fontforge-variable-font 0.2.0

A FontForge_plugin to create a variable font

Fontforge Variable Font Plugin

A FontForge_plugin to create a variable font

As of October 2025, Fontforge supports legacy (maybe obsolete) multiple master formats but not yet OpenType variable fonts. This plugin adds frontend of fontmake and fonttools so that variable fonts can be created through Fontforge interface.

This module can also export to WOFF2; in this case the woff2 tool will be used as backend.

This module requires Python 3.10 or later.

Install

pip3 install fontforge-variable-font

Make sure Fontforge Python module is usable

In interactive mode of Python, run:

import fontforge

If it raises ModuleNotFoundError exception, install Fontforge first. If installed, make sure the build option set that the Python module gets also installed. If already so, Python interpreter does not recognize the module path where the required module.

export PYTHONPATH=/path/to/fontforge/python/module:$PYTHONPATH

Usage

Interactive usage

As a Fontforge plugin, fontforgeVF adds 'Variable Font' submenu to 'Tools' menu which is dedicated for plugins.

• Variable Font
  • Open a variable font
    • By named instance...
    • By parameter...
  • Generate a variable font...
  • Design axes...
  • Named instances...
  • Delete VF info

[!IMPORTANT] Since the plugin feature has been hardly (maybe never) used (hence it can be tested not well,) Fontforge may crash especially after a dialog is shown. You are advised to back up your font project before use.

Open a variable font

Shows a dialog to open a variable font

[!TIP] If you open a webfont (WOFF2,) the plugin will first copy it to a temporary directory, then decompress with calling woff2_decompress in order to open as a TTF.

[!TIP] VF-specific metadata will be loaded to font.persistent. Minimum, default, and maximum values of axis values are also loaded in font.persistent['VF'], but are not used when re-exporting.

By named instance

Open file dialog is shown first. If a variable font is selected, then another dialog is shown to select (one or more) named instances. If a non-variable font is selected, simply opens that font.

[!NOTE] If an empty list gets shown, the font does not have any named instances. Use 'By parameter' in such case.

By parameter

Like above, but the second dialog is not to select a named instance, but to specify design axis parameters.

[!TIP] Valid range will be shown together with the name for each axis.

Generate a variable font

Shows a dialog where you can set output file name and other options.

In order to build a variable font, SFD must be converted into UFO and create a designspace document. This plugin will do this first, and then required modification. The required files will be created in a temporary directory, and deleted after everything is done. So users won't see intermediate files.

Fontforge may export with postscriptIsFixedPitch flag clear when it should be set. The plugin checks if monospaced font is intended and fix the flag. Unlike Fontforge itself, only U+0020 to U+007E will be checked their width, because combining marks may have zero width even for monospaced fonts.

In a feature file, 'aalt' feature is specially treated. Fontforge may export incompatible 'aalt' feature (concretely 'script' or 'language' instructions must not be included unlike other features.) This function fix this first.

[!TIP] You do not have to add 'aalt' lookups manually. You can still do it for 'aalt'-only glyph substitutions.

Currently available options:

• Remove nested refs: Tell fontmake to decompose nested references into simple ones. Nested references are known to cause problems in certain environments.
• Add 'aalt' feature: Calculate and output 'aalt' feature to UFO.

[!TIP] To generate web font (instead of TTF), specify output file name ending with '.woff2'; in this case the plugin calls woff2_compress after generating TTF.

[!IMPORTANT] If the font family has both roman (non-italic) and italic styles, you have to specify 2 output files. This is because roman and italic files are usually incompatible since they are designed separately.

[!IMPORTANT] You need all masters open before you use this menu item. Also, make sure the family name is consistent among the masters, or such masters will be ignored.

[!NOTE] This item will not be active if active font does not have VF data.

Design axes

Shows a dialog where you can set design axes.

[!NOTE] If there is already non-dict value in font.persistent, warns that that data will be lost.

This master

This section is needed for all masters.

For active font as one of VF masters, sets position in each design axis of VF master. Leave unset for unused axes. Registered axes can use default values which refers font properties.

• Italic: default value is whether font.italicangle is negative. This axis is boolean: you choose the master is for italic or not. Seldom used together with slant axis.
• Optical size: can default to font.design_size. Set in points. Must be positive.
• Slant: can default to font.italicangle. 0 if upright, negative if oblique. This value is hardly positive (left-slanted.)
• Width: can default using font.os2_width. 100 if normal width, less if condensed, greater if expanded. Must be positive.
• Weight: can default to font.os2_weight. 400 if regular weight, 700 if bold. The minimum is 1 (hairline thin) and the maximum is 999 (extreme bold.)
• Custom axes: there is a room for 3 user-defined axes. No default values.

