Improve type hints (#9317)

Tests/test_file_gribstub.py

@@ -59,7 +59,7 @@ def test_handler(tmp_path: Path) -> None:
         def open(self, im: Image.Image) -> None:
             self.opened = True
 
-        def load(self, im: Image.Image) -> Image.Image:
+        def load(self, im: ImageFile.ImageFile) -> Image.Image:
             self.loaded = True
             im.fp.close()
             return Image.new("RGB", (1, 1))

Tests/test_file_hdf5stub.py

@@ -61,7 +61,7 @@ def test_handler(tmp_path: Path) -> None:
         def open(self, im: Image.Image) -> None:
             self.opened = True
 
-        def load(self, im: Image.Image) -> Image.Image:
+        def load(self, im: ImageFile.ImageFile) -> Image.Image:
             self.loaded = True
             im.fp.close()
             return Image.new("RGB", (1, 1))

Tests/test_file_iptc.py

@@ -143,6 +143,7 @@ def test_getiptcinfo_tiff() -> None:
 
     # Test with LONG tag type
     with Image.open("Tests/images/hopper.Lab.tif") as im:
+        assert isinstance(im, TiffImagePlugin.TiffImageFile)
         im.tag_v2.tagtype[TiffImagePlugin.IPTC_NAA_CHUNK] = TiffTags.LONG
         iptc = IptcImagePlugin.getiptcinfo(im)
 

Tests/test_file_libtiff.py

@@ -11,7 +11,15 @@ from typing import Any, NamedTuple
 
 import pytest
 
-from PIL import Image, ImageFilter, ImageOps, TiffImagePlugin, TiffTags, features
+from PIL import (
+    Image,
+    ImageFile,
+    ImageFilter,
+    ImageOps,
+    TiffImagePlugin,
+    TiffTags,
+    features,
+)
 from PIL.TiffImagePlugin import OSUBFILETYPE, SAMPLEFORMAT, STRIPOFFSETS, SUBIFD
 
 from .helper import (
@@ -27,7 +35,7 @@ from .helper import (
 
 @skip_unless_feature("libtiff")
 class LibTiffTestCase:
-    def _assert_noerr(self, tmp_path: Path, im: TiffImagePlugin.TiffImageFile) -> None:
+    def _assert_noerr(self, tmp_path: Path, im: ImageFile.ImageFile) -> None:
         """Helper tests that assert basic sanity about the g4 tiff reading"""
         # 1 bit
         assert im.mode == "1"
@@ -370,6 +378,7 @@ class TestFileLibTiff(LibTiffTestCase):
         im.save(out, tiffinfo=ifd)
 
         with Image.open(out) as reloaded:
+            assert isinstance(reloaded, TiffImagePlugin.TiffImageFile)
             assert reloaded.tag_v2[37000] == 100
 
     def test_inknames_tag(
@@ -1146,9 +1155,9 @@ class TestFileLibTiff(LibTiffTestCase):
         with Image.open("Tests/images/g4_orientation_1.tif") as base_im:
             for i in range(2, 9):
                 with Image.open("Tests/images/g4_orientation_" + str(i) + ".tif") as im:
-                    im = ImageOps.exif_transpose(im)
+                    im_transposed = ImageOps.exif_transpose(im)
 
-                    assert_image_similar(base_im, im, 0.7)
+                assert_image_similar(base_im, im_transposed, 0.7)
 
     @pytest.mark.parametrize(
         "test_file",

Tests/test_file_png.py

@@ -787,7 +787,9 @@ class TestFilePng:
             im.save(test_file, exif=im.getexif())
 
         with Image.open(test_file) as reloaded:
+            assert isinstance(reloaded, PngImagePlugin.PngImageFile)
             exif = reloaded._getexif()
+        assert exif is not None
         assert exif[305] == "Adobe Photoshop CS Macintosh"
 
     def test_exif_argument(self, tmp_path: Path) -> None:

src/PIL/GifImagePlugin.py

@@ -116,8 +116,8 @@ class GifImageFile(ImageFile.ImageFile):
             # check if palette contains colour indices
             p = self.fp.read(3 << bits)
             if self._is_palette_needed(p):
-                p = ImagePalette.raw("RGB", p)
-                self.global_palette = self.palette = p
+                palette = ImagePalette.raw("RGB", p)
+                self.global_palette = self.palette = palette
 
         self._fp = self.fp  # FIXME: hack
         self.__rewind = self.fp.tell()
@@ -256,7 +256,7 @@ class GifImageFile(ImageFile.ImageFile):
                         info["comment"] += b"\n" + comment
                     else:
                         info["comment"] = comment
-                    s = None
+                    s = b""
                     continue
                 elif s[0] == 255 and frame == 0 and block is not None:
                     #
@@ -299,7 +299,7 @@ class GifImageFile(ImageFile.ImageFile):
                 bits = self.fp.read(1)[0]
                 self.__offset = self.fp.tell()
                 break
-            s = None
+            s = b""
 
         if interlace is None:
             msg = "image not found in GIF frame"

src/PIL/Image.py

@@ -1519,6 +1519,9 @@ class Image:
                     "".join(self.info["Raw profile type exif"].split("\n")[3:])
                 )
             elif hasattr(self, "tag_v2"):
+                from . import TiffImagePlugin
+
+                assert isinstance(self, TiffImagePlugin.TiffImageFile)
                 self._exif.bigtiff = self.tag_v2._bigtiff
                 self._exif.endian = self.tag_v2._endian
                 self._exif.load_from_fp(self.fp, self.tag_v2._offset)

src/PIL/XVThumbImagePlugin.py

@@ -66,10 +66,10 @@ class XVThumbImageFile(ImageFile.ImageFile):
                 break
 
         # parse header line (already read)
-        s = s.strip().split()
+        w, h = s.strip().split(maxsplit=2)[:2]
 
         self._mode = "P"
-        self._size = int(s[0]), int(s[1])
+        self._size = int(w), int(h)
 
         self.palette = ImagePalette.raw("RGB", PALETTE)