feat: Use pluginlib to load streamer plugins at runtime, general refactor

AUTHORS.md

@@ -1,9 +1,8 @@
-Original Authors
-----------------
+# Original Authors
 
- * Mitchell Wills (mwills@wpi.edu)
+ * Mitchell Wills <mwills@wpi.edu>
 
-Contributors
-------------
+# Contributors
 
- * [Russell Toris](http://users.wpi.edu/~rctoris/) (rctoris@wpi.edu)
+ * Russell Toris <rctoris@wpi.edu>
+ * Błażej Sowa <blazej@fictionlab.pl>

CMakeLists.txt

@@ -10,8 +10,10 @@ find_package(ament_cmake_ros REQUIRED)
 find_package(async_web_server_cpp REQUIRED)
 find_package(cv_bridge REQUIRED)
 find_package(image_transport REQUIRED)
+find_package(pluginlib REQUIRED)
 find_package(rclcpp REQUIRED)
 find_package(rclcpp_components REQUIRED)
+find_package(rmw REQUIRED)
 find_package(sensor_msgs REQUIRED)
 
 find_package(OpenCV REQUIRED)
@@ -39,36 +41,60 @@ if(${cv_bridge_VERSION} VERSION_LESS "3.3.0")
   add_compile_definitions(CV_BRIDGE_USES_OLD_HEADERS)
 endif()
 
-## Specify additional locations of header files
-include_directories(include
-  ${avcodec_INCLUDE_DIRS}
-  ${avformat_INCLUDE_DIRS}
-  ${avutil_INCLUDE_DIRS}
-  ${swscale_INCLUDE_DIRS}
-)
-
 ## Declare a cpp library
 add_library(${PROJECT_NAME} SHARED
   src/web_video_server.cpp
-  src/image_streamer.cpp
-  src/libav_streamer.cpp
-  src/vp8_streamer.cpp
-  src/h264_streamer.cpp
-  src/vp9_streamer.cpp
   src/multipart_stream.cpp
-  src/ros_compressed_streamer.cpp
-  src/jpeg_streamers.cpp
-  src/png_streamers.cpp
+  src/streamer.cpp
   src/utils.cpp
 )
 
+target_include_directories(${PROJECT_NAME}
+  PUBLIC
+    "$<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include>"
+    "$<INSTALL_INTERFACE:include/${PROJECT_NAME}>"
+)
+
 ## Specify libraries to link a library or executable target against
 target_link_libraries(${PROJECT_NAME}
+  PUBLIC
+    async_web_server_cpp::async_web_server_cpp
+    pluginlib::pluginlib
+    rclcpp::rclcpp
+    rmw::rmw
+    Boost::boost
+  PRIVATE
+    rclcpp_components::component
+)
+
+add_library(${PROJECT_NAME}_streamers SHARED
+  src/streamers/image_transport_streamer.cpp
+  src/streamers/libav_streamer.cpp
+  src/streamers/h264_streamer.cpp
+  src/streamers/jpeg_streamers.cpp
+  src/streamers/png_streamers.cpp
+  src/streamers/ros_compressed_streamer.cpp
+  src/streamers/vp8_streamer.cpp
+  src/streamers/vp9_streamer.cpp
+)
+
+target_include_directories(${PROJECT_NAME}_streamers
+  PUBLIC
+    "$<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include>"
+    "$<INSTALL_INTERFACE:include/${PROJECT_NAME}>"
+    ${avcodec_INCLUDE_DIRS}
+    ${avformat_INCLUDE_DIRS}
+    ${avutil_INCLUDE_DIRS}
+    ${swscale_INCLUDE_DIRS}
+)
+
+target_link_libraries(${PROJECT_NAME}_streamers
+  ${PROJECT_NAME}
   async_web_server_cpp::async_web_server_cpp
   cv_bridge::cv_bridge
   image_transport::image_transport
+  pluginlib::pluginlib
   rclcpp::rclcpp
-  rclcpp_components::component
   ${sensor_msgs_TARGETS}
   Boost::boost
   Boost::system
@@ -90,24 +116,34 @@ target_link_libraries(${PROJECT_NAME}_node
 
 rclcpp_components_register_nodes(${PROJECT_NAME} "web_video_server::WebVideoServer")
 
+pluginlib_export_plugin_description_file(web_video_server plugins.xml)
+
 #############
 ## Install ##
 #############
 