[!TIP] You can find an example of custom axes at Google Fonts site, and they are explained at the glossary.

[!NOTE] 'Italic' axis is exceptionally treated. Unlike other axes, it cannot be interpolated (anything like "semi-italic" will never be available.) Roman and italic styles will be exported separately, hence you do not have to match numbers of points or of contours between them.

[!IMPORTANT] Custom axes will not be treated like italic axis. If you want custom discrete axes, you must open only those masters which have the same positions on such axes at once. For example, wonky axis allows only 0 (off) or 1 (on;) you must open masters with WONK=0 and generate WONK=0 VF first, close all masters and then open WONK=1 masters and generate VF.

Custom axes

This section is needed for default master (choose one master as default.)

Sets the tag for each custom axis. A tag must be up to 4-letter alphanumeric. No known axis tags use less than 4 letters; if it happens, pad with trailing space. Leave them blank if not used.

[!NOTE] You must set a tag before a custom axis can be used.

[!NOTE] Axis tags with less than 4 letters are not tested.

[!CAUTION] Do not set tags which is duplicate or same as predefined ones, or undefined behavior occurs.

Axis order

This section is needed for default master (choose one master as default.)

Sets the order of design axes.

Axis map

This section is needed for default master (choose one master as default.)

Maps user position to design position.

Input must be comma-separated values and even number of elements. Each pair consists of user and design positions in this order.

Axis name

This section is needed for default master (choose one master as default.)

Names the design axes. For predefined axes can use default name. Custom axes must be named if used.

• Axis name: name of axis itself.
• Labels: comma-separated list which consists of multiple of 4 of elements. Leading and trailing spaces will be trimmed. Every group of 4 elements:
  • Axis value
  • Flags
    • 0: Neither
    • 1: OLDER_SIBLING_FONT_ATTRIBUTE
    • 2: ELIDABLE_AXIS_VALUE_NAME
    • 3: Both
  • Linked value if exist
  • Name

Localized names

This section is needed for default master (choose one master as default.)

Design axes can have translated names. Each page for each language. Set language code before you use. Choose a language from the list.

By default there is a room for 8 languages, but this will be extended if already more than 4 languages are defined.

• Axis name: name of axis itself.
• Labels: comma-separated list which consists of even number of elements. Leading and trailing spaces will be trimmed. Every pair of elements:
  • Axis value
  • Name

[!CAUTION] Do not select the same language more than once, or undefined behavior will occur.

Instance list

Shows a dialog where you can set named instances. Instance list is needed for default master (choose one master as default.)

[!NOTE] If there is already non-dict value in font.persistent, warns that that data will be lost.

Instance

At these pages you can set PostScript name, subfamily name, and associated design positions on each axis.

By default the pages are named 'Instance 1' and so on, but will be same as subfamily name if already set.

By default there is a room for 8 instances, but this will be extended if already more than 4 instances are defined.

Localized names

Instances can have translated names. Each page (or group or pages) for each language. Choose a language from the list first. If there are already 13 instances or more, multiple pages for each language.

By default there is a room for 8 languages, but this will be extended if already more than 4 languages are defined.

[!CAUTION] Do not select the same language more than once, or undefined behavior will occur.

Delete VF info

Deletes VF data.

[!WARNING] You will see no warning.

Script usage

As a Python module, in addition to fontforge module, scripting to export variable fonts from SFD projects will be possible.

import fontforge
import fontforgeVF

# Open all masters
fontCL = fontforge.open('MyFont-UltraCondensed-ExtraLight.sfd')
fontCB = fontforge.open('MyFont-UltraCondensed-ExtraBold.sfd')
fontXL = fontforge.open('MyFont-UltraExpanded-ExtraLight.sfd')
fontXB = fontforge.open('MyFont-UltraExpanded-ExtraBold.sfd')

# Open an instance from an existing variable font
font1 = fontforgeVF.openVariableFont('MyFont[wdth,wght].ttf', {'wdth': 100, 'wght': 400})  # by parameters
font2 = fontforgeVF.openVariableFont('MyFont[wdth,wght].ttf', 'Regular')  # named instance
font3 = fontforgeVF.openVariableFont('MyFont[wdth,wght].ttf', 2)  # list index (instances are listed in 'fvar' table)

