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
- 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
LICENSING¶
Copyright (c) 1998-2013, 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.