NAME

Font::TTF::GDEF - Opentype GDEF table support

DESCRIPTION

The GDEF table contains various global lists of information which are apparantly used in other places in an OpenType renderer. But precisely where is open to speculation...

INSTANCE VARIABLES

There are up to 5 tables in the GDEF table, each with their own structure:

GLYPH: This is an Font::TTF::Coverage Class Definition table containing information as to what type each glyph is.
ATTACH: The attach table consists of a coverage table and then attachment points for each glyph in the coverage table:

COVERAGE: This is a coverage table
POINTS: This is an array of point elements. Each element is an array of curve points corresponding to the attachment points on that glyph. The order of the curve points in the array corresponds to the attachment point number specified in the MARKS coverage table (see below).

LIG: This contains the ligature caret positioning information for ligature glyphs

COVERAGE: A coverage table to say which glyphs are ligatures
LIGS: An array of elements for each ligature. Each element is an array of information for each caret position in the ligature (there being number of components - 1 of these, generally)

FMT: This is the format of the information and is important to provide the semantics for the value. This value must be set correctly before output
VAL: The value which has meaning according to FMT
DEVICE: For FMT = 3, a device table is also referenced which is stored here

MARKS: This class definition table defines the classes of mark glyphs that can be selected for processing using the MarkAttachmentType field of lookup FLAG words.
MARKSETS: Contains an array of coverage tables indexed by the FILTER value of a lookup.