From 27e5182677fe84d40b8e02fd1db1b0f4ae07c551 Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Wed, 22 May 2024 18:46:01 -0600
Subject: [PATCH] [VARC/instancer] Implement

---
 Lib/fontTools/varLib/instancer/__init__.py | 57 ++++++++++++++++++++++
 Lib/fontTools/varLib/multiVarStore.py      |  6 ++-
 2 files changed, 62 insertions(+), 1 deletion(-)

diff --git a/Lib/fontTools/varLib/instancer/__init__.py b/Lib/fontTools/varLib/instancer/__init__.py
index 78b608ef2..4f8833cea 100644
--- a/Lib/fontTools/varLib/instancer/__init__.py
+++ b/Lib/fontTools/varLib/instancer/__init__.py
@@ -465,6 +465,60 @@ class OverlapMode(IntEnum):
     REMOVE_AND_IGNORE_ERRORS = 3
 
 
+def instantiateVARC(varfont, axisLimits):
+    log.info("Instantiating VARC tables")
+
+    varc = varfont["VARC"].table
+    if varc.VarCompositeGlyphs:
+        for glyph in varc.VarCompositeGlyphs.glyphs:
+            for component in glyph.components:
+                newLocation = {}
+                for tag, loc in component.location.items():
+                    if tag not in axisLimits:
+                        newLocation[tag] = loc
+                        continue
+                    if component.flags & VarComponentFlags.AXES_HAVE_VARIATION:
+                        raise NotImplementedError(
+                            "Instancing accross VarComponent axes with variation is not supported."
+                        )
+                    limits = axisLimits[tag]
+                    loc = limits.renormalizeValue(loc, extrapolate=False)
+                    newLocation[tag] = loc
+                component.location = newLocation
+
+    if varc.MultiVarStore:
+        store = varc.MultiVarStore
+        store.prune_regions()
+
+        fvar = varfont["fvar"]
+        location = axisLimits.pinnedLocation()
+        for region in store.VarRegionList.Region:
+            assert len(region.VarRegionAxis) == len(fvar.axes)
+            newRegionAxis = []
+            for regionTriple, fvarAxis in zip(region.VarRegionAxis, fvar.axes):
+                tag = fvarAxis.axisTag
+                if tag in location:
+                    continue
+                if tag in axisLimits:
+                    limits = axisLimits[tag]
+                    triple = (
+                        regionTriple.StartCoord,
+                        regionTriple.PeakCoord,
+                        regionTriple.EndCoord,
+                    )
+                    triple = tuple(
+                        limits.renormalizeValue(v, extrapolate=False) for v in triple
+                    )
+                    (
+                        regionTriple.StartCoord,
+                        regionTriple.PeakCoord,
+                        regionTriple.EndCoord,
+                    ) = triple
+                newRegionAxis.append(regionTriple)
+            region.VarRegionAxis = newRegionAxis
+            region.VarRegionAxisCount = len(newRegionAxis)
+
+
 def instantiateTupleVariationStore(
     variations, axisLimits, origCoords=None, endPts=None
 ):
@@ -1579,6 +1633,9 @@ def instantiateVariableFont(
         log.info("Updating name table")
         names.updateNameTable(varfont, axisLimits)
 
+    if "VARC" in varfont:
+        instantiateVARC(varfont, normalizedLimits)
+
     if "CFF2" in varfont:
         instantiateCFF2(varfont, normalizedLimits, downgrade=downgradeCFF2)
 
diff --git a/Lib/fontTools/varLib/multiVarStore.py b/Lib/fontTools/varLib/multiVarStore.py
index 365e7aad1..b3440cc63 100644
--- a/Lib/fontTools/varLib/multiVarStore.py
+++ b/Lib/fontTools/varLib/multiVarStore.py
@@ -198,7 +198,11 @@ def MultiVarStore_subset_varidxes(self, varIdxes):
     return ot.VarStore.subset_varidxes(self, varIdxes, VarData="MultiVarData")
 
 
-ot.MultiVarStore.prune_regions = ot.VarStore.prune_regions
+def MultiVarStore_prune_regions(self, *, VarData="VarData"):
+    return ot.VarStore.prune_regions(self, VarData="MultiVarData")
+
+
+ot.MultiVarStore.prune_regions = MultiVarStore_prune_regions
 ot.MultiVarStore.subset_varidxes = MultiVarStore_subset_varidxes