# Set VF-specific metadata
fontforgeVF.initPersistentDict(fontCL)
fontforgeVF.setVFValue(fontCL, "axes.wght.active", True)
fontforgeVF.setVFValue(fontCL, "axes.wght.useDefault", False)
fontforgeVF.setVFValue(fontCL, "axes.wght.value", 200)
fontforgeVF.setVFValue(fontCL, "axes.wdth.active", True)
fontforgeVF.setVFValue(fontCL, "axes.wdth.useDefault", False)
fontforgeVF.setVFValue(fontCL, "axes.wdth.value", 50)
fontforgeVF.setVFValue(fontCL, "axes.ital.active", True)
fontforgeVF.setVFValue(fontCL, "axes.ital.useDefault", False)
fontforgeVF.setVFValue(fontCL, "axes.ital.value", False)

fontforgeVF.initPersistentDict(fontCB)
fontforgeVF.setVFValue(fontCB, "axes.wght.active", True)
fontforgeVF.setVFValue(fontCB, "axes.wght.useDefault", True)
fontforgeVF.setVFValue(fontCB, "axes.wdth.active", True)
fontforgeVF.setVFValue(fontCB, "axes.wdth.useDefault", True)
fontforgeVF.setVFValue(fontCB, "axes.ital.active", True)
fontforgeVF.setVFValue(fontCB, "axes.ital.useDefault", True)

fontforgeVF.initPersistentDict(fontXL)
fontforgeVF.setVFValue(fontXL, "axes.wght.active", True)
fontforgeVF.setVFValue(fontXL, "axes.wght.useDefault", True)
fontforgeVF.setVFValue(fontXL, "axes.wdth.active", True)
fontforgeVF.setVFValue(fontXL, "axes.wdth.useDefault", True)
fontforgeVF.setVFValue(fontXL, "axes.ital.active", True)
fontforgeVF.setVFValue(fontXL, "axes.ital.useDefault", True)

fontforgeVF.initPersistentDict(fontXB)
fontforgeVF.setVFValue(fontXB, "axes.wght.active", True)
fontforgeVF.setVFValue(fontXB, "axes.wght.useDefault", False)
fontforgeVF.setVFValue(fontXB, "axes.wght.value", 800)
fontforgeVF.setVFValue(fontXB, "axes.wdth.active", True)
fontforgeVF.setVFValue(fontXB, "axes.wdth.useDefault", False)
fontforgeVF.setVFValue(fontXB, "axes.wdth.value", 200)
fontforgeVF.setVFValue(fontXB, "axes.ital.active", True)
fontforgeVF.setVFValue(fontXB, "axes.ital.useDefault", False)
fontforgeVF.setVFValue(fontXB, "axes.ital.value", False)

# Font-family-wide metadata
# Here assume fontCL as the default font
fontforgeVF.setVFValue(fontCL, "axes.wght.name", "Weight")
fontforgeVF.setVFValue(fontCL, "axes.wght.order", 1)
fontforgeVF.setVFValue(fontCL, "axes.wght.localNames.0x407", "Strichstärke")
fontforgeVF.setVFValue(fontCL, "axes.wdth.map", [(200, 200), (400, 350), (800, 800)])
fontforgeVF.setVFValue(fontCL, "axes.wdth.name", "Width")
fontforgeVF.setVFValue(fontCL, "axes.wdth.order", 0)
fontforgeVF.setVFValue(fontCL, "axes.wdth.map[0]", (50, 50))
fontforgeVF.setVFValue(fontCL, "axes.wdth.map[1]", (200, 200))
fontforgeVF.setVFValue(fontCL, "axes.wdth.localNames.0x407", "Laufweite")  # 0x407 stands for German (Germany)
fontforgeVF.setVFValue(fontCL, "axes.ital.name", "Italic")
fontforgeVF.setVFValue(fontCL, "axes.ital.order", 2)
fontforgeVF.setVFValue(fontCL, "axes.ital.localNames.0x407", "Kursiv")

