Method Gz.compress()

Method compress

string compress(string data, void|int(0..1) raw, void|int(0..9) level, void|int strategy, void|int(8..15) window_size)

Description

Encodes and returns the input data according to the deflate format defined in RFC 1951.

Parameter data

The data to be encoded.

Parameter raw

If set, the data is encoded without the header and footer defined in RFC 1950. Example of uses is the ZIP container format.

Parameter level

Indicates the level of effort spent to make the data compress well. Zero means no packing, 2-3 is considered 'fast', 6 is default and higher is considered 'slow' but gives better packing.

Parameter strategy

The strategy to be used when compressing the data. One of the following.

`DEFAULT_STRATEGY`	The default strategy as selected in the zlib library.
`FILTERED`	This strategy is intented for data created by a filter or predictor and will put more emphasis on huffman encoding and less on LZ string matching. This is between DEFAULT_STRATEGY and HUFFMAN_ONLY.
`RLE`	This strategy is even closer to the HUFFMAN_ONLY in that it only looks at the latest byte in the window, i.e. a window size of 1 byte is sufficient for decompression. This mode is not available in all zlib versions.
`HUFFMAN_ONLY`	This strategy will turn of string matching completely, only doing huffman encoding. Window size doesn't matter in this mode and the data can be decompressed with a zero size window.
`FIXED`	In this mode dynamic huffman codes are disabled, allowing for a simpler decoder for special applications. This mode is not available in all zlib versions.

Parameter window_size

Defines the size of the LZ77 window from 256 bytes to 32768 bytes, expressed as 2^x.