From 653455b68e328ed97887bcc44ef087cacee45459 Mon Sep 17 00:00:00 2001
From: Jens Kutilek <webmail@kutilek.de>
Date: Wed, 4 Sep 2024 15:22:13 +0200
Subject: [PATCH] Handle rounding of component transforms when calculating
 glyph hashes

---
 Lib/extractor/formats/opentype.py | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/Lib/extractor/formats/opentype.py b/Lib/extractor/formats/opentype.py
index 8b9845d..6abbe7b 100644
--- a/Lib/extractor/formats/opentype.py
+++ b/Lib/extractor/formats/opentype.py
@@ -1,6 +1,8 @@
 import time
+from fontTools.misc.fixedTools import floatToFixedToFloat
 from fontTools.pens.boundsPen import ControlBoundsPen
 from fontTools.pens.hashPointPen import HashPointPen
+from fontTools.pens.roundingPen import RoundingPointPen
 from fontTools.ttLib import TTFont, TTLibError
 from fontTools.ttLib.tables._g_l_y_f import (
     OVERLAP_COMPOUND,
@@ -8,6 +10,7 @@
     USE_MY_METRICS,
 )
 from fontTools.ttLib.tables._h_e_a_d import mac_epoch_diff
+from functools import partial
 from extractor.exceptions import ExtractorError
 from extractor.stream import InstructionStream
 from extractor.tools import RelaxedInfo, copyAttr
@@ -157,7 +160,11 @@ def extractGlyphPrograms(source, destination):
             continue
 
         hash_pen = HashPointPen(dest_glyph.width, destination)
-        dest_glyph.drawPoints(hash_pen)
+        round_pen = RoundingPointPen(
+            hash_pen,
+            transformRoundFunc=partial(floatToFixedToFloat, precisionBits=14)
+        )
+        dest_glyph.drawPoints(round_pen)
         lib = dest_glyph.lib[TRUETYPE_INSTRUCTIONS_KEY] = {
             "formatVersion": "1",
             "id": hash_pen.hash,