Add support for pickling TrueType fonts

Tests/test_pickle.py

@@ -2,9 +2,12 @@
 
 import pytest
 
-from PIL import Image
+from PIL import Image, ImageDraw, ImageFont
 
-from .helper import skip_unless_feature
+from .helper import assert_image_equal, skip_unless_feature
+
+FONT_SIZE = 20
+FONT_PATH = "Tests/fonts/DejaVuSans/DejaVuSans.ttf"
 
 
 def helper_pickle_file(tmp_path, pickle, protocol, test_file, mode):
@@ -92,3 +95,48 @@ def test_pickle_tell():
 
     # Assert
     assert unpickled_image.tell() == 0
+
+
+def helper_assert_pickled_font_images(font1, font2):
+    # Arrange
+    im1 = Image.new(mode="RGBA", size=(300, 100))
+    im2 = Image.new(mode="RGBA", size=(300, 100))
+    draw1 = ImageDraw.Draw(im1)
+    draw2 = ImageDraw.Draw(im2)
+    txt = "Hello World!"
+
+    # Act
+    draw1.text((10, 10), txt, font=font1)
+    draw2.text((10, 10), txt, font=font2)
+
+    # Assert
+    assert_image_equal(im1, im2)
+
+
+@pytest.mark.parametrize("protocol", list(range(0, pickle.HIGHEST_PROTOCOL + 1)))
+def test_pickle_font_string(protocol):
+    # Arrange
+    font = ImageFont.truetype(FONT_PATH, FONT_SIZE)
+
+    # Act: roundtrip
+    pickled_font = pickle.dumps(font, protocol)
+    unpickled_font = pickle.loads(pickled_font)
+
+    # Assert
+    helper_assert_pickled_font_images(font, unpickled_font)
+
+
+@pytest.mark.parametrize("protocol", list(range(0, pickle.HIGHEST_PROTOCOL + 1)))
+def test_pickle_font_file(tmp_path, protocol):
+    # Arrange
+    font = ImageFont.truetype(FONT_PATH, FONT_SIZE)
+    filename = str(tmp_path / "temp.pkl")
+
+    # Act: roundtrip
+    with open(filename, "wb") as f:
+        pickle.dump(font, f, protocol)
+    with open(filename, "rb") as f:
+        unpickled_font = pickle.load(f)
+
+    # Assert
+    helper_assert_pickled_font_images(font, unpickled_font)

docs/releasenotes/9.0.0.rst

@@ -72,6 +72,22 @@ Support has been added for the "title" argument in
 argument will also now be supported, e.g. ``im.show(title="My Image")`` and
 ``ImageShow.show(im, title="My Image")``.
 
+Added support for pickling TrueType fonts
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+TrueType fonts may now be pickled and unpickled. For example:
+
+.. code-block:: python
+
+    import pickle
+    from PIL import ImageFont
+
+    font = ImageFont.truetype("arial.ttf", size=30)
+    pickled_font = pickle.dumps(font, protocol=pickle.HIGHEST_PROTOCOL)
+
+    # Later...
+    unpickled_font = pickle.loads(pickled_font)
+
 Security
 ========
 

src/PIL/ImageFont.py

@@ -196,6 +196,13 @@ def load_from_bytes(f):
         else:
             load_from_bytes(font)
 
+    def __getstate__(self):
+        return [self.path, self.size, self.index, self.encoding, self.layout_engine]
+
+    def __setstate__(self, state):
+        path, size, index, encoding, layout_engine = state
+        self.__init__(path, size, index, encoding, layout_engine)
+
     def _multiline_split(self, text):
         split_character = "\n" if isinstance(text, str) else b"\n"
         return text.split(split_character)