Add opencv video publisher (#58)

ros_packages/learn_ros/src/opencv_video_publisher/opencv_video_publisher/opencv_video_publisher.py

@@ -0,0 +1,94 @@
+"""
+ROS2 program to publish real-time streaming  video from your built-in webcam
+"""
+import rclpy
+from rclpy.node import Node
+from sensor_msgs.msg import Image 
+from cv_bridge import CvBridge 
+import cv2 
+
+NODE_NAME: str = "opencv_video_publisher"
+TOPIC_NAME: str ="opencv_video_frames"
+IMAGES_QUEUE_SIZE = 10
+PUBLISH_MESSAGE_RATE: float = 5.0
+
+
+class OpenCVVideoPublisher(Node):
+  """
+  Create an ImagePublisher class, which is a subclass of the Node class.
+  """
+
+  def __init__(self, topic_name: str=TOPIC_NAME, 
+  	images_queue_size: int = IMAGES_QUEUE_SIZE,
+  	publish_message_rate: float=PUBLISH_MESSAGE_RATE):
+    """
+    Class constructor to set up the node
+    """
+    # Initiate the Node class's constructor and give it a name
+    super().__init__(NODE_NAME)
+
+    # Create the publisher. This publisher will publish an Image
+    # to the video_frames topic. The queue size is 10 messages.
+    self.publisher_ = self.create_publisher(Image, topic_name, images_queue_size)
+
+    # We will publish a message every 0.1 seconds
+    timer_period = 0.1  # seconds
+
+    # Create the timer
+    self.timer = self.create_timer(publish_message_rate, self.timer_callback)
+
+    # Create a VideoCapture object
+    # The argument '0' gets the default webcam.
+    self.cap = cv2.VideoCapture(0)
+
+    # Used to convert between ROS and OpenCV images
+    self.br = CvBridge()
+
+    self.get_logger().info(f'Finished {NODE_NAME} initialization')
+    self.get_logger().info(f'{NODE_NAME} publishes on topic {topic_name}')
+    self.get_logger().info(f'{NODE_NAME} images_queue_size {images_queue_size}')
+    self.get_logger().info(f'{NODE_NAME} publish message rate {publish_message_rate}')
+
+  def timer_callback(self):
+    """
+    Callback function.
+    This function gets called every 0.1 seconds.
+    """
+
+    # Capture frame-by-frame
+    # This method returns True/False as well
+    # as the video frame.
+    ret, frame = self.cap.read()
+
+    if ret == True:
+      # Publish the image.
+      # The 'cv2_to_imgmsg' method converts an OpenCV
+      # image to a ROS 2 image message
+      self.publisher_.publish(self.br.cv2_to_imgmsg(frame))
+
+    # Display the message on the console
+    self.get_logger().info('Publishing video frame')
+
+def main(args=None):
+
+  # Initialize the rclpy library
+  rclpy.init(args=args)
+
+  # Create the node
+  image_publisher = OpenCVVideoPublisher(topic_name=TOPIC_NAME,
+  	                                     images_queue_size=IMAGES_QUEUE_SIZE,
+  	                                     publish_message_rate=PUBLISH_MESSAGE_RATE)
+
+  # Spin the node so the callback function is called.
+  rclpy.spin(image_publisher)
+
+  # Destroy the node explicitly
+  # (optional - otherwise it will be done automatically
+  # when the garbage collector destroys the node object)
+  image_publisher.destroy_node()
+
+  # Shutdown the ROS client library for Python
+  rclpy.shutdown()
+
+if __name__ == '__main__':
+  main()

ros_packages/learn_ros/src/opencv_video_publisher/package.xml

@@ -0,0 +1,25 @@
+<?xml version="1.0"?>
+<?xml-model href="http://download.ros.org/schema/package_format3.xsd" schematypens="http://www.w3.org/2001/XMLSchema"?>
+<package format="3">
+  <name>opencv_video_publisher</name>
+  <version>0.0.0</version>
+  <description>TODO: Package description</description>
+  <maintainer email="a.giavaras@gmail.com">alex</maintainer>
+  <license>TODO: License declaration</license>
+
+  <depend>rclpy</depend>
+  <depend>image_transport</depend>
+  <depend>cv_bridge</depend>
+  <depend>sensor_msgs</depend>
+  <depend>std_msgs</depend>
+  <depend>opencv2</depend>
+
+  <test_depend>ament_copyright</test_depend>
+  <test_depend>ament_flake8</test_depend>
+  <test_depend>ament_pep257</test_depend>
+  <test_depend>python3-pytest</test_depend>
+
+  <export>
+    <build_type>ament_python</build_type>
+  </export>
+</package>

ros_packages/learn_ros/src/opencv_video_publisher/setup.cfg

@@ -0,0 +1,4 @@
+[develop]
+script_dir=$base/lib/opencv_video_publisher
+[install]
+install_scripts=$base/lib/opencv_video_publisher

ros_packages/learn_ros/src/opencv_video_publisher/setup.py

@@ -0,0 +1,26 @@
+from setuptools import find_packages, setup
+
+package_name = 'opencv_video_publisher'
+
+setup(
+    name=package_name,
+    version='0.0.0',
+    packages=find_packages(exclude=['test']),
+    data_files=[
+        ('share/ament_index/resource_index/packages',
+            ['resource/' + package_name]),
+        ('share/' + package_name, ['package.xml']),
+    ],
+    install_requires=['setuptools'],
+    zip_safe=True,
+    maintainer='alex',
+    maintainer_email='a.giavaras@gmail.com',
+    description='TODO: Package description',
+    license='TODO: License declaration',
+    tests_require=['pytest'],
+    entry_points={
+        'console_scripts': [
+            'opencv_video_publisher = opencv_video_publisher.opencv_video_publisher:main',
+        ],
+    },
+)

ros_packages/learn_ros/src/opencv_video_publisher/test/test_copyright.py

@@ -0,0 +1,25 @@
+# Copyright 2015 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 ament_copyright.main import main
+import pytest
+
+
+# Remove the `skip` decorator once the source file(s) have a copyright header
+@pytest.mark.skip(reason='No copyright header has been placed in the generated source file.')
+@pytest.mark.copyright
+@pytest.mark.linter
+def test_copyright():
+    rc = main(argv=['.', 'test'])
+    assert rc == 0, 'Found errors'

ros_packages/learn_ros/src/opencv_video_publisher/test/test_flake8.py

@@ -0,0 +1,25 @@
+# Copyright 2017 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 ament_flake8.main import main_with_errors
+import pytest
+
+
+@pytest.mark.flake8
+@pytest.mark.linter
+def test_flake8():
+    rc, errors = main_with_errors(argv=[])
+    assert rc == 0, \
+        'Found %d code style errors / warnings:\n' % len(errors) + \
+        '\n'.join(errors)

ros_packages/learn_ros/src/opencv_video_publisher/test/test_pep257.py

@@ -0,0 +1,23 @@
+# Copyright 2015 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 ament_pep257.main import main
+import pytest
+
+
+@pytest.mark.linter
+@pytest.mark.pep257
+def test_pep257():
+    rc = main(argv=['.', 'test'])
+    assert rc == 0, 'Found code style errors / warnings'