CODEWITHSUNDEEP
cx11
user1833852
user1833852

Reputation: 51

Window Id using X11

I am very new to X11 programming.

I tried the following piece of code to display Window Id of the new window created but it is displayed Window Id twice (different Window Id). I am getting correct and once only for every new window created using FVWM (fvwm socket). If I launch firefox from command then it displays window around 5 times.

I want to display correct Window Id once for each new Window creation instead of twice.

#include <stdio.h>
#include <stdlib.h>
#include <X11/Xlib.h>
#include <X11/Xutil.h>
int main()
{
                Display* display = XOpenDisplay(":0");
                XSetWindowAttributes attributes;
//                attributes.event_mask = SubstructureNotifyMask | StructureNotifyMask;
                attributes.event_mask = SubstructureNotifyMask | VisibilityChangeMask | EnterWindowMask;
                attributes.backing_store = Always;
                Window win = XDefaultRootWindow(display);
                printf("Deafult root window %x\n", win);
                XChangeWindowAttributes(display, win, CWEventMask, &attributes);

                while (1)
                {
                   XEvent event;
                   XNextEvent(display, &event);
                   if (event.type == CreateNotify)
                   {
                         puts("create Notify event occured\n");
                        printf("Window ID: %x\n", event.xcreatewindow.window);
                        printf("Window ID: %d\n", event.xcreatewindow.window);

                        printf("Parent Window ID: %x\n", event.xcreatewindow.parent);
                  }
                }
}

Following is the Output for "xclock".

[root@localhost src]# ./XWindow.out 
create Notify event occured

Window ID: 3e0000c
Window ID: 65011724
create Notify event occured

Window ID: 100118f
Window ID: 16781711
create Notify event occured

Following is to conform same from "xprop" command

[root@localhost src]# xclock &
[2] 6564
[root@localhost src]# xprop 
_NET_WM_STATE(ATOM) = 
WM_STATE(WM_STATE):
        window state: Normal
        icon window: 0x0
_NET_WM_DESKTOP(CARDINAL) = 0
_NET_FRAME_EXTENTS(CARDINAL) = 1, 1, 39, 1
_NET_WM_ALLOWED_ACTIONS(ATOM) = _NET_WM_ACTION_MOVE, _NET_WM_ACTION_RESIZE, _NET_WM_ACTION_FULLSCREEN, _NET_WM_ACTION_MINIMIZE, _NET_WM_ACTION_SHADE, _NET_WM_ACTION_MAXIMIZE_HORZ, _NET_WM_ACTION_MAXIMIZE_VERT, _NET_WM_ACTION_CHANGE_DESKTOP, _NET_WM_ACTION_CLOSE, _NET_WM_ACTION_ABOVE, _NET_WM_ACTION_BELOW
_NET_WM_PID(CARDINAL) = 6564
WM_PROTOCOLS(ATOM): protocols  WM_DELETE_WINDOW
SM_CLIENT_ID(STRING) = "10b83f0cefdd07ca73150167045190887900000031930078"
WM_CLIENT_LEADER(WINDOW): window id # 0x3e0000c
WM_LOCALE_NAME(STRING) = "C"
WM_CLASS(STRING) = "xclock", "XClock"
WM_HINTS(WM_HINTS):
        Client accepts input or input focus: False
        Initial state is Normal State.
        bitmap id # to use for icon: 0x3e00001
        bitmap id # of mask for icon: 0x3e00003
WM_NORMAL_HINTS(WM_SIZE_HINTS):
        program specified size: 164 by 164
        window gravity: NorthWest
WM_CLIENT_MACHINE(STRING) = "localhost.localdomain"
WM_COMMAND(STRING) = { "xclock" }
WM_ICON_NAME(STRING) = "xclock"
WM_NAME(STRING) = "xclock"
[root@localhost src]#

Do you have any idea about the piece of code which displays Window id whenever new window (e.g. xclock or firefox) is created in Linux only once.

Upvotes: 1

Views: 3878

Answers (1)

Andrey Sidorov
Andrey Sidorov

Reputation: 25466

Most window managers re-parent new toplevel windows to manage borders/top bar/buttons. I'm pretty sure what you see is application window id + wm window id. You can check that by looking at window's owner pid - it's in _NET_WM_PID poroperty ( xprop -id wid _NET_WM_PID ) - see How to convert a X11 window id to a process id

Upvotes: 1

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