projects / screensavers / blame
| Commit | Line | Data |
|---|---|---|
| 3144ee8a AT |
1 | /* xscreensaver, Copyright (c) 1998, 1999, 2006 |
| 2 | * by Jamie Zawinski <jwz@jwz.org> | |
| 3 | * | |
| 4 | * Permission to use, copy, modify, distribute, and sell this software and its | |
| 5 | * documentation for any purpose is hereby granted without fee, provided that | |
| 6 | * the above copyright notice appear in all copies and that both that | |
| 7 | * copyright notice and this permission notice appear in supporting | |
| 8 | * documentation. No representations are made about the suitability of this | |
| 9 | * software for any purpose. It is provided "as is" without express or | |
| 10 | * implied warranty. | |
| 11 | */ | |
| 12 | ||
| 13 | /* The XDBE (Double Buffering) extension is pretty tricky to use, since you | |
| 14 | can get X errors at inconvenient times during initialization. This file | |
| 15 | contains a utility routine to make it easier to deal with. | |
| 16 | */ | |
| 17 | ||
| 18 | #include "utils.h" | |
| 19 | #include "xdbe.h" | |
| 20 | #include "resources.h" /* for get_string_resource() */ | |
| 21 | ||
| 22 | /* #define DEBUG */ | |
| 23 | ||
| 24 | #ifdef DEBUG | |
| 25 | # include <X11/Xmu/Error.h> | |
| 26 | #endif | |
| 27 | ||
| 28 | extern char *progname; | |
| 29 | ||
| 30 | #ifdef HAVE_DOUBLE_BUFFER_EXTENSION /* whole file */ | |
| 31 | ||
| 32 | static Bool xdbe_got_x_error = False; | |
| 33 | static int | |
| 34 | xdbe_ehandler (Display *dpy, XErrorEvent *error) | |
| 35 | { | |
| 36 | xdbe_got_x_error = True; | |
| 37 | ||
| 38 | #ifdef DEBUG | |
| 39 | fprintf (stderr, "\n%s: ignoring X error from DOUBLE-BUFFER:\n", progname); | |
| 40 | XmuPrintDefaultErrorMessage (dpy, error, stderr); | |
| 41 | fprintf (stderr, "\n"); | |
| 42 | #endif | |
| 43 | ||
| 44 | return 0; | |
| 45 | } | |
| 46 | ||
| 47 | ||
| 48 | XdbeBackBuffer | |
| 49 | xdbe_get_backbuffer (Display *dpy, Window window, | |
| 50 | XdbeSwapAction action) | |
| 51 | { | |
| 52 | XdbeBackBuffer b; | |
| 53 | XErrorHandler old_handler; | |
| 54 | int maj, min; | |
| 55 | ||
| 56 | if (!get_boolean_resource(dpy, "useDBE", "Boolean")) | |
| 57 | return 0; | |
| 58 | ||
| 59 | if (!XdbeQueryExtension (dpy, &maj, &min)) | |
| 60 | return 0; | |
| 61 | ||
| 62 | XSync (dpy, False); | |
| 63 | xdbe_got_x_error = False; | |
| 64 | old_handler = XSetErrorHandler (xdbe_ehandler); | |
| 65 | b = XdbeAllocateBackBufferName(dpy, window, XdbeUndefined); | |
| 66 | XSync (dpy, False); | |
| 67 | XSetErrorHandler (old_handler); | |
| 68 | ||
| 69 | if (xdbe_got_x_error) | |
| 70 | return 0; | |
| 71 | ||
| 72 | return b; | |
| 73 | } | |
| 74 | ||
| 75 | #endif /* HAVE_DOUBLE_BUFFER_EXTENSION */ |