Use enums for Modes and RawModes in C

.ci/requirements-mypy.txt

@@ -9,4 +9,4 @@ sphinx
 types-atheris
 types-defusedxml
 types-olefile
-types-setuptools
+types-setuptools>=75.2.0

setup.py

@@ -16,11 +16,14 @@
 import sys
 import warnings
 from collections.abc import Iterator
-from typing import Any
+from typing import TYPE_CHECKING, Any
 
 from setuptools import Extension, setup
 from setuptools.command.build_ext import build_ext
 
+if TYPE_CHECKING:
+    from setuptools import _BuildInfo
+
 
 def get_version() -> str:
     version_file = "src/PIL/_version.py"
@@ -1001,16 +1004,20 @@ def debug_build() -> bool:
     return hasattr(sys, "gettotalrefcount") or FUZZING_BUILD
 
 
+libraries: list[tuple[str, _BuildInfo]] = [
+    ("pil_imaging_mode", {"sources": ["src/libImaging/Mode.c"]}),
+]
+
 files: list[str | os.PathLike[str]] = ["src/_imaging.c"]
 for src_file in _IMAGING:
     files.append("src/" + src_file + ".c")
 for src_file in _LIB_IMAGING:
     files.append(os.path.join("src/libImaging", src_file + ".c"))
 ext_modules = [
-    Extension("PIL._imaging", files),
-    Extension("PIL._imagingft", ["src/_imagingft.c"]),
-    Extension("PIL._imagingcms", ["src/_imagingcms.c"]),
-    Extension("PIL._webp", ["src/_webp.c"]),
+    Extension("PIL._imaging", files, libraries=["pil_imaging_mode"]),
+    Extension("PIL._imagingft", ["src/_imagingft.c"], libraries=["pil_imaging_mode"]),
+    Extension("PIL._imagingcms", ["src/_imagingcms.c"], libraries=["pil_imaging_mode"]),
+    Extension("PIL._webp", ["src/_webp.c"], libraries=["pil_imaging_mode"]),
     Extension("PIL._imagingtk", ["src/_imagingtk.c", "src/Tk/tkImaging.c"]),
     Extension("PIL._imagingmath", ["src/_imagingmath.c"]),
     Extension("PIL._imagingmorph", ["src/_imagingmorph.c"]),
@@ -1026,6 +1033,7 @@ def debug_build() -> bool:
     setup(
         cmdclass={"build_ext": pil_build_ext},
         ext_modules=ext_modules,
+        libraries=libraries,
         zip_safe=not (debug_build() or PLATFORM_MINGW),
     )
 except RequiredDependencyException as err:

src/Tk/tkImaging.c

@@ -121,15 +121,16 @@ PyImagingPhotoPut(
 
     /* Mode */
 
-    if (strcmp(im->mode, "1") == 0 || strcmp(im->mode, "L") == 0) {
+    if (im->mode == IMAGING_MODE_1 || im->mode == IMAGING_MODE_L) {
         block.pixelSize = 1;
         block.offset[0] = block.offset[1] = block.offset[2] = block.offset[3] = 0;
-    } else if (strncmp(im->mode, "RGB", 3) == 0) {
+    } else if (im->mode == IMAGING_MODE_RGB || im->mode == IMAGING_MODE_RGBA ||
+               im->mode == IMAGING_MODE_RGBX || im->mode == IMAGING_MODE_RGBa) {
         block.pixelSize = 4;
         block.offset[0] = 0;
         block.offset[1] = 1;
         block.offset[2] = 2;
-        if (strcmp(im->mode, "RGBA") == 0) {
+        if (im->mode == IMAGING_MODE_RGBA) {
             block.offset[3] = 3; /* alpha (or reserved, under Tk 8.2) */
         } else {
             block.offset[3] = 0; /* no alpha */