[系统运维]linux下模拟键盘输入(与pcl点云库结合使用)

linux下模拟键盘输入

有时候我们需要模拟键盘输入，在windows下，有 keybd_event 模拟键盘按下。在linux下可以使用Xlib提供的接口去模拟键盘按下。
代码如下：

// main.cpp
#include <X11/Xlib.h>
#include <X11/keysym.h>
#include <X11/extensions/XTest.h>

void ClickKey()
{
    Display* p_display = XOpenDisplay( NULL );
    KeySym keysym = XK_X;
    KeyCode keycode = NoSymbol;
    keycode = XKeysymToKeycode( p_display , keysym );

    XTestFakeKeyEvent( p_display , keycode , True  , 0 ); // 键盘按下"x"
    XTestFakeKeyEvent( p_display , keycode , False , 0 ); // 键盘释放"x"
    XFlush( p_display );

    XCloseDisplay( p_display );
}

int main(){
    ClickKey();
}

需要链接-lX11 -lXtst.
编译指令： g++ main.cpp -o main -lX11 -lXtst.

应用

模拟键盘输入可以应用在pcl框选点云中，我们知道pcl款选事件默认是按下键盘"X"才可以款选点云，我们可以模拟键盘按下“X”,这样就可以不用按下"X"了。代码如下：

#include <pcl/io/pcd_io.h>
#include <pcl/point_cloud.h>
#include <pcl/point_types.h>
#include <pcl/visualization/pcl_visualizer.h>
#include <iostream>
#include <thread>
#include <vector>
#include <X11/Xlib.h>
#include <X11/keysym.h>
#include <X11/extensions/XTest.h>

pcl::PointCloud<pcl::PointXYZ>::Ptr cloud(new pcl::PointCloud<pcl::PointXYZ>());

boost::shared_ptr<pcl::visualization::PCLVisualizer> viewer(new pcl::visualization::PCLVisualizer("viewer"));

pcl::PointCloud<pcl::PointXYZ>::Ptr clicked_points_3d(new pcl::PointCloud<pcl::PointXYZ>);

int num = 0;

void pp_callback(const pcl::visualization::AreaPickingEvent &event, void *args) {

    std::vector<int> indices;

    if (event.getPointsIndices(indices) == -1)

        return;

    for (int i = 0; i < indices.size(); ++i) {

        clicked_points_3d->points.push_back(cloud->points.at(indices[i]));

    }

    pcl::visualization::PointCloudColorHandlerCustom<pcl::PointXYZ> red(clicked_points_3d, 255, 0, 0);
    std::stringstream ss;
    std::string cloudName;
    ss << num++;
    ss >> cloudName;
    cloudName += "_cloudName";
    viewer->addPointCloud(clicked_points_3d, red, cloudName);
    viewer->setPointCloudRenderingProperties(pcl::visualization::PCL_VISUALIZER_POINT_SIZE, 10, cloudName);
    Display *p_display = XOpenDisplay(NULL);
    KeySym keysym = XK_X;
    KeyCode keycode = NoSymbol;
    keycode = XKeysymToKeycode(p_display, keysym);
    XTestFakeKeyEvent(p_display, keycode, True, 0); // 键盘按下event
    XTestFakeKeyEvent(p_display, keycode, False, 0); // 键盘释放event
    XFlush(p_display);
}

int main() {

    if (pcl::io::loadPCDFile("/home/ls/Downloads/code/wr_ls_udp/points23.pcd", *cloud)) {
        std::cerr << "ERROR: Cannot open file " << std::endl;
        return -1;

    }

    viewer->addPointCloud(cloud, "bunny");
    viewer->setCameraPosition(0, 0, -2, 0, -1, 0, 0);
    viewer->registerAreaPickingCallback(pp_callback, (void *) &cloud);
    Display *p_display = XOpenDisplay(nullptr);
    KeySym keysym = XK_X;
    KeyCode keycode = NoSymbol;
    keycode = XKeysymToKeycode(p_display, keysym);
    XTestFakeKeyEvent(p_display, keycode, True, 0); // 键盘按下event
    XTestFakeKeyEvent(p_display, keycode, False, 0); // 键盘释放event
    XFlush(p_display);

    while (!viewer->wasStopped()) {
        viewer->spinOnce(100);
        std::this_thread::sleep_for(std::chrono::microseconds(1));
    }
}

CMakeLists.txt如下：

cmake_minimum_required(VERSION 3.10)
project(test)

set(CMAKE_CXX_STANDARD 14)

FIND_PACKAGE(PCL REQUIRED)

#pcl
include_directories(${PCL_INCLUDE_DIRS})
# 设置依赖库链接目录
link_directories(${PCL_LIBRARY_DIRS})
# 添加预处理器和编译器标记
add_definitions(${PCL_DEFINITIONS})

add_executable(pcl_keyborad pcl_keyborad.cpp)
target_link_libraries(pcl_keyborad -lX11 -lXtst ${PCL_LIBRARIES} -lpthread)

其他应用

模拟键盘按下事件结合pcl点云以及可以在Qt中有很多用处。

参考链接

1.Simulate keypress in a Linux C console application：
https://stackoverflow.com/questions/1262310/simulate-keypress-in-a-linux-c-console-application
Xlib Linux下模拟键盘按下：https://www.cnblogs.com/chaichengxun/p/15425727.html