NAME

       Font::TTF::Font - Memory representation of a font

SYNOPSIS

       Here is the regression test (you provide your own font). Run it once and then again on the
       output of the first run. There should be no differences between the outputs of the two
       runs.

           $f = Font::TTF::Font->open($ARGV[0]);

           # force a read of all the tables
           $f->tables_do(sub { $_[0]->read; });

           # force read of all glyphs (use read_dat to use lots of memory!)
           # $f->{'loca'}->glyphs_do(sub { $_[0]->read; });
           $f->{'loca'}->glyphs_do(sub { $_[0]->read_dat; });
           # NB. no need to $g->update since $f->{'glyf'}->out will do it for us

           $f->out($ARGV[1]);
           $f->release;            # clear up memory forcefully!

DESCRIPTION

       A Truetype font consists of a header containing a directory of tables which constitute the
       rest of the file. This class holds that header and directory and also creates objects of
       the appropriate type for each table within the font.  Note that it does not read each
       table into memory, but creates a short reference which can be read using the form:

           $f->{$tablename}->read;

       Classes are included that support many of the different TrueType tables. For those for
       which no special code exists, the table type "table" is used, which defaults to
       Font::TTF::Table. The current tables which are supported are:

           table       Font::TTF::Table      - for unknown tables
           EBDT        Font::TTF::EBDT
           EBLC        Font::TTF::EBLC
           Feat        Font::TTF::GrFeat
           GDEF        Font::TTF::GDEF
           GPOS        Font::TTF::GPOS
           GSUB        Font::TTF::GSUB
           Glat        Font::TTF::Glat
           Gloc        Font::TTF::Gloc
           LTSH        Font::TTF::LTSH
           OS/2        Font::TTF::OS_2
           PCLT        Font::TTF::PCLT
           Sill        Font::TTF::Sill
           Silf        Font::TTF::Silf
           bsln        Font::TTF::Bsln
           cmap        Font::TTF::Cmap       - see also Font::TTF::OldCmap
           cvt         Font::TTF::Cvt_
           fdsc        Font::TTF::Fdsc
           feat        Font::TTF::Feat
           fmtx        Font::TTF::Fmtx
           fpgm        Font::TTF::Fpgm
           glyf        Font::TTF::Glyf       - see also Font::TTF::Glyph
           hdmx        Font::TTF::Hdmx
           head        Font::TTF::Head
           hhea        Font::TTF::Hhea
           hmtx        Font::TTF::Hmtx
           kern        Font::TTF::Kern       - see alternative Font::TTF::AATKern
           loca        Font::TTF::Loca
           maxp        Font::TTF::Maxp
           mort        Font::TTF::Mort       - see also Font::TTF::OldMort
           name        Font::TTF::Name
           post        Font::TTF::Post
           prep        Font::TTF::Prep
           prop        Font::TTF::Prop
           vhea        Font::TTF::Vhea
           vmtx        Font::TTF::Vmtx
           DSIG        FONT::TTF::DSIG

       Links are:

       Font::TTF::Table Font::TTF::EBDT Font::TTF::EBLC Font::TTF::GrFeat Font::TTF::GDEF
       Font::TTF::GPOS Font::TTF::GSUB Font::TTF::Glat Font::TTF::Gloc Font::TTF::LTSH
       Font::TTF::OS_2 Font::TTF::PCLT Font::TTF::Sill Font::TTF::Silf Font::TTF::Bsln
       Font::TTF::Cmap Font::TTF::Cvt_ Font::TTF::Fdsc Font::TTF::Feat Font::TTF::Fmtx
       Font::TTF::Fpgm Font::TTF::Glyf Font::TTF::Hdmx Font::TTF::Head Font::TTF::Hhea
       Font::TTF::Hmtx Font::TTF::Kern Font::TTF::Loca Font::TTF::Maxp Font::TTF::Mort
       Font::TTF::Name Font::TTF::Post Font::TTF::Prep Font::TTF::Prop Font::TTF::Vhea
       Font::TTF::Vmtx Font::TTF::OldCmap Font::TTF::Glyph Font::TTF::AATKern Font::TTF::OldMort
       Font::TTF::DSIG

INSTANCE VARIABLES

       Instance variables begin with a space (and have lengths greater than the 4 characters
       which make up table names).

       nocsum
           This is used during output to disable the creation of the file checksum in the head
           table. For example, during DSIG table creation, this flag will be set to ensure that
           the file checksum is left at zero.

       noharmony
           If set, do not harmonize the script and lang trees of GPOS and GSUB tables. See
           Font::TTF::Ttopen for more info.

       nocompress
           Is the default value controlling WOFF output table compression. If undef, all tables
           will be compressed if there is a size benefit in doing so.  It may be set to an array
           of tagnames naming tables that should not be compressed, or to a scalar integer
           specifying a table size threshold below which tables will not be compressed.  Note
           that individual Font::TTF::Table objects may override this default. See
           Font::TTF::Table for more info.

       fname (R)
           Contains the filename of the font which this object was read from.

