Path: utzoo!attcan!uunet!seismo!sundc!pitstop!sun!amdcad!ames!mailrus!tut.cis.ohio-state.edu!bloom-beacon!EXPO.LCS.MIT.EDU!converse
From: converse@EXPO.LCS.MIT.EDU (Donna Converse)
Newsgroups: comp.windows.x
Subject: Re: How to Pause After XCreateWindow?
Message-ID: <8903151703.AA16114@expo.lcs.mit.edu>
Date: 15 Mar 89 17:03:10 GMT
References: <4188@alvin.mcnc.org>
Sender: daemon@bloom-beacon.MIT.EDU
Organization: X Consortium, MIT Laboratory for Computer Science
Lines: 64


> The problem is that I call XCreateWindow, but it doesn't pause.  My
> application speeds right along, eventually calling XGetWindowAttributes
> BEFORE I've placed and sized the new window.

Wait for the first expose event before determining the size of the window,
or drawing in the window.  XNextEvent blocks on the event queue. This
code is rude to the window manager; see David Rosenthal's "Hello World"
for a proper version; but you should read it & get the right idea.

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

main(argc, argv)
    int		argc;
    char	**argv;
{
    Display			*dpy;
    int				screen;
    unsigned int		width, height;
    XSetWindowAttributes	xswa;
    unsigned long		valuemask;
    Window			window;
    XEvent			event;
    XExposeEvent		*expose_event;
    XWindowAttributes		xwa;


    if ((dpy = XOpenDisplay((char *) NULL)) == NULL)
    {
	(void) fprintf(stderr, "%s: cannot open display \"%s\".\n", argv,
		       XDisplayName((char *) NULL));
	exit(1);
    }
    screen = DefaultScreen(dpy);
    xswa.background_pixel = WhitePixel(dpy, screen);
    xswa.border_pixel = BlackPixel(dpy, screen);
    xswa.event_mask = ExposureMask;
    valuemask = CWBackPixel | CWBorderPixel | CWEventMask;
    window = XCreateWindow(dpy, RootWindow(dpy, screen), 10, 10, 100, 100, 2, 
			   CopyFromParent, InputOutput, CopyFromParent,
			   valuemask, &xswa);
    XStoreName(dpy, window, "Demo");
    XMapWindow(dpy, window);

    width = height = 0;
    expose_event = (XExposeEvent *) &event;
    while (1)
    {
	XNextEvent(dpy, &event);
	if (event.type == Expose && expose_event->count == 0)
	{
	    if (XGetWindowAttributes(dpy, window, &xwa) == 0)
		break;
	    if (width != xwa.width || height != xwa.height)
	    {	
		width = xwa.width;
		height = xwa.height;
		printf("The current window size is %d by %d.\n", width,
		       height);
	    }
	}
    }
}