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Python

from fontTools.varLib.models import VariationModel
from fontTools.varLib.varStore import VarStoreInstancer
from fontTools.misc.fixedTools import fixedToFloat as fi2fl
from itertools import product
import sys
def _denormalize(v, axis):
if v >= 0:
return axis.defaultValue + v * (axis.maxValue - axis.defaultValue)
else:
return axis.defaultValue + v * (axis.defaultValue - axis.minValue)
def _pruneLocations(locations, poles, axisTags):
# Now we have all the input locations, find which ones are
# not needed and remove them.
# Note: This algorithm is heavily tied to how VariationModel
# is implemented. It assumes that input was extracted from
# VariationModel-generated object, like an ItemVariationStore
# created by fontmake using varLib.models.VariationModel.
# Some CoPilot blabbering:
# I *think* I can prove that this algorithm is correct, but
# I'm not 100% sure. It's possible that there are edge cases
# where this algorithm will fail. I'm not sure how to prove
# that it's correct, but I'm also not sure how to prove that
# it's incorrect. I'm not sure how to write a test case that
# would prove that it's incorrect. I'm not sure how to write
# a test case that would prove that it's correct.
model = VariationModel(locations, axisTags)
modelMapping = model.mapping
modelSupports = model.supports
pins = {tuple(k.items()): None for k in poles}
for location in poles:
i = locations.index(location)
i = modelMapping[i]
support = modelSupports[i]
supportAxes = set(support.keys())
for axisTag, (minV, _, maxV) in support.items():
for v in (minV, maxV):
if v in (-1, 0, 1):
continue
for pin in pins.keys():
pinLocation = dict(pin)
pinAxes = set(pinLocation.keys())
if pinAxes != supportAxes:
continue
if axisTag not in pinAxes:
continue
if pinLocation[axisTag] == v:
break
else:
# No pin found. Go through the previous masters
# and find a suitable pin. Going backwards is
# better because it can find a pin that is close
# to the pole in more dimensions, and reducing
# the total number of pins needed.
for candidateIdx in range(i - 1, -1, -1):
candidate = modelSupports[candidateIdx]
candidateAxes = set(candidate.keys())
if candidateAxes != supportAxes:
continue
if axisTag not in candidateAxes:
continue
candidate = {
k: defaultV for k, (_, defaultV, _) in candidate.items()
}
if candidate[axisTag] == v:
pins[tuple(candidate.items())] = None
break
else:
assert False, "No pin found"
return [dict(t) for t in pins.keys()]
def mappings_from_avar(font, denormalize=True):
fvarAxes = font["fvar"].axes
axisMap = {a.axisTag: a for a in fvarAxes}
axisTags = [a.axisTag for a in fvarAxes]
axisIndexes = {a.axisTag: i for i, a in enumerate(fvarAxes)}
if "avar" not in font:
return {}, {}
avar = font["avar"]
axisMaps = {
tag: seg
for tag, seg in avar.segments.items()
if seg and seg != {-1: -1, 0: 0, 1: 1}
}
mappings = []
if getattr(avar, "majorVersion", 1) == 2:
