Deprecate boost and use nanobind for the python binding

cv_bridge/CMakeLists.txt

@@ -18,27 +18,6 @@ if(ANDROID)
   set(CV_BRIDGE_DISABLE_PYTHON ON)
 endif()
 
-if(CV_BRIDGE_DISABLE_PYTHON)
-  find_package(Boost REQUIRED)
-  set(boost_python_target "")
-else()
-  find_package(Python3 REQUIRED COMPONENTS Development NumPy)
-  find_package(Boost QUIET)
-  if(Boost_VERSION_STRING VERSION_LESS "1.67")
-    # This is a bit of a hack to suppress a warning
-    #   No header defined for python3; skipping header check
-    # Which should only affect Boost versions < 1.67
-    # Resolution for newer versions:
-    #  https://gitlab.kitware.com/cmake/cmake/issues/16391
-    set(_Boost_PYTHON3_HEADERS "boost/python.hpp")
-    find_package(Boost REQUIRED COMPONENTS python3)
-    set(boost_python_target "Boost::python3")
-  else()
-    find_package(Boost REQUIRED COMPONENTS python${Python3_VERSION_MAJOR}${Python3_VERSION_MINOR})
-    set(boost_python_target "Boost::python${Python3_VERSION_MAJOR}${Python3_VERSION_MINOR}")
-  endif()
-endif()
-
 find_package(rclcpp REQUIRED)
 find_package(rcpputils REQUIRED)
 find_package(sensor_msgs REQUIRED)

cv_bridge/package.xml

@@ -19,9 +19,6 @@
   <buildtool_depend>ament_cmake_ros</buildtool_depend>
   <buildtool_depend>python_cmake_module</buildtool_depend>
 
-  <build_depend>libboost-dev</build_depend>
-  <build_depend>libboost-python-dev</build_depend>
-
   <depend>libopencv-dev</depend>
   <depend>python3-numpy</depend>
   <depend>rclcpp</depend>
@@ -30,7 +27,6 @@
   <depend>python3-opencv</depend>
 
   <exec_depend>ament_index_python</exec_depend>
-  <exec_depend>libboost-python</exec_depend>
 
   <test_depend>ament_cmake_gtest</test_depend>
   <test_depend>ament_cmake_pytest</test_depend>

cv_bridge/python/cv_bridge/__init__.py

@@ -3,6 +3,6 @@
 # python bindings
 # This try is just to satisfy doc jobs that are built differently.
 try:
-    from cv_bridge.boost.cv_bridge_boost import cvtColorForDisplay, getCvType
+    from cv_bridge.nanobind.cv_bridge_nanobind import cvtColorForDisplay, getCvType
 except ImportError:
     pass

cv_bridge/python/cv_bridge/core.py

@@ -89,11 +89,11 @@ def dtype_with_channels_to_cvtype2(self, dtype, n_channels):
         return '%sC%d' % (self.numpy_type_to_cvtype[dtype.name], n_channels)
 
     def cvtype2_to_dtype_with_channels(self, cvtype):
-        from cv_bridge.boost.cv_bridge_boost import CV_MAT_CNWrap, CV_MAT_DEPTHWrap
+        from cv_bridge.nanobind.cv_bridge_nanobind import CV_MAT_CNWrap, CV_MAT_DEPTHWrap
         return self.cvdepth_to_numpy_depth[CV_MAT_DEPTHWrap(cvtype)], CV_MAT_CNWrap(cvtype)
 
     def encoding_to_cvtype2(self, encoding):
-        from cv_bridge.boost.cv_bridge_boost import getCvType
+        from cv_bridge.nanobind.cv_bridge_nanobind import getCvType
 
         try:
             return getCvType(encoding)
@@ -135,7 +135,7 @@ def compressed_imgmsg_to_cv2(self, cmprs_img_msg, desired_encoding='passthrough'
         if desired_encoding == 'passthrough':
             return im
 
