From e821f1fb9eb6025cbce8ffd2c3dcf83c8c04ced5 Mon Sep 17 00:00:00 2001
From: Cosimo Lupo <clupo@google.com>
Date: Thu, 12 Dec 2019 11:54:58 +0000
Subject: [PATCH] fontBuilder: add FontBuilder.addFeatureVariations method

like the existing addOpenTypeFeatures
it simply forwards to featureVars.addFeatureVariations
---
 Lib/fontTools/fontBuilder.py            |  14 +++
 Tests/fontBuilder/data/test_var.ttf.ttx | 112 ++++++++++++++++++++++--
 Tests/fontBuilder/fontBuilder_test.py   |  24 ++++-
 3 files changed, 139 insertions(+), 11 deletions(-)

diff --git a/Lib/fontTools/fontBuilder.py b/Lib/fontTools/fontBuilder.py
index bd6b2e50e..29d58fb6f 100644
--- a/Lib/fontTools/fontBuilder.py
+++ b/Lib/fontTools/fontBuilder.py
@@ -751,6 +751,20 @@ class FontBuilder(object):
         from .feaLib.builder import addOpenTypeFeaturesFromString
         addOpenTypeFeaturesFromString(self.font, features, filename=filename, tables=tables)
 
+    def addFeatureVariations(self, conditionalSubstitutions, featureTag="rvrn"):
+        """Add conditional substitutions to a Variable Font.
+
+        See `fontTools.varLib.featureVars.addFeatureVariations`.
+        """
+        from .varLib import featureVars
+
+        if "fvar" not in self.font:
+            raise KeyError("'fvar' table is missing; can't add FeatureVariations.")
+
+        featureVars.addFeatureVariations(
+            self.font, conditionalSubstitutions, featureTag=featureTag
+        )
+
 
 def buildCmapSubTable(cmapping, format, platformID, platEncID):
     subTable = cmap_classes[format](format)
diff --git a/Tests/fontBuilder/data/test_var.ttf.ttx b/Tests/fontBuilder/data/test_var.ttf.ttx
index 382d29e10..bc1aae250 100644
--- a/Tests/fontBuilder/data/test_var.ttf.ttx
+++ b/Tests/fontBuilder/data/test_var.ttf.ttx
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<ttFont sfntVersion="\x00\x01\x00\x00" ttLibVersion="3.32">
+<ttFont sfntVersion="\x00\x01\x00\x00" ttLibVersion="4.2">
 
   <GlyphOrder>
     <!-- The 'id' attribute is only for humans; it is ignored when parsed. -->
@@ -19,7 +19,7 @@
     <unitsPerEm value="1024"/>
     <created value="Thu Nov  1 20:29:01 2018"/>
     <modified value="Thu Nov  1 20:29:01 2018"/>
-    <xMin value="100"/>
+    <xMin value="50"/>
     <yMin value="0"/>
     <xMax value="500"/>
     <yMax value="400"/>
@@ -36,7 +36,7 @@
     <descent value="200"/>
     <lineGap value="0"/>
     <advanceWidthMax value="600"/>
-    <minLeftSideBearing value="100"/>
+    <minLeftSideBearing value="50"/>
     <minRightSideBearing value="100"/>
     <xMaxExtent value="500"/>
     <caretSlopeRise value="1"/>
@@ -126,7 +126,7 @@
     <mtx name=".notdef" width="600" lsb="0"/>
     <mtx name=".null" width="600" lsb="0"/>
     <mtx name="A" width="600" lsb="100"/>
-    <mtx name="a" width="600" lsb="100"/>
+    <mtx name="a" width="600" lsb="50"/>
   </hmtx>
 
   <cmap>
@@ -164,12 +164,12 @@
       <instructions/>
     </TTGlyph>
 
-    <TTGlyph name="a" xMin="100" yMin="0" xMax="500" yMax="400">
+    <TTGlyph name="a" xMin="50" yMin="0" xMax="250" yMax="200">
       <contour>
-        <pt x="100" y="0" on="1"/>
-        <pt x="100" y="400" on="1"/>
-        <pt x="500" y="400" on="1"/>
-        <pt x="500" y="0" on="1"/>
+        <pt x="50" y="0" on="1"/>
+        <pt x="50" y="200" on="1"/>
+        <pt x="250" y="200" on="1"/>
+        <pt x="250" y="0" on="1"/>
       </contour>
       <instructions/>
     </TTGlyph>
@@ -269,6 +269,100 @@
     </extraNames>
   </post>
 
