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
    LTSH        Font::TTF::LTSH
    OS/2        Font::TTF::OS_2
    PCLT        Font::TTF::PCLT
    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

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::LTSH Font::TTF::OS_2 Font::TTF::PCLT 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

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.

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¶

    &func($table, $name);

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

Copyright Martin Hosken 1998.

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