fonttools: A Python repository from typoman

What is this?

fontTools is a library for manipulating fonts, written in Python. The project includes the TTX tool, that can convert TrueType and OpenType fonts to and from an XML text format, which is also called TTX. It supports TrueType, OpenType, AFM and to an extent Type 1 and some Mac-specific formats. The project has an MIT open-source licence.

Among other things this means you can use it free of charge.

Installation

FontTools 4.x requires Python 3.6 or later. FontTools 3.x requires Python 2.7 or later.

NOTE From August 2019, until no later than January 1 2020, the support for Python 2.7 will be limited to only critical bug fixes, and no new features will be added to the py27 branch. You can read more here and here for the reasons behind this decision.

The package is listed in the Python Package Index (PyPI), so you can install it with pip:

pip install fonttools

If you would like to contribute to its development, you can clone the repository from GitHub, install the package in 'editable' mode and modify the source code in place. We recommend creating a virtual environment, using virtualenv or Python 3 venv module.

# download the source code to 'fonttools' folder
git clone https://github.com/fonttools/fonttools.git
cd fonttools

# create new virtual environment called e.g. 'fonttools-venv', or anything you like
python -m virtualenv fonttools-venv

# source the `activate` shell script to enter the environment (Un*x); to exit, just type `deactivate`
. fonttools-venv/bin/activate

# to activate the virtual environment in Windows `cmd.exe`, do
fonttools-venv\Scripts\activate.bat

# install in 'editable' mode
pip install -e .

TTX – From OpenType and TrueType to XML and Back

Once installed you can use the ttx command to convert binary font files (.otf, .ttf, etc) to the TTX XML format, edit them, and convert them back to binary format. TTX files have a .ttx file extension.

ttx /path/to/font.otf
ttx /path/to/font.ttx

The TTX application can be used in two ways, depending on what platform you run it on:

As a command line tool (Windows/DOS, Unix, macOS)
By dropping files onto the application (Windows, macOS)

TTX detects what kind of files it is fed: it will output a .ttx file when it sees a .ttf or .otf, and it will compile a .ttf or .otf when the input file is a .ttx file. By default, the output file is created in the same folder as the input file, and will have the same name as the input file but with a different extension. TTX will never overwrite existing files, but if necessary will append a unique number to the output filename (before the extension) such as Arial#1.ttf

When using TTX from the command line there are a bunch of extra options. These are explained in the help text, as displayed when typing ttx -h at the command prompt. These additional options include:

specifying the folder where the output files are created
specifying which tables to dump or which tables to exclude
merging partial .ttx files with existing .ttf or .otf files
listing brief table info instead of dumping to .ttx
splitting tables to separate .ttx files
disabling TrueType instruction disassembly

The TTX file format

The following tables are currently supported:

BASE, CBDT, CBLC, CFF, CFF2, COLR, CPAL, DSIG, EBDT, EBLC, FFTM,
Feat, GDEF, GMAP, GPKG, GPOS, GSUB, Glat, Gloc, HVAR, JSTF, LTSH,
MATH, META, MVAR, OS/2, SING, STAT, SVG, Silf, Sill, TSI0, TSI1,
TSI2, TSI3, TSI5, TSIB, TSID, TSIJ, TSIP, TSIS, TSIV, TTFA, VDMX,
VORG, VVAR, ankr, avar, bsln, cidg, cmap, cvar, cvt, feat, fpgm,
fvar, gasp, gcid, glyf, gvar, hdmx, head, hhea, hmtx, kern, lcar,
loca, ltag, maxp, meta, mort, morx, name, opbd, post, prep, prop,
sbix, trak, vhea and vmtx

Other tables are dumped as hexadecimal data.

TrueType fonts use glyph indices (GlyphIDs) to refer to glyphs in most places. While this is fine in binary form, it is really hard to work with for humans. Therefore we use names instead.

The glyph names are either extracted from the CFF table or the post table, or are derived from a Unicode cmap table. In the latter case the Adobe Glyph List is used to calculate names based on Unicode values. If all of these methods fail, names are invented based on GlyphID (eg glyph00142)

It is possible that different glyphs use the same name. If this happens, we force the names to be unique by appending #n to the name (n being an integer number.) The original names are being kept, so this has no influence on a "round tripped" font.

Because the order in which glyphs are stored inside the binary font is important, we maintain an ordered list of glyph names in the font.

Other Tools

Commands for merging and subsetting fonts are also available:

pyftmerge
pyftsubset

fontTools Python Module

The fontTools Python module provides a convenient way to programmatically edit font files.

>>> from fontTools.ttLib import TTFont
>>> font = TTFont('/path/to/font.ttf')
>>> font
<fontTools.ttLib.TTFont object at 0x10c34ed50>
>>>

A selection of sample Python programs is in the Snippets directory.

Optional Requirements

The fontTools package currently has no (required) external dependencies besides the modules included in the Python Standard Library. However, a few extra dependencies are required by some of its modules, which are needed to unlock optional features. The fonttools PyPI distribution also supports so-called "extras", i.e. a set of keywords that describe a group of additional dependencies, which can be used when installing via pip, or when specifying a requirement. For example:

pip install fonttools[ufo,lxml,woff,unicode]

This command will install fonttools, as well as the optional dependencies that are required to unlock the extra features named "ufo", etc.

Lib/fontTools/misc/etree.py

The module exports a ElementTree-like API for reading/writing XML files, and allows to use as the backend either the built-in xml.etree module or lxml. The latter is preferred whenever present, as it is generally faster and more secure.

