From e2a875b26c8b25525928be983a5c29606b25bc70 Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Tue, 9 Aug 2022 17:18:58 -0600
Subject: [PATCH] [instancer] Implement featureVariations L4 instancing

I *think* this is all.
---
 Lib/fontTools/varLib/instancer/__init__.py | 18 ++++++------
 Tests/varLib/instancer/instancer_test.py   | 32 ++++++++++++----------
 2 files changed, 26 insertions(+), 24 deletions(-)

diff --git a/Lib/fontTools/varLib/instancer/__init__.py b/Lib/fontTools/varLib/instancer/__init__.py
index 102166989..e3b50e283 100644
--- a/Lib/fontTools/varLib/instancer/__init__.py
+++ b/Lib/fontTools/varLib/instancer/__init__.py
@@ -678,21 +678,21 @@ def _featureVariationRecordIsUnique(rec, seen):
         return True
 
 
-def _limitFeatureVariationConditionRange(condition, axisRange):
+def _limitFeatureVariationConditionRange(condition, axisLimit):
     minValue = condition.FilterRangeMinValue
     maxValue = condition.FilterRangeMaxValue
 
     if (
         minValue > maxValue
-        or minValue > axisRange.maximum
-        or maxValue < axisRange.minimum
+        or minValue > axisLimit.maximum
+        or maxValue < axisLimit.minimum
     ):
         # condition invalid or out of range
         return
 
     values = [minValue, maxValue]
     for i, value in enumerate(values):
-        values[i] = normalizeValue(value, (axisRange.minimum, 0, axisRange.maximum))
+        values[i] = normalizeValue(value, axisLimit)
 
     return AxisRange(*values)
 
@@ -737,15 +737,15 @@ def _instantiateFeatureVariationRecord(
     return applies, shouldKeep
 
 
-def _limitFeatureVariationRecord(record, axisRanges, axisOrder):
+def _limitFeatureVariationRecord(record, axisLimits, axisOrder):
     newConditions = []
     for i, condition in enumerate(record.ConditionSet.ConditionTable):
         if condition.Format == 1:
             axisIdx = condition.AxisIndex
             axisTag = axisOrder[axisIdx]
-            if axisTag in axisRanges:
-                axisRange = axisRanges[axisTag]
-                newRange = _limitFeatureVariationConditionRange(condition, axisRange)
+            if axisTag in axisLimits:
+                axisLimit = axisLimits[axisTag]
+                newRange = _limitFeatureVariationConditionRange(condition, axisLimit)
                 if newRange:
                     # keep condition with updated limits and remapped axis index
                     condition.FilterRangeMinValue = newRange.minimum
@@ -786,7 +786,7 @@ def _instantiateFeatureVariations(table, fvarAxes, axisLimits):
             record, i, location, fvarAxes, axisIndexMap
         )
         if shouldKeep:
-            shouldKeep = _limitFeatureVariationRecord(record, axisRanges, axisOrder)
+            shouldKeep = _limitFeatureVariationRecord(record, axisLimits, axisOrder)
 
         if shouldKeep and _featureVariationRecordIsUnique(record, uniqueRecords):
             newRecords.append(record)
diff --git a/Tests/varLib/instancer/instancer_test.py b/Tests/varLib/instancer/instancer_test.py
index 1adb67313..93403daf4 100644
--- a/Tests/varLib/instancer/instancer_test.py
+++ b/Tests/varLib/instancer/instancer_test.py
@@ -1589,7 +1589,9 @@ class InstantiateFeatureVariationsTest(object):
             ]
         )
 
-        instancer.instantiateFeatureVariations(font, location)
+        limits = {tag:instancer.NormalizedAxisTent(l, l, l)
+                  for tag,l in location.items()}
+        instancer.instantiateFeatureVariations(font, limits)
 
         gsub = font["GSUB"].table
         featureVariations = gsub.FeatureVariations
@@ -1668,7 +1670,7 @@ class InstantiateFeatureVariationsTest(object):
         rec1.ConditionSet.ConditionTable[0].Format = 2
 
         with caplog.at_level(logging.WARNING, logger="fontTools.varLib.instancer"):
-            instancer.instantiateFeatureVariations(font, {"wdth": 0})
+            instancer.instantiateFeatureVariations(font, {"wdth": instancer.NormalizedAxisTent(0,0,0)})
 
         assert (
             "Condition table 0 of FeatureVariationRecord 0 "
@@ -1864,25 +1866,25 @@ class LimitTupleVariationAxisRangesTest:
 
 
 @pytest.mark.parametrize(
-    "oldRange, newRange, expected",
+    "oldRange, newLimit, expected",
     [
-        ((1.0, -1.0), (-1.0, 1.0), None),  # invalid oldRange min > max
-        ((0.6, 1.0), (0, 0.5), None),
-        ((-1.0, -0.6), (-0.5, 0), None),
-        ((0.4, 1.0), (0, 0.5), (0.8, 1.0)),
-        ((-1.0, -0.4), (-0.5, 0), (-1.0, -0.8)),
-        ((0.4, 1.0), (0, 0.4), (1.0, 1.0)),
-        ((-1.0, -0.4), (-0.4, 0), (-1.0, -1.0)),
-        ((-0.5, 0.5), (-0.4, 0.4), (-1.0, 1.0)),
-        ((0, 1.0), (-1.0, 0), (0, 0)),  # or None?
-        ((-1.0, 0), (0, 1.0), (0, 0)),  # or None?
+        ((1.0, -1.0), (-1.0, 0, 1.0), None),  # invalid oldRange min > max
+        ((0.6, 1.0), (0, 0, 0.5), None),
+        ((-1.0, -0.6), (-0.5, 0, 0), None),
+        ((0.4, 1.0), (0, 0, 0.5), (0.8, 1.0)),
+        ((-1.0, -0.4), (-0.5, 0, 0), (-1.0, -0.8)),
+        ((0.4, 1.0), (0, 0, 0.4), (1.0, 1.0)),
+        ((-1.0, -0.4), (-0.4, 0, 0), (-1.0, -1.0)),
+        ((-0.5, 0.5), (-0.4, 0, 0.4), (-1.0, 1.0)),
+        ((0, 1.0), (-1.0, 0, 0), (0, 0)),  # or None?
+        ((-1.0, 0), (0, 0, 1.0), (0, 0)),  # or None?
     ],
 )
-def test_limitFeatureVariationConditionRange(oldRange, newRange, expected):
+def test_limitFeatureVariationConditionRange(oldRange, newLimit, expected):
     condition = featureVars.buildConditionTable(0, *oldRange)
 
     result = instancer._limitFeatureVariationConditionRange(
-        condition, instancer.NormalizedAxisRange(*newRange)
+        condition, instancer.NormalizedAxisTent(*newLimit)
     )
 
     assert result == expected