[instancer] Split featureVars code into own module

Towards fixing https://github.com/fonttools/fonttools/issues/2737

Lib/fontTools/varLib/instancer/__init__.py

@@ -100,6 +100,7 @@ from fontTools.varLib import builder
 from fontTools.varLib.mvar import MVAR_ENTRIES
 from fontTools.varLib.merger import MutatorMerger
 from fontTools.varLib.instancer import names
+from .featureVars import instantiateFeatureVariations
 from fontTools.misc.cliTools import makeOutputFileName
 from fontTools.varLib.instancer import solver
 import collections
@@ -834,165 +835,6 @@ def instantiateOTL(varfont, axisLimits):
             del varfont["GDEF"]
 
 
-def instantiateFeatureVariations(varfont, axisLimits):
-    for tableTag in ("GPOS", "GSUB"):
-        if tableTag not in varfont or not getattr(
-            varfont[tableTag].table, "FeatureVariations", None
-        ):
-            continue
-        log.info("Instantiating FeatureVariations of %s table", tableTag)
-        _instantiateFeatureVariations(
-            varfont[tableTag].table, varfont["fvar"].axes, axisLimits
-        )
-        # remove unreferenced lookups
-        varfont[tableTag].prune_lookups()
-
-
-def _featureVariationRecordIsUnique(rec, seen):
-    conditionSet = []
-    for cond in rec.ConditionSet.ConditionTable:
-        if cond.Format != 1:
-            # can't tell whether this is duplicate, assume is unique
-            return True
-        conditionSet.append(
-            (cond.AxisIndex, cond.FilterRangeMinValue, cond.FilterRangeMaxValue)
-        )
-    # besides the set of conditions, we also include the FeatureTableSubstitution
-    # version to identify unique FeatureVariationRecords, even though only one
-    # version is currently defined. It's theoretically possible that multiple
-    # records with same conditions but different substitution table version be
-    # present in the same font for backward compatibility.
-    recordKey = frozenset([rec.FeatureTableSubstitution.Version] + conditionSet)
-    if recordKey in seen:
-        return False
-    else:
-        seen.add(recordKey)  # side effect
-        return True
-
-
-def _limitFeatureVariationConditionRange(condition, axisLimit):
-    minValue = condition.FilterRangeMinValue
-    maxValue = condition.FilterRangeMaxValue
-
-    if (
-        minValue > maxValue
-        or minValue > axisLimit.maximum
-        or maxValue < axisLimit.minimum
-    ):
-        # condition invalid or out of range
-        return
-
-    return tuple(normalizeValue(v, axisLimit) for v in (minValue, maxValue))
-
-
-def _instantiateFeatureVariationRecord(
-    record, recIdx, axisLimits, fvarAxes, axisIndexMap
-):
-    applies = True
-    newConditions = []
-    default_triple = NormalizedAxisTriple(-1, 0, +1)
-    for i, condition in enumerate(record.ConditionSet.ConditionTable):
-        if condition.Format == 1:
-            axisIdx = condition.AxisIndex
-            axisTag = fvarAxes[axisIdx].axisTag
-
-            minValue = condition.FilterRangeMinValue
-            maxValue = condition.FilterRangeMaxValue
-            triple = axisLimits.get(axisTag, default_triple)
-            if not (minValue <= triple.default <= maxValue):
-                applies = False
-                # condition not met so remove entire record
-                if triple.minimum > maxValue or triple.maximum < minValue:
-                    newConditions = None
-                    break
-
-            if axisTag in axisIndexMap:
-                # remap axis index
-                condition.AxisIndex = axisIndexMap[axisTag]
-                newConditions.append(condition)
-        else:
-            log.warning(
-                "Condition table {0} of FeatureVariationRecord {1} has "
-                "unsupported format ({2}); ignored".format(i, recIdx, condition.Format)
-            )
-            applies = False
-            newConditions.append(condition)
-
-    if newConditions:
-        record.ConditionSet.ConditionTable = newConditions
-        shouldKeep = True
-    else:
-        shouldKeep = False
-
-    return applies, shouldKeep
-
-
-def _limitFeatureVariationRecord(record, axisLimits, axisOrder):
-    newConditions = []
-    for condition in record.ConditionSet.ConditionTable:
-        if condition.Format == 1:
-            axisIdx = condition.AxisIndex
-            axisTag = axisOrder[axisIdx]
-            if axisTag in axisLimits:
-                axisLimit = axisLimits[axisTag]
-                newRange = _limitFeatureVariationConditionRange(condition, axisLimit)
-                if newRange:
-                    # keep condition with updated limits
-                    minimum, maximum = newRange
-                    condition.FilterRangeMinValue = minimum
-                    condition.FilterRangeMaxValue = maximum
-                    if minimum != -1 or maximum != +1:
-                        newConditions.append(condition)
-                else:
-                    # condition out of range, remove entire record
-                    newConditions = None
-                    break
-            else:
-                newConditions.append(condition)
-        else:
-            newConditions.append(condition)
-
-    record.ConditionSet.ConditionTable = newConditions
-    return newConditions is not None
-
-
-def _instantiateFeatureVariations(table, fvarAxes, axisLimits):
-    pinnedAxes = set(axisLimits.pinnedLocation())
-    axisOrder = [axis.axisTag for axis in fvarAxes if axis.axisTag not in pinnedAxes]
-    axisIndexMap = {axisTag: axisOrder.index(axisTag) for axisTag in axisOrder}
-
-    featureVariationApplied = False
-    uniqueRecords = set()
-    newRecords = []
-
-    for i, record in enumerate(table.FeatureVariations.FeatureVariationRecord):
-        applies, shouldKeep = _instantiateFeatureVariationRecord(
-            record, i, axisLimits, fvarAxes, axisIndexMap
-        )
-        if shouldKeep:
-            shouldKeep = _limitFeatureVariationRecord(record, axisLimits, axisOrder)
-
-        if shouldKeep and _featureVariationRecordIsUnique(record, uniqueRecords):
-            newRecords.append(record)
-
-        if applies and not featureVariationApplied:
-            assert record.FeatureTableSubstitution.Version == 0x00010000
-            for rec in record.FeatureTableSubstitution.SubstitutionRecord:
-                table.FeatureList.FeatureRecord[rec.FeatureIndex].Feature = deepcopy(
-                    rec.Feature
-                )
-            # Set variations only once
-            featureVariationApplied = True
-
-    if newRecords:
-        table.FeatureVariations.FeatureVariationRecord = newRecords
-        table.FeatureVariations.FeatureVariationCount = len(newRecords)
-    else:
-        del table.FeatureVariations
-        # downgrade table version if there are no FeatureVariations left
-        table.Version = 0x00010000
-
-
 def _isValidAvarSegmentMap(axisTag, segmentMap):
     if not segmentMap:
         return True

