ReMutateSupportGlyphs.py

#menuTitle: ReMutate Support Layer

import ufoProcessor
import mojo.UI
import pathlib

# ----------------------------------------


def get_sources_paths(designspace):
    path = pathlib.Path(designspace.path)
    root = path.parent
    return [root / source.path for source in designspace.sources]


def get_support_layer_names(designspace):
    return [source.layerName for source in designspace.sources if source.layerName]


def get_sources_by_support_layer_name(designspace, support_layer_name):
    for source in designspace.sources:
        if source.layerName == support_layer_name:
            return source

# ----------------------------------------


designSpacePath = mojo.UI.GetFile(message="Select your design space", fileTypes=("designspace",))
f = CurrentFont()
g = CurrentGlyph()

designspace = ufoProcessor.DesignSpaceProcessor(ufoVersion=3)
designspace.roundGeometry = True
designspace.useVarlib = True
designspace.read(designSpacePath)
designspace.loadFonts()
designspace.findDefault()

# check that the design space is relevant to the current font
font_path = pathlib.Path(f.path)
sources_path = get_sources_paths(designspace)
assert font_path in sources_path, f"Oups, This designspace does not features the ufo {font_path.name}"

# check that the design space is relevant to the current layer
support_layer_name = g.layer.name
support_layers = get_support_layer_names(designspace)
assert g.layer.name in support_layers, f"Oups, This designspace does not features the support layer {support_layer_name}"

print(f"Mutating support layer {support_layer_name} for {g.name}")

# mute the support layer as a source,
# we dont want it to influence itself
support_source = get_sources_by_support_layer_name(designspace, support_layer_name)
support_source.mutedGlyphNames = f.keys()

glyph_mutator = designspace.getGlyphMutator(g.name)
mutated_glyph = glyph_mutator.makeInstance(support_source.location)

g.prepareUndo("ReMutate Support Layer")
g.clear()
mutated_glyph.drawPoints(g.getPointPen())
g.width = mutated_glyph.width
g.performUndo()

Note: anchors are not supported right now, for some reasons…