setasign\SetaPDF2\Core\Filter

Predictor Class handling predictor functions

File: /SetaPDF v2/Core/Filter/Predictor.php
Old class name (alias): \SetaPDF_Core_Filter_Predictor

Class hierarchy

Implements

Summary

Properties

$_bitsPerComponent

protected int Predictor::$_bitsPerComponent = 8

$_colors

protected int Predictor::$_colors = 1

$_columns

protected int Predictor::$_columns = 1

$_predictor

protected int Predictor::$_predictor = 1

$alwaysWritePredictorByte

Whether or not to only write algorithm byte if predictor value is 15.

If set to true, the algorithm byte is written at the beginning of every line for all PNG predictors.

If set to false, this byte is only written for optimum png compression, which can vary the compression algorithm for each row.


Methods

__construct()

public Predictor::__construct (
int $predictor = null,
int $colors = null,
int $bitsPerComponent = null,
int $columns = null
)

The constructor.

Parameters
$predictor : int
 
$colors : int
 
$bitsPerComponent : int
 
$columns : int
 

_decodePng()

protected Predictor::_decodePng (
string $data
): string

Decode png predictors.

Parameters
$data : string
 
Exceptions

Throws Exception

_paethPredictor()

protected Predictor::_paethPredictor (
int|float $left,
int|float $above,
int|float $upperLeft
): int|float

Value prediction using the Alan W. Paeth algorithm.

Parameters
$left : int|float

The value to the left of the processed data entry.

$above : int|float

The value above the processed data entry.

$upperLeft : int|float

The value to the upper left of the processed data entry.

Return Values

Returns the prediction value according to the Peath algorithm

decode()

public Predictor::decode (
string $data
): string

Decodes a string using a predictor function.

Parameters
$data : string

The input string

Return Values

The decoded data

Exceptions

Throws Exception

Throws \setasign\SetaPDF2\NotImplementedException

encode()

public Predictor::encode (
string $data
): string

Encodes a string using a predictor function.

Parameters
$data : string

The input string

Return Values

The encoded data

Exceptions

Throws Exception

Throws \setasign\SetaPDF2\NotImplementedException