The behaviour of these functions is affected by settings in php.ini.
The zlib extension offers the option to transparently compress
your pages on-the-fly, if the requesting browser supports
this. Therefore there are three options in the configuration filephp.ini.
Zlib Configuration Options
Name
Default
Changeable
Changelog
zlib.output_compression
"0"
PHP_INI_ALL
Available since PHP 4.0.5.
zlib.output_compression_level
"-1"
PHP_INI_ALL
Available since PHP 4.3.0.
zlib.output_handler
""
PHP_INI_ALL
Available since PHP 4.3.0.
For further details and definitions of the
PHP_INI_* constants, see the php.ini directives.
Here's a short explanation of
the configuration directives.
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.
In runtime, it can be set only before sending any output.
This option also accepts integer values instead of boolean
"On"/"Off", using this you can set the output buffer size
(default is 4KB).
Note:
output_handler must be
empty if this is set 'On' ! Instead you must use zlib.output_handler.
You cannot specify additional output handlers if zlib.output_compression
is activated here. This setting does the same as
output_handler but in a different order.