<description>A minimal image publisher and subscriber node that uses OpenCV</description>
<maintainer email="automaticaddison@todo.todo">automaticaddison</maintainer>
<license>Apache License 2.0</license>

# Basic ROS 2 program to publish real-time streaming 
# video from your built-in webcam
# Author:
# - Addison Sears-Collins
# - https://automaticaddison.com
 
# Import the necessary libraries
import rclpy # Python Client Library for ROS 2
from rclpy.node import Node # Handles the creation of nodes
from sensor_msgs.msg import Image # Image is the message type
from cv_bridge import CvBridge # Package to convert between ROS and OpenCV Images
import cv2 # OpenCV library

class ImagePublisher(Node):
  """
  Create an ImagePublisher class, which is a subclass of the Node class.
  """
  def __init__(self):
    """
    Class constructor to set up the node
    """
    # Initiate the Node class's constructor and give it a name
    super().__init__('image_publisher')
     
    # 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, 'video_frames', 10)
     
    # We will publish a message every 0.1 seconds
    timer_period = 0.1  # seconds
     
    # Create the timer
    self.timer = self.create_timer(timer_period, 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()
  
  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 = ImagePublisher()
 
  # 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()

    entry_points={
        'console_scripts': [
          'img_publisher = cv_basics.webcam_pub:main',
        ],
    },

# Basic ROS 2 program to subscribe to real-time streaming 
# video from your built-in webcam
# Author:
# - Addison Sears-Collins
# - https://automaticaddison.com
 
# Import the necessary libraries
import rclpy # Python library for ROS 2
from rclpy.node import Node # Handles the creation of nodes
from sensor_msgs.msg import Image # Image is the message type
from cv_bridge import CvBridge # Package to convert between ROS and OpenCV Images
import cv2 # OpenCV library

class ImageSubscriber(Node):
  """
  Create an ImageSubscriber class, which is a subclass of the Node class.
  """
  def __init__(self):
    """
    Class constructor to set up the node
    """
    # Initiate the Node class's constructor and give it a name
    super().__init__('image_subscriber')
     
    # Create the subscriber. This subscriber will receive an Image
    # from the video_frames topic. The queue size is 10 messages.
    self.subscription = self.create_subscription(
      Image, 
      'video_frames', 
      self.listener_callback, 
      10)
    self.subscription # prevent unused variable warning
     
    # Used to convert between ROS and OpenCV images
    self.br = CvBridge()
  
  def listener_callback(self, data):
    """
    Callback function.
    """
    # Display the message on the console
    self.get_logger().info('Receiving video frame')

    # Convert ROS Image message to OpenCV image
    current_frame = self.br.imgmsg_to_cv2(data)
   
    # Display image
    cv2.imshow("camera", current_frame)
   
    cv2.waitKey(1)
 
def main(args=None):
 
  # Initialize the rclpy library
  rclpy.init(args=args)
 
  # Create the node
  image_subscriber = ImageSubscriber()
 
  # Spin the node so the callback function is called.
  rclpy.spin(image_subscriber)
 
  # Destroy the node explicitly
  # (optional - otherwise it will be done automatically
  # when the garbage collector destroys the node object)
  image_subscriber.destroy_node()
 
  # Shutdown the ROS client library for Python
  rclpy.shutdown()
 
if __name__ == '__main__':
  main()

    entry_points={
        'console_scripts': [
          'img_publisher = cv_basics.webcam_pub:main',
          'img_subscriber = cv_basics.webcam_sub:main',
        ],
    },