>
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<entry>Font library</entry>
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<entry>Download</entry>
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<entry>Notes</entry>
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</row>
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</thead>
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<tbody>
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<row>
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<entry><literal>FreeType 1.x</literal></entry>
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<entry><ulink url="&url.freetype;">&url.freetype;</ulink></entry>
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<entry></entry>
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</row>
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<row>
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<entry><literal>FreeType 2</literal></entry>
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<entry><ulink url="&url.freetype;">&url.freetype;</ulink></entry>
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<entry></entry>
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</row>
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<row>
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<entry><literal>T1lib</literal></entry>
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<entry><ulink url="&url.t1lib;">&url.t1lib;</ulink>)</entry>
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<entry>
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Support for Type 1 fonts.
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</entry>
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</row>
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</tbody>
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</tgroup>
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</table>
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</para>
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<para>
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If you have PHP compiled with <option role="configure">--enable-exif</option>
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you are able to work with information stored in headers of
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<acronym>JPEG</acronym> and <acronym>TIFF</acronym> images. This way you can
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read meta data generated by digital cameras as mentioned above. These
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functions does not require the <acronym>GD</acronym> library.
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<note>
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<simpara>
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PHP does not require any additional library for the exif module.
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</simpara>
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</note>
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</para>
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</section>
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&reference.image.configure;
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&reference.image.ini;
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<section id="image.resources">
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&reftitle.resources;
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&no.resource;
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</section>
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&reference.image.constants;
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<section id="image.examples">
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&reftitle.examples;
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<para>
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<example>
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<title>PNG creation with PHP</title>
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<programlisting role="php">
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<![CDATA[
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<?php
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header("Content-type: image/png");
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$string = $_GET['text'];
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$im = imagecreatefrompng("images/button1.png");
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$orange = imagecolorallocate($im, 220, 210, 60);
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$px = (imagesx($im) - 7.5 * strlen($string)) / 2;
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imagestring($im, 3, $px, 9, $string, $orange);
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imagepng($im);
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imagedestroy($im);
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?>
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]]>
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</programlisting>
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</example>
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This example would be called from a page with a tag like: <img
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src="button.php?text=text">. The above button.php script
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then takes this "text" string and overlays it on top of a
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base image which in this case is "images/button1.png"
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and outputs the resulting image. This is a very convenient way to
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avoid having to draw new button images every time you want to
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change the text of a button. With this method they are
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dynamically generated.
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</para>
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</section>
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</partintro>
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&reference.image.functions;
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</reference>
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<!-- Keep this comment at the end of the file
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Local variables:
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mode: sgml
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sgml-omittag:t
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sgml-shorttag:t
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sgml-minimize-attributes:nil
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sgml-always-quote-attributes:t
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sgml-indent-step:1
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sgml-indent-data:t
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indent-tabs-mode:nil
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sgml-parent-document:nil
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sgml-default-dtd-file:"../../../manual.ced"
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sgml-exposed-tags:nil
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sgml-local-catalogs:nil
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sgml-local-ecat-files:nil
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End:
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vim600: syn=xml fen fdm=syntax fdl=2 si
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vim: et tw=78 syn=sgml
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vi: ts=1 sw=1
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-->
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