feat: python bindings for image_transport and publish

image_transport/include/image_transport/image_transport.hpp

@@ -112,6 +112,12 @@ class ImageTransport
   IMAGE_TRANSPORT_PUBLIC
   explicit ImageTransport(rclcpp::Node::SharedPtr node);
 
+  IMAGE_TRANSPORT_PUBLIC
+  ImageTransport(const ImageTransport & other);
+
+  IMAGE_TRANSPORT_PUBLIC
+  ImageTransport & operator=(const ImageTransport & other);
+
   IMAGE_TRANSPORT_PUBLIC
   ~ImageTransport();
 
@@ -364,6 +370,11 @@ class ImageTransport
   std::unique_ptr<Impl> impl_;
 };
 
+struct ImageTransport::Impl
+{
+  rclcpp::Node::SharedPtr node_;
+};
+
 }  // namespace image_transport
 
 #endif  // IMAGE_TRANSPORT__IMAGE_TRANSPORT_HPP_

image_transport/src/image_transport.cpp

@@ -128,10 +128,8 @@ std::vector<std::string> getLoadableTransports()
   return loadableTransports;
 }
 
-struct ImageTransport::Impl
-{
-  rclcpp::Node::SharedPtr node_;
-};
+ImageTransport::ImageTransport(const ImageTransport & other)
+: impl_(std::make_unique<Impl>(*other.impl_)) {}
 
 ImageTransport::ImageTransport(rclcpp::Node::SharedPtr node)
 : impl_(std::make_unique<ImageTransport::Impl>())

image_transport_py/CHANGELOG.rst

@@ -0,0 +1,3 @@
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+Changelog for package image_transport_py
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

image_transport_py/CMakeLists.txt

@@ -0,0 +1,75 @@
+cmake_minimum_required(VERSION 3.5)
+project(image_transport_py)
+
+# Default to C99
+if(NOT CMAKE_C_STANDARD)
+  set(CMAKE_C_STANDARD 99)
+endif()
+
+# Default to C++17
+if(NOT CMAKE_CXX_STANDARD)
+  set(CMAKE_CXX_STANDARD 17)
+  set(CMAKE_CXX_STANDARD_REQUIRED ON)
+endif()
+
+if(CMAKE_COMPILER_IS_GNUCXX OR CMAKE_CXX_COMPILER_ID MATCHES "Clang")
+  add_compile_options(-Wall -Wextra -Wpedantic)
+endif()
+
+# Figure out Python3 debug/release before anything else can find_package it
+if(WIN32 AND CMAKE_BUILD_TYPE STREQUAL "Debug")
+  find_package(python_cmake_module REQUIRED)
+  find_package(PythonExtra REQUIRED)
+
+  # Force FindPython3 to use the debug interpreter where ROS 2 expects it
+  set(Python3_EXECUTABLE "${PYTHON_EXECUTABLE_DEBUG}")
+endif()
+
+find_package(ament_cmake REQUIRED)
+find_package(ament_cmake_python REQUIRED)
+find_package(ament_cmake_ros REQUIRED)
+find_package(image_transport REQUIRED)
+find_package(rclcpp REQUIRED)
+find_package(sensor_msgs REQUIRED)
+
+# Find python before pybind11
+find_package(Python3 REQUIRED COMPONENTS Interpreter Development)
+
+find_package(pybind11_vendor REQUIRED)
+find_package(pybind11 REQUIRED)
+
+ament_python_install_package(${PROJECT_NAME})
+
+pybind11_add_module(_image_transport MODULE
+  src/image_transport_py/pybind_image_transport.cpp
+)
+
+target_include_directories(_image_transport PUBLIC
+  "$<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include>"
+  "$<INSTALL_INTERFACE:include/${PROJECT_NAME}>")
+
+target_link_libraries(_image_transport PUBLIC
+  image_transport::image_transport
+  rclcpp::rclcpp
+  ${sensor_msgs_TARGETS}
+)
+
+# Install cython modules as sub-modules of the project
+install(
+  TARGETS
+    _image_transport
+  DESTINATION "${PYTHON_INSTALL_DIR}/${PROJECT_NAME}"
+)
+
+if(BUILD_TESTING)
+  find_package(ament_lint_auto REQUIRED)
+
+  list(APPEND AMENT_LINT_AUTO_EXCLUDE
+    ament_cmake_cppcheck
+  )
+  ament_lint_auto_find_test_dependencies()
+
+  ament_cppcheck(LANGUAGE "c++")
+endif()
+
+ament_package()

