Information on PNG file chunks can be found at http://www.w3.org/TR/PNG/#11Chunks Some other info on PNG that I used http://garethrees.org/2007/11/14/pngcrush/. More...

Public Member Functions
	__construct ($contents)
	Prepares file for handling metadata.

	add_chunks ($type, $key, $value)
	Adds a chunk with keyword and data to the file content.

	check_chunks ($type, $check)
	Checks if a key already exists in the chunk of said type.

Detailed Description

Information on PNG file chunks can be found at http://www.w3.org/TR/PNG/#11Chunks Some other info on PNG that I used http://garethrees.org/2007/11/14/pngcrush/.

Example of use: $png = new PNG_MetaDataHandler('file.png');

if ($png->check_chunks("tEXt", "openbadge")) { $newcontents = $png->add_chunks("tEXt", "openbadge", 'http://some.public.url/to.your.assertion.file'); }

file_put_contents('file.png', $newcontents);

Constructor & Destructor Documentation

PNG_MetaDataHandler::__construct ( $contents )

Prepares file for handling metadata.

Verifies that this file is a valid PNG file. Unpacks file chunks and reads them into an array.

Parameters

string $contents File content as a string

PNG_MetaDataHandler::add_chunks	(	$type,
		$key,
		$value
	)

Adds a chunk with keyword and data to the file content.

Chunk is added to the end of the file, before IEND image trailer.

Parameters

string	$type	Chunk type, like iTXt, tEXt, etc.
string	$key	Keyword that needs to be added.
string	$value	Currently an assertion URL that is added to an image metadata.

Return values

string::$result File content with a new chunk as a string. Can be used in file_put_contents() to write to a file.

Exceptions

moodle_exception when unsupported chunk type is defined.

PNG_MetaDataHandler::check_chunks	(	$type,
		$check
	)

Checks if a key already exists in the chunk of said type.

We need to avoid writing same keyword into file chunks.

Parameters

string	$type	Chunk type, like iTXt, tEXt, etc.
string	$check	Keyword that needs to be checked.

Return values

boolean (true|false) True if file is safe to write this keyword, false otherwise.

The documentation for this class was generated from the following file: