API Documentation

Zend/Pdf/FileParser/Font/OpenType.php

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Zend Framework

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Category
Zend  
Copyright
Copyright (c) 2005-2012 Zend Technologies USA Inc. (http://www.zend.com)  
License
New BSD License  
Package
Zend_Pdf  
Subpackage
FileParser  
Version
$Id: OpenType.php 24594 2012-01-05 21:27:01Z matthew $  

\Zend_Pdf_FileParser_Font_OpenType

Package: Zend\Pdf\FileParser

Abstract base class for OpenType font file parsers.

TrueType was originally developed by Apple and was adopted as the default font format for the Microsoft Windows platform. OpenType is an extension of TrueType, developed jointly by Microsoft and Adobe, which adds support for PostScript font data.

This abstract parser class forms the foundation for concrete subclasses which extract either TrueType or PostScript font data from the file.

All OpenType files use big-endian byte ordering.

The full TrueType and OpenType specifications can be found at:

  • {@link http://developer.apple.com/textfonts/TTRefMan/}
  • {@link http://www.microsoft.com/typography/OTSPEC/}
  • {@link http://partners.adobe.com/public/developer/opentype/index_spec.html}
Parent(s)
\Zend_Pdf_FileParser_Font < \Zend_Pdf_FileParser
Children
\Zend_Pdf_FileParser_Font_OpenType_TrueType
Copyright
Copyright (c) 2005-2012 Zend Technologies USA Inc. (http://www.zend.com)  
License
New BSD License  

Properties

Propertyprotectedinteger  $_scalerType= '0'

Stores the scaler type (font type) for the font file. See {@link _readScalerType()}.

Default value0Details
Type
integer
Propertyprotectedarray  $_tableDirectory= 'array()'

Stores the byte offsets to the various information tables.

Default valuearray()Details
Type
array

Methods

methodprotected_jumpToTable( string $tableName ) : void

Validates a given table's existence, then sets the file pointer to the start of that table.

Parameters
Name Type Description
$tableName string
Throws
Exception Description
\Zend_Pdf_Exception
methodprotected_languageCodeForPlatform( integer $platformID,  $languageID ) : string

Utility method that returns ISO 639 two-letter language codes from the TrueType platform and language ID. Returns NULL for languages that are not supported.

Parameters
Name Type Description
$platformID integer
$languageID
Returns
Type Description
string | null
methodprotected_parseCmapTable( ) : void

Parses the OpenType cmap (Character to Glyph Mapping) table.

The cmap table provides the maps from character codes to font glyphs. There are usually at least two character maps in a font: Microsoft Unicode and Macintosh Roman. For very complex fonts, there may also be mappings for the characters in the Unicode Surrogates Area, which are UCS-4 characters.

Throws
Exception Description
\Zend_Pdf_Exception
Details
Todo
Need to rework the selection logic for picking a subtable. We should have an explicit list of preferences, followed by a list of those that are tolerable. Most specifically, since everything above this layer deals in Unicode, we need to be sure to only accept format 0 MacRoman tables.  
methodprotected_parseHeadTable( ) : void

Parses the OpenType head (Font Header) table.

The head table contains global information about the font such as the revision number and global metrics.

Throws
Exception Description
\Zend_Pdf_Exception
methodprotected_parseHheaTable( ) : void

Parses the OpenType hhea (Horizontal Header) table.

The hhea table contains information used for horizontal layout. It also contains some vertical layout information for Apple systems. The vertical layout information for the PDF file is usually taken from the OS/2 table.

Throws
Exception Description
\Zend_Pdf_Exception
methodprotected_parseHmtxTable( ) : void

Parses the OpenType hmtx (Horizontal Metrics) table.

The hmtx table contains the horizontal metrics for every glyph contained within the font. These are the critical values for horizontal layout of text.

Throws
Exception Description
\Zend_Pdf_Exception
methodprotected_parseMaxpTable( ) : void

Parses the OpenType hhea (Horizontal Header) table.

The hhea table contains information used for horizontal layout. It also contains some vertical layout information for Apple systems. The vertical layout information for the PDF file is usually taken from the OS/2 table.

Throws
Exception Description
\Zend_Pdf_Exception
methodprotected_parseNameTable( ) : void

Parses the OpenType name (Naming) table.

The name table contains all of the identifying strings associated with the font such as its name, copyright, trademark, license, etc.

Throws
Exception Description
\Zend_Pdf_Exception
methodprotected_parseOs2Table( ) : void

Parses the OpenType OS/2 (OS/2 and Windows Metrics) table.

The OS/2 table contains additional metrics data that is required to use the font on the OS/2 or Microsoft Windows platforms. It is not required for Macintosh fonts, so may not always be present. When available, we use this table to determine most of the vertical layout and stylistic information and for the font.

Throws
Exception Description
\Zend_Pdf_Exception
methodprotected_parsePostTable( ) : void

Parses the OpenType post (PostScript Information) table.

The post table contains additional information required for using the font on PostScript printers. It also contains the preferred location and thickness for an underline, which is used by our layout code.

Throws
Exception Description
\Zend_Pdf_Exception
methodprotected_parseTableDirectory( ) : void

Parses the OpenType table directory.

The table directory contains the identifier, checksum, byte offset, and length of each of the information tables housed in the font file.

Throws
Exception Description
\Zend_Pdf_Exception
methodprotected_readScalerType( ) : integer

Reads the scaler type from the header of the OpenType font file and returns it as an unsigned long integer.

The scaler type defines the type of font: OpenType font files may contain TrueType or PostScript outlines. Throws an exception if the scaler type is not recognized.

Returns
Type Description
integer
Throws
Exception Description
\Zend_Pdf_Exception
methodprotected_readTableVersion( float $minVersion,  $maxVersion ) : float

Reads the fixed 16.16 table version number and checks for compatibility.

If the version is incompatible, throws an exception. If it is compatible, returns the version number.

Parameters
Name Type Description
$minVersion float

Minimum compatible version number.

$maxVersion
Returns
Type Description
float Table version number.
Throws
Exception Description
\Zend_Pdf_Exception
methodpublicparse( ) : void

Reads and parses the font data from the file on disk.

NOTE: This method should be overridden in subclasses to add type- specific parsing and set $this->isParsed.

Throws
Exception Description
\Zend_Pdf_Exception
methodpublicscreen( ) : void

Verifies that the font file is in the expected format.

NOTE: This method should be overridden in subclasses to check the specific format and set $this->_isScreened!

Throws
Exception Description
\Zend_Pdf_Exception
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