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)