[feaLib] Support hhea table

Lib/fontTools/feaLib/ast.py

@@ -631,3 +631,13 @@ class OS2Field(Statement):
 
     def build(self, builder):
         builder.add_os2_field(self.key, self.value)
+
+
+class HheaField(Statement):
+    def __init__(self, location, key, value):
+        Statement.__init__(self, location)
+        self.key = key
+        self.value = value
+
+    def build(self, builder):
+        builder.add_hhea_field(self.key, self.value)

Lib/fontTools/feaLib/builder.py

@@ -69,12 +69,15 @@ class Builder(object):
         self.markFilterSets_ = {}  # frozenset({"acute", "grave"}) --> 4
         # for table 'OS/2'
         self.os2_ = {}
+        # for table 'hhea'
+        self.hhea_ = {}
 
     def build(self):
         self.parseTree = Parser(self.file).parse()
         self.parseTree.build(self)
         self.build_feature_aalt_()
         self.build_head()
+        self.build_hhea()
         self.build_name()
         self.build_OS_2()
         for tag in ('GPOS', 'GSUB'):
@@ -185,6 +188,23 @@ class Builder(object):
             table.created = table.modified = 3406620153  # 2011-12-13 11:22:33
         table.fontRevision = self.fontRevision_
 
+    def build_hhea(self):
+        if not self.hhea_:
+            return
+        table = self.font.get("hhea")
+        if not table:  # this only happens for unit tests
+            table = self.font["hhea"] = getTableClass("hhea")()
+            table.decompile(b"\0" * 36, self.font)
+            table.tableVersion = 1.0
+        if "caretoffset" in self.hhea_:
+            table.caretOffset = self.hhea_["caretoffset"]
+        if "ascender" in self.hhea_:
+            table.ascent = self.hhea_["ascender"]
+        if "descender" in self.hhea_:
+            table.descent = self.hhea_["descender"]
+        if "linegap" in self.hhea_:
+            table.lineGap = self.hhea_["linegap"]
+
     def get_user_name_id(self, table):
         # Try to find first unused font-specific name id
         nameIDs = [name.nameID for name in table.names]
@@ -922,6 +942,9 @@ class Builder(object):
     def add_os2_field(self, key, value):
         self.os2_[key] = value
 
+    def add_hhea_field(self, key, value):
+        self.hhea_[key] = value
+
 
 def makeOpenTypeAnchor(anchor):
     """ast.Anchor --> otTables.Anchor"""

Lib/fontTools/feaLib/builder_test.py

@@ -57,7 +57,7 @@ class BuilderTest(unittest.TestCase):
         spec5f_ii_1 spec5f_ii_2 spec5f_ii_3 spec5f_ii_4
         spec5h1 spec6b_ii spec6d2 spec6e spec6f
         spec6h_ii spec6h_iii_1 spec6h_iii_3d spec8a spec8b spec8c
-        spec9a spec9b spec9c1 spec9c2 spec9c3 spec9e spec9f
+        spec9a spec9b spec9c1 spec9c2 spec9c3 spec9d spec9e spec9f
         bug453 bug463 bug501 bug502 bug505 bug506 bug509 bug512
         name size size2
     """.split()
@@ -104,7 +104,7 @@ class BuilderTest(unittest.TestCase):
     def expect_ttx(self, font, expected_ttx):
         path = self.temp_path(suffix=".ttx")
         font.saveXML(path, tables=['head', 'name', 'BASE', 'GDEF', 'GSUB',
-                                   'GPOS', 'OS/2'])
+                                   'GPOS', 'OS/2', 'hhea'])
         actual = self.read_ttx(path)
         expected = self.read_ttx(expected_ttx)
         if actual != expected:

Lib/fontTools/feaLib/parser.py

@@ -698,6 +698,7 @@ class Parser(object):
         handler = {
             "GDEF": self.parse_table_GDEF_,
             "head": self.parse_table_head_,
+            "hhea": self.parse_table_hhea_,
             "name": self.parse_table_name_,
             "BASE": self.parse_table_BASE_,
             "OS/2": self.parse_table_OS_2_,
@@ -743,6 +744,23 @@ class Parser(object):
                 raise FeatureLibError("Expected FontRevision",
                                       self.cur_token_location_)
 
+    def parse_table_hhea_(self, table):
+        statements = table.statements
+        fields = ("CaretOffset", "Ascender", "Descender", "LineGap")
+        while self.next_token_ != "}":
+            self.advance_lexer_()
+            if self.cur_token_type_ is Lexer.NAME and self.cur_token_ in fields:
+                key = self.cur_token_.lower()
+                value = self.expect_number_()
+                statements.append(
+                    ast.HheaField(self.cur_token_location_, key, value))
+            elif self.cur_token_ == ";":
+                continue
+            else:
+                raise FeatureLibError("Expected CaretOffset, Ascender, "
+                                      "Descender or LineGap",
+                                      self.cur_token_location_)
+
     def parse_table_name_(self, table):
         statements = table.statements
         while self.next_token_ != "}":

Lib/fontTools/feaLib/testdata/spec9d.fea

@@ -0,0 +1,6 @@
+table hhea {
+   CaretOffset -50;
+   Ascender 800;
+   Descender 200;
+   LineGap 200;
+} hhea;

Lib/fontTools/feaLib/testdata/spec9d.ttx

@@ -0,0 +1,24 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<ttFont>
+
+  <hhea>
+    <tableVersion value="1.0"/>
+    <ascent value="800"/>
+    <descent value="200"/>
+    <lineGap value="200"/>
+    <advanceWidthMax value="0"/>
+    <minLeftSideBearing value="0"/>
+    <minRightSideBearing value="0"/>
+    <xMaxExtent value="0"/>
+    <caretSlopeRise value="0"/>
+    <caretSlopeRun value="0"/>
+    <caretOffset value="-50"/>
+    <reserved0 value="0"/>
+    <reserved1 value="0"/>
+    <reserved2 value="0"/>
+    <reserved3 value="0"/>
+    <metricDataFormat value="0"/>
+    <numberOfHMetrics value="0"/>
+  </hhea>
+
+</ttFont>