phpman > perldoc > Font::TTF::Kern

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 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

  $t->minsize()
    Returns the minimum size this table can be. If it is smaller than this, then the table must be
    bad and should be deleted or whatever.

BUGS
    *   Only supports kerning table types 0 & 2.

    *   No real support functions to *do* anything with the kerning tables yet.

AUTHOR
    Martin Hosken <http://scripts.sil.org/FontUtils>.

LICENSING
    Copyright (c) 1998-2016, SIL International (http://www.sil.org)

    This module is released under the terms of the Artistic License 2.0. For details, see the full
    text of the license in the file LICENSE.