/ 
Font-TTF-0.12
River stage two • 6 direct dependents • 54 total dependents
/ Font::TTF::Font

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->DESTROY;               # forces close of $in and maybe memory reclaim!

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
LTSH        Font::TTF::LTSH
OS/2        Font::TTF::OS_2
PCLT        Font::TTF::PCLT
cmap        Font::TTF::Cmap
cvt         Font::TTF::Cvt_
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
loca        Font::TTF::Loca
maxp        Font::TTF::Maxp
name        Font::TTF::Name
post        Font::TTF::Post
prep        Font::TTF::Prep
vhea        Font::TTF::Vhea
vmtx        Font::TTF::Vmtx

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.

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.

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 the current location 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. Only those tables which this font object has in its directory, will be output. Thus the following code is applicable:

$font->out($fname, keys %$font)

which will output all the tables in $font.

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

All output files must include the head 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->tables_do(&func)

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);

$f->DESTROY

Closes the file for this font, if this is not an embedded font

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:

Font::TTF::Post

Version 4 format types are not supported yet.

Font::TTF::Cmap

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

Font::TTF::Kern

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

Font::TTF::TTC

The current Font::TTF::Font::out method does not support the writing of TrueType Collections.

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 Martin_Hosken@sil.org

Copyright Martin Hosken 1998.

No warranty or expression of effectiveness, least of all regarding anyone's safety, is implied in this software or documentation.

Licensing

The Perl TTF module is licensed under the Perl Artistic License.