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/* xscreensaver, Copyright (c) 1998, 1999, 2006
* by Jamie Zawinski <jwz@jwz.org>
*
* Permission to use, copy, modify, distribute, and sell this software and its
* documentation for any purpose is hereby granted without fee, provided that
* the above copyright notice appear in all copies and that both that
* copyright notice and this permission notice appear in supporting
* documentation. No representations are made about the suitability of this
* software for any purpose. It is provided "as is" without express or
* implied warranty.
*/
/* The XDBE (Double Buffering) extension is pretty tricky to use, since you
can get X errors at inconvenient times during initialization. This file
contains a utility routine to make it easier to deal with.
*/
#include "utils.h"
#include "xdbe.h"
#include "resources.h" /* for get_string_resource() */
/* #define DEBUG */
#ifdef DEBUG
# include <X11/Xmu/Error.h>
#endif
extern char *progname;
#ifdef HAVE_DOUBLE_BUFFER_EXTENSION /* whole file */
static Bool xdbe_got_x_error = False;
static int
xdbe_ehandler (Display *dpy, XErrorEvent *error)
{
xdbe_got_x_error = True;
#ifdef DEBUG
fprintf (stderr, "\n%s: ignoring X error from DOUBLE-BUFFER:\n", progname);
XmuPrintDefaultErrorMessage (dpy, error, stderr);
fprintf (stderr, "\n");
#endif
return 0;
}
XdbeBackBuffer
xdbe_get_backbuffer (Display *dpy, Window window,
XdbeSwapAction action)
{
XdbeBackBuffer b;
XErrorHandler old_handler;
int maj, min;
if (!get_boolean_resource(dpy, "useDBE", "Boolean"))
return 0;
if (!XdbeQueryExtension (dpy, &maj, &min))
return 0;
XSync (dpy, False);
xdbe_got_x_error = False;
old_handler = XSetErrorHandler (xdbe_ehandler);
b = XdbeAllocateBackBufferName(dpy, window, XdbeUndefined);
XSync (dpy, False);
XSetErrorHandler (old_handler);
if (xdbe_got_x_error)
return 0;
return b;
}
#endif /* HAVE_DOUBLE_BUFFER_EXTENSION */
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