Nagarjun's profile - activity

I am publishing images to another node and while publishing I am also subscribing a string. When that string is true I will save the image of the published data at that moment. I am having some trouble because of the following error: no match operator '=' for the subscriber which I don't understand why.

/home/rrcam/catkin_ws/src/image_pub/src/im_pub_sub.cpp: In constructor ‘Node::Node()’:
/home/rrcam/catkin_ws/src/image_pub/src/im_pub_sub.cpp:47:73: error: no match for ‘operator=’ (operand types are ‘image_transport::Subscriber’ and ‘ros::Subscriber’)
             sub = nh_.subscribe("/chatter",1, &Node::imageCallback, this);
                                                                         ^
In file included from /opt/ros/melodic/include/image_transport/image_transport.h:39:0,
                 from /home/rrcam/catkin_ws/src/image_pub/src/im_pub_sub.cpp:2:
/opt/ros/melodic/include/image_transport/subscriber.h:61:7: note: candidate: image_transport::Subscriber& image_transport::Subscriber::operator=(const image_transport::Subscriber&)
 class Subscriber
       ^~~~~~~~~~
/opt/ros/melodic/include/image_transport/subscriber.h:61:7: note:   no known conversion for argument 1 from ‘ros::Subscriber’ to ‘const image_transport::Subscriber&’
/opt/ros/melodic/include/image_transport/subscriber.h:61:7: note: candidate: image_transport::Subscriber& image_transport::Subscriber::operator=(image_transport::Subscriber&&)
/opt/ros/melodic/include/image_transport/subscriber.h:61:7: note:   no known conversion for argument 1 from ‘ros::Subscriber’ to ‘image_transport::Subscriber&&’
image_pub/CMakeFiles/i_pub_sub.dir/build.make:62: recipe for target 'image_pub/CMakeFiles/i_pub_sub.dir/src/im_pub_sub.cpp.o' failed
make[2]: *** [image_pub/CMakeFiles/i_pub_sub.dir/src/im_pub_sub.cpp.o] Error 1
CMakeFiles/Makefile2:1521: recipe for target 'image_pub/CMakeFiles/i_pub_sub.dir/all' failed
make[1]: *** [image_pub/CMakeFiles/i_pub_sub.dir/all] Error 2
Makefile:140: recipe for target 'all' failed
make: *** [all] Error 2
Invoking "make -j4 -l4" failed

The Script is as follows: I don't get it what's wrong. I have also tried using boost::bind for binding this pointer and msg in subscriber callback function:

#include <cv_bridge/cv_bridge.h>
#include <image_transport/image_transport.h>
#include <opencv2/highgui/highgui.hpp>
#include <ros/ros.h>
#include <sensor_msgs/image_encodings.h>
#include <exception>
#include <iostream>
#include <opencv2/imgcodecs.hpp>
#include "std_msgs/String.h"

class Node{

    public:
        cv::Mat frame1;
        std::string GSpipeline1 = "nvarguscamerasrc sensor-id=0 ee-mode=0 ! video/x-raw(memory:NVMM), format=(string)NV12 ! nvvidconv ! video/x-raw, format=(string)BGRx ! videoconvert ! video/x-raw, format=(string)BGR ! appsink";
        int count =0;
        ros::NodeHandle nh_;
        ros::Rate loop_rate =10;
        cv::VideoCapture cap1;
        sensor_msgs::ImagePtr msg1;
        image_transport::ImageTransport it;
        image_transport::Publisher pub_frame1;
        image_transport::Subscriber sub;

    public:
        Node():it(nh_),cap1(GSpipeline1, cv::CAP_GSTREAMER){
            if (!cap1.isOpened())
            {
                std::cout << "Failed to open camera1." << std::endl;
                return;
            }
            pub_frame1 = it.advertise("/cam1",1);

            // sub = it.subscribe("/chatter",1, boost::bind(&Node::imageCallback, this));
            sub = nh_.subscribe("/chatter",1, &Node::imageCallback, this);
        }

        ~Node(){

        }

        void imageCallback(const std_msgs::String::ConstPtr& msg)
        {
            std::cout<<"I am here"<<std::endl;
            if(msg->data.getData() == 'true'){
                this->count++;
                cv::imwrite("/home/rrcam/sensor0/img_"+ std::to_string(this->count)+".png",this->frame1);
            }

        }

        void start(){

            while (this->nh_.ok()) {
                this->cap1 >> this->frame1;
                // this->cap1.read(this->frame1);
                if (this->frame1.empty()) {
                    ROS_ERROR_STREAM("Failed to capture1 image!");
                    ros::shutdown();
                    break;
                }
                int k = cv::waitKey(20) & 0xff ...