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fix: load Pillow's FreeType before Pango to stop symbol clash (#16) #17

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Merged
AmitMY merged 2 commits into from
Oct 7, 2026
Merged

fix: load Pillow's FreeType before Pango to stop symbol clash (#16) #17

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61769b6
fix: load Pillow's FreeType before Pango to stop symbol clash (#16)
AmitMY Oct 7, 2026
401210b
fix: guard every Pango import, not just the pixel_renderer package
AmitMY Oct 7, 2026
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4 changes: 4 additions & 0 deletions font_configurator/font_configurator.py
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Original file line number Diff line number Diff line change
Expand Up @@ -22,6 +22,10 @@

gi.require_version("Pango", "1.0")
gi.require_version("PangoCairo", "1.0")
# Pillow's FreeType must be loaded before Pango: GI loads Pango with RTLD_GLOBAL, after which Pillow's
# bundled FreeType/HarfBuzz would bind to the system libraries and corrupt SignWriting rendering.
# See https://github.com/sign/pixel-renderer/issues/16
from PIL import ImageFont # noqa: E402, F401, I001
from gi.repository import Pango, PangoCairo # type: ignore # noqa: E402, F401

FONTCONFIG_CACHE_DIR = pathlib.Path(user_cache_dir("font_configurator"))
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4 changes: 4 additions & 0 deletions pixel_renderer/renderer.py
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Expand Up @@ -11,6 +11,10 @@
gi.require_version("Pango", "1.0")
gi.require_version("PangoCairo", "1.0")
gi.require_foreign("cairo")
# Pillow's FreeType must be loaded before Pango: GI loads Pango with RTLD_GLOBAL, after which Pillow's
# bundled FreeType/HarfBuzz would bind to the system libraries and corrupt SignWriting rendering.
# See https://github.com/sign/pixel-renderer/issues/16
from PIL import ImageFont # noqa: E402, F401, I001
from gi.repository import Pango, PangoCairo # noqa: E402

# Reusable measurement context - avoids creating new surface/context/layout per call
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17 changes: 17 additions & 0 deletions tests/pixel_renderer/test_freetype_isolation.py
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@@ -0,0 +1,17 @@
import subprocess
import sys

import pytest

FREETYPE_VERSION = "from PIL import ImageFont, features; print(features.version('freetype2'))"


def freetype_version_after(setup: str) -> str:
code = f"{setup}\n{FREETYPE_VERSION}"
return subprocess.run([sys.executable, "-c", code], capture_output=True, text=True, check=True).stdout.strip()


@pytest.mark.parametrize("module", ["pixel_renderer", "pixel_renderer.renderer", "font_configurator.font_configurator"])
def test_pillow_keeps_its_own_freetype(module):
"""Pillow must not bind to the system FreeType loaded by Pango (issue #16)."""
assert freetype_version_after(f"import {module}") == freetype_version_after("")
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