clean up dependencies

Makefile

@@ -20,7 +20,7 @@ force_clean:
 	docker run --rm -v `pwd`:`pwd` -w `pwd` -it alpine/make make clean
 
 pytest:
-	python3 -m pip install pytest numpy
+	python3 -m pip install pytest numpy pillow
 	pytest tests # --capture=tee-sys
 .PHONY: test pytest
 

pyproject.toml

@@ -5,33 +5,31 @@ build-backend = "scikit_build_core.build"
 
 [project]
 name = "pybind11_pixelmatch"
-version = "0.1.5"
+version = "0.1.6"
 description="A C++17 port of the JavaScript pixelmatch library (with python binding), providing a small pixel-level image comparison library."
 readme = "README.md"
 authors = [
   { name = "district10", email = "dvorak4tzx@gmail.com" },
 ]
-requires-python = ">=3.7"
+requires-python = ">=3.9"
 classifiers = [
   "Development Status :: 4 - Beta",
   "License :: OSI Approved :: MIT License",
   "Programming Language :: Python :: 3 :: Only",
-  "Programming Language :: Python :: 3.7",
-  "Programming Language :: Python :: 3.8",
   "Programming Language :: Python :: 3.9",
   "Programming Language :: Python :: 3.10",
   "Programming Language :: Python :: 3.11",
+  "Programming Language :: Python :: 3.12",
+  "Programming Language :: Python :: 3.13",
+  "Programming Language :: Python :: 3.14",
 ]
-dependencies = [
-  "numpy",
-  "opencv-python",
-]
+dependencies = []
 
 [project.urls]
 Homepage = "https://github.com/cubao/pybind11_pixelmatch"
 
 [project.optional-dependencies]
-test = ["pytest"]
+test = ["pytest", "Pillow", "numpy", "opencv-python-headless"]
 
 
 # docs: https://scikit-build-core.readthedocs.io/en/latest/configuration.html

src/pybind11_pixelmatch/__init__.py

@@ -1,6 +1,10 @@
 from __future__ import annotations
 
 from pathlib import Path
+from typing import TYPE_CHECKING, Literal
+
+if TYPE_CHECKING:
+    import numpy as np
 
 from ._core import (
     Color,
@@ -11,31 +15,74 @@
     rgb2yiq,
 )
 
+Backend = Literal["cv2", "pillow"]
 
-def read_image(path):
-    import cv2
-    import numpy as np
 
+def read_image(
+    path: str,
+    *,
+    backend: Backend | None = None,
+) -> np.ndarray:
     assert Path(path).is_file(), f"{path} does not exist"
-    img = cv2.imread(path, cv2.IMREAD_UNCHANGED)
-    if img.shape[2] == 3:
-        B, G, R = cv2.split(img)
-        A = np.ones(B.shape, dtype=B.dtype) * 255
-        img = cv2.merge((R, G, B, A))
-    elif img.shape[2] == 4:
-        img = cv2.cvtColor(img, cv2.COLOR_BGRA2RGBA)
-    return img
-
-
-def write_image(path, img):
-    import cv2
-
-    if img.shape[2] == 3:
-        img = cv2.cvtColor(img, cv2.COLOR_RGB2BGR)
-    else:
-        img = cv2.cvtColor(img, cv2.COLOR_RGBA2BGRA)
+
+    if backend is None:
+        try:
+            import PIL  # noqa: F401
+
+            backend = "pillow"
+        except ImportError:
+            backend = "cv2"
+
+    if backend == "cv2":
+        import cv2
+        import numpy as np
+
+        img = cv2.imread(str(path), cv2.IMREAD_UNCHANGED)
+        if img.shape[2] == 3:
+            B, G, R = cv2.split(img)
+            A = np.ones(B.shape, dtype=B.dtype) * 255
+            img = cv2.merge((R, G, B, A))
+        elif img.shape[2] == 4:
+            img = cv2.cvtColor(img, cv2.COLOR_BGRA2RGBA)
+        return img
+
+    # pillow backend
+    import numpy as np
+    from PIL import Image
+
+    return np.array(Image.open(path).convert("RGBA"))
+
+
+def write_image(
+    path: str,
+    img: np.ndarray,
+    *,
+    backend: Backend | None = None,
+) -> None:
     Path(path).resolve().parent.mkdir(parents=True, exist_ok=True)
-    cv2.imwrite(path, img)
+
+    if backend is None:
+        try:
+            import PIL  # noqa: F401
+
+            backend = "pillow"
+        except ImportError:
+            backend = "cv2"
+
+    if backend == "cv2":
+        import cv2
+
+        if img.shape[2] == 3:
+            img = cv2.cvtColor(img, cv2.COLOR_RGB2BGR)
+        else:
+            img = cv2.cvtColor(img, cv2.COLOR_RGBA2BGRA)
+        cv2.imwrite(str(path), img)
+        return
+
+    # pillow backend
+    from PIL import Image
+
+    Image.fromarray(img).save(path)
 
 
 def normalize_color(rgba):

src/pybind11_pixelmatch/viewer.py

@@ -3,7 +3,7 @@
 import json
 import sys
 import tkinter as tk
-from functools import lru_cache
+from functools import cache
 from pathlib import Path
 
 import cv2
@@ -571,7 +571,7 @@ def align_image(
     return warp_matrix, aligned
 
 
-@lru_cache(maxsize=None)
+@cache
 def diff_image_options(
     threshold: float = 0.1,
     include_aa: bool = False,

tests/test_binding.py

@@ -68,3 +68,26 @@ def test_pixelmatch():
     num = pixelmatch(img1, img2, output=diff)
     assert num == 163889
     write_image("diff.png", diff)
+
+
+def test_read_image_backends_equivalent():
+    project_source_dir = str(Path(__file__).resolve().parent.parent)
+    path = f"{project_source_dir}/data/pic1.png"
+
+    img_cv2 = read_image(path, backend="cv2")
+    img_pil = read_image(path, backend="pillow")
+
+    assert img_cv2.shape == img_pil.shape
+    assert img_cv2.dtype == img_pil.dtype
+    assert np.array_equal(img_cv2, img_pil)
+
+
+def test_write_image_round_trip(tmp_path):
+    project_source_dir = str(Path(__file__).resolve().parent.parent)
+    original = read_image(f"{project_source_dir}/data/pic1.png")
+
+    for backend in ("cv2", "pillow"):
+        out = str(tmp_path / f"out_{backend}.png")
+        write_image(out, original, backend=backend)
+        reloaded = read_image(out, backend=backend)
+        assert np.array_equal(original, reloaded), f"round-trip failed for {backend}"