CXI. Zlib Compression Functions

Bevezet�s

This module enables you to transparently read and write gzip (.gz) compressed files, through versions of most of the filesystem functions which work with gzip-compressed files (and uncompressed files, too, but not with sockets).

Megjegyz�s: Version 4.0.4 introduced a fopen-wrapper for .gz-files, so that you can use a special 'zlib:' URL to access compressed files transparently using the normal f*() file access functions if you prepend the filename or path with a 'zlib:' prefix when calling fopen().
In version 4.3.0, this special prefix has been changed to 'zlib://' to prevent ambiguities with filenames containing ':'.
This feature requires a C runtime library that provides the fopencookie() function. To my current knowledge the GNU libc is the only library that provides this feature.

K�vetelm�nyek

This module uses the functions of by Jean-loup Gailly and Mark Adler. You have to use a zlib version >= 1.0.9 with this module.

Fut�sidej� be�ll�t�sok

The zlib extension offers the option to transparently compress your pages on-the-fly, if the requesting browser supports this. Therefore there are two options in the configuration file php.ini.

T�bl�zat 1. Zlib Configuration Options

Name	Default	Changeable
zlib.output_compression	"0"	PHP_INI_ALL
zlib.output_compression_level	"-1"	PHP_INI_ALL

For further details and definition of the PHP_INI_* constants see ini_set().

Here is a short explanation of the configuration directives.

zlib.output_compression boolean/integer

Whether to transparently compress pages. If this option is set to "On" in php.ini or the Apache configuration, pages are compressed if the browser sends an "Accept-Encoding: gzip" or "deflate" header. "Content-Encoding: gzip" (respectively "deflate") and "Vary: Accept-Encoding" headers are added to the output.

You can use ini_set() to disable this in your script if the headers aren't already sent. If you output a "Content-Type: image/" header the compression is disabled, too (in order to circumvent a Netscape bug). You can reenable it, if you add "ini_set('zlib.output_compression', 'On')" after the header call which added the image content-type.

This option also accepts integer values instead of boolean "On"/"Off", using this you can set the output buffer size.

zlib.output_compression_level integer

Compression level used for transparent output compression.

Er�forr�s t�pusok

Ez a kiterjeszt�s semmilyen er�forr�s t�pust nem defini�l.

El�re defini�lt �lland�k

Az itt list�zott �lland�kat ez a kiterjeszt�s defini�lja, �s csak akkor el�rhet�ek, ha az adott kiterjeszt�s be van ford�tva a PHP-be, vagy dinamikusan bet�lt�tt.

FORCE_GZIP (integer)
FORCE_DEFLATE (integer)

P�ld�k

This example opens a temporary file and writes a test string to it, then it prints out the content of this file twice.

P�lda 1. Small Zlib Example

<?php

$filename = tempnam ('/tmp', 'zlibtest').'.gz';
print "<html>\n<head></head>\n<body>\n<pre>\n";
$s = "Only a test, test, test, test, test, test, test, test!\n";

// open file for writing with maximum compression
$zp = gzopen($filename, "w9");

// write string to file
gzwrite($zp, $s);

// close file
gzclose($zp);

// open file for reading
$zp = gzopen($filename, "r");

// read 3 char
print gzread($zp, 3);

// output until end of the file and close it.
gzpassthru($zp);

print "\n";

// open file and print content (the 2nd time).
if (readgzfile($filename) != strlen($s)) {
        echo "Error with zlib functions!";
}
unlink($filename);
print "</pre>\n</h1></body>\n</html>\n";

?>

Tartalom
gzclose -- Close an open gz-file pointer
gzcompress -- Compress a string
gzdeflate -- Deflate a string
gzencode -- Create a gzip compressed string
gzeof -- Test for end-of-file on a gz-file pointer
gzfile -- Read entire gz-file into an array
gzgetc -- Get character from gz-file pointer
gzgets -- Get line from file pointer
gzgetss -- Get line from gz-file pointer and strip HTML tags
gzinflate -- Inflate a deflated string
gzopen -- Open gz-file
gzpassthru -- Output all remaining data on a gz-file pointer
gzputs -- Write to a gz-file pointer
gzread -- Binary-safe gz-file read
gzrewind -- Rewind the position of a gz-file pointer
gzseek -- Seek on a gz-file pointer
gztell -- Tell gz-file pointer read/write position
gzuncompress -- Uncompress a deflated string
gzwrite -- Binary-safe gz-file write
readgzfile -- Output a gz-file


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