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from fontTools.pens.areaPen import AreaPen | ||
from fontTools.varLib.models import piecewiseLinearMap | ||
from fontTools.misc.cliTools import makeOutputFileName | ||
from math import exp, log | ||
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WEIGHTS = [100, 200, 300, 400, 500, 600, 700, 800, 900] | ||
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SAMPLES = 8 | ||
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def getGlyphsetWeight(glyphset): | ||
wght_sum = wdth_sum = 0 | ||
for glyph_name in glyphset: | ||
glyph = glyphset[glyph_name] | ||
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pen = AreaPen(glyphset=glyphset) | ||
glyph.draw(pen) | ||
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wght_sum += abs(pen.value) | ||
wdth_sum += glyph.width | ||
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return wght_sum / wdth_sum | ||
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def planWeightAxis(font, minValue, defaultValue, maxValue, weights=WEIGHTS): | ||
print("Weight min/default/max:", minValue, defaultValue, maxValue) | ||
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out = {} | ||
outNormalized = {} | ||
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upem = font["head"].unitsPerEm | ||
axisWeightAverage = {} | ||
for weight in sorted({minValue, defaultValue, maxValue}): | ||
glyphset = font.getGlyphSet(location={"wght": weight}) | ||
axisWeightAverage[weight] = getGlyphsetWeight(glyphset) / upem | ||
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print("Calculated average glyph black ratio:", axisWeightAverage) | ||
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outNormalized[-1] = -1 | ||
for extremeValue in sorted({minValue, maxValue} - {defaultValue}): | ||
rangeMin = min(defaultValue, extremeValue) | ||
rangeMax = max(defaultValue, extremeValue) | ||
targetWeights = {w for w in weights if rangeMin < w < rangeMax} | ||
if not targetWeights: | ||
continue | ||
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bias = -1 if extremeValue < defaultValue else 0 | ||
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print("Planning target weights", targetWeights) | ||
print("Sampling", SAMPLES, "points in range", rangeMin, rangeMax) | ||
weightBlackRatio = axisWeightAverage.copy() | ||
for sample in range(1, SAMPLES + 1): | ||
weight = rangeMin + (rangeMax - rangeMin) * sample / (SAMPLES + 1) | ||
print("Sampling weight", weight) | ||
glyphset = font.getGlyphSet(location={"wght": weight}) | ||
weightBlackRatio[weight] = getGlyphsetWeight(glyphset) / upem | ||
print("Sampled average glyph black ratio:", weightBlackRatio) | ||
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blackRatioWeight = {} | ||
for weight in sorted(weightBlackRatio): | ||
blackRatioWeight[weightBlackRatio[weight]] = weight | ||
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logMin = log(weightBlackRatio[rangeMin]) | ||
logMax = log(weightBlackRatio[rangeMax]) | ||
out[rangeMin] = rangeMin | ||
outNormalized[bias] = bias | ||
for weight in sorted(targetWeights): | ||
t = (weight - rangeMin) / (rangeMax - rangeMin) | ||
targetBlackRatio = exp(logMin + t * (logMax - logMin)) | ||
targetWeight = piecewiseLinearMap(targetBlackRatio, blackRatioWeight) | ||
print("Planned mapping weight %g to %g" % (weight, targetWeight)) | ||
out[weight] = targetWeight | ||
outNormalized[t + bias] = (targetWeight - rangeMin) / ( | ||
rangeMax - rangeMin | ||
) + bias | ||
out[rangeMax] = rangeMax | ||
outNormalized[bias + 1] = bias + 1 | ||
outNormalized[+1] = +1 | ||
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print("Planned mapping:", out) | ||
print("Planned normalized mapping:", outNormalized) | ||
return out, outNormalized | ||
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def main(args=None): | ||
if args is None: | ||
import sys | ||
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args = sys.argv[1:] | ||
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from fontTools.ttLib import TTFont | ||
import argparse | ||
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parser = argparse.ArgumentParser( | ||
"fonttools varLib.avarPlanner", | ||
description="Plan `avar` table for variable font", | ||
) | ||
parser.add_argument("font", metavar="font.ttf", help="Font file.") | ||
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options = parser.parse_args(args) | ||
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font = TTFont(options.font) | ||
fvar = font["fvar"] | ||
wghtAxis = slntAxis = None | ||
for axis in fvar.axes: | ||
if axis.axisTag == "wght": | ||
wghtAxis = axis | ||
elif axis.axisTag == "slnt": | ||
slntAxis = axis | ||
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_, mapping = planWeightAxis( | ||
font, wghtAxis.minValue, wghtAxis.defaultValue, wghtAxis.maxValue | ||
) | ||
if "avar" in font: | ||
print("Existing weight mapping:", font["avar"].segments["wght"]) | ||
else: | ||
font["avar"] = newTable("avar") | ||
avar = font["avar"] | ||
avar.segments["wght"] = mapping | ||
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outfile = makeOutputFileName(options.font, overWrite=True, suffix=".avar") | ||
font.save(outfile) | ||
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if __name__ == "__main__": | ||
import sys | ||
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sys.exit(main()) |