-## Mark executables and/or libraries for installation
 install(
   DIRECTORY include/
   DESTINATION include/${PROJECT_NAME}
 )
 
 install(
-  TARGETS ${PROJECT_NAME}
+  TARGETS ${PROJECT_NAME} ${PROJECT_NAME}_streamers
   EXPORT export_${PROJECT_NAME}
   LIBRARY DESTINATION lib
   ARCHIVE DESTINATION lib
   RUNTIME DESTINATION bin
 )
 ament_export_targets(export_${PROJECT_NAME} HAS_LIBRARY_TARGET)
+ament_export_dependencies(
+  async_web_server_cpp
+  cv_bridge
+  image_transport
+  pluginlib
+  rclcpp
+  rmw
+  sensor_msgs
+)
 
 set_target_properties(${PROJECT_NAME}_node PROPERTIES OUTPUT_NAME ${PROJECT_NAME})
 install(
@@ -132,4 +168,6 @@ if(BUILD_TESTING)
   ament_lint_auto_find_test_dependencies()
 endif()
 
-ament_package()
+ament_package(
+  CONFIG_EXTRAS "config-extras.cmake"
+)

README.md

@@ -1,6 +1,6 @@
-# web_video_server - HTTP Streaming of ROS Image Topics in Multiple Formats
+# web_video_server - HTTP Streaming of ROS Topics in Multiple Formats
 
-This node provides HTTP streaming of ROS image topics in various formats, making it easy to view robot camera feeds and other image topics in a web browser without requiring special plugins or extensions.
+This node provides HTTP streaming of ROS topics in various formats, making it easy to view robot camera feeds and other topics in a web browser without requiring special plugins or extensions.
 
 ## Features
 
@@ -10,10 +10,14 @@ This node provides HTTP streaming of ROS image topics in various formats, making
   - VP9 (WebM)
   - H264 (MP4)
   - PNG streams
-  - ROS compressed image topics
+  - ROS compressed image streams
+- Query snapshots of image topics in multiple formats:
+  - JPEG
+  - PNG
+  - ROS compressed image
+- Plugin-based architecture for easy addition of new streaming formats
 - Adjustable quality, size, and other streaming parameters
 - Web interface to browse available image topics
-- Single image snapshot capability
 - Support for different QoS profiles in ROS 2
 
 ## Installation
@@ -109,7 +113,7 @@ http://localhost:8080/
 The interface allows quick navigation between different topics and formats without having to manually construct URLs.
 
 This page displays:
-- All available ROS image topics currently being published
+- All available streamable ROS topics
 - Direct links to view each topic in different formats:
   - Web page with streaming image
   - Direct stream
@@ -166,19 +170,22 @@ http://localhost:8080/snapshot?topic=/camera/image_raw
 | Parameter | Type | Default | Possible Values | Description |
 |-----------|------|---------|----------------|-------------|
 | `topic` | string | (required) | Any valid ROS image topic | The ROS image topic to stream |
+| `type` | string | "jpeg" | "jpeg", "png", "ros_compressed" | Snapshot image format |
 | `width` | int | 0 | 0+ | Width of output picture (0 = original width) |
 | `height` | int | 0 | 0+ | Height of output picture (0 = original height) |
 | `quality` | int | 95 | 1-100 | Quality for JPEG snapshots |
 | `invert` | flag | not present | present/not present | Invert image when parameter is present |
 | `default_transport` | string | "raw" | "raw", "compressed", "theora" | Image transport to use |
 | `qos_profile` | string | "default" | "default", "system_default", "sensor_data", "services_default" | QoS profile for ROS 2 subscribers |
 
-## About
+## Creating custom streamer plugins
+See the [custom streamer plugin tutorial](doc/custom-streamer-plugin.md) for information on how to write your own streamer plugins.
 
+## About
 This project is released as part of the [Robot Web Tools](https://robotwebtools.github.io/) effort.
 
-## License
+### License
 web_video_server is released with a BSD license. For full terms and conditions, see the [LICENSE](LICENSE) file.
 
-## Authors
+### Authors
 See the [AUTHORS](AUTHORS.md) file for a full list of contributors.

config-extras.cmake

@@ -0,0 +1,32 @@
+# Copyright (c) 2025, The Robot Web Tools Contributors
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are met:
+#
+#    * Redistributions of source code must retain the above copyright
+#      notice, this list of conditions and the following disclaimer.
+#
+#    * Redistributions in binary form must reproduce the above copyright
+#      notice, this list of conditions and the following disclaimer in the
+#      documentation and/or other materials provided with the distribution.
+#
+#    * Neither the name of the copyright holder nor the names of its
+#      contributors may be used to endorse or promote products derived from
+#      this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+# POSSIBILITY OF SUCH DAMAGE.
+
+# ament_export_dependencies fails to propagate Boost components
+# so we need to explicitly find Boost here
+find_package(Boost REQUIRED COMPONENTS system)