From 145d4b1e3ba3528300ac41be09ecd624af412ed3 Mon Sep 17 00:00:00 2001
From: Chen Jiali <chenjiali@radxa.com>
Date: Wed, 11 Sep 2024 20:02:06 +0800
Subject: [PATCH] OpenCVDetectPython.cmake: prefer using FindPython

Reason for change:

1. PythonInterp will misdetect Python3 as Python2 in distributions using newer versions of CMake:

```
-- Found PythonInterp: /usr/bin/python3 (found suitable version "3.11.2", minimum required is "2.7")
-- Found PythonLibs: /usr/lib/aarch64-linux-gnu/libpython3.11.so (found suitable exact version "3.11.2")
-- Found PythonInterp: /usr/bin/python3 (found suitable version "3.11.2", minimum required is "3")
-- Found PythonLibs: /usr/lib/aarch64-linux-gnu/libpython3.11.so (found suitable exact version "3.11.2")
```

2. PythonInterp will be removed soon and unusable: https://cmake.org/cmake/help/latest/module/FindPythonInterp.html, for Debian that is Debian 13

Signed-off-by: Chen Jiali <chenjiali@radxa.com>
---
 cmake/modules/OpenCVDetectPython.cmake | 64 ++++++++++++++++++--------
 1 file changed, 45 insertions(+), 19 deletions(-)

diff --git a/cmake/modules/OpenCVDetectPython.cmake b/cmake/modules/OpenCVDetectPython.cmake
index c0441c458..5f3db2d89 100644
--- a/cmake/modules/OpenCVDetectPython.cmake
+++ b/cmake/modules/OpenCVDetectPython.cmake
@@ -29,29 +29,55 @@ function(find_python preferred_version min_version library_env include_dir_env
 if(NOT ${found})
   if(${executable})
     set(PYTHON_EXECUTABLE "${${executable}}")
+    set(Python_EXECUTABLE "${${executable}}")
   endif()
 
-  find_package(PythonInterp "${preferred_version}")
-  if(NOT PYTHONINTERP_FOUND)
-    find_package(PythonInterp "${min_version}")
-  endif()
+  if(${CMAKE_VERSION} VERSION_GREATER_EQUAL "3.12")
+    find_package(Python "${preferred_version}" COMPONENTS Interpreter)
+    if(NOT Python_Interpreter_FOUND)
+      find_package(Python "${min_version}" COMPONENTS Interpreter)
+    endif()
 
-  if(PYTHONINTERP_FOUND)
-    # Copy outputs
-    set(_found ${PYTHONINTERP_FOUND})
-    set(_executable ${PYTHON_EXECUTABLE})
-    set(_version_string ${PYTHON_VERSION_STRING})
-    set(_version_major ${PYTHON_VERSION_MAJOR})
-    set(_version_minor ${PYTHON_VERSION_MINOR})
-    set(_version_patch ${PYTHON_VERSION_PATCH})
+    if(Python_Interpreter_FOUND)
+      # Copy outputs
+      set(_found ${Python_Interpreter_FOUND})
+      set(_executable ${Python_EXECUTABLE})
+      set(_version_string ${Python_VERSION})
+      set(_version_major ${Python_VERSION_MAJOR})
+      set(_version_minor ${Python_VERSION_MINOR})
+      set(_version_patch ${Python_VERSION_PATCH})
 
-    # Clear find_host_package side effects
-    unset(PYTHONINTERP_FOUND)
-    unset(PYTHON_EXECUTABLE CACHE)
-    unset(PYTHON_VERSION_STRING)
-    unset(PYTHON_VERSION_MAJOR)
-    unset(PYTHON_VERSION_MINOR)
-    unset(PYTHON_VERSION_PATCH)
+      # Clear find_host_package side effects
+      unset(Python_Interpreter_FOUND)
+      unset(Python_EXECUTABLE CACHE)
+      unset(Python_VERSION)
+      unset(Python_VERSION_MAJOR)
+      unset(Python_VERSION_MINOR)
+      unset(Python_VERSION_PATCH)
+    endif()
+  else()
+    find_package(PythonInterp "${preferred_version}")
+    if(NOT PYTHONINTERP_FOUND)
+      find_package(PythonInterp "${min_version}")
+    endif()
+
+    if(PYTHONINTERP_FOUND)
+      # Copy outputs
+      set(_found ${PYTHONINTERP_FOUND})
+      set(_executable ${PYTHON_EXECUTABLE})
+      set(_version_string ${PYTHON_VERSION_STRING})
+      set(_version_major ${PYTHON_VERSION_MAJOR})
+      set(_version_minor ${PYTHON_VERSION_MINOR})
+      set(_version_patch ${PYTHON_VERSION_PATCH})
+
+      # Clear find_host_package side effects
+      unset(PYTHONINTERP_FOUND)
+      unset(PYTHON_EXECUTABLE CACHE)
+      unset(PYTHON_VERSION_STRING)
+      unset(PYTHON_VERSION_MAJOR)
+      unset(PYTHON_VERSION_MINOR)
+      unset(PYTHON_VERSION_PATCH)
+    endif()
   endif()
 
   if(_found)