Lib/fontTools/varLib/instancer/featureVars.py

@@ -0,0 +1,168 @@
+
+from fontTools.varLib.models import normalizeValue
+from copy import deepcopy
+import logging
+
+
+log = logging.getLogger("fontTools.varLib.instancer.featureVars")
+
+
+def _featureVariationRecordIsUnique(rec, seen):
+    conditionSet = []
+    for cond in rec.ConditionSet.ConditionTable:
+        if cond.Format != 1:
+            # can't tell whether this is duplicate, assume is unique
+            return True
+        conditionSet.append(
+            (cond.AxisIndex, cond.FilterRangeMinValue, cond.FilterRangeMaxValue)
+        )
+    # besides the set of conditions, we also include the FeatureTableSubstitution
+    # version to identify unique FeatureVariationRecords, even though only one
+    # version is currently defined. It's theoretically possible that multiple
+    # records with same conditions but different substitution table version be
+    # present in the same font for backward compatibility.
+    recordKey = frozenset([rec.FeatureTableSubstitution.Version] + conditionSet)
+    if recordKey in seen:
+        return False
+    else:
+        seen.add(recordKey)  # side effect
+        return True
+
+
+def _limitFeatureVariationConditionRange(condition, axisLimit):
+    minValue = condition.FilterRangeMinValue
+    maxValue = condition.FilterRangeMaxValue
+
+    if (
+        minValue > maxValue
+        or minValue > axisLimit.maximum
+        or maxValue < axisLimit.minimum
+    ):
+        # condition invalid or out of range
+        return
+
+    return tuple(normalizeValue(v, axisLimit) for v in (minValue, maxValue))
+
+
+def _instantiateFeatureVariationRecord(
+    record, recIdx, axisLimits, fvarAxes, axisIndexMap
+):
+    applies = True
+    newConditions = []
+    from fontTools.varLib.instancer import NormalizedAxisTriple
+    default_triple = NormalizedAxisTriple(-1, 0, +1)
+    for i, condition in enumerate(record.ConditionSet.ConditionTable):
+        if condition.Format == 1:
+            axisIdx = condition.AxisIndex
+            axisTag = fvarAxes[axisIdx].axisTag
+
+            minValue = condition.FilterRangeMinValue
+            maxValue = condition.FilterRangeMaxValue
+            triple = axisLimits.get(axisTag, default_triple)
+            if not (minValue <= triple.default <= maxValue):
+                applies = False
+                # condition not met so remove entire record
+                if triple.minimum > maxValue or triple.maximum < minValue:
+                    newConditions = None
+                    break
+
+            if axisTag in axisIndexMap:
+                # remap axis index
+                condition.AxisIndex = axisIndexMap[axisTag]
+                newConditions.append(condition)
+        else:
+            log.warning(
+                "Condition table {0} of FeatureVariationRecord {1} has "
+                "unsupported format ({2}); ignored".format(i, recIdx, condition.Format)
+            )
+            applies = False
+            newConditions.append(condition)
+
+    if newConditions:
+        record.ConditionSet.ConditionTable = newConditions
+        shouldKeep = True
+    else:
+        shouldKeep = False
+
+    return applies, shouldKeep
+
+
+def _limitFeatureVariationRecord(record, axisLimits, axisOrder):
+    newConditions = []
+    for condition in record.ConditionSet.ConditionTable:
+        if condition.Format == 1:
+            axisIdx = condition.AxisIndex
+            axisTag = axisOrder[axisIdx]
+            if axisTag in axisLimits:
+                axisLimit = axisLimits[axisTag]
+                newRange = _limitFeatureVariationConditionRange(condition, axisLimit)
+                if newRange:
