XSelectInput is not working for ButtonPressEvents,how to do it?

问题

I am writing a simple programmes in C where i want to capture all the mouse and Keyboard events that are taking place. I tried to use "XGrabPointer" but it results in locking the screen and i can not go to other applications. I tried with "XSelectInput()" and now i am receiving the keyboard events successfully but i am not getting any mouse click events.

Any idea how can i do it?

The code snippet is as follows:

#include <stdio.h>
#include <stdlib.h>
#include <X11/Xlib.h>
#include <X11/Xutil.h>
#include <X11/keysym.h>

int main(int argc, char **argv)
{
   Display *dpy;
   Window root;
  unsigned long event_mask;
    event_mask = FocusChangeMask | KeyPressMask | KeyReleaseMask | ButtonPressMask  | ButtonReleaseMask;
    if((dpy = XOpenDisplay(NULL)) == NULL) {
        perror(argv[0]);
        exit(1);
    }
dpy = XOpenDisplay(NULL);
root = XDefaultRootWindow(dpy);

int state;
XWindowAttributes attributes;

XGetInputFocus(dpy,&root,&state);
printf("window id = %d\n"); 
XSelectInput(dpy,root,event_mask);


XEvent ev;
   while(1) {


      XNextEvent(dpy, &ev);
    if(ev.type==ButtonRelease){
    printf("button release\n");
    }

      if (ev.type== KeyPress) {
    printf("keypress event\n");
      }


  }

 return 0;

}

回答1:

As you're using the root window, there's probably something else getting the event, to make sure you get all events you will need to grab the mouse but nothing else will get the events so you need a way to exit like the q key in this example:

#include <stdio.h>
#include <stdlib.h>
#include <X11/Xlib.h>
#include <X11/Xutil.h>
#include <X11/keysym.h>

int main(int argc, char **argv)
{
    Display *dpy;
    Window root;
    unsigned long event_mask;
    event_mask = KeyReleaseMask | ButtonReleaseMask;
    if((dpy = XOpenDisplay(NULL)) == NULL) {
        perror(argv[0]);
        exit(1);
    }
    dpy = XOpenDisplay(NULL);
    root = XDefaultRootWindow(dpy);

    XGrabPointer(dpy, root, False, ButtonReleaseMask, GrabModeAsync, 
         GrabModeAsync, None, None, CurrentTime);

    int state;
    XWindowAttributes attributes;

    XGetInputFocus(dpy,&root,&state);
    printf("window id = %d\n"); 
    XSelectInput(dpy,root,event_mask);


    XEvent ev;
    while(1) {


    XNextEvent(dpy, &ev);
    printf("Type: %d\n", ev.type);

    if(ev.type==ButtonRelease){
        printf("button release\n");
    }

    if (ev.type== KeyRelease) {
        printf("keypress event\n");
        if (XLookupKeysym(&ev.xkey, 0) == XK_q) {
        exit(0);
        }

    }


    }

    return 0;

}

来源：https://stackoverflow.com/questions/16977872/xselectinput-is-not-working-for-buttonpressevents-how-to-do-it