#class http\Encoding\Stream\Deflate
 extends http\Encoding\Stream

A deflate stream supporting deflate, zlib and gzip encodings.

Constants:#

• 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

Properties:#

None.

Functions:#

• Deflate::encode#

  Encode data with deflate/zlib/gzip encoding.

  static string http\Encoding\Stream\Deflate::encode(string $data[, int $flags = 0])