python: support free-threading

CMakeLists.txt

@@ -15,6 +15,7 @@ include (CTest)
 
 check_cxx_compiler_flag (-Wa,-mbig-obj HAVE_MBIG_OBJ)
 check_cxx_compiler_flag (/bigobj HAVE_BIGOBJ)
+check_cxx_compiler_flag (/Zc:preprocessor HAVE_ZC_PREPROCESSOR)
 
 find_package (Boost 1.70 COMPONENTS unit_test_framework NO_MODULE)
 find_package (Eigen3 3.3.7 REQUIRED NO_MODULE)
@@ -30,6 +31,14 @@ endif (MSVC AND MSVC_VERSION GREATER_EQUAL 1930)
 
 check_cxx_symbol_exists (std::execution::par execution HAVE_EXECUTION)
 
+if (WIN32)
+  add_compile_definitions (WIN32_LEAN_AND_MEAN)
+endif (WIN32)
+
+if (HAVE_ZC_PREPROCESSOR)
+  add_compile_options (/Zc:preprocessor)
+endif (HAVE_ZC_PREPROCESSOR)
+
 add_library (hogpp INTERFACE)
 add_library (hogpp::hogpp ALIAS hogpp)
 
@@ -81,6 +90,7 @@ if (pybind11_FOUND AND Python_Development_FOUND)
     python/blocknormalizer.hpp
     python/formatter.hpp
     python/hogpp.cpp
+    python/hogpp.hpp
     python/integralhogdescriptor.cpp
     python/integralhogdescriptor.hpp
     python/magnitude.cpp

python/hogpp.cpp

@@ -26,11 +26,19 @@
 
 #include "binning.hpp"
 #include "blocknormalizer.hpp"
+#include "hogpp.hpp"
 #include "integralhogdescriptor.hpp"
 #include "magnitude.hpp"
 #include "type_caster/bounds.hpp"
 
-PYBIND11_MODULE(hogpp, m)
+#if defined(HOGPP_GIL_DISABLED)
+#define HOGPP_MODULE(name, module, ...) \
+    PYBIND11_MODULE(name, module, pybind11::mod_gil_not_used())
+#else // !defined(HOGPP_GIL_DISABLED)
+#define HOGPP_MODULE PYBIND11_MODULE
+#endif // defined(HOGPP_GIL_DISABLED)
+
+HOGPP_MODULE(hogpp, m)
 {
     namespace py = pybind11;
 

python/hogpp.hpp

@@ -0,0 +1,36 @@
+//
+// HOGpp - Fast histogram of oriented gradients computation using integral
+// histograms
+//
+// Copyright 2024 Sergiu Deitsch <sergiu.deitsch@gmail.com>
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+#ifndef PYTHON_HOGPP_HPP
+#define PYTHON_HOGPP_HPP
+
+#include <pybind11/pybind11.h>
+
+#define HOGPP_PYBIND11_MAKE_VERSION(major, minor, patch) \
+    ((major) << 16 | (minor) << 8 | (patch))
+
+#define HOGPP_PYBIND11_VERSION_AT_LEAST(...)          \
+    (((PYBIND11_VERSION_HEX & 0xFF'FF'FF'00) >> 8) >= \
+     HOGPP_PYBIND11_MAKE_VERSION(__VA_ARGS__))
+
+#if defined(Py_GIL_DISABLED) && HOGPP_PYBIND11_VERSION_AT_LEAST(2, 13, 0)
+#define HOGPP_GIL_DISABLED
+#endif // (defined(Py_GIL_DISABLED) && HOGPP_PYBIND11_AT_LEAST(2, 13, 0))
+
+#endif // PYTHON_HOGPP_HPP

python/integralhogdescriptor.cpp

@@ -40,6 +40,7 @@
 #if defined(HAVE_OPENCV)
 #include "type_caster/opencv.hpp"
 #endif // defined(HAVE_OPENCV)
+#include "hogpp.hpp"
 #include "type_caster/tensor.hpp"
 
 namespace {
@@ -547,7 +548,9 @@ pybind11::object IntegralHOGDescriptor::featuresROIs(
         };
 
         {
+#if !defined(HOGPP_GIL_DISABLED)
             pybind11::gil_scoped_release release;
+#endif // !defined(HOGPP_GIL_DISABLED)
 
             // Process the remaining bounds
             std::for_each(