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191 lines
6.9 KiB
Python
191 lines
6.9 KiB
Python
from fontTools.ttLib.tables import otTables as ot
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from copy import deepcopy
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import logging
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log = logging.getLogger("fontTools.varLib.instancer")
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def _featureVariationRecordIsUnique(rec, seen):
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conditionSet = []
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conditionSets = (
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rec.ConditionSet.ConditionTable if rec.ConditionSet is not None else []
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)
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for cond in conditionSets:
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if cond.Format != 1:
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# can't tell whether this is duplicate, assume is unique
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return True
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conditionSet.append(
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(cond.AxisIndex, cond.FilterRangeMinValue, cond.FilterRangeMaxValue)
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)
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# besides the set of conditions, we also include the FeatureTableSubstitution
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# version to identify unique FeatureVariationRecords, even though only one
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# version is currently defined. It's theoretically possible that multiple
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# records with same conditions but different substitution table version be
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# present in the same font for backward compatibility.
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recordKey = frozenset([rec.FeatureTableSubstitution.Version] + conditionSet)
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if recordKey in seen:
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return False
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else:
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seen.add(recordKey) # side effect
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return True
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def _limitFeatureVariationConditionRange(condition, axisLimit):
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minValue = condition.FilterRangeMinValue
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maxValue = condition.FilterRangeMaxValue
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if (
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minValue > maxValue
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or minValue > axisLimit.maximum
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or maxValue < axisLimit.minimum
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):
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# condition invalid or out of range
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return
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return tuple(
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axisLimit.renormalizeValue(v, extrapolate=False) for v in (minValue, maxValue)
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)
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def _instantiateFeatureVariationRecord(
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record, recIdx, axisLimits, fvarAxes, axisIndexMap
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):
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applies = True
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shouldKeep = False
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newConditions = []
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from fontTools.varLib.instancer import NormalizedAxisTripleAndDistances
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default_triple = NormalizedAxisTripleAndDistances(-1, 0, +1)
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if record.ConditionSet is None:
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record.ConditionSet = ot.ConditionSet()
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record.ConditionSet.ConditionTable = []
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record.ConditionSet.ConditionCount = 0
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for i, condition in enumerate(record.ConditionSet.ConditionTable):
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if condition.Format == 1:
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axisIdx = condition.AxisIndex
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axisTag = fvarAxes[axisIdx].axisTag
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minValue = condition.FilterRangeMinValue
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maxValue = condition.FilterRangeMaxValue
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triple = axisLimits.get(axisTag, default_triple)
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if not (minValue <= triple.default <= maxValue):
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applies = False
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# if condition not met, remove entire record
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if triple.minimum > maxValue or triple.maximum < minValue:
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newConditions = None
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break
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if axisTag in axisIndexMap:
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# remap axis index
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condition.AxisIndex = axisIndexMap[axisTag]
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# remap condition limits
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newRange = _limitFeatureVariationConditionRange(condition, triple)
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if newRange:
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# keep condition with updated limits
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minimum, maximum = newRange
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condition.FilterRangeMinValue = minimum
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condition.FilterRangeMaxValue = maximum
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shouldKeep = True
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if minimum != -1 or maximum != +1:
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newConditions.append(condition)
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else:
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# condition out of range, remove entire record
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newConditions = None
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break
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else:
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log.warning(
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"Condition table {0} of FeatureVariationRecord {1} has "
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"unsupported format ({2}); ignored".format(i, recIdx, condition.Format)
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)
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applies = False
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newConditions.append(condition)
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if newConditions is not None and shouldKeep:
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record.ConditionSet.ConditionTable = newConditions
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if not newConditions:
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record.ConditionSet = None
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shouldKeep = True
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else:
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shouldKeep = False
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# Does this *always* apply?
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universal = shouldKeep and not newConditions
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return applies, shouldKeep, universal
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def _instantiateFeatureVariations(table, fvarAxes, axisLimits):
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pinnedAxes = set(axisLimits.pinnedLocation())
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axisOrder = [axis.axisTag for axis in fvarAxes if axis.axisTag not in pinnedAxes]
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axisIndexMap = {axisTag: axisOrder.index(axisTag) for axisTag in axisOrder}
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featureVariationApplied = False
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uniqueRecords = set()
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newRecords = []
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defaultsSubsts = None
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for i, record in enumerate(table.FeatureVariations.FeatureVariationRecord):
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applies, shouldKeep, universal = _instantiateFeatureVariationRecord(
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record, i, axisLimits, fvarAxes, axisIndexMap
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)
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if shouldKeep and _featureVariationRecordIsUnique(record, uniqueRecords):
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newRecords.append(record)
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if applies and not featureVariationApplied:
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assert record.FeatureTableSubstitution.Version == 0x00010000
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defaultsSubsts = deepcopy(record.FeatureTableSubstitution)
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for default, rec in zip(
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defaultsSubsts.SubstitutionRecord,
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record.FeatureTableSubstitution.SubstitutionRecord,
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):
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default.Feature = deepcopy(
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table.FeatureList.FeatureRecord[rec.FeatureIndex].Feature
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)
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table.FeatureList.FeatureRecord[rec.FeatureIndex].Feature = deepcopy(
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rec.Feature
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)
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# Set variations only once
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featureVariationApplied = True
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# Further records don't have a chance to apply after a universal record
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if universal:
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break
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# Insert a catch-all record to reinstate the old features if necessary
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if featureVariationApplied and newRecords and not universal:
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defaultRecord = ot.FeatureVariationRecord()
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defaultRecord.ConditionSet = ot.ConditionSet()
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defaultRecord.ConditionSet.ConditionTable = []
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defaultRecord.ConditionSet.ConditionCount = 0
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defaultRecord.FeatureTableSubstitution = defaultsSubsts
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newRecords.append(defaultRecord)
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if newRecords:
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table.FeatureVariations.FeatureVariationRecord = newRecords
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table.FeatureVariations.FeatureVariationCount = len(newRecords)
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else:
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del table.FeatureVariations
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# downgrade table version if there are no FeatureVariations left
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table.Version = 0x00010000
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def instantiateFeatureVariations(varfont, axisLimits):
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for tableTag in ("GPOS", "GSUB"):
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if tableTag not in varfont or not getattr(
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varfont[tableTag].table, "FeatureVariations", None
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):
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continue
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log.info("Instantiating FeatureVariations of %s table", tableTag)
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_instantiateFeatureVariations(
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varfont[tableTag].table, varfont["fvar"].axes, axisLimits
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)
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# remove unreferenced lookups
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varfont[tableTag].prune_lookups()
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