Runtime Configuration

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
file php.ini.

For further details and definitions of the PHP_INI_* modes, see the
Where a
configuration setting may be set.

Here’s 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. 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.

zlib.output_compression_level integer

Compression level used for transparent output
compression. Specify a value between 0 (no compression) to 9 (most
compression). The default value, -1, lets the server decide which
level to use.

zlib.output_handler string

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.