draw_text_nodelet.cpp

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#include <string>

#include <opencv2/core/core.hpp>
#include <opencv2/imgproc/imgproc.hpp>

#include <ros/ros.h>
#include <nodelet/nodelet.h>
#include <image_transport/image_transport.h>
#include <sensor_msgs/image_encodings.h>
#include <sensor_msgs/Image.h>
#include <cv_bridge/cv_bridge.h>
#include <swri_math_util/math_util.h>

namespace swri_image_util
{
  class DrawTextNodelet : public nodelet::Nodelet
  {
  public:
      DrawTextNodelet() :
        text_("label"),
        offset_x_(0),
        offset_y_(0),
        font_scale_(1.0),
        font_thickness_(1)
    {
    }

    ~DrawTextNodelet()
    {
    }

    void onInit()
    {
      ros::NodeHandle &node = getNodeHandle();
      ros::NodeHandle &priv = getPrivateNodeHandle();

      priv.param("text", text_, text_);
      priv.param("offset_x", offset_x_, offset_x_);
      priv.param("offset_y", offset_y_, offset_y_);
      priv.param("font_scale", font_scale_, font_scale_);
      priv.param("font_thickness", font_thickness_, font_thickness_);

      image_transport::ImageTransport it(node);
      image_pub_ = it.advertise("stamped_image", 1);
      image_sub_ = it.subscribe("image", 1, &DrawTextNodelet::ImageCallback, this);
    }

    void ImageCallback(const sensor_msgs::ImageConstPtr& image)
    {
      cv_bridge::CvImagePtr cv_image = cv_bridge::toCvCopy(image);

      cv::putText(
        cv_image->image, 
        text_,
        cv::Point(offset_x_, offset_y_),
        cv::FONT_HERSHEY_SIMPLEX, 
        font_scale_,
        cv::Scalar(255, 255, 255),
        font_thickness_);

      image_pub_.publish(cv_image->toImageMsg());
    }

  private:
    std::string text_;
    double offset_x_;
    double offset_y_;
    double font_scale_;
    int font_thickness_;
    
    image_transport::Subscriber image_sub_;
    image_transport::Publisher image_pub_;
  };
}

// Register nodelet plugin
#include <swri_nodelet/class_list_macros.h>
SWRI_NODELET_EXPORT_CLASS(swri_image_util, DrawTextNodelet)