ubuntu|终端获取键值

需要浏览某文件夹中的所有.pcd文件，通过键盘进行.pcd文件的更新（切换）。

期望通过 < >两个按键做到将当前点云数据切换为上一个或下一个.pcd文件，目前实现了C++的非阻塞获取键值和使用ros发布键盘话题两种方法。

一、非阻塞获取键值

#include <stdio.h>
#include <stdlib.h>
#include <string>

#include <iostream> //标准输入输出流
#include <pcl/io/pcd_io.h> //PCL的PCD格式文件的输入输出头文件
#include <pcl/point_types.h> //PCL对各种格式的点的支持头文件
#include <pcl/visualization/cloud_viewer.h>
 
#define TTY_PATH            "/dev/tty"
#define STTY_US             "stty raw -echo -F "
#define STTY_DEF            "stty -raw echo -F "
  
using namespace std;
int get_char();
 //非阻塞获取键值
int get_char()
{
    fd_set rfds;
    struct timeval tv;
    int ch = 0;
 
    FD_ZERO(&rfds);
    FD_SET(0, &rfds);
    tv.tv_sec = 0;
    tv.tv_usec = 10; //设置等待超时时间
 
    //检测键盘是否有输入
    if (select(1, &rfds, NULL, NULL, &tv) > 0){
        ch = getchar(); 
    }
    return ch;
}
 
int main(int argc, char** argv)
{
  typedef pcl::PointXYZRGB PointT;
	//pcl::PointCloud::Ptr cloud(new pcl::PointCloud);
  
	pcl::PointCloud<pcl::PointXYZ>::Ptr cloud(new pcl::PointCloud<pcl::PointXYZ>); // 创建点云（指针）
  
    int index = 1;
	if (pcl::io::loadPCDFile("./"+to_string(index)+".pcd", *cloud) == -1) {
		//* load the file 
		PCL_ERROR("Couldn't read PCD file \n");
		return (-1);
	}
	printf("Loaded %d data points from PCD\n",
		cloud->width * cloud->height);
 
	pcl::visualization::PCLVisualizer viewer("Cloud viewer");
 
	pcl::visualization::PointCloudColorHandlerCustom<pcl::PointXYZ> single_color(cloud, 255, 255, 255); // green
    pcl::PointXYZ a, b, c, o;
    o.x=0;
    o.y=0;
    o.z=0;
    a.x=1000;
    a.y=0;
    a.z=0;
    b.x=0;
    b.y=1000;
    b.z=0;
    c.x=0;
    c.y=0;
    c.z=1000;
    viewer.addLine(o, a, 255, 0, 0, "line1"); 
    viewer.addLine(o, c, 0, 255, 0, "line2"); 
    viewer.addLine(o, b, 0, 0, 255, "line3"); 
	viewer.setCameraPosition(0, 0, -3.0, 0, -1, 0);
	viewer.addCoordinateSystem(0.3);
	// pcl::PointCloud<pcl::PointXYZ>::Ptr yuanzhu(new pcl::PointCloud<pcl::PointXYZ>);
	viewer.addPointCloud(cloud,"123");


    int ch = 0;
    system(STTY_US TTY_PATH);
 
    while(1){
        ch = get_char();
        switch (ch)
        {
        case ',':
            index--;
            cout<<index<<endl;
            pcl::io::loadPCDFile("./"+to_string(index)+".pcd", *cloud) ;
            viewer.updatePointCloud(cloud,"123");
          break;
        case '.':
            index++;
            printf("%d\t\n",index);
            pcl::io::loadPCDFile("./"+to_string(index)+".pcd", *cloud) ;
            viewer.updatePointCloud(cloud,"123");
          break;
        
        default:
          viewer.spinOnce(100);
          break;
        }
    }
}

二、使用ros发布键盘话题

直接下载小乌龟的键值获取节点，并修改重新设置新的节点和话题

修改后的代码

#include <ros/ros.h>
#include <geometry_msgs/Twist.h>
#include<base_sks_msgs/testmsg.h>
#include <signal.h>
#include <stdio.h>
#ifndef _WIN32
# include <termios.h>
# include <unistd.h>
#else
# include <windows.h>
#endif

#define KEYCODE_RIGHT 0x43
#define KEYCODE_LEFT 0x44
#define KEYCODE_UP 0x41
#define KEYCODE_DOWN 0x42
#define KEYCODE_B 0x62
#define KEYCODE_C 0x63
#define KEYCODE_D 0x64
#define KEYCODE_E 0x65
#define KEYCODE_F 0x66
#define KEYCODE_G 0x67
#define KEYCODE_Q 0x71
#define KEYCODE_R 0x72
#define KEYCODE_T 0x74
#define KEYCODE_V 0x76

class KeyboardReader
{
public:
  KeyboardReader()
#ifndef _WIN32
    : kfd(0)
#endif
  {
#ifndef _WIN32
    // get the console in raw mode
    tcgetattr(kfd, &cooked);
    struct termios raw;
    memcpy(&raw, &cooked, sizeof(struct termios));
    raw.c_lflag &=~ (ICANON | ECHO);
    // Setting a new line, then end of file
    raw.c_cc[VEOL] = 1;
    raw.c_cc[VEOF] = 2;
    tcsetattr(kfd, TCSANOW, &raw);
#endif
  }
  void readOne(char * c)
  {
#ifndef _WIN32
    int rc = read(kfd, c, 1);

    if (rc < 0)
    {
      throw std::runtime_error("read failed");
    }
#else
    return;
  }
#endif
  }
  void shutdown()
  {
#ifndef _WIN32
    tcsetattr(kfd, TCSANOW, &cooked);
#endif
  }
private:
#ifndef _WIN32
  int kfd;
  struct termios cooked;
#endif
};

KeyboardReader input;

class TeleopTurtle
{
public:
  TeleopTurtle();
  void keyLoop();

private:

  
  ros::NodeHandle nh_;

  ros::Publisher msg_pub_;
  
};

TeleopTurtle::TeleopTurtle()
{
  msg_pub_ = nh_.advertise<base_sks_msgs::testmsg>("testmsg", 1);
}

void quit(int sig)
{
  (void)sig;
  input.shutdown();
  ros::shutdown();
  exit(0);
}


int main(int argc, char** argv)
{
  ros::init(argc, argv, "teleop_turtle");
  TeleopTurtle teleop_turtle;

  signal(SIGINT,quit);

  teleop_turtle.keyLoop();
  quit(0);
  
  return(0);
}


void TeleopTurtle::keyLoop()
{
  char c;
  bool dirty=false;

  puts("Reading from keyboard");
  puts("---------------------------");
  puts("123.");


  for(;;)
  {
    // get the next event from the keyboard  
    try
    {
      input.readOne(&c);
      base_sks_msgs::testmsg msg;
      msg.key = c;
      msg_pub_.publish(msg);
    }
    catch (const std::runtime_error &)
    {
      perror("read():");
      return;
    }

    ROS_DEBUG("value: 0x%02X\n", c);
  
    switch(c)
    {
      case KEYCODE_Q:
        ROS_DEBUG("quit");
        return;
    }

    if(dirty ==true)
    {
      dirty=false;
    }
  }
  return;
}