Linux, how to capture screen, and simulate mouse movements

Question

I need to capture screen (as print screen) in the way so I can access pixel color data, to do some image recognition, after that I will need to generate mouse events on the

Answer 1

//sg

//Solution using Xlib for those who use Linux
#include <X11/Xlib.h>
#include<stdio.h>
#include<unistd.h>
#include <stdlib.h>
#include <string.h>

#include <unistd.h>

#include <X11/Xlib.h>
#include <X11/Xutil.h>

void mouseClick(int button)
{
    Display *display = XOpenDisplay(NULL);

    XEvent event;

    if(display == NULL)
    {
        fprintf(stderr, "Cannot initialize the display\n");
        exit(EXIT_FAILURE);
    }

    memset(&event, 0x00, sizeof(event));

    event.type = ButtonPress;
    event.xbutton.button = button;
    event.xbutton.same_screen = True;

    XQueryPointer(display, RootWindow(display, DefaultScreen(display)), &event.xbutton.root, &event.xbutton.window, &event.xbutton.x_root, &event.xbutton.y_root, &event.xbutton.x, &event.xbutton.y, &event.xbutton.state);

    event.xbutton.subwindow = event.xbutton.window;

    while(event.xbutton.subwindow)
    {
        event.xbutton.window = event.xbutton.subwindow;

        XQueryPointer(display, event.xbutton.window, &event.xbutton.root, &event.xbutton.subwindow, &event.xbutton.x_root, &event.xbutton.y_root, &event.xbutton.x, &event.xbutton.y, &event.xbutton.state);
    }

    if(XSendEvent(display, PointerWindow, True, 0xfff, &event) == 0) fprintf(stderr, "Error\n");

    XFlush(display);

    usleep(100000);

    event.type = ButtonRelease;
    event.xbutton.state = 0x100;

    if(XSendEvent(display, PointerWindow, True, 0xfff, &event) == 0) fprintf(stderr, "Error\n");

    XFlush(display);

    XCloseDisplay(display);
}
int main(int argc,char * argv[]) {

    int x , y;
    x=atoi(argv[1]);
    y=atoi(argv[2]);
    Display *display = XOpenDisplay(0);

    Window root = DefaultRootWindow(display);
    XWarpPointer(display, None, root, 0, 0, 0, 0, x, y);
    mouseClick(Button1);
    XFlush(display);
    XCloseDisplay(display);
    return 0;
}

Build it and then to simulate a click at x ,y do:

$ ./a.out x y

i.e.

$ g++ -lX11 sgmousesim2.cpp

$ ./a.out 123 13

Just in case you are still interested.

Answer 2

Swinput is a solution for simulating mouse/key events. You need to compile it probably for your kernel. Xorg provided some headers for recording mouse/key events but I think it is broken at the moment. There is a C code evtest that can be used to capture events from /dev/input/eventX, /dev/input/mice files. It can be helpful.

Edit:

The bug was fixed in Xorg record extension, so it may be working too.

Answer 3

For it to work correctly, you must call XFlush after you warp the pointer

Tested on linux Mint19 (Cinamon 3.8) XWarpPointer(display, None, root, 0, 0, 0, 0, x, y); XFlush(display);

Answer 4

I couldn't get the clicking working with the method @axiom used, only movement of the pointer. I used this instead: (Ubuntu 18.04).

Compiles with: g++ mouse_click.cpp -lX11 -lXtst -lstdc++

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

#include <unistd.h>

#include <X11/Xlib.h>
#include <X11/Xutil.h>
#include <X11/extensions/XTest.h>


void mouseClick(int button)
{
    Display *display = XOpenDisplay(NULL);

    // click left button
    XTestFakeButtonEvent(display, Button1, true, 0);
    XFlush(display);

    usleep(10000);

    // release left mouse
    XTestFakeButtonEvent(display, Button1, false, 0);
    XFlush(display);


    XCloseDisplay(display);


}
int main(int argc,char * argv[]) {

    int x , y;
    x=atoi(argv[1]);
    y=atoi(argv[2]);
    Display *display = XOpenDisplay(0);

    Window root = DefaultRootWindow(display);
    XTestFakeMotionEvent(display, root, x, y, 0);
    XFlush(display);
    mouseClick(Button1);
    XFlush(display);
    XCloseDisplay(display);
    return 0;
}