Merge pull request #19982 from TolyaTalamanov:at/new-python-operation-api

G-API: New python operations API

* Reimplement test using decorators

* Custom python operation API

* Remove wip status

* python: support Python code in bindings (through loader only)

* cleanup, skip tests for Python 2.x (not supported)

* python 2.x can't skip unittest modules

* Clean up

* Clean up

* Fix segfault python3.9

Co-authored-by: Alexander Alekhin <alexander.a.alekhin@gmail.com>

modules/python/common.cmake

@@ -218,6 +218,28 @@ if(NOT OPENCV_SKIP_PYTHON_LOADER)
   endif()
   configure_file("${PYTHON_SOURCE_DIR}/package/template/config-x.y.py.in" "${__python_loader_install_tmp_path}/cv2/${__target_config}" @ONLY)
   install(FILES "${__python_loader_install_tmp_path}/cv2/${__target_config}" DESTINATION "${OPENCV_PYTHON_INSTALL_PATH}/cv2/" COMPONENT python)
+
+  # handle Python extra code
+  foreach(m ${OPENCV_MODULES_BUILD})
+    if (";${OPENCV_MODULE_${m}_WRAPPERS};" MATCHES ";python;" AND HAVE_${m}
+        AND EXISTS "${OPENCV_MODULE_${m}_LOCATION}/misc/python/package"
+    )
+      set(__base "${OPENCV_MODULE_${m}_LOCATION}/misc/python/package")
+      file(GLOB_RECURSE extra_py_files
+          RELATIVE "${__base}"
+          "${__base}/**/*.py"
+      )
+      if(extra_py_files)
+        list(SORT extra_py_files)
+        foreach(f ${extra_py_files})
+          configure_file("${__base}/${f}" "${__loader_path}/cv2/_extra_py_code/${f}" COPYONLY)
+          install(FILES "${__base}/${f}" DESTINATION "${OPENCV_PYTHON_INSTALL_PATH}/cv2/_extra_py_code/${f}" COMPONENT python)
+        endforeach()
+      else()
+        message(WARNING "Module ${m} has no .py files in misc/python/package")
+      endif()
+    endif()
+  endforeach(m)
 endif()  # NOT OPENCV_SKIP_PYTHON_LOADER
 
 unset(PYTHON_SRC_DIR)

modules/python/package/cv2/__init__.py

@@ -4,6 +4,8 @@ OpenCV Python binary extension loader
 import os
 import sys
 
+__all__ = []
+
 try:
     import numpy
     import numpy.core.multiarray
@@ -13,6 +15,14 @@ except ImportError:
     print('    pip install numpy')
     raise
 
+
+py_code_loader = None
+if sys.version_info[:2] >= (3, 0):
+    try:
+        from . import _extra_py_code as py_code_loader
+    except:
+        pass
+
 # TODO
 # is_x64 = sys.maxsize > 2**32
 
@@ -97,6 +107,11 @@ def bootstrap():
     except:
         pass
 
+    if DEBUG: print('OpenCV loader: binary extension... OK')
+
+    if py_code_loader:
+        py_code_loader.init('cv2')
+
     if DEBUG: print('OpenCV loader: DONE')
 
 bootstrap()

modules/python/package/cv2/_extra_py_code/__init__.py

@@ -0,0 +1,53 @@
+import sys
+import importlib
+
+__all__ = ['init']
+
+
+DEBUG = False
+if hasattr(sys, 'OpenCV_LOADER_DEBUG'):
+    DEBUG = True
+
+
+def _load_py_code(base, name):
+    try:
+        m = importlib.import_module(__name__ + name)
+    except ImportError:
+        return  # extension doesn't exist?
+
+    if DEBUG: print('OpenCV loader: added python code extension for: ' + name)
+
+    if hasattr(m, '__all__'):
+        export_members = { k : getattr(m, k) for k in m.__all__ }
+    else:
+        export_members = m.__dict__
+
+    for k, v in export_members.items():
+        if k.startswith('_'):  # skip internals
+            continue
+        if isinstance(v, type(sys)):  # don't bring modules
+            continue
+        if DEBUG: print('    symbol: {} = {}'.format(k, v))
+        setattr(sys.modules[base + name ], k, v)
+
+    del sys.modules[__name__ + name]
+
+
+# TODO: listdir
+def init(base):
+    _load_py_code(base, '.cv2')  # special case
+    prefix = base
+    prefix_len = len(prefix)
+
+    modules = [ m for m in sys.modules.keys() if m.startswith(prefix) ]
+    for m in modules:
+        m2 = m[prefix_len:]  # strip prefix
+        if len(m2) == 0:
+            continue
+        if m2.startswith('._'):  # skip internals
+            continue
+        if m2.startswith('.load_config_'):  # skip helper files
+            continue
+        _load_py_code(base, m2)
+
+    del sys.modules[__name__]

modules/python/python_loader.cmake

@@ -25,10 +25,12 @@ endif()
 set(PYTHON_LOADER_FILES
     "setup.py" "cv2/__init__.py"
     "cv2/load_config_py2.py" "cv2/load_config_py3.py"
+    "cv2/_extra_py_code/__init__.py"
 )
 foreach(fname ${PYTHON_LOADER_FILES})
   get_filename_component(__dir "${fname}" DIRECTORY)
-  file(COPY "${PYTHON_SOURCE_DIR}/package/${fname}" DESTINATION "${__loader_path}/${__dir}")
+  # avoid using of file(COPY) to rerun CMake on changes
+  configure_file("${PYTHON_SOURCE_DIR}/package/${fname}" "${__loader_path}/${fname}" COPYONLY)
   if(fname STREQUAL "setup.py")
     if(OPENCV_PYTHON_SETUP_PY_INSTALL_PATH)
       install(FILES "${PYTHON_SOURCE_DIR}/package/${fname}" DESTINATION "${OPENCV_PYTHON_SETUP_PY_INSTALL_PATH}" COMPONENT python)