Extra: lxml
Lib/fontTools/ufoLib

Package for reading and writing UFO source files; it requires:
- fs: (aka pyfilesystem2) filesystem abstraction layer.
- enum34: backport for the built-in enum module (only required on Python < 3.4).
Extra: ufo
Lib/fontTools/ttLib/woff2.py

Module to compress/decompress WOFF 2.0 web fonts; it requires:
- brotli: Python bindings of the Brotli compression library.
Extra: woff
Lib/fontTools/ttLib/sfnt.py

To better compress WOFF 1.0 web fonts, the following module can be used instead of the built-in zlib library:
- zopfli: Python bindings of the Zopfli compression library.
Extra: woff
Lib/fontTools/unicode.py

To display the Unicode character names when dumping the cmap table with ttx we use the unicodedata module in the Standard Library. The version included in there varies between different Python versions. To use the latest available data, you can install:
- unicodedata2: unicodedata backport for Python 2.7 and 3.x updated to the latest Unicode version 12.0. Note this is not necessary if you use Python 3.8 as the latter already comes with an up-to-date unicodedata.
Extra: unicode
Lib/fontTools/varLib/interpolatable.py

Module for finding wrong contour/component order between different masters. It requires one of the following packages in order to solve the so-called "minimum weight perfect matching problem in bipartite graphs", or the Assignment problem:
- scipy: the Scientific Library for Python, which internally uses NumPy arrays and hence is very fast;
- munkres: a pure-Python module that implements the Hungarian or Kuhn-Munkres algorithm.
Extra: interpolatable
Lib/fontTools/varLib/plot.py

Module for visualizing DesignSpaceDocument and resulting VariationModel.
- matplotlib: 2D plotting library.
Extra: plot
Lib/fontTools/misc/symfont.py

Advanced module for symbolic font statistics analysis; it requires:
- sympy: the Python library for symbolic mathematics.
Extra: symfont
Lib/fontTools/t1Lib.py

To get the file creator and type of Macintosh PostScript Type 1 fonts on Python 3 you need to install the following module, as the old MacOS module is no longer included in Mac Python:
- xattr: Python wrapper for extended filesystem attributes (macOS platform only).
Extra: type1
Lib/fontTools/pens/cocoaPen.py

Pen for drawing glyphs with Cocoa NSBezierPath, requires:
- PyObjC: the bridge between Python and the Objective-C runtime (macOS platform only).
Lib/fontTools/pens/qtPen.py

Pen for drawing glyphs with Qt's QPainterPath, requires:
- PyQt5: Python bindings for the Qt cross platform UI and application toolkit.
Lib/fontTools/pens/reportLabPen.py

Pen to drawing glyphs as PNG images, requires:
- reportlab: Python toolkit for generating PDFs and graphics.

Testing

To run the test suite, you need to install pytest. When you run the pytest command, the tests will run against the installed fontTools package, or the first one found in the PYTHONPATH.

You can also use tox to automatically run tests on different Python versions in isolated virtual environments.

pip install tox
tox

Note that when you run tox without arguments, the tests are executed for all the environments listed in tox.ini's envlist. In our case, this includes Python 3.6 and 3.7, so for this to work the python3.6 and python3.7 executables must be available in your PATH.

You can specify an alternative environment list via the -e option, or the TOXENV environment variable:

tox -e py36
TOXENV="py36-cov,htmlcov" tox

Development Community

TTX/FontTools development is ongoing in an active community of developers, that includes professional developers employed at major software corporations and type foundries as well as hobbyists.

Feature requests and bug reports are always welcome at https://github.com/fonttools/fonttools/issues/

The best place for discussions about TTX from an end-user perspective as well as TTX/FontTools development is the https://groups.google.com/d/forum/fonttools mailing list. There is also a development https://groups.google.com/d/forum/fonttools-dev mailing list for continuous integration notifications. You can also email Behdad privately at behdad@behdad.org

History

The fontTools project was started by Just van Rossum in 1999, and was maintained as an open source project at http://sourceforge.net/projects/fonttools/. In 2008, Paul Wise (pabs3) began helping Just with stability maintenance. In 2013 Behdad Esfahbod began a friendly fork, thoroughly reviewing the codebase and making changes at https://github.com/behdad/fonttools to add new features and support for new font formats.

Acknowledgements

In alphabetical order:

Olivier Berten, Samyak Bhuta, Erik van Blokland, Petr van Blokland, Jelle Bosma, Sascha Brawer, Tom Byrer, Frédéric Coiffier, Vincent Connare, Dave Crossland, Simon Daniels, Peter Dekkers, Behdad Esfahbod, Behnam Esfahbod, Hannes Famira, Sam Fishman, Matt Fontaine, Yannis Haralambous, Greg Hitchcock, Jeremie Hornus, Khaled Hosny, John Hudson, Denis Moyogo Jacquerye, Jack Jansen, Tom Kacvinsky, Jens Kutilek, Antoine Leca, Werner Lemberg, Tal Leming, Peter Lofting, Cosimo Lupo, Masaya Nakamura, Dave Opstad, Laurence Penney, Roozbeh Pournader, Garret Rieger, Read Roberts, Guido van Rossum, Just van Rossum, Andreas Seidel, Georg Seifert, Miguel Sousa, Adam Twardoch, Adrien Tétar, Vitaly Volkov, Paul Wise.

Copyrights

See LICENSE for the full license.

Have fun!

typoman/fonttools