[dehinter.font] conditionally clear head flags bit 4 only when LTSH and hdmx are not present

Author: chrissimpkins

lib/dehinter/font.py

@@ -186,8 +186,13 @@ def update_maxp_table(tt):
 # =========================================
 def update_head_table_flags(tt):
     if is_bit_k_set(tt["head"].flags, 4):
-        new_flags = clear_bit_k(tt["head"].flags, 4)
-        tt["head"].flags = new_flags
-        return True
+        # confirm that there is no LTSH or hdmx table
+        # bit 4 should be set if either of these tables are present in font
+        if has_hdmx_table(tt) or has_ltsh_table(tt):
+            return False
+        else:
+            new_flags = clear_bit_k(tt["head"].flags, 4)
+            tt["head"].flags = new_flags
+            return True
     else:
         return False

tests/test_font.py

@@ -249,14 +249,42 @@ def test_update_maxp_table():
 # =========================================
 # head table edits
 # =========================================
-def test_update_head_table_flags():
+def test_update_head_table_flags_without_ltsh_hdmx():
     tt = TTFont(FILEPATH_HINTED_TTF)
     assert (tt["head"].flags & (1 << 4)) != 0
+    remove_hdmx_table(tt)
+    remove_ltsh_table(tt)
     response = update_head_table_flags(tt)
     assert response is True
     assert (tt["head"].flags & (1 << 4)) == 0
 
 
+def test_update_head_table_flags_with_ltsh_hdmx():
+    tt = TTFont(FILEPATH_HINTED_TTF)
+    assert (tt["head"].flags & (1 << 4)) != 0
+    response = update_head_table_flags(tt)
+    assert response is False
+    assert (tt["head"].flags & (1 << 4)) != 0
+
+
+def test_update_head_table_flags_with_ltsh():
+    tt = TTFont(FILEPATH_HINTED_TTF)
+    assert (tt["head"].flags & (1 << 4)) != 0
+    remove_hdmx_table(tt)
+    response = update_head_table_flags(tt)
+    assert response is False
+    assert (tt["head"].flags & (1 << 4)) != 0
+
+
+def test_update_head_table_flags_with_hdmx():
+    tt = TTFont(FILEPATH_HINTED_TTF)
+    assert (tt["head"].flags & (1 << 4)) != 0
+    remove_ltsh_table(tt)
+    response = update_head_table_flags(tt)
+    assert response is False
+    assert (tt["head"].flags & (1 << 4)) != 0
+
+
 def test_update_head_table_flags_previously_cleared():
     tt = TTFont(FILEPATH_HINTED_TTF_2)
     assert (tt["head"].flags & (1 << 4)) == 0