From 973072b25932b5cb455558ab979bd09f070338fc Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Tue, 23 Apr 2024 12:57:14 -0600
Subject: [PATCH] [Condition] Implement ConditionValue

Shift other Condition format numbers.

Implements
https://github.com/adobe-type-tools/opentype-spec-drafts/blob/main/condvalue_spec.md
---
 Lib/fontTools/ttLib/tables/otData.py | 38 +++++++++++++++++++++-------
 Lib/fontTools/ttLib/ttGlyphSet.py    | 31 ++++++++++++++++++-----
 2 files changed, 53 insertions(+), 16 deletions(-)

diff --git a/Lib/fontTools/ttLib/tables/otData.py b/Lib/fontTools/ttLib/tables/otData.py
index 8e4800a97..3a01f5934 100644
--- a/Lib/fontTools/ttLib/tables/otData.py
+++ b/Lib/fontTools/ttLib/tables/otData.py
@@ -3238,18 +3238,18 @@ otData = [
         [
             ("uint16", "Format", None, None, "Format, = 2"),
             (
-                "uint8",
-                "ConditionCount",
+                "int16",
+                "DefaultValue",
                 None,
                 None,
-                "Index for the variation axis within the fvar table, base 0.",
+                "Value at default instance.",
             ),
             (
-                "Offset24",
-                "ConditionTable",
-                "ConditionCount",
-                0,
-                "Array of condition tables for this conjunction (AND) expression.",
+                "uint32",
+                "VarIdx",
+                None,
+                None,
+                "Variation index to vary the value based on current designspace location.",
             ),
         ],
     ),
@@ -3269,7 +3269,7 @@ otData = [
                 "ConditionTable",
                 "ConditionCount",
                 0,
-                "Array of condition tables for this disjunction (OR) expression.",
+                "Array of condition tables for this conjunction (AND) expression.",
             ),
         ],
     ),
@@ -3277,6 +3277,26 @@ otData = [
         "ConditionTableFormat4",
         [
             ("uint16", "Format", None, None, "Format, = 4"),
+            (
+                "uint8",
+                "ConditionCount",
+                None,
+                None,
+                "Index for the variation axis within the fvar table, base 0.",
+            ),
+            (
+                "Offset24",
+                "ConditionTable",
+                "ConditionCount",
+                0,
+                "Array of condition tables for this disjunction (OR) expression.",
+            ),
+        ],
+    ),
+    (
+        "ConditionTableFormat5",
+        [
+            ("uint16", "Format", None, None, "Format, = 5"),
             (
                 "Offset24",
                 "ConditionTable",
diff --git a/Lib/fontTools/ttLib/ttGlyphSet.py b/Lib/fontTools/ttLib/ttGlyphSet.py
index e4f035ad6..0c565bcea 100644
--- a/Lib/fontTools/ttLib/ttGlyphSet.py
+++ b/Lib/fontTools/ttLib/ttGlyphSet.py
@@ -276,8 +276,9 @@ class _TTGlyphCFF(_TTGlyph):
         self.glyphSet.charStrings[self.name].draw(pen, self.glyphSet.blender)
 
 
-def _evaluateCondition(condition, fvarAxes, location):
+def _evaluateCondition(condition, fvarAxes, location, instancer):
     if condition.Format == 1:
+        # ConditionAxisRange
         axisIndex = condition.AxisIndex
         axisTag = fvarAxes[axisIndex].axisTag
         axisValue = location.get(axisTag, 0)
@@ -285,20 +286,27 @@ def _evaluateCondition(condition, fvarAxes, location):
         maxValue = condition.FilterRangeMaxValue
         return minValue <= axisValue <= maxValue
     elif condition.Format == 2:
+        # ConditionValue
+        value = condition.DefaultValue
+        value += instancer[condition.VarIdx]
+        return value > 0
+    elif condition.Format == 3:
         # ConditionAnd
         for subcondition in condition.ConditionTable:
-            if not _evaluateCondition(subcondition, fvarAxes, location):
+            if not _evaluateCondition(subcondition, fvarAxes, location, instancer):
                 return False
         return True
-    elif condition.Format == 3:
+    elif condition.Format == 4:
         # ConditionOr
         for subcondition in condition.ConditionTable:
-            if _evaluateCondition(subcondition, fvarAxes, location):
+            if _evaluateCondition(subcondition, fvarAxes, location, instancer):
                 return True
         return False
-    elif condition.Format == 4:
+    elif condition.Format == 5:
         # ConditionNegate
-        return not _evaluateCondition(condition.conditionTable, fvarAxes, location)
+        return not _evaluateCondition(
+            condition.conditionTable, fvarAxes, location, instancer
+        )
     else:
         return False  # Unkonwn condition format
 
@@ -319,17 +327,26 @@ class _TTGlyphVARC(_TTGlyph):
         glyph = varc.VarCompositeGlyphs.VarCompositeGlyph[idx]
 
         from fontTools.varLib.multiVarStore import MultiVarStoreInstancer
+        from fontTools.varLib.varStore import VarStoreInstancer
 
         fvarAxes = glyphSet.font["fvar"].axes
         instancer = MultiVarStoreInstancer(
             varc.MultiVarStore, fvarAxes, self.glyphSet.location
         )
+        gdef = glyphSet.font.get("GDEF") if "GDEF" in glyphSet.font else None
+        gdefInstancer = VarStoreInstancer(
+            getattr(gdef.table, "VarStore") if gdef is not None else None,
+            fvarAxes,
+            self.glyphSet.location,
+        )
 
         for comp in glyph.components:
 
             if comp.flags & VarComponentFlags.HAVE_CONDITION:
                 condition = varc.ConditionList.ConditionTable[comp.conditionIndex]
-                if not _evaluateCondition(condition, fvarAxes, self.glyphSet.location):
+                if not _evaluateCondition(
+                    condition, fvarAxes, self.glyphSet.location, gdefInstancer
+                ):
                     continue
 
             location = {}