1. class
  2. http
  3. \
  4. Encoding
  5. \
  6. Stream
  7. \
  8. Deflate

Deflate

class Deflate extends Stream (View source)

A deflate stream supporting deflate, zlib and gzip encodings.

Constants

FLUSH_NONE

Do no intermittent flushes.
FLUSH_SYNC

Flush at appropriate transfer points.
FLUSH_FULL

Flush at each IO operation.
TYPE_GZIP

Gzip encoding. RFC1952
TYPE_ZLIB

Zlib encoding. RFC1950
TYPE_RAW

Deflate encoding. RFC1951
LEVEL_DEF

Default compression level.
LEVEL_MIN

Least compression level.
LEVEL_MAX

Greatest compression level.
STRATEGY_DEF

Default compression strategy.
STRATEGY_FILT

Filtered compression strategy.
STRATEGY_HUFF

Huffman strategy only.
STRATEGY_RLE

Run-length encoding strategy.
STRATEGY_FIXED

Encoding with fixed Huffman codes only.

A note on the compression strategy:

The strategy parameter is used to tune the compression algorithm.

Use the value DEFAULT_STRATEGY for normal data, FILTERED for data produced by a filter (or predictor), HUFFMAN_ONLY to force Huffman encoding only (no string match), or RLE to limit match distances to one (run-length encoding).

Filtered data consists mostly of small values with a somewhat random distribution. In this case, the compression algorithm is tuned to compress them better. The effect of FILTERED is to force more Huffman coding and less string matching; it is somewhat intermediate between DEFAULT_STRATEGY and HUFFMAN_ONLY.

RLE is designed to be almost as fast as HUFFMAN_ONLY, but give better compression for PNG image data.

FIXED prevents the use of dynamic Huffman codes, allowing for a simpler decoder for special applications.

The strategy parameter only affects the compression ratio but not the correctness of the compressed output even if it is not set appropriately.

Source: zlib Manual

Methods

__construct(int $flags = 0)

Base constructor for encoding stream implementations.

from  Stream
bool
done()

Check whether the encoding stream is already done.

from  Stream
string
finish()

Finish and reset the encoding stream.

from  Stream
string
flush()

Flush the encoding stream.

from  Stream
string
update(string $data)

Update the encoding stream with more input.

from  Stream
string
encode(string $data, int $flags = 0)

Encode data with deflate/zlib/gzip encoding.

Details

in Stream at line 2675
__construct(int $flags = 0)

Base constructor for encoding stream implementations.

Parameters

int $flags

See http\Encoding\Stream and implementation specific constants.

Exceptions

InvalidArgumentException
RuntimeException

in Stream at line 2682
bool done()

Check whether the encoding stream is already done.

Return Value

bool

whether the encoding stream is completed.

in Stream at line 2690
string finish()

Finish and reset the encoding stream.

Returns any pending data.

Return Value

string

any pending data.

in Stream at line 2698
string flush()

Flush the encoding stream.

Returns any pending data.

Return Value

string

any pending data.

in Stream at line 2706
string update(string $data)

Update the encoding stream with more input.

Parameters

string $data

The data to pass through the stream.

Return Value

string

processed data.

at line 2828
string encode(string $data, int $flags = 0)

Encode data with deflate/zlib/gzip encoding.

Parameters

string $data

The data to compress.
int $flags

Any compression tuning flags. See http\Encoding\Stream\Deflate and http\Encoding\Stream constants.

Return Value

string

the compressed data.