varStore = avar.table.VarStore
regions = varStore.VarRegionList.Region
# Find all the input locations; this finds "poles", that are
# locations of the peaks, and "corners", that are locations
# of the corners of the regions. These two sets of locations
# together constitute inputLocations to consider.
poles = {(): None} # Just using it as an ordered set
inputLocations = set({()})
for varData in varStore.VarData:
regionIndices = varData.VarRegionIndex
for regionIndex in regionIndices:
peakLocation = []
corners = []
region = regions[regionIndex]
for axisIndex, axis in enumerate(region.VarRegionAxis):
if axis.PeakCoord == 0:
continue
axisTag = axisTags[axisIndex]
peakLocation.append((axisTag, axis.PeakCoord))
corner = []
if axis.StartCoord != 0:
corner.append((axisTag, axis.StartCoord))
if axis.EndCoord != 0:
corner.append((axisTag, axis.EndCoord))
corners.append(corner)
corners = set(product(*corners))
peakLocation = tuple(peakLocation)
poles[peakLocation] = None
inputLocations.add(peakLocation)
inputLocations.update(corners)
# Sort them by number of axes, then by axis order
inputLocations = [
dict(t)
for t in sorted(
inputLocations,
key=lambda t: (len(t), tuple(axisIndexes[tag] for tag, _ in t)),
)
]
poles = [dict(t) for t in poles.keys()]
inputLocations = _pruneLocations(inputLocations, list(poles), axisTags)
# Find the output locations, at input locations
varIdxMap = avar.table.VarIdxMap
instancer = VarStoreInstancer(varStore, fvarAxes)
for location in inputLocations:
instancer.setLocation(location)
outputLocation = {}
for axisIndex, axisTag in enumerate(axisTags):
varIdx = axisIndex
if varIdxMap is not None:
varIdx = varIdxMap[varIdx]
delta = instancer[varIdx]
if delta != 0:
v = location.get(axisTag, 0)
v = v + fi2fl(delta, 14)
# See https://github.com/fonttools/fonttools/pull/3598#issuecomment-2266082009
# v = max(-1, min(1, v))
outputLocation[axisTag] = v
mappings.append((location, outputLocation))
# Remove base master we added, if it maps to the default location
assert mappings[0][0] == {}
if mappings[0][1] == {}:
mappings.pop(0)
if denormalize:
for tag, seg in axisMaps.items():
if tag not in axisMap:
raise ValueError(f"Unknown axis tag {tag}")
denorm = lambda v: _denormalize(v, axisMap[tag])
axisMaps[tag] = {denorm(k): denorm(v) for k, v in seg.items()}
for i, (inputLoc, outputLoc) in enumerate(mappings):
inputLoc = {
tag: _denormalize(val, axisMap[tag]) for tag, val in inputLoc.items()
}
outputLoc = {
tag: _denormalize(val, axisMap[tag]) for tag, val in outputLoc.items()
}
mappings[i] = (inputLoc, outputLoc)
return axisMaps, mappings
def unbuild(font, f=sys.stdout):
fvar = font["fvar"]
axes = fvar.axes
segments, mappings = mappings_from_avar(font)
if "name" in font:
name = font["name"]
axisNames = {axis.axisTag: name.getDebugName(axis.axisNameID) for axis in axes}
else:
axisNames = {a.axisTag: a.axisTag for a in axes}
print("<?xml version='1.0' encoding='UTF-8'?>", file=f)
print('<designspace format="5.1">', file=f)
print(" <axes>", file=f)
for axis in axes:
axisName = axisNames[axis.axisTag]
triplet = (axis.minValue, axis.defaultValue, axis.maxValue)
triplet = [int(v) if v == int(v) else v for v in triplet]
axisMap = segments.get(axis.axisTag)
closing = "/>" if axisMap is None else ">"
print(
f' <axis tag="{axis.axisTag}" name="{axisName}" minimum="{triplet[0]}" maximum="{triplet[2]}" default="{triplet[1]}"{closing}',
file=f,
)
if axisMap is not None:
for k in sorted(axisMap.keys()):
v = axisMap[k]
k = int(k) if k == int(k) else k
v = int(v) if v == int(v) else v
print(f' <map input="{k}" output="{v}"/>', file=f)
print(" </axis>", file=f)
if mappings:
print(" <mappings>", file=f)
for inputLoc, outputLoc in mappings:
print(" <mapping>", file=f)
print(" <input>", file=f)
for tag in sorted(inputLoc.keys()):
v = inputLoc[tag]
v = int(v) if v == int(v) else v
print(
f' <dimension name="{axisNames[tag]}" xvalue="{v}"/>',
file=f,
)
print(" </input>", file=f)
print(" <output>", file=f)
for tag in sorted(outputLoc.keys()):
v = outputLoc[tag]
v = int(v) if v == int(v) else v
print(
f' <dimension name="{axisNames[tag]}" xvalue="{v}"/>',
file=f,
)
print(" </output>", file=f)
print(" </mapping>", file=f)
print(" </mappings>", file=f)
print(" </axes>", file=f)
print("</designspace>", file=f)
def main(args=None):
"""Print `avar` table as a designspace snippet."""
if args is None:
args = sys.argv[1:]
from fontTools.ttLib import TTFont
import argparse
parser = argparse.ArgumentParser(
"fonttools varLib.avar.unbuild",
description="Print `avar` table as a designspace snippet.",
)
parser.add_argument("font", metavar="varfont.ttf", help="Variable-font file.")
options = parser.parse_args(args)
font = TTFont(options.font)
if "fvar" not in font:
print("Not a variable font.", file=sys.stderr)
return 1
unbuild(font)
if __name__ == "__main__":
import sys
sys.exit(main())