[VARC] Take a stab at instancing

Lib/fontTools/varLib/instancer/__init__.py

@@ -475,70 +475,31 @@ def instantiateVARC(varfont, axisLimits):
 
     varc = varfont["VARC"].table
     fvarAxes = varfont["fvar"].axes if "fvar" in varfont else []
-    if varc.VarCompositeGlyphs is not None:
-        for glyph in varc.VarCompositeGlyphs.VarCompositeGlyph:
-            for comp in glyph.components:
-                if comp.axisIndicesIndex is None:
-                    continue
 
-                axisIndices = varc.AxisIndicesList.Item[comp.axisIndicesIndex]
+    location = axisLimits.pinnedLocation()
-                axisValues = comp.axisValues
+    axisMap = [i for i, axis in enumerate(fvarAxes) if axis.axisTag not in location]
+    reverseAxisMap = {i: j for j, i in enumerate(axisMap)}
 
-                comp.axisValues = []
+    if varc.AxisIndicesList:
-                for axisIndex, axisValue in zip(axisIndices, axisValues):
+        axisIndicesList = varc.AxisIndicesList.Item
-                    tag = fvarAxes[axisIndex].axisTag
+        for i, axisIndices in enumerate(axisIndicesList):
-                    if tag in axisLimits:
+            if any(fvarAxes[j].axisTag in axisLimits for j in axisIndices):
-                        axisValue = axisLimits[tag].renormalizeValue(
-                            axisValue, extrapolate=False
-                        )
-                    comp.axisValues.append(axisValue)
-
-                """
-                newLocation = {}
-                for tag, loc in component.location.items():
-                    if tag not in axisLimits:
-                        newLocation[tag] = loc
-                        continue
-                    if comp.flags & VarComponentFlags.AXIS_VALUES_HAVE_VARIATION:
                 raise NotImplementedError(
-                            "Instancing accross VarComponent axes with variation is not supported."
+                    "Instancing across VarComponent axes is not supported."
                 )
-                    limits = axisLimits[tag]
+            axisIndicesList[i] = [reverseAxisMap[j] for j in axisIndices]
-                    loc = limits.renormalizeValue(loc, extrapolate=False)
-                    newLocation[tag] = loc
-                component.location = newLocation
-                """
 
     store = varc.MultiVarStore
     if store:
-        store.prune_regions()  # Needed?
-
-        fvar = varfont["fvar"]
-        location = axisLimits.pinnedLocation()
         for region in store.SparseVarRegionList.Region:
             newRegionAxis = []
             for regionRecord in region.SparseVarRegionAxis:
-                tag = fvar.axes[regionRecord.AxisIndex].axisTag
+                tag = fvarAxes[regionRecord.AxisIndex].axisTag
-                if tag in location:
-                    continue
                 if tag in axisLimits:
-                    limits = axisLimits[tag]
+                    raise NotImplementedError(
-                    triple = (
+                        "Instancing across VarComponent axes is not supported."
-                        regionRecord.StartCoord,
-                        regionRecord.PeakCoord,
-                        regionRecord.EndCoord,
                     )
-                    triple = tuple(
+                regionRecord.AxisIndex = reverseAxisMap[regionRecord.AxisIndex]
-                        limits.renormalizeValue(v, extrapolate=False) for v in triple
-                    )
-                    (
-                        regionRecord.StartCoord,
-                        regionRecord.PeakCoord,
-                        regionRecord.EndCoord,
-                    ) = triple
-                newRegionAxis.append(regionRecord)
-            region.VarRegionAxis = newRegionAxis
-            region.VarRegionAxisCount = len(newRegionAxis)
 
 
 def instantiateTupleVariationStore(

Tests/varLib/instancer/instancer_test.py

@@ -1699,12 +1699,18 @@ class InstantiateVariableFontTest(object):
 
     def test_varComposite(self):
         input_path = os.path.join(
-            TESTDATA, "..", "..", "..", "ttLib", "data", "varc-ac00-ac01.ttf"
+            TESTDATA, "..", "..", "..", "ttLib", "data", "varc-6868.ttf"
         )
         varfont = ttLib.TTFont(input_path)
 
         location = {"wght": 600}
 
+        # We currently do not allow this either; although in theory
+        # it should be possible.
+        with pytest.raises(
+            NotImplementedError,
+            match="is not supported.",
+        ):
             instance = instancer.instantiateVariableFont(
                 varfont,
                 location,
@@ -1714,7 +1720,7 @@ class InstantiateVariableFontTest(object):
 
         with pytest.raises(
             NotImplementedError,
-            match="Instancing accross VarComponent axes with variation is not supported.",
+            match="is not supported.",
         ):
             instance = instancer.instantiateVariableFont(
                 varfont,