#include <X11/Xlib.h>
#include <X11/extensions/Xcomposite.h>
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>

static int comp_event;
static int comp_error;

/* This program demonstrates that redirected windows that are
 * raised on top of non-redirected ones get their backgrounds
 * drawn and have expose events sent.
 */

static void
disaster (const char *what)
{
    fprintf (stderr, "Error: %s\n", what);
    exit (0);
}

static void
dump_events (Display *dpy, const char *header)
{
    XSync (dpy, False);
    
    if (header)
	printf ("%s", header);
    
    while (XPending (dpy))
    {
	XEvent event;
	
	XNextEvent (dpy, &event);

	if (header)
	    printf ("  event: %d  (%lx)\n", event.type, event.xany.window);
    }
}

int
main (int argc, char **argv)
{
    Display *dpy;
    Window main_window;
    Window redirected_window;
    Window non_redirected_window;
    XGCValues gc_values;
    GC gc;

    dpy = XOpenDisplay (NULL);

    /* Create main window */
    
    main_window = XCreateSimpleWindow (dpy, XDefaultRootWindow (dpy),
				       100, 100, 600, 400, 0, 0, 0xffffffff);
    XMapWindow (dpy, main_window);

    if (!XCompositeQueryExtension (dpy, &comp_event, &comp_error))
	disaster ("No composite extension found\n");
    
    XCompositeRedirectSubwindows (dpy,
				  main_window,
				  CompositeRedirectManual);
    
    /* (1) Create redirected subwindow with a blue background */

    redirected_window = XCreateSimpleWindow (dpy, main_window,
					     50, 50, 500, 300,
					     0, 0, 0x000000ff);
    XSelectInput (dpy, redirected_window, ExposureMask);
    XMapWindow (dpy, redirected_window);

    /* (2) Create unredirected subwindow, completely covering
     * the redirected one
     */
    non_redirected_window = XCreateSimpleWindow (dpy, main_window,
						 25, 25, 550, 350,
						 0, 0, 0xaaaaaaaa);
    XMapWindow (dpy, non_redirected_window);

    XCompositeUnredirectWindow (dpy, non_redirected_window,
				CompositeRedirectManual);

    /* Discard events caused by unredirect */
    dump_events (dpy, NULL);
    
    /* (3) Paint the redirected window pink */
    gc_values.foreground = 0x00ff00ff;  /* pink */
    gc = XCreateGC (dpy, redirected_window, GCForeground, &gc_values);
    XFillRectangle (dpy, redirected_window, gc, 0, 0, 1000, 300);

    /* (4) Copy all of the redirected window to the non-redirected one,
     * making the non-redirected window mostly pink
     */
    XCopyArea (dpy, redirected_window, non_redirected_window, gc,
	       0, 0, 500, 300, 0, 0);

    /* Discard all events so far */
    dump_events (dpy, NULL);

    /* (5) Sleep for one second, during which the non-redirected window should
     * be pink
     */
    sleep (1);

    /* (6) Raise the redirected window. Since it's redirected, this
     * should have no effect, but it does:
     *
     *    - expose events are sent
     *    - the redirected window has its background painted
     *    - damage events are also sent (not demonstrated by this program)
     *
     */
    XRaiseWindow (dpy, redirected_window);

    dump_events (dpy, "Events after raising the redirected window");

    /* (7) Raise the non redirected window again */
    XRaiseWindow (dpy, non_redirected_window);

    /* (8) Paint it black */
    gc_values.foreground = 0x00000000;
    gc = XCreateGC (dpy, non_redirected_window, GCForeground, &gc_values);
    XFillRectangle (dpy, non_redirected_window, gc, 0, 0, 550, 350);
    
    /* (9) Copy all of the redirected window to the non-redirected one */
    XCopyArea (dpy, redirected_window, non_redirected_window, gc,
	       0, 0, 500, 300, 0, 0);

    XFlush (dpy);

    /* (10) We should now be seeing a pink rectangle, but we do in fact
     * see a blue one, since the redirected window had its background
     * painted
     */
    
    sleep (100);
}