Merge pull request #814 from googlefonts/component-hash-ttf

Check glyph hashes more thoroughly
googlefonts · May 13, 2024 · 779bbad · 779bbad
2 parents c85b363 + 7716a37
commit 779bbad
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Showing 3 changed files with 28 additions and 19 deletions.
diff --git a/Lib/ufo2ft/instructionCompiler.py b/Lib/ufo2ft/instructionCompiler.py
@@ -2,10 +2,13 @@
 
 import array
 import logging
+from functools import partial
 from typing import TYPE_CHECKING, Optional
 
 from fontTools import ttLib
+from fontTools.misc.fixedTools import floatToFixedToFloat
 from fontTools.pens.hashPointPen import HashPointPen
+from fontTools.pens.roundingPen import RoundingPointPen
 from fontTools.ttLib import newTable
 from fontTools.ttLib.tables._g_l_y_f import (
     OVERLAP_COMPOUND,
@@ -42,27 +45,28 @@ def __init__(
             self.autoUseMyMetrics = lambda ttGlyph, glyphName: None
 
     def _check_glyph_hash(
-        self, glyphName: str, ttglyph: TTGlyph, glyph_hash: Optional[str]
+        self, glyph: Glyph, ttglyph: TTGlyph, stored_hash: Optional[str]
     ) -> bool:
-        """Check if the supplied glyph hash from the ufo matches the current outlines."""
-        if glyph_hash is None:
+        """Check if the supplied stored glyph hash from the ufo matches the TTGlyph."""
+        if stored_hash is None:
             # The glyph hash is required
             logger.error(
-                f"Glyph hash missing, glyph '{glyphName}' will have "
+                f"Glyph hash missing, glyph '{glyph.name}' will have "
                 "no instructions in font."
             )
             return False
 
-        # Check the glyph hash against the TTGlyph that is being built
-
-        ttwidth = self.otf["hmtx"][glyphName][0]
+        ttwidth = self.otf["hmtx"][glyph.name][0]
         hash_pen = HashPointPen(ttwidth, self.otf.getGlyphSet())
-        ttglyph.drawPoints(hash_pen, self.otf["glyf"])
+        round_pen = RoundingPointPen(
+            hash_pen, transformRoundFunc=partial(floatToFixedToFloat, precisionBits=14)
+        )
+        ttglyph.drawPoints(round_pen, self.otf["glyf"])
 
-        if glyph_hash != hash_pen.hash:
+        if stored_hash != hash_pen.hash:
             logger.error(
-                f"The stored hash for glyph '{glyphName}' does not match the TrueType "
-                "output glyph. Glyph will have no instructions in the font."
+                f"The stored hash for glyph '{glyph.name}' does not match the "
+                "TrueType output glyph. Glyph will have no instructions in the font."
             )
             return False
         return True
@@ -132,7 +136,7 @@ def _compile_tt_glyph_program(
     ) -> None:
         self._check_tt_data_format(ttdata, f"glyph '{glyph.name}'")
         glyph_hash = ttdata.get("id", None)
-        if not self._check_glyph_hash(glyph.name, ttglyph, glyph_hash):
+        if not self._check_glyph_hash(glyph, ttglyph, glyph_hash):
             return
 
         # Compile the glyph program

diff --git a/tests/infoCompiler_test.py b/tests/infoCompiler_test.py
@@ -20,7 +20,6 @@ def testufo(FontClass):
 
 
 class InfoCompilerTest:
-
     def test_head(self, testttf, testufo):
         info = {"versionMajor": 5, "versionMinor": 6}
         compiler = InfoCompiler(testttf, testufo, info)

diff --git a/tests/instructionCompiler_test.py b/tests/instructionCompiler_test.py
@@ -1,8 +1,11 @@
 import logging
+from functools import partial
 
 import pytest
 from fontTools.cu2qu.ufo import font_to_quadratic
+from fontTools.misc.fixedTools import floatToFixedToFloat
 from fontTools.pens.hashPointPen import HashPointPen
+from fontTools.pens.roundingPen import RoundingPointPen
 from fontTools.ttLib.tables._g_l_y_f import (
     OVERLAP_COMPOUND,
     ROUND_XY_TO_GRID,
@@ -40,7 +43,10 @@ def expect_maxp(
 
 def get_hash_ufo(glyph, ufo):
     hash_pen = HashPointPen(glyph.width, ufo)
-    glyph.drawPoints(hash_pen)
+    round_pen = RoundingPointPen(
+        hash_pen, transformRoundFunc=partial(floatToFixedToFloat, precisionBits=14)
+    )
+    glyph.drawPoints(round_pen)
     return hash_pen.hash
 
 
@@ -89,15 +95,15 @@ def test_check_glyph_hash_match(self, quaduforeversed, quadfont):
         ttglyph = quadfont["glyf"]["a"]
 
         ic = InstructionCompiler(quaduforeversed, quadfont)
-        result = ic._check_glyph_hash(glyph.name, ttglyph, ufo_hash)
+        result = ic._check_glyph_hash(glyph, ttglyph, ufo_hash)
         assert result
 
     def test_check_glyph_hash_missing(self, quaduforeversed, quadfont):
         glyph = quaduforeversed["a"]
 
         ic = InstructionCompiler(quaduforeversed, quadfont)
         result = ic._check_glyph_hash(
-            glyph.name,
+            glyph,
             quadfont["glyf"]["a"],
             None,
         )
@@ -113,7 +119,7 @@ def test_check_glyph_hash_mismatch(self, testufo, quadfont):
 
         ic = InstructionCompiler(testufo, quadfont)
         result = ic._check_glyph_hash(
-            glyph.name,
+            glyph,
             ttglyph,
             ufo_hash,
         )
@@ -129,7 +135,7 @@ def test_check_glyph_hash_mismatch_composite(self, testufo, quadfont):
 
         ic = InstructionCompiler(testufo, quadfont)
         result = ic._check_glyph_hash(
-            glyph.name,
+            glyph,
             ttglyph,
             ufo_hash,
         )
@@ -146,7 +152,7 @@ def test_check_glyph_hash_mismatch_width(self, quaduforeversed, quadfont):
 
         ic = InstructionCompiler(quaduforeversed, quadfont)
         result = ic._check_glyph_hash(
-            glyph.name,
+            glyph,
             ttglyph,
             ufo_hash,
         )