Scripting a designspace

It can be useful to build a designspace with a script rather than construct one with an interface like Superpolator or DesignSpaceEditor. But the designSpaceDocument also offers a method of building designspaces in Python. This document offers some examples on how to do that.

So, suppose you installed the designSpaceDocument package through your favorite git client.

The DesignSpaceDocument object represents the document, whether it already exists or not. Make a new one:

import os
from designSpaceDocument import DesignSpaceDocument, AxisDescriptor, SourceDescriptor, InstanceDescriptor
doc = DesignSpaceDocument()

We want to create definitions for axes, sources and instances. That means a lot of attributes to set, so the DesignSpaceDocument object uses objects to descibe the axes, sources and instances. These are relatively simple objects, just a collection of attributes.

Source descriptor attributes and example.
Instance descriptor attributes and example.
Axis descriptor attributes and example.
Read about subclassing descriptors

Making some axes

Make a descriptor object and add it to the document.

a1 = AxisDescriptor()
a1.initial = 0
a1.maximum = 1000
a1.minimum = 0
a1.default = 0
a1.name = "weight"
a1.tag = "wght"
doc.addAxis(a1)

You can add as many axes as you need. OpenType has a maximum of around 64K. DesignSpaceEditor has a maximum of 5.

Make a source object

A source is an object that points to a UFO file. It provides the outline geometry, kerning and font.info that we want to work with.

s0 = SourceDescriptor()
s0.path = "my/path/to/thin.ufo"
s0.name = "master.thin"
s0.location = dict(weight=0)
doc.addSource(s0)

You'll need to have at least 2 sources in your document, so go ahead and add another one.
The location attribute is a dictionary with the designspace location for this master.
The axis names in the location have to match one of the axis.name values you defined before.
The path attribute is the absolute path to an existing UFO.

So go ahead and add another master:

s1 = SourceDescriptor()
s1.path = "my/path/to/bold.ufo"
s1.name = "master.bold"
s1.location = dict(weight=1000)
doc.addSource(s1)

Make an instance object

An instance is description of a UFO that you want to generate with the designspace. For an instance you can define more things. If you want to generate UFO instances with MutatorMath then you can define different names and set flags for if you want to generate kerning and font info and so on. You can also set a path where to generate the instance.

i0 = InstanceDescriptor()
i0.familyName = "MyVariableFontPrototype"
i0.styleName = "Medium"
i0.postScriptFontName = "MyVariableFontPrototype-Medium"
i0.path = os.path.join(root, "instances","MyVariableFontPrototype-Medium.ufo")
i0.location = dict(weight=500)
i0.kerning = True
i0.info = True
doc.addInstance(i0)

The path attribute needs to be the absolute (real or intended) path for the instance. When the document is saved this path will written as relative to the path of the document.
instance paths should be on the same level as the document, or in a level below.

Saving

path = "myprototype.designspace"
doc.write(path)

Generating?

You can generate the UFO's with MutatorMath:

from mutatorMath.ufo import build
build("whatevs/myprototype.designspace")

Assuming the outline data in the masters is compatible.

Or you can use the file in making a variable font with varlib.

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