wselect.c

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

#include <X11/X.h>
#include <X11/Xos.h>
#include <X11/Xlib.h>
#include <X11/Xutil.h>
#include <X11/Xatom.h>
#include <X11/cursorfont.h>

#define USED(x)
#define MASK (ButtonPressMask|ButtonReleaseMask)

static char	*argv0;

static void
exits(char *p)
{
	fprintf(stderr, "%s: %s\n", argv0, p);
	exit(EXIT_FAILURE);
}

static Window
get_window_id(Display * dpy, int screen, int button)
{
	Cursor cursor;
	Window root;
	Window retwin = None;
	int retbutton = -1;
	int pressed = 0;
	int idummy;
	unsigned udummy;
	XEvent event;

	root = RootWindow(dpy, screen);

	cursor = XCreateFontCursor(dpy, XC_draped_box);
	if(cursor == None)
		exits("unable to create selection cursor");

	if(XGrabPointer(dpy, root, False, MASK, GrabModeSync, GrabModeAsync, None, cursor, CurrentTime) != GrabSuccess)
		exits("unable to grab cursor");

	while(retwin == None || pressed != 0) {
		XAllowEvents(dpy, SyncPointer, CurrentTime);
		XWindowEvent(dpy, root, MASK, &event);
		switch(event.type) {
		case ButtonPress:
			if(retwin == None) {
				retbutton = event.xbutton.button;
				retwin =((event.xbutton.subwindow != None) ?
					event.xbutton.subwindow : root);
			}
			pressed++;
			break;
		case ButtonRelease:
			if(pressed > 0)
				pressed--;
			break;
		}
	}

	XUngrabPointer(dpy, CurrentTime);
	XFreeCursor(dpy, cursor);
	XSync(dpy, 0);
	
	/* Find the client window corresponding to the window that was clicked in. */
	if (XGetGeometry(dpy, retwin, &root, &idummy, &idummy, &udummy, &udummy, &udummy, &udummy) && retwin != root)
		retwin = XmuClientWindow(dpy, retwin);

	return (button == -1 || retbutton == button) ? retwin : None;
}

extern int
main(int argc, char **argv)
{
	Display * display;
	int screen;
	Window id;

	USED(argc);
	argv0 = argv[0];

	display = XOpenDisplay("");
	if(display == 0)
		exits("can't open display");

	screen = DefaultScreen(display);

	id = get_window_id(display, screen, 1);
	if(id == None)
		return EXIT_FAILURE;
	
	printf("%#x\n",(int) id);
	return 0;
}