ufo2ft ("UFO to FontTools") is a fork of ufo2fdk whose goal is to generate OpenType font binaries from UFOs without the FDK dependency.
The library provides two functions, compileOTF and compileTTF,
which work exactly the same way:
from defcon import Font
from ufo2ft import compileOTF
ufo = Font('MyFont-Regular.ufo')
otf = compileOTF(ufo)
otf.save('MyFont-Regular.otf')In most cases, the behavior of ufo2ft should match that of ufo2fdk, whose documentation is retained further below (and hopefully is still accurate).
ufo2ft by default tries to do little more than what the UFO specification
demands. Popular font design applications that came after the specification was
made and specific workflows however may demand more. ufo2ft obeys certain keys
in a UFO's "lib", i.e. key-value pairs in the UFO's lib.plist file.
Filters can modify glyphs before ("pre" = True) or after ("pre" = False) decomposition of composite glyphs. The default is running filters after decomposition ("pre" = False).
You would insert the following into a UFO's lib.plist:
<key>com.github.googlei18n.ufo2ft.filters</key>
<array>
<dict>
<key>name</key>
<string>propagateAnchors</key>
<key>pre</key>
<true />
<!-- Optionally, specify a list of glyphs to in- or exclude for
this filter (the default is to include all glyphs). "include"
and "exclude" are mutually exclusive. -->
<key>include</key>
<array>
<string>a</string>
<string>b</string>
</array>
</dict>
</array>Or in code:
from defcon import Font
from ufo2ft import compileOTF
ufo = Font("MyFont-Regular.ufo")
ufo.lib["com.github.googlei18n.ufo2ft.filters"] = [
{"name": "propagateAnchors", "pre": True, "include": ["a", "b"]}
]
otf = compileOTF(ufo)
otf.save("MyFont-Regular.otf")Using code allows you to define an inclusion function (not available for exclusion), like so:
from defcon import Font
from ufo2ft import compileOTF
def my_filter_function(glyph):
"""Include all glyphs with a Unicode value between U+007F and U+00FF."""
if glyph.unicode:
return 0x007F < glyph.unicode < 0x00FF
return False
ufo = Font("MyFont-Regular.ufo")
ufo.lib["com.github.googlei18n.ufo2ft.filters"] = [
{"name": "propagateAnchors", "pre": True, "include": my_filter_function}
]
otf = compileOTF(ufo)
otf.save("MyFont-Regular.otf")Converts outlines from cubic (PostScript flavor) to quadratic (TrueType flavor).
It is run by default when producing TrueType-flavored OpenType fonts. Honors the
UFO's com.github.googlei18n.cu2qu.curve_type lib key.
<key>com.github.googlei18n.ufo2ft.filters</key>
<array>
<dict>
<key>name</key>
<string>cubicToQuadratic</key>
<!-- Optionally, the filter can save the result of the conversion
to the UFO's lib key "com.github.googlei18n.cu2qu.curve_type",
which can be either "cubic" or "quadratic". Turn this off if
you want to run the filter multiple times. You can also
manually set the lib key to "quadratic" if your font is made
using quadratic curves, which saves you further explicit
configuration. -->
<key>rememberCurveType</key>
<true /> <!-- The default. -->
<!-- The conversion process is necessarily an approximation. Set
the acceptable error here, expressed in the maximum distance
between the original and converted curve, and it's relative
to the UPM of the font (default: 1/1000 or 0.001) -->
<key>conversionError</key>
<real>0.001</real> <!-- The default. -->
<!-- Cubic (PostScript flavored) curves are typically oriented
counter-clockwise, quadratic (TrueType flavored) curves are
typically oriented clockwise. Reversing the direction is
recommended. -->
<key>reverseDirection</key>
<true /> <!-- The default. -->
</dict>
</array>When to modify the filter settings:
- You want fine-grained control over the conversion error.
- Your font is or some glyphs are drawn using quadratic curves and you want to prevent contour direction reversal.
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As with any OpenType compiler, you have to set the font naming data to a particular standard for your naming to be set correctly. In ufo2fdk, you can get away with setting two naming attributes in your font.info object for simple fonts:
- familyName: The name for your family. For example, "My Garamond".
