Merge pull request #20370 from ddacw:stub-gen-next

Python typing stub generation #20370

Add stub generation to `gen2.py`, addressing #14590.

### Pull Request Readiness Checklist

See details at https://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request

- [x] I agree to contribute to the project under Apache 2 License.
- [x] To the best of my knowledge, the proposed patch is not based on a code under GPL or other license that is incompatible with OpenCV
- [x] The PR is proposed to proper branch
- [x] There is reference to original bug report and related work
- [ ] There is accuracy test, performance test and test data in opencv_extra repository, if applicable
      Patch to opencv_extra has the same branch name.
- [ ] The feature is well documented and sample code can be built with the project CMake

modules/python/package/setup.py

@@ -1,9 +1,19 @@
 import os
-import sys
-import platform
 import setuptools
 
-SCRIPT_DIR=os.path.dirname(os.path.abspath(__file__))
+
+SCRIPT_DIR = os.path.dirname(os.path.abspath(__file__))
+
+
+def collect_module_typing_stub_files(root_module_path):
+    stub_files = []
+    for module_path, _, files in os.walk(root_module_path):
+        stub_files.extend(
+            map(lambda p: os.path.join(module_path, p),
+                filter(lambda f: f.endswith(".pyi"), files))
+        )
+    return stub_files
+
 
 def main():
     os.chdir(SCRIPT_DIR)
@@ -13,6 +23,13 @@ def main():
 
     long_description = 'Open Source Computer Vision Library Python bindings'  # TODO
 
+    root_module_path = os.path.join(SCRIPT_DIR, "cv2")
+    py_typed_path = os.path.join(root_module_path, "py.typed")
+    if os.path.isfile(py_typed_path):
+        typing_stub_files = collect_module_typing_stub_files(root_module_path)
+        if len(typing_stub_files) > 0:
+            typing_stub_files.append(py_typed_path)
+
     setuptools.setup(
         name=package_name,
         version=package_version,
@@ -22,6 +39,9 @@ def main():
         long_description=long_description,
         long_description_content_type="text/markdown",
         packages=setuptools.find_packages(),
+        package_data={
+            "cv2": typing_stub_files
+        },
         maintainer="OpenCV Team",
         install_requires="numpy",
         classifiers=[
@@ -55,5 +75,6 @@ def main():
         ],
     )
 
+
 if __name__ == '__main__':
     main()