-        from cv_bridge.boost.cv_bridge_boost import cvtColor2
+        from cv_bridge.nanobind.cv_bridge_nanobind import cvtColor2
 
         try:
             res = cvtColor2(im, 'bgr8', desired_encoding)
@@ -183,12 +183,12 @@ def imgmsg_to_cv2(self, img_msg, desired_encoding='passthrough'):
 
         # If the byte order is different between the message and the system.
         if img_msg.is_bigendian == (sys.byteorder == 'little'):
-            im = im.byteswap().newbyteorder()
+            im = im.byteswap().view(im.dtype.newbyteorder())
 
         if desired_encoding == 'passthrough':
             return im
 
-        from cv_bridge.boost.cv_bridge_boost import cvtColor2
+        from cv_bridge.nanobind.cv_bridge_nanobind import cvtColor2
 
         try:
             res = cvtColor2(im, img_msg.encoding, desired_encoding)

cv_bridge/src/CMakeLists.txt

@@ -18,7 +18,6 @@ target_link_libraries(${PROJECT_NAME} PUBLIC
   rclcpp::rclcpp
 )
 target_link_libraries(${PROJECT_NAME} PRIVATE
-  Boost::headers
   rcpputils::rcpputils)
 
 install(TARGETS ${PROJECT_NAME} EXPORT export_${PROJECT_NAME}
@@ -32,20 +31,28 @@ install(FILES
   DESTINATION include/${PROJECT_NAME}/${PROJECT_NAME})
 
 if(NOT CV_BRIDGE_DISABLE_PYTHON)
-  Python3_add_library(${PROJECT_NAME}_boost MODULE module.cpp module_opencv4.cpp)
-  target_link_libraries(${PROJECT_NAME}_boost PRIVATE
+  find_package(Python 3 COMPONENTS Interpreter Development REQUIRED)
+  include(FetchContent)
+  FetchContent_Declare(
+    nanobind
+    GIT_REPOSITORY https://github.com/wjakob/nanobind.git
+    GIT_TAG v2.9.2
+  )
+
+  FetchContent_MakeAvailable(nanobind)
+  nanobind_add_module(${PROJECT_NAME}_nanobind MODULE module.cpp)
+  target_link_libraries(${PROJECT_NAME}_nanobind PRIVATE
     ${PROJECT_NAME}
-    ${boost_python_target}
-    Python3::NumPy)
-  target_compile_definitions(${PROJECT_NAME}_boost PRIVATE PYTHON3)
+  )
+  target_compile_definitions(${PROJECT_NAME}_nanobind PRIVATE PYTHON3)
 
   if(OpenCV_VERSION_MAJOR VERSION_EQUAL 4)
-    target_compile_definitions(${PROJECT_NAME}_boost PRIVATE OPENCV_VERSION_4)
+    target_compile_definitions(${PROJECT_NAME}_nanobind PRIVATE OPENCV_VERSION_4)
   endif()
 
-  set_target_properties(${PROJECT_NAME}_boost PROPERTIES
-                        LIBRARY_OUTPUT_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/boost/
+  set_target_properties(${PROJECT_NAME}_nanobind PROPERTIES
+                        LIBRARY_OUTPUT_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/nanobind/
                         PREFIX ""
   )
-  install(TARGETS ${PROJECT_NAME}_boost DESTINATION ${PYTHON_INSTALL_DIR}/${PROJECT_NAME}/boost/)
+  install(TARGETS ${PROJECT_NAME}_nanobind DESTINATION ${PYTHON_INSTALL_DIR}/${PROJECT_NAME}/nanobind/)
 endif()

cv_bridge/src/cv_bridge.cpp

@@ -36,7 +36,6 @@
 
 #include <cv_bridge/cv_bridge.hpp>
 #include <cv_bridge/rgb_colors.hpp>
-#include <boost/endian/conversion.hpp>
 #include <opencv2/imgcodecs.hpp>
 #include <opencv2/imgproc/imgproc.hpp>
 #include <sensor_msgs/image_encodings.hpp>