image_transport_py/README.md

@@ -0,0 +1,203 @@
+# image_transport_py: Python Bindings for ROS 2 Image Transport
+
+## Introduction
+
+`image_transport_py` is a Python package that provides bindings for `image_transport`. It enables efficient publishing and subscribing of images in Python, leveraging various transport plugins (e.g., `raw`, `compressed`). 
+The package allows developers to handle image topics more efficiently and with less overhead than using standard ROS 2 topics.
+
+## Usage
+
+### Publishing Images
+
+To publish images using `image_transport_py`, you create an `ImageTransport` object and use it to advertise an image topic. The first parameter for `ImageTransport` is the image transport
+node's name which needs to be unique in the namespace. 
+
+Steps:
+
+1. Import Necessary Modules:
+
+```python
+import rclpy
+from rclpy.node import Node
+from sensor_msgs.msg import Image
+from image_transport_py import ImageTransport
+```
+
+2. Initialize the Node and ImageTransport:
+
+```python
+class ImagePublisher(Node):
+    def __init__(self):
+        super().__init__('image_publisher')
+        self.image_transport = ImageTransport("imagetransport_pub", image_transport="raw")
+        self.publisher = self.image_transport.advertise('camera/image', 10)
+
+        # read images at 10Hz frequency
+        self.timer = self.create_timer(0.1, self.publish_image)
+```
+
+3. Publish Images in the Callback:
+```python
+    def publish_image(self):
+        image_msg = .. # Read image from your devices
+
+        image_msg.header.stamp = self.get_clock().now().to_msg()
+        self.publisher.publish(image_msg)
+```
+
+`advertise_camera` can publish `CameraInfo` along with `Image` message.
+
+### Subscribing to Images
+
+To subscribe to images, use `ImageTransport` to create a subscription to the image topic.
+
+Steps:
+
+1. Import Necessary Modules:
+
+```python
+import rclpy
+from rclpy.node import Node
+from sensor_msgs.msg import Image
+from image_transport_py import ImageTransport
+```
+
+2. Initialize the Node and ImageTransport:
+```python
+class ImageSubscriber(Node):
+    def __init__(self):
+        super().__init__('image_subscriber')
+        self.image_transport = ImageTransport("imagetransport_sub", image_transport="raw")
+        self.subscription = self.image_transport.subscribe('camera/image', 10, self.image_callback)
+```
+
+3. Handle Incoming Images:
+```python
+    def image_callback(self, msg):
+        # do something with msg (= sensor_msgs.msg.Image type)
+```
+
+`subscribe_camera` will add `CameraInfo` along with `Image` message for the callback.
+
+### Transport Selection
+
+By default, `image_transport` uses the `raw` transport. You can specify a different transport by passing `image_transport` parameter to `ImageTransport`. Alternatively,
+you can use your own ROS2 parameter file for the imagetransport node via `launch_params_filepath` parameter.
+
+## Classes
+
+### Publisher
+
+A publisher for images.
+
+#### Methods
+
+- `get_topic()`
+
+  Returns the base image topic.
+
+- `get_num_subscribers()`
+
+  Returns the number of subscribers this publisher is connected to.
+
+- `shutdown()`
+
+  Unsubscribe the callback associated with this Publisher.
+
+- `publish(img)`
+
+  Publish an image on the topics associated with this Publisher.
+
+### CameraPublisher
+
+A publisher for images with camera info.
+
+#### Methods
+
+- `get_topic()`
+
+  Returns the base (image) topic of this CameraPublisher.
+
+- `get_num_subscribers()`
+
+  Returns the number of subscribers this camera publisher is connected to.
+
+- `shutdown()`
+
+  Unsubscribe the callback associated with this CameraPublisher.
+
+- `publish(img, info)`
+
+  Publish an image and camera info on the topics associated with this Publisher.
+
+### ImageTransport
+
+An object for image transport operations.
+
+#### Constructor
+
+- `__init__(node_name, image_transport="", launch_params_filepath="")`
+
+  Initialize an ImageTransport object with its node name, `image_transport` and launch params file path. If no `image_transport` specified, the default `raw` plugin will be initialized.
+
+#### Methods
+
+- `advertise(base_topic, queue_size, latch=False)`
+
+  Advertise an image topic.
+
+- `advertise_camera(base_topic, queue_size, latch=False)`
+
+  Advertise an image topic with camera info.
+
+- `subscribe(base_topic, queue_size, callback)`
+
+  Subscribe to an image topic.
+
+- `subscribe_camera(base_topic, queue_size, callback)`
+
+  Subscribe to an image topic with camera info.
+
+### Subscriber
+
+A subscriber for images.
+
+#### Methods
+
+- `get_topic()`
+
+  Returns the base image topic.
+
+- `get_num_publishers()`
+
+  Returns the number of publishers this subscriber is connected to.
+
+- `get_transport()`
+
+  Returns the name of the transport being used.
+
+- `shutdown()`
+
+  Unsubscribe the callback associated with this Subscriber.
+
+### CameraSubscriber
+
+A subscriber for images with camera info.
+
+#### Methods
+
+- `get_topic()`
+
+  Returns the base image topic.
+
+- `get_num_publishers()`
+
+  Returns the number of publishers this subscriber is connected to.
+
+- `get_transport()`
+
+  Returns the name of the transport being used.
+
+- `shutdown()`
+
+  Unsubscribe the callback associated with this CameraSubscriber.

image_transport_py/image_transport_py/__init__.py

@@ -0,0 +1,36 @@
+# Copyright 2024 Open Source Robotics Foundation, Inc.
+#
+# 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.
+
+from rpyutils import add_dll_directories_from_env
+
+# Since Python 3.8, on Windows we should ensure DLL directories are explicitly added
+# to the search path.
+# See https://docs.python.org/3/whatsnew/3.8.html#bpo-36085-whatsnew
+with add_dll_directories_from_env('PATH'):
+    from image_transport_py._image_transport import (
+        ImageTransport,
+        Publisher,
+        Subscriber,
+        CameraPublisher,
+        CameraSubscriber,
+    )
+
+
+__all__ = [
+    'ImageTransport',
+    'Publisher',
+    'Subscriber',
+    'CameraPublisher',
+    'CameraSubscriber',
+]