From 469c9ad963294a3acc2f48f16171dfdb131d0af1 Mon Sep 17 00:00:00 2001
From: Cosimo Lupo <clupo@google.com>
Date: Tue, 23 May 2023 13:16:02 +0100
Subject: [PATCH] add option to skip glyphDataFormat check for speed

If one is certain that the glyph data has compatible format and prefers not to wait for each glyph flag to checked...
---
 Lib/fontTools/fontBuilder.py          | 9 ++++-----
 Tests/fontBuilder/fontBuilder_test.py | 4 ++++
 2 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/Lib/fontTools/fontBuilder.py b/Lib/fontTools/fontBuilder.py
index 58ecce43a..8bbcc6ac5 100644
--- a/Lib/fontTools/fontBuilder.py
+++ b/Lib/fontTools/fontBuilder.py
@@ -648,7 +648,7 @@ class FontBuilder(object):
         for fontDict in topDict.FDArray:
             fontDict.Private.vstore = vstore
 
-    def setupGlyf(self, glyphs, calcGlyphBounds=True):
+    def setupGlyf(self, glyphs, calcGlyphBounds=True, checkFormat=True):
         """Create the `glyf` table from a dict, that maps glyph names
         to `fontTools.ttLib.tables._g_l_y_f.Glyph` objects, for example
         as made by `fontTools.pens.ttGlyphPen.TTGlyphPen`.
@@ -657,13 +657,12 @@ class FontBuilder(object):
         calculated. Only pass False if your glyph objects already have
         their bounding box values set.
 
-        Raises ValueError if any of the glyphs contains cubic curves or is a variable
-        composite but the `head` table has `glyphDataFormat` set to 0 (instead of 1).
+        If `checkFormat` is True, raise ValueError if any of the glyphs contains
+        cubic curves or is a variable composite but head.glyphDataFormat=0.
         """
         assert self.isTTF
 
-        glyphDataFormat = self.font["head"].glyphDataFormat
-        if glyphDataFormat == 0:
+        if checkFormat and self.font["head"].glyphDataFormat == 0:
             for name, g in glyphs.items():
                 if g.isVarComposite():
                     raise ValueError(
diff --git a/Tests/fontBuilder/fontBuilder_test.py b/Tests/fontBuilder/fontBuilder_test.py
index 589bc676b..6131a972c 100644
--- a/Tests/fontBuilder/fontBuilder_test.py
+++ b/Tests/fontBuilder/fontBuilder_test.py
@@ -145,12 +145,16 @@ def test_build_cubic_ttf(tmp_path):
     glyph = pen.glyph()
     glyphs = {"A": glyph}
 
+    # cubic outlines are not allowed in glyf table format 0
     fb = FontBuilder(1000, isTTF=True, glyphDataFormat=0)
     with pytest.raises(
         ValueError, match="Glyph 'A' has cubic Bezier outlines, but glyphDataFormat=0"
     ):
         fb.setupGlyf(glyphs)
+    # can skip check if feeling adventurous
+    fb.setupGlyf(glyphs, checkFormat=False)
 
+    # cubics are (will be) allowed in glyf table format 1
     fb = FontBuilder(1000, isTTF=True, glyphDataFormat=1)
     fb.setupGlyf(glyphs)
     assert "A" in fb.font["glyf"].glyphs