- styleName: The style name for this particular font. For example, "Display Light Italic"
ufo2fdk will create all of the other naming data based on thse two
fields. If you want to use the fully automatic naming system, all of the
other name attributes should be set to None in your font. However,
if you want to override the automated system at any level, you can
specify particular naming attributes and ufo2fdk will honor your
settings. You don't have to set all of the attributes, just the ones
you don't want to be automated. For example, in the family "My Garamond"
you have eight weights. It would be nice to style map the italics to the
romans for each weight. To do this, in the individual romans and
italics, you need to set the style mapping data. This is done through
the styleMapFamilyName and styleMapStyleName attributes. In each
of your roman and italic pairs you would do this:
My Garamond-Light.ufo
- familyName = "My Garamond"
- styleName = "Light"
- styleMapFamilyName = "My Garamond Display Light"
- styleMapStyleName = "regular"
My Garamond-Light Italic.ufo
- familyName = "My Garamond"
- styleName = "Display Light Italic"
- styleMapFamilyName = "My Garamond Display Light"
- styleMapStyleName = "italic"
My Garamond-Book.ufo
- familyName = "My Garamond"
- styleName = "Book"
- styleMapFamilyName = "My Garamond Display Book"
- styleMapStyleName = "regular"
My Garamond-Book Italic.ufo
- familyName = "My Garamond"
- styleName = "Display Book Italic"
- styleMapFamilyName = "My Garamond Display Book"
- styleMapStyleName = "italic"
etc.
Additionally, if you have defined any naming data, or any data for that matter, in table definitions within your font's features that data will be honored.
If your font's features do not contain kerning/mark/mkmk features, ufo2ft will create them based on your font's kerning/anchor data.
In addition to
Adobe OpenType feature files,
ufo2ft also supports the
MTI/Monotype format.
For example, a GPOS table in this format would be stored within the UFO at
data/com.github.googlei18n.ufo2ft.mtiFeatures/GPOS.mti.
Most of the fallbacks have static values. To see what is set for these,
look at fontInfoData.py in the source code.
In some cases, the fallback values are dynamically generated from other data in the info object. These are handled internally with functions.
If the UFO data directory has a com.github.fonttools.ttx folder with TTX
files ending with .ttx, these will be merged in the generated font.
The index TTX (generated when using using ttx -s) is not required.
ufo2ft supports building COLR and CPAL tables.
If there is com.github.googlei18n.ufo2ft.colorPalettes key in font lib, and
com.github.googlei18n.ufo2ft.colorLayerMapping key in the font or
in any of the glyphs lib, then ufo2ft will build CPAL table from the color
palettes, and COLR table from the color layers.
colorPalettes is a array of palettes, each palette is a array of colors and
each color is a array of floats representing RGBA colors. For example:
<key>com.github.googlei18n.ufo2ft.colorPalettes</key>
<array>
<array>
<array>
<real>0.26</real>
<real>0.0</real>
<real>0.23</real>
<real>1.0</real>
</array>
<array>
<real>0.86</real>
<real>0.73</real>
<real>0.28</real>
<real>1.0</real>
</array>
</array>
</array>colorLayerMapping is a array of color layers, each color layer is a array of
layer name and palette color index. It is a per-glyph key, but if present in
the font lib then it will be used for all glyphs that lack it. For example:
<key>com.github.googlei18n.ufo2ft.colorLayerMapping</key>
<array>
<array>
<string>color.1</string>
<integer>1</integer>
</array>
<array>
<string>color.2</string>
<integer>0</integer>
</array>
</array>With these this key present, ufo2ft will copy the color layers into individual
glyphs and setup COLR table.
Alternatively, if the color layers are already separate UFO glyphs, the
com.github.googlei18n.ufo2ft.colorLayers font lib key can be used. It uses
a table keyed by base glyph, and the value is an array of color layers, each
color layer is an array of glyph name and palette color index. For example:
<key>com.github.googlei18n.ufo2ft.colorLayers</key>
<dict>
<key>alef-ar</key>
<array>
<array>
<string>alef-ar.color0</string>
<integer>2</integer>
</array>
</array>
<key>alefHamzaabove-ar</key>
<array>
<array>
<string>alefHamzaabove-ar.color0</string>
<integer>1</integer>
</array>
<array>
<string>alefHamzaabove-ar.color1</string>
<integer>2</integer>
</array>
</array>
<dict>If you are installing ufo2ft from source, note that the strict dependency versions in requirements.txt are for testing, see setup.py's install_requires and extras_requires for more relaxed dependency requirements.