+                    # keep condition with updated limits
+                    minimum, maximum = newRange
+                    condition.FilterRangeMinValue = minimum
+                    condition.FilterRangeMaxValue = maximum
+                    if minimum != -1 or maximum != +1:
+                        newConditions.append(condition)
+                else:
+                    # condition out of range, remove entire record
+                    newConditions = None
+                    break
+            else:
+                newConditions.append(condition)
+        else:
+            newConditions.append(condition)
+
+    record.ConditionSet.ConditionTable = newConditions
+    return newConditions is not None
+
+
+def _instantiateFeatureVariations(table, fvarAxes, axisLimits):
+    pinnedAxes = set(axisLimits.pinnedLocation())
+    axisOrder = [axis.axisTag for axis in fvarAxes if axis.axisTag not in pinnedAxes]
+    axisIndexMap = {axisTag: axisOrder.index(axisTag) for axisTag in axisOrder}
+
+    featureVariationApplied = False
+    uniqueRecords = set()
+    newRecords = []
+
+    for i, record in enumerate(table.FeatureVariations.FeatureVariationRecord):
+        applies, shouldKeep = _instantiateFeatureVariationRecord(
+            record, i, axisLimits, fvarAxes, axisIndexMap
+        )
+        if shouldKeep:
+            shouldKeep = _limitFeatureVariationRecord(record, axisLimits, axisOrder)
+
+        if shouldKeep and _featureVariationRecordIsUnique(record, uniqueRecords):
+            newRecords.append(record)
+
+        if applies and not featureVariationApplied:
+            assert record.FeatureTableSubstitution.Version == 0x00010000
+            for rec in record.FeatureTableSubstitution.SubstitutionRecord:
+                table.FeatureList.FeatureRecord[rec.FeatureIndex].Feature = deepcopy(
+                    rec.Feature
+                )
+            # Set variations only once
+            featureVariationApplied = True
+
+    if newRecords:
+        table.FeatureVariations.FeatureVariationRecord = newRecords
+        table.FeatureVariations.FeatureVariationCount = len(newRecords)
+    else:
+        del table.FeatureVariations
+        # downgrade table version if there are no FeatureVariations left
+        table.Version = 0x00010000
+
+
+def instantiateFeatureVariations(varfont, axisLimits):
+    for tableTag in ("GPOS", "GSUB"):
+        if tableTag not in varfont or not getattr(
+            varfont[tableTag].table, "FeatureVariations", None
+        ):
+            continue
+        log.info("Instantiating FeatureVariations of %s table", tableTag)
+        _instantiateFeatureVariations(
+            varfont[tableTag].table, varfont["fvar"].axes, axisLimits
+        )
+        # remove unreferenced lookups
+        varfont[tableTag].prune_lookups()
+

Tests/varLib/instancer/instancer_test.py

@@ -9,6 +9,7 @@ from fontTools.ttLib.tables import otTables
 from fontTools.ttLib.tables.TupleVariation import TupleVariation
 from fontTools import varLib
 from fontTools.varLib import instancer
+from fontTools.varLib.instancer import featureVars as instancer_featureVars
 from fontTools.varLib.mvar import MVAR_ENTRIES
 from fontTools.varLib import builder
 from fontTools.varLib import featureVars
@@ -1975,7 +1976,7 @@ class LimitTupleVariationAxisRangesTest:
 def test_limitFeatureVariationConditionRange(oldRange, newLimit, expected):
     condition = featureVars.buildConditionTable(0, *oldRange)
 
-    result = instancer._limitFeatureVariationConditionRange(
+    result = instancer_featureVars._limitFeatureVariationConditionRange(
         condition, instancer.NormalizedAxisTriple(*newLimit)
     )