fontforgeVF.setVFValue(fontCL, "axes.wght.labels.200.name", "Extra Light")
fontforgeVF.setVFValue(fontCL, "axes.wght.labels.300.name", "Light")
fontforgeVF.setVFValue(fontCL, "axes.wght.labels.400.name", "Regular")
fontforgeVF.setVFValue(fontCL, "axes.wght.labels.400.olderSibling", False)
fontforgeVF.setVFValue(fontCL, "axes.wght.labels.400.elidable", True)
fontforgeVF.setVFValue(fontCL, "axes.wght.labels.400.linkedValue", 700)
fontforgeVF.setVFValue(fontCL, "axes.wght.labels.500.name", "Medium")
fontforgeVF.setVFValue(fontCL, "axes.wght.labels.600.name", "Semibold")
fontforgeVF.setVFValue(fontCL, "axes.wght.labels.700.name", "Bold")
fontforgeVF.setVFValue(fontCL, "axes.wght.labels.800.name", "Extra Bold")

fontforgeVF.setVFValue(fontCL, "axes.wght.labels.200.localNames.0x407", "Extramager")
fontforgeVF.setVFValue(fontCL, "axes.wght.labels.300.localNames.0x407", "Mager")
fontforgeVF.setVFValue(fontCL, "axes.wght.labels.400.localNames.0x407", "Standard")
fontforgeVF.setVFValue(fontCL, "axes.wght.labels.500.localNames.0x407", "Mittel")
fontforgeVF.setVFValue(fontCL, "axes.wght.labels.600.localNames.0x407", "Halbfett")
fontforgeVF.setVFValue(fontCL, "axes.wght.labels.700.localNames.0x407", "Fett")
fontforgeVF.setVFValue(fontCL, "axes.wght.labels.800.localNames.0x407", "Extrafett")

# User-defined axes (custom1 to custom3)
fontforgeVF.setVFValue(fontCL, "axes.custom1.active", True)
fontforgeVF.setVFValue(fontCL, "axes.custom1.value", 15)
fontforgeVF.setVFValue(fontCL, "axes.custom1.tag", "abc")  # needed for custom axes; will be padded with space
fontforgeVF.setVFValue(fontCL, "axes.custom1.name", "User-defined axis")
fontforgeVF.setVFValue(fontCL, "axes.custom1.order", 3)
fontforgeVF.setVFValue(fontCL, "axes.custom1.localNames.0x407", "Benutzerdefinierte Achse")

# Instances
fontforgeVF.setVFValue(fontCL, "instances[0].psName", "MyFont-ExtraLight")
fontforgeVF.setVFValue(fontCL, "instances[0].name", "ExtraLight")
fontforgeVF.setVFValue(fontCL, "instances[0].wght", 200)
fontforgeVF.setVFValue(fontCL, "instances[0].wdth", 100)
fontforgeVF.setVFValue(fontCL, "instances[0].ital", False)
fontforgeVF.setVFValue(fontCL, "instances[0].localNames.0x407", "Extramager")

# Export TTF
fontforgeVF.export(fontCL, 'MyFont.ttf')
fontforgeVF.export(fontCL, 'MyFont.ttf', 'MyFont-Italic.ttf')  # if ``ital`` axis enabled
fontforgeVF.export(fontCL, 'MyFont.ttf',
                   decomposeNestedRefs=True,
                   decomposeTransformedRefs=True,
                   addAalt=True)  # these options default to False

# Export Webfont
fontforgeVF.export(fontCL, 'MyFont.woff2')

# In case you want to drop the VF info
fontforgeVF.deleteVFInfo(fontCL)

Some example of language codes

Code	Language
0x401	Arabic (Saudi Arabia)
0xc01	Arabic (Egypt)
0x403	Catalan
0x404	Chinese (Taiwan)
0x804	Chinese (Mainland)
0xc04	Chinese (Hong Kong)
0x407	German (Germany)
0x807	German (Switzerland)
0x408	Greek
0x409	English (US) (default)
0x809	English (UK)
0xc09	English (Australia)
0x1009	English (Canada)
0x1409	English (New Zealand)
0x80a	Spanish (Mexico)
0xc0a	Spanish (Spain, modern sort)
0x40c	French (France)
0x80c	French (Belgium)
0xc0c	French (Canada)
0x100c	French (Switzerland)
0x40d	Hebrew
0x410	Italian (Italy)
0x810	Italian (Switzerland)
0x411	Japanese
0x412	Korean
0x413	Dutch
0x813	Flemish
0x416	Portuguese (Brazil)
0x816	Portuguese (Portugal)
0x417	Romansh
0x419	Russian
0x420	Urdu
0x439	Hindi

[!NOTE] Language code 0x409 (American English) is used as default and specially treated. You do not have to use it for localName.