Replace io.BytesIO in type hints

.coveragerc

@@ -10,6 +10,9 @@ exclude_also =
     if DEBUG:
     # Don't complain about compatibility code for missing optional dependencies
     except ImportError
+    # Empty bodies in protocols or abstract methods
+    ^\s*def [a-zA-Z0-9_]+\(.*\)(\s*->.*)?:\s*\.\.\.(\s*#.*)?$
+    ^\s*\.\.\.(\s*#.*)?$
 
 [run]
 omit =

Tests/test_util.py

@@ -1,27 +1,16 @@
 from __future__ import annotations
 
+from pathlib import Path, PurePath
+
 import pytest
 
 from PIL import _util
 
 
-def test_is_path():
-    # Arrange
-    fp = "filename.ext"
-
-    # Act
-    it_is = _util.is_path(fp)
-
-    # Assert
-    assert it_is
-
-
-def test_path_obj_is_path():
-    # Arrange
-    from pathlib import Path
-
-    test_path = Path("filename.ext")
-
+@pytest.mark.parametrize(
+    "test_path", ["filename.ext", Path("filename.ext"), PurePath("filename.ext")]
+)
+def test_is_path(test_path):
     # Act
     it_is = _util.is_path(test_path)
 

docs/reference/internal_design.rst

@@ -1,5 +1,5 @@
-Internal Reference Docs
-=======================
+Internal Reference
+==================
 
 .. toctree::
   :maxdepth: 2

docs/reference/internal_modules.rst

@@ -33,6 +33,18 @@ Internal Modules
 Provides a convenient way to import type hints that are not available
 on some Python versions.
 
+.. py:class:: FileDescriptor
+
+    Typing alias.
+
+.. py:class:: StrOrBytesPath
+
+    Typing alias.
+
+.. py:class:: SupportsRead
+
+    An object that supports the read method.
+
 .. py:data:: TypeGuard
     :value: typing.TypeGuard
 

src/PIL/GdImageFile.py

@@ -27,11 +27,12 @@ class is not registered for use with :py:func:`PIL.Image.open()`.  To open a
 """
 from __future__ import annotations
 
-from io import BytesIO
+from typing import IO
 
 from . import ImageFile, ImagePalette, UnidentifiedImageError
 from ._binary import i16be as i16
 from ._binary import i32be as i32
+from ._typing import FileDescriptor, StrOrBytesPath
 
 
 class GdImageFile(ImageFile.ImageFile):
@@ -80,7 +81,9 @@ def _open(self) -> None:
         ]
 
 
-def open(fp: BytesIO, mode: str = "r") -> GdImageFile:
+def open(
+    fp: StrOrBytesPath | FileDescriptor | IO[bytes], mode: str = "r"
+) -> GdImageFile:
     """
     Load texture from a GD image file.
 

src/PIL/ImageFont.py

@@ -230,7 +230,7 @@ def load_from_bytes(f):
             )
 
         if is_path(font):
-            if isinstance(font, Path):
+            if isinstance(font, os.PathLike):
                 font = str(font)
             if sys.platform == "win32":
                 font_bytes_path = font if isinstance(font, bytes) else font.encode()

src/PIL/MpegImagePlugin.py

@@ -14,17 +14,16 @@
 #
 from __future__ import annotations
 
-from io import BytesIO
-
 from . import Image, ImageFile
 from ._binary import i8
+from ._typing import SupportsRead
 
 #
 # Bitstream parser
 
 
 class BitStream:
-    def __init__(self, fp: BytesIO) -> None:
+    def __init__(self, fp: SupportsRead[bytes]) -> None:
         self.fp = fp
         self.bits = 0
         self.bitbuffer = 0

src/PIL/_typing.py

@@ -1,6 +1,8 @@
 from __future__ import annotations
 
+import os
 import sys
+from typing import Protocol, TypeVar, Union
 
 if sys.version_info >= (3, 10):
     from typing import TypeGuard
@@ -15,4 +17,16 @@ def __class_getitem__(cls, item: Any) -> type[bool]:
                 return bool
 
 
-__all__ = ["TypeGuard"]
+_T_co = TypeVar("_T_co", covariant=True)
+
+
+class SupportsRead(Protocol[_T_co]):
+    def read(self, __length: int = ...) -> _T_co:
+        ...
+
+
+FileDescriptor = int
+StrOrBytesPath = Union[str, bytes, "os.PathLike[str]", "os.PathLike[bytes]"]
+
+
+__all__ = ["FileDescriptor", "TypeGuard", "StrOrBytesPath", "SupportsRead"]

src/PIL/_util.py

@@ -4,11 +4,11 @@
 from pathlib import Path
 from typing import Any, NoReturn
 
-from ._typing import TypeGuard
+from ._typing import StrOrBytesPath, TypeGuard
 
 
-def is_path(f: Any) -> TypeGuard[bytes | str | Path]:
-    return isinstance(f, (bytes, str, Path))
+def is_path(f: Any) -> TypeGuard[StrOrBytesPath]:
+    return isinstance(f, (bytes, str, os.PathLike))
 
 
 def is_directory(f: Any) -> TypeGuard[bytes | str | Path]: