make_designspace.py

from fontTools import designspaceLib
import os.path


# define axes names, tags and min/default/max
AXES = [
    dict(name="Weight", tag="wght", minimum=400, default=400, maximum=700),
    dict(name="Width", tag="wdth", minimum=50, default=100, maximum=100),
]

# assign each master a location in the designspace. Ensure that at least
# one master is at the default location along all the axes as defined above;
# this will be treated as the 'neutral' or default master.
# XXX Replace the font filenames with actual ones.
MASTERS_PATHS_AND_LOCATIONS = [
    ("MyFont-1.ttf", {"Weight": 400, "Width": 100}),  # this is the base master
    ("MyFont-2.ttf", {"Weight": 700, "Width": 100}),
    ("MyFont-3.ttf", {"Weight": 400, "Width": 50}),
    ("MyFont-4.ttf", {"Weight": 700, "Width": 50}),
]

# optionally, define the location and style name of named instances
NAMED_INSTANCES = [
    ("Regular", {"Weight": 400, "Width": 100}),
    # ("Medium", {"Weight": 500, "Width": 100}),
    # ("SemiBold", {"Weight": 600, "Width": 100}),
    # ("Bold", {"Weight": 700, "Width": 100}),
    # ("Condensed", {"Weight": 400, "Width": 75}),
    # ("Condensed Medium", {"Weight": 500, "Width": 75}),
    # ("Condensed SemiBold", {"Weight": 600, "Width": 75}),
    # ("Condensed Bold", {"Weight": 700, "Width": 75}),
    # ("UltraCondensed", {"Weight": 400, "Width": 50}),
    # ("UltraCondensed Medium", {"Weight": 500, "Width": 50}),
    # ("UltraCondensed SemiBold", {"Weight": 600, "Width": 50}),
    # ("UltraCondensed Bold", {"Weight": 700, "Width": 50}),
]


def build_designspace(axes, masters, instances=None):
    # create a new designspace document
    designspace = designspaceLib.DesignSpaceDocument()

    for axis_data in axes:
        designspace.addAxisDescriptor(**axis_data)

    for source_path, location in masters:
        # the source.name is an optional identifier only used for error messages
        source_name = os.path.basename(os.path.splitext(source_path)[0])
        designspace.addSourceDescriptor(
            name=source_name, location=location, path=source_path
        )

    if instances is not None:
        for style_name, location in instances:
            designspace.addInstanceDescriptor(styleName=style_name, location=location)

    return designspace


if __name__ == "__main__":
    import sys

    designspace = build_designspace(AXES, MASTERS_PATHS_AND_LOCATIONS, NAMED_INSTANCES)

    try:
        output_path = sys.argv[1]
    except IndexError:
        sys.exit(f"usage: {sys.argv[0]} MyFont.designspace")

    designspace.write(output_path)