(Fx_backspace_delete_keys_p): New function.

(syms_of_xfns): Defsubr it.

1 files changed, 64 insertions, 1 deletions

diff --git a/src/xfns.c b/src/xfns.c
index b560c70c0d6..04ef282a175 100644
--- a/src/xfns.c
+++ b/src/xfns.c
@@ -11059,6 +11059,68 @@ selection dialog's entry field, if MUSTMATCH is non-nil.")
 
 
 /***********************************************************************
+                               Keyboard
+ ***********************************************************************/
+
+#ifdef HAVE_XKBGETKEYBOARD
+#include <X11/XKBlib.h>
+#include <X11/keysym.h>
+#endif
+
+DEFUN ("x-backspace-delete-keys-p", Fx_backspace_delete_keys_p,
+       Sx_backspace_delete_keys_p, 0, 1, 0,
+  "Check if both Backspace and Delete keys are on the keyboard of FRAME.\n\
+FRAME nil means use the selected frame.\n\
+Value is t if we know that both keys are present, and are mapped to the\n\
+usual X keysyms.")
+  (frame)
+     Lisp_Object frame;
+{
+#ifdef HAVE_XKBGETKEYBOARD
+  XkbDescPtr kb;
+  struct frame *f = check_x_frame (frame);
+  Display *dpy = FRAME_X_DISPLAY (f);
+  Lisp_Object have_keys;
+
+  have_keys = Qnil;
+
+  BLOCK_INPUT;
+  kb = XkbGetKeyboard (dpy, XkbAllComponentsMask, XkbUseCoreKbd);
+  if (kb)
+    {
+      int delete_keycode = 0, backspace_keycode = 0, i;
+      
+      for (i = kb->min_key_code;
+           (i < kb->max_key_code
+            && (delete_keycode == 0 || backspace_keycode == 0));
+           ++i)
+        {
+          /* The XKB symbolic key names can be seen most easily
+             in the PS file generated by `xkbprint -label name $DISPLAY'.  */
+          if (bcmp ("DELE", kb->names->keys[i].name, 4) == 0)
+            delete_keycode = i;
+          else if (bcmp ("BKSP", kb->names->keys[i].name, 4) == 0)
+            backspace_keycode = i;
+        }
+
+      XkbFreeKeyboard (kb, XkbAllComponentsMask, True);
+  
+      if (delete_keycode
+          && backspace_keycode
+          && XKeysymToKeycode (dpy, XK_Delete) == delete_keycode
+          && XKeysymToKeycode (dpy, XK_BackSpace) == backspace_keycode)
+        have_keys = Qt;
+    }
+  UNBLOCK_INPUT;
+  return have_keys;
+#else /* not HAVE_XKBGETKEYBOARD */
+  return Qnil;
+#endif /* not HAVE_XKBGETKEYBOARD */
+}
+
+
+
+/***********************************************************************
                             Initialization
  ***********************************************************************/
 
@@ -11326,7 +11388,8 @@ meaning don't clear the cache.");
   defsubr (&Sx_display_list);
   defsubr (&Sx_synchronize);
   defsubr (&Sx_focus_frame);
-
+  defsubr (&Sx_backspace_delete_keys_p);
+  
   /* Setting callback functions for fontset handler.  */
   get_font_info_func = x_get_font_info;