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Document bzip2 filters

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git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@156218 c90b9560-bf6c-de11-be94-00142212c4b1
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Sara Golemon 2004-04-16 04:07:28 +00:00
parent 1904408f6d
commit 945c876b07
1 changed files with 67 additions and 2 deletions
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69
appendices/filters.xml
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@ -1,5 +1,5 @@
<?xml version="1.0" encoding="iso-8859-1"?>
<!-- $Revision: 1.5 $ -->
<!-- $Revision: 1.6 $ -->
<appendix id="filters">
<title>List of Available Filters</title>
<para>
@ -236,7 +236,7 @@ fwrite($fp, "This is a test.\n");
While the <xref linkend="wrappers.compression"/> provide a way of creating
gzip and bz2 compatable files on the local filesystem, they do not provide a
means for generalized compression over network streams, nor do they provide a
means begin with a non-compressed stream and transition to a compressed one.
means to begin with a non-compressed stream and transition to a compressed one.
For this, a compression filter may be applied to any stream resource at any time.
</simpara>
@ -353,6 +353,71 @@ The compressed file is 56 bytes long.
</programlisting>
</example>
<simpara>
<literal>bzip2.compress</literal> and
<literal>bzip2.decompress</literal>
work in the same manner as the zlib filters described above.
The <literal>bzip2.compress</literal> filter accepts up to two parameters given as
elements of an associative array:
<parameter>blocks</parameter> is an integer value
from 1 to 9 specifying the number of 100kbyte blocks of memory to allocate for
workspace.
<parameter>work</parameter> is also an integer value ranging from
0 to 250 indicating how much effort to expend using the normal compression method
before falling back on a slower, but more reliable method. Tuning this parameter
effects only compression speed. Neither size of compressed output nor memory usage
are changed by this setting. A work factor of 0 instructs the bzip library to use
an internal default.
The <literal>bzip2.decompress</literal> filter only accepts one parameter,
which can be passed as either an ordinary boolean value as the
<parameter>small</parameter> element of an associative array.
<parameter>small</parameter>, when set to a &true; value, instructs the bzip library
to perform decompression in a minimal memory footprint at the cost of speed.
</simpara>
<note>
<simpara>
The bzip2.* filters are not currently built into the PHP core. To enable these filters
in <literal>PHP 5</literal>, install the <ulink url="&url.pecl.package;bz2_filter">bz2_filter</ulink>
package from <ulink url="&url.pecl;">PECL</ulink>. These filters are <emphasis>not</emphasis>
available for <literal>PHP 4</literal>.
</simpara>
</note>
<example>
<title>
<literal>bzip2.compress</literal> and
<literal>bzip2.decompress</literal>
</title>
<programlisting role="php">
<![CDATA[
<?php
$param = array('blocks' => 9, 'work' => 0);
echo "The original file is " . filesize('LICENSE') . " bytes long.\n";
$fp = fopen('LICENSE.compressed', 'w');
stream_filter_append($fp, 'bzip2.compress', STREAM_FILTER_WRITE, $param);
fwrite($fp, file_get_contents('LICENSE'));
fclose($fp);
echo "The compressed file is " . filesize('LICENSE.compressed') . " bytes long.\n";
/* Generates output:
The original text is 3288 characters long.
The compressed file is 1488 bytes long.
*/
?>
]]>
</programlisting>
</example>
</section>
</appendix>