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Font::TTF::Coverage - Opentype coverage and class definition objects


Coverage tables and class definition objects are virtually identical concepts in OpenType. Their difference comes purely in their storage. Therefore we can say that a coverage table is a class definition in which the class definition for each glyph is the corresponding index in the coverage table. The resulting data structure is that a Coverage table has the following fields:

A boolean to indicate whether this table is a coverage table ( TRUE ) or a class definition ( FALSE )


A hash of glyph ids against values (either coverage index or class value)


The storage format used is given here, but is recalculated when the table is written out.


A count of the elements in a coverage table for use with add. Each subsequent addition is added with the current count and increments the count.


Maximum class value in a class table.


new($isCover [, vals])
Creates a new coverage table or class definition table, depending upon the value of $isCover. if $isCover then vals may be a list of glyphs to include in order. If no $isCover, then vals is a hash of glyphs against class values.

Reads the coverage/class table from the given file handle

out($fh, $state)
Writes the coverage/class table to the given file handle. If $state is 1 then the output string is returned rather than being output to a filehandle.

$c->add($glyphid[, $class])
Adds a glyph id to the coverage or class table. Returns the index or class number of the glyphid added.

Returns a vector of all the glyph ids covered by this coverage table or class

Sorts the coverage table so that indexes are in ascending order of glyphid. Returns a map such that $map[$new_index]=$old_index.

Outputs this coverage/class in XML


Martin Hosken <>.


Copyright (c) 1998-2016, SIL International (

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.