find_contours_nodelet.cpp

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// https://github.com/Itseez/opencv/blob/2.4/samples/cpp/tutorial_code/ShapeDescriptors/findContours_Demo.cpp
#include <ros/ros.h>
#include "opencv_apps/nodelet.h"
#include <image_transport/image_transport.h>
#include <sensor_msgs/image_encodings.h>
#include <cv_bridge/cv_bridge.h>
#include <sensor_msgs/image_encodings.h>

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

#include <dynamic_reconfigure/server.h>
#include "opencv_apps/FindContoursConfig.h"
#include "opencv_apps/Contour.h"
#include "opencv_apps/ContourArray.h"
#include "opencv_apps/ContourArrayStamped.h"

namespace find_contours {
class FindContoursNodelet : public opencv_apps::Nodelet
{
  image_transport::Publisher img_pub_;
  image_transport::Subscriber img_sub_;
  image_transport::CameraSubscriber cam_sub_;
  ros::Publisher msg_pub_;

  boost::shared_ptr<image_transport::ImageTransport> it_;

  typedef find_contours::FindContoursConfig Config;
  typedef dynamic_reconfigure::Server<Config> ReconfigureServer;
  Config config_;
  boost::shared_ptr<ReconfigureServer> reconfigure_server_;

  bool debug_view_;
  ros::Time prev_stamp_;

  int low_threshold_;

  std::string window_name_;
  static bool need_config_update_;

  void reconfigureCallback(Config &new_config, uint32_t level)
  {
    config_ = new_config;
    low_threshold_ = config_.canny_low_threshold;
  }

  const std::string &frameWithDefault(const std::string &frame, const std::string &image_frame)
  {
    if (frame.empty())
      return image_frame;
    return frame;
  }

  void imageCallbackWithInfo(const sensor_msgs::ImageConstPtr& msg, const sensor_msgs::CameraInfoConstPtr& cam_info)
  {
    do_work(msg, cam_info->header.frame_id);
  }
  
  void imageCallback(const sensor_msgs::ImageConstPtr& msg)
  {
    do_work(msg, msg->header.frame_id);
  }

  static void trackbarCallback( int, void* )
  {
    need_config_update_ = true;
  }

  void do_work(const sensor_msgs::ImageConstPtr& msg, const std::string input_frame_from_msg)
  {
    // Work on the image.
    try
    {
      // Convert the image into something opencv can handle.
      cv::Mat frame = cv_bridge::toCvShare(msg, sensor_msgs::image_encodings::BGR8)->image;

      // Messages
      opencv_apps::ContourArrayStamped contours_msg;
      contours_msg.header = msg->header;

      // Do the work
      cv::Mat src_gray;

      if ( frame.channels() > 1 ) {
        cv::cvtColor( frame, src_gray, cv::COLOR_RGB2GRAY );
      } else {
        src_gray = frame;
      }
      cv::GaussianBlur( src_gray, src_gray, cv::Size(3,3), 0, 0, cv::BORDER_DEFAULT );

      if( debug_view_) {
        cv::namedWindow( window_name_, cv::WINDOW_AUTOSIZE );
      }
      
      cv::Mat canny_output;
      int max_thresh = 255;
      std::vector<std::vector<cv::Point> > contours;
      std::vector<cv::Vec4i> hierarchy;
      cv::RNG rng(12345);

      cv::blur( src_gray, canny_output, cv::Size(3,3) );

      cv::Canny( canny_output, canny_output, low_threshold_, low_threshold_*2, 3 );

      cv::findContours( canny_output, contours, hierarchy, CV_RETR_TREE, CV_CHAIN_APPROX_SIMPLE, cv::Point(0, 0) );

      cv::Mat drawing = cv::Mat::zeros( canny_output.size(), CV_8UC3 );
      for( size_t i = 0; i< contours.size(); i++ )
      {
        cv::Scalar color = cv::Scalar( rng.uniform(0, 255), rng.uniform(0,255), rng.uniform(0,255) );
        cv::drawContours( drawing, contours, (int)i, color, 2, 8, hierarchy, 0, cv::Point() );
        
        opencv_apps::Contour contour_msg;
        for ( size_t j = 0; j < contours[i].size(); j++ ) {
          opencv_apps::Point2D point_msg;
          point_msg.x = contours[i][j].x;
          point_msg.y = contours[i][j].y;
          contour_msg.points.push_back(point_msg);
        }
        contours_msg.contours.push_back(contour_msg);
      }

      if( debug_view_) {
        if (need_config_update_) {
          config_.canny_low_threshold = low_threshold_;
          reconfigure_server_->updateConfig(config_);
          need_config_update_ = false;
        }
        cv::createTrackbar( "Canny thresh:", window_name_, &low_threshold_, max_thresh, trackbarCallback);

        cv::imshow( window_name_, drawing );
        int c = cv::waitKey(1);
      }

      // Publish the image.
      sensor_msgs::Image::Ptr out_img = cv_bridge::CvImage(msg->header, sensor_msgs::image_encodings::BGR8, drawing).toImageMsg();
      img_pub_.publish(out_img);
      msg_pub_.publish(contours_msg);
    }
    catch (cv::Exception &e)
    {
      NODELET_ERROR("Image processing error: %s %s %s %i", e.err.c_str(), e.func.c_str(), e.file.c_str(), e.line);
    }

    prev_stamp_ = msg->header.stamp;
  }

  void subscribe()
  {
    NODELET_DEBUG("Subscribing to image topic.");
    if (config_.use_camera_info)
      cam_sub_ = it_->subscribeCamera("image", 3, &FindContoursNodelet::imageCallbackWithInfo, this);
    else
      img_sub_ = it_->subscribe("image", 3, &FindContoursNodelet::imageCallback, this);
  }

  void unsubscribe()
  {
    NODELET_DEBUG("Unsubscribing from image topic.");
    img_sub_.shutdown();
    cam_sub_.shutdown();
  }

public:
  virtual void onInit()
  {
    Nodelet::onInit();
    it_ = boost::shared_ptr<image_transport::ImageTransport>(new image_transport::ImageTransport(*nh_));

    pnh_->param("debug_view", debug_view_, false);
    if (debug_view_) {
      always_subscribe_ = true;
    }
    prev_stamp_ = ros::Time(0, 0);

    window_name_ = "Demo code to find contours in an image";
    low_threshold_ = 100; // only for canny
    
    reconfigure_server_ = boost::make_shared<dynamic_reconfigure::Server<Config> >(*pnh_);
    dynamic_reconfigure::Server<Config>::CallbackType f =
      boost::bind(&FindContoursNodelet::reconfigureCallback, this, _1, _2);
    reconfigure_server_->setCallback(f);

    img_pub_ = advertiseImage(*pnh_, "image", 1);
    msg_pub_ = advertise<opencv_apps::ContourArrayStamped>(*pnh_, "contours", 1);

    onInitPostProcess();
  }
};
bool FindContoursNodelet::need_config_update_ = false;
}

#include <pluginlib/class_list_macros.h>
PLUGINLIB_EXPORT_CLASS(find_contours::FindContoursNodelet, nodelet::Nodelet);