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

static int damage_event;
static int damage_error;

/* This program demonstrates that just moving a window
 * around generates damage events on it.
 */
static void
disaster (const char *what)
{
    fprintf (stderr, "Error: %s\n", what);
    exit (0);
}

static void
dump_events (Display *dpy, const char *header)
{
    int did_header = 0;
    
    XSync (dpy, False);
    
    while (XPending (dpy))
    {
	XEvent event;
	
	XNextEvent (dpy, &event);

	if (header)
	{
	    if (!did_header)
	    {
		printf ("%s", header);
		did_header = 1;
	    }

	    if (event.type == damage_event)
	    {
		printf ("  event: damage  (%lx)\n", 
			event.xany.window);
	    }
	}
    }
}

int
main (int argc, char **argv)
{
    Display *dpy;
    Window main_window;
    Window subwindow;
    int pos;
    int i;

    dpy = XOpenDisplay (NULL);

    if (!XDamageQueryExtension (dpy, &damage_event, &damage_error))
	;
    
    /* Create main window */
    main_window = XCreateSimpleWindow (dpy, XDefaultRootWindow (dpy),
				       100, 100, 600, 400, 0, 0, 0xffffffff);
    XMapWindow (dpy, main_window);

    /* (1) Create blue subwindow */

    subwindow = XCreateSimpleWindow (dpy, main_window,
				     50, 50, 500, 300,
				     0, 0, 0x000000ff);

    printf ("ID of subwindow: %lx\n", subwindow);
    
    XDamageCreate (dpy, subwindow, XDamageReportRawRectangles);

    XMapWindow (dpy, subwindow);

    XFlush (dpy);

    pos = 50;
    for (i = 0; i < 10; ++i)
    {
	dump_events (dpy, "events\n");

	pos += 5;
	if (pos > 100)
	    pos = 0;

	XMoveWindow (dpy, subwindow, pos, 50);
	usleep (5000);
	XFlush (dpy);
    }
    
    sleep (10);
    
}