Font::TTF::Kern(3) User Contributed Perl Documentation Font::TTF::Kern(3)
NAME
Font::TTF::Kern - Kerning tables
DESCRIPTION
Kerning tables are held as an ordered collection of subtables each giving incremental information regarding the kerning of various pairs of
glyphs.
The basic structure of the kerning data structure is:
$kern = $f->{'kern'}{'tables'}[$tnum]{'kerns'}{$leftnum}{$rightnum};
Due to the possible complexity of some kerning tables the above information is insufficient. Reference also needs to be made to the type of
the table and the coverage field.
INSTANCE VARIABLES
The instance variables for a kerning table are relatively straightforward.
Version
Version number of the kerning table
Num Number of subtables in the kerning table
tables
Array of subtables in the kerning table
Each subtable has a number of instance variables.
kern
A two level hash array containing kerning values. The indexing is left value and then right value. In the case of type 2 tables,
the indexing is via left class and right class. It may seem using hashes is strange, but most tables are not type 2 and this method
saves empty array values.
type
Stores the table type. Only type 0 and type 2 tables are specified for TrueType so far.
coverage
A bit field of coverage information regarding the kerning value. See the TrueType specification for details.
Version
Contains the version number of the table.
Num
Number of kerning pairs in this type 0 table.
left
An array indexed by glyph - left_first which returns a class number for the glyph in type 2 tables.
right
An array indexed by glyph - right_first which returns a class number for the glyph in type 2 tables.
left_first
the glyph number of the first element in the left array for type 2 tables.
right_first
the glyph number of the first element in the right array for type 2 tables.
num_left
Number of left classes
num_right
Number of right classes
METHODS
$t->read
Reads the whole kerning table into structures
$t->out($fh)
Outputs the kerning tables to the given file
$t->XML_element($context, $depth, $key, $value)
Handles outputting the kern hash into XML a little more tidily
BUGS
o Only supports kerning table types 0 & 2.
o No real support functions to do anything with the kerning tables yet.
AUTHOR
Martin Hosken Martin_Hosken@sil.org. See Font::TTF::Font for copyright and licensing.
POD ERRORS
Hey! The above document had some coding errors, which are explained below:
Around line 38:
You can't have =items (as at line 42) unless the first thing after the =over is an =item
perl v5.16.3 2012-02-23 Font::TTF::Kern(3)