       INFILE (P)
           The file handle which reflects the source file for this font.

       OFFSET (P)
           Contains the offset from the beginning of the read file of this particular font
           directory, thus providing support for TrueType Collections.

       WOFF
           Contains a reference to a "Font::TTF::Woff" object.

METHODS

   Font::TTF::Font->AddTable($tablename, $class)
       Adds the given class to be used when representing the given table name. It also 'requires'
       the class for you.

   Font::TTF::Font->Init
       For those people who like making fonts without reading them. This subroutine will require
       all the table code for the various table types for you. Not needed if using
       Font::TTF::Font::read before using a table.

   Font::TTF::Font->new(%props)
       Creates a new font object and initialises with the given properties. This is primarily for
       use when a TTF is embedded somewhere. Notice that the properties are automatically
       preceded by a space when inserted into the object. This is in order that fields do not
       clash with tables.

   Font::TTF::Font->open($fname)
       Reads the header and directory for the given font file and creates appropriate objects for
       each table in the font.

   $f->read
       Reads a Truetype font directory starting from location "$self-"{' OFFSET'}> in the file.
       This has been separated from the "open" function to allow support for embedded TTFs for
       example in TTCs. Also reads the "head" and "maxp" tables immediately.

   $f->out($fname [, @tablelist])
       Writes a TTF file consisting of the tables in tablelist. The list is checked to ensure
       that only tables that exist are output. (This means that you cannot have non table
       information stored in the font object with key length of exactly 4)

       In many cases the user simply wants to output all the tables in alphabetical order.  This
       can be done by not including a @tablelist, in which case the subroutine will output all
       the defined tables in the font in alphabetical order.

       Returns $f on success and undef on failure, including warnings.

       All output files must include the "head" table.

   $f->out_xml($filename [, @tables])
       Outputs the font in XML format

   $f->XML_start($context, $tag, %attrs)
       Handles start messages from the XML parser. Of particular interest to us are <font> and
       <table>.

   $f->update
       Sends update to all the tables in the font and then resets all the isDirty flags on each
       table. The data structure in now consistent as a font (we hope).

   $f->dirty
       Dirties all the tables in the font

   $f->tables_do(&func [, tables])
       Calls &func for each table in the font. Calls the table in alphabetical sort order as per
       the order in the directory:

           &func($table, $name);

       May optionally take a list of table names in which case func is called for each of them in
       the given order.

   $f->release
       Releases ALL of the memory used by the TTF font and all of its component objects.  After
       calling this method, do NOT expect to have anything left in the "Font::TTF::Font" object.

       NOTE, that it is important that you call this method on any "Font::TTF::Font" object when
       you wish to destruct it and free up its memory.  Internally, we track things in a
       structure that can result in circular references, and without calling '"release()"' these
       will not properly get cleaned up by Perl.  Once you've called this method, though, don't
       expect to be able to do anything else with the "Font::TTF::Font" object; it'll have no
       internal state whatsoever.

       Developer note: As part of the brute-force cleanup done here, this method will throw a
       warning message whenever unexpected key values are found within the "Font::TTF::Font"
       object.  This is done to help ensure that any unexpected and unfreed values are brought to
       your attention so that you can bug us to keep the module updated properly; otherwise the
       potential for memory leaks due to dangling circular references will exist.

BUGS

       Bugs abound aplenty I am sure. There is a lot of code here and plenty of scope.  The parts
       of the code which haven't been implemented yet are:

       Post
           Version 4 format types are not supported yet.

       Cmap
           Format type 2 (MBCS) has not been implemented yet and therefore may cause somewhat
           spurious results for this table type.

       Kern
           Only type 0 & type 2 tables are supported (type 1 & type 3 yet to come).

       TTC and WOFF
           The current Font::TTF::Font::out method does not support the writing of TrueType
           Collections or WOFF files.

       DSIG
           Haven't figured out how to correctly calculate and output digital signature (DSIG)
           table

       In addition there are weaknesses or features of this module library

       •   There is very little (or no) error reporting. This means that if you have garbled data
           or garbled data structures, then you are liable to generate duff fonts.

       •   The exposing of the internal data structures everywhere means that doing radical re-
           structuring is almost impossible. But it stop the code from becoming ridiculously
           large.

       Apart from these, I try to keep the code in a state of "no known bugs", which given the
       amount of testing this code has had, is not a guarantee of high quality, yet.

       For more details see the appropriate class files.

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.