+  <GSUB>
+    <Version value="0x00010001"/>
+    <ScriptList>
+      <!-- ScriptCount=1 -->
+      <ScriptRecord index="0">
+        <ScriptTag value="DFLT"/>
+        <Script>
+          <DefaultLangSys>
+            <ReqFeatureIndex value="65535"/>
+            <!-- FeatureCount=1 -->
+            <FeatureIndex index="0" value="0"/>
+          </DefaultLangSys>
+          <!-- LangSysCount=0 -->
+        </Script>
+      </ScriptRecord>
+    </ScriptList>
+    <FeatureList>
+      <!-- FeatureCount=1 -->
+      <FeatureRecord index="0">
+        <FeatureTag value="rclt"/>
+        <Feature>
+          <!-- LookupCount=0 -->
+        </Feature>
+      </FeatureRecord>
+    </FeatureList>
+    <LookupList>
+      <!-- LookupCount=1 -->
+      <Lookup index="0">
+        <LookupType value="1"/>
+        <LookupFlag value="0"/>
+        <!-- SubTableCount=1 -->
+        <SingleSubst index="0" Format="1">
+          <Substitution in="A" out="a"/>
+        </SingleSubst>
+      </Lookup>
+    </LookupList>
+    <FeatureVariations>
+      <Version value="0x00010000"/>
+      <!-- FeatureVariationCount=2 -->
+      <FeatureVariationRecord index="0">
+        <ConditionSet>
+          <!-- ConditionCount=2 -->
+          <ConditionTable index="0" Format="1">
+            <AxisIndex value="3"/>
+            <FilterRangeMinValue value="0.8"/>
+            <FilterRangeMaxValue value="1.0"/>
+          </ConditionTable>
+          <ConditionTable index="1" Format="1">
+            <AxisIndex value="0"/>
+            <FilterRangeMinValue value="0.8"/>
+            <FilterRangeMaxValue value="1.0"/>
+          </ConditionTable>
+        </ConditionSet>
+        <FeatureTableSubstitution>
+          <Version value="0x00010000"/>
+          <!-- SubstitutionCount=1 -->
+          <SubstitutionRecord index="0">
+            <FeatureIndex value="0"/>
+            <Feature>
+              <!-- LookupCount=1 -->
+              <LookupListIndex index="0" value="0"/>
+            </Feature>
+          </SubstitutionRecord>
+        </FeatureTableSubstitution>
+      </FeatureVariationRecord>
+      <FeatureVariationRecord index="1">
+        <ConditionSet>
+          <!-- ConditionCount=2 -->
+          <ConditionTable index="0" Format="1">
+            <AxisIndex value="1"/>
+            <FilterRangeMinValue value="0.8"/>
+            <FilterRangeMaxValue value="1.0"/>
+          </ConditionTable>
+          <ConditionTable index="1" Format="1">
+            <AxisIndex value="2"/>
+            <FilterRangeMinValue value="0.8"/>
+            <FilterRangeMaxValue value="1.0"/>
+          </ConditionTable>
+        </ConditionSet>
+        <FeatureTableSubstitution>
+          <Version value="0x00010000"/>
+          <!-- SubstitutionCount=1 -->
+          <SubstitutionRecord index="0">
+            <FeatureIndex value="0"/>
+            <Feature>
+              <!-- LookupCount=1 -->
+              <LookupListIndex index="0" value="0"/>
+            </Feature>
+          </SubstitutionRecord>
+        </FeatureTableSubstitution>
+      </FeatureVariationRecord>
+    </FeatureVariations>
+  </GSUB>
+
   <fvar>
 
     <!-- Left -->
diff --git a/Tests/fontBuilder/fontBuilder_test.py b/Tests/fontBuilder/fontBuilder_test.py
index e13f11616..8c5127626 100644
--- a/Tests/fontBuilder/fontBuilder_test.py
+++ b/Tests/fontBuilder/fontBuilder_test.py
@@ -164,13 +164,20 @@ def test_build_var(tmpdir):
     pen.lineTo((500, 400))
     pen.lineTo((500, 000))
     pen.closePath()
+    glyph1 = pen.glyph()
 
-    glyph = pen.glyph()
+    pen = TTGlyphPen(None)
+    pen.moveTo((50, 0))
+    pen.lineTo((50, 200))
+    pen.lineTo((250, 200))
+    pen.lineTo((250, 0))
+    pen.closePath()
+    glyph2 = pen.glyph()
 
     pen = TTGlyphPen(None)
     emptyGlyph = pen.glyph()
 
-    glyphs = {".notdef": emptyGlyph, "A": glyph, "a": glyph, ".null": emptyGlyph}
+    glyphs = {".notdef": emptyGlyph, "A": glyph1, "a": glyph2, ".null": emptyGlyph}
     fb.setupGlyf(glyphs)
     metrics = {}
     glyphTable = fb.font["glyf"]
@@ -206,6 +213,19 @@ def test_build_var(tmpdir):
     ]
     fb.setupGvar(variations)
 
+    fb.addFeatureVariations(
+        [
+            (
+                [
+                    {"LEFT": (0.8, 1), "DOWN": (0.8, 1)},
+                    {"RGHT": (0.8, 1), "UPPP": (0.8, 1)},
+                  ],
+                {"A": "a"}
+            )
+        ],
+        featureTag="rclt",
+    )
+
     fb.setupOS2()
     fb.setupPost()
     fb.setupDummyDSIG()