Program Listing for File simple_publisher_plugin.hpp

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// Copyright (c) 2009, Willow Garage, Inc.
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#ifndef IMAGE_TRANSPORT__SIMPLE_PUBLISHER_PLUGIN_HPP_
#define IMAGE_TRANSPORT__SIMPLE_PUBLISHER_PLUGIN_HPP_

#include <memory>
#include <string>

#include "rclcpp/node.hpp"
#include "rclcpp/logger.hpp"
#include "rclcpp/logging.hpp"

#include "image_transport/publisher_plugin.hpp"
#include "image_transport/visibility_control.hpp"

namespace image_transport
{

template<class M>
class SimplePublisherPlugin : public PublisherPlugin
{
public:
  virtual ~SimplePublisherPlugin() {}

  virtual size_t getNumSubscribers() const
  {
    if (simple_impl_) {
      return simple_impl_->pub_->get_subscription_count();
    }
    return 0;
  }

  virtual std::string getTopic() const
  {
    if (simple_impl_) {return simple_impl_->pub_->get_topic_name();}
    return std::string();
  }

  virtual void publish(const sensor_msgs::msg::Image & message) const
  {
    if (!simple_impl_ || !simple_impl_->pub_) {
      auto logger = simple_impl_ ? simple_impl_->logger_ : rclcpp::get_logger("image_transport");
      RCLCPP_ERROR(
        logger,
        "Call to publish() on an invalid image_transport::SimplePublisherPlugin");
      return;
    }

    publish(message, bindInternalPublisher(simple_impl_->pub_.get()));
  }

  virtual void shutdown()
  {
    simple_impl_.reset();
  }

protected:
  virtual void advertiseImpl(
    rclcpp::Node * node, const std::string & base_topic,
    rmw_qos_profile_t custom_qos)
  {
    std::string transport_topic = getTopicToAdvertise(base_topic);
    simple_impl_ = std::make_unique<SimplePublisherPluginImpl>(node);

    RCLCPP_DEBUG(simple_impl_->logger_, "getTopicToAdvertise: %s", transport_topic.c_str());
    auto qos = rclcpp::QoS(rclcpp::QoSInitialization::from_rmw(custom_qos), custom_qos);
    simple_impl_->pub_ = node->create_publisher<M>(transport_topic, qos);
  }

  typedef std::function<void (const M &)> PublishFn;

  virtual void publish(
    const sensor_msgs::msg::Image & message,
    const PublishFn & publish_fn) const = 0;

  virtual std::string getTopicToAdvertise(const std::string & base_topic) const
  {
    return base_topic + "/" + getTransportName();
  }

private:
  struct SimplePublisherPluginImpl
  {
    explicit SimplePublisherPluginImpl(rclcpp::Node * node)
    : node_(node),
      logger_(node->get_logger())
    {
    }

    rclcpp::Node * node_;
    rclcpp::Logger logger_;
    typename rclcpp::Publisher<M>::SharedPtr pub_;
  };

  std::unique_ptr<SimplePublisherPluginImpl> simple_impl_;

  typedef std::function<void (const sensor_msgs::msg::Image &)> ImagePublishFn;

  template<class PubT>
  PublishFn bindInternalPublisher(PubT * pub) const
  {
    // Bind PubT::publish(const Message&) as PublishFn
    typedef void (PubT::* InternalPublishMemFn)(const M &);
    InternalPublishMemFn internal_pub_mem_fn = &PubT::publish;
    return std::bind(internal_pub_mem_fn, pub, std::placeholders::_1);
  }
};

}  // namespace image_transport

#endif  // IMAGE_TRANSPORT__SIMPLE_PUBLISHER_PLUGIN_HPP_