I want to record all incoming key pressed events no matter what window is in focus or where the pointer is.
I have written a sample code which should capture the key pressed events of the current Window in focus.
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <locale.h>
#include <stdint.h>
#include <stdarg.h>
#include <errno.h>
#include <pthread.h>
#include <X11/Xlib.h>
#include <X11/Xos.h>
#include <X11/Xfuncs.h>
#include <X11/Xutil.h>
#include <X11/Xatom.h>
int _invalid_window_handler(Display *dsp, XErrorEvent *err) {
return 0;
}
int main()
{
Display *display = XOpenDisplay(NULL);
int iError;
KeySym k;
int revert_to;
Window window;
XEvent event;
Time time;
XSetErrorHandler(_invalid_window_handler);
XGetInputFocus(display, &window, &revert_to);
XSelectInput(display, window, KeyPressMask | KeyReleaseMask );
iError = XGrabKeyboard(display, window,
KeyPressMask | KeyReleaseMask,
GrabModeAsync,
GrabModeAsync,
CurrentTime);
if (iError != GrabSuccess && iError == AlreadyGrabbed) {
XUngrabPointer(display, CurrentTime);
XFlush(display);
printf("Already Grabbed\n");
} else if (iError == GrabSuccess) {
printf("Grabbed\n");
}
while(1) {
XNextEvent(display,&event);
switch (event.type) {
case KeyPress : printf("Key Pressed\n"); break;
case KeyRelease : printf("Key Released\n"); break;
case EnterNotify : printf("Enter\n"); break;
}
}
XCloseDisplay(display);
return 0;
}
I am calling XGrabKeyboard to capture the keyboard as the application who created the window might have the keyboard events already grabbed. With the above mentioned code I am able to grab the keyboard but am unable to receive either of KeyPress or KeyRelease events for any keys on the keyboard inside the while loop. Is there anything that I am missing in the code due to which I am unable to receive the events ? Any help is highly appreciated.
My final aim is to capture key press events on the screen irrespective of the Window in focus. I have given the sample code for only window in focus for the code to be readable . I would do XQueryTree to get all the Windows and apply the same logic given above to get the expected result.
