address@hidden: Re: x-backspace-delete-keys-p]

[Richard Stallman]

Could people please study this, and try it, and see if it causes
any problems?

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From: Gabor Melis <address@hidden>
To: address@hidden
Subject: Re: x-backspace-delete-keys-p
Date: Wed, 2 Feb 2005 11:25:06 +0100
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On Wednesday 02 February 2005 08:29, Richard Stallman wrote:
>     I don't know much about other keyboards but checking only
>     whether XK_Delete/XK_Backspace is mapped to a keycode that belongs
> to _any_
>     key in the current keyboard sounds enough.
>
> Maybe you are right, but I don't know how to do this, or if there
> is a way to do this.  Do you want to find out?

This patch (against 21.3) does what I described. It could probably be improved 
by checking for the the geometry in case the keycode belongs to a key, but 
that key is not present on the physical keyboard. I tested it with my lisp 
machine, us and us-without-a-backspace-key layouts and it seems to work 
returning t, t an nil respectively.

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- --- xfns.c.orig       2005-02-02 11:15:23.000000000 +0100
+++ xfns.c      2005-02-02 11:07:46.000000000 +0100
@@ -11350,6 +11350,16 @@
 #include <X11/keysym.h>
 #endif
 
+#ifdef HAVE_XKBGETKEYBOARD
+static int
+is_keycode_mapped (XkbDescPtr kb, int keycode)
+{
+  /* We could also check if the key is physically present in the
+     geometry component, but that is more trouble than it is worth. */
+  return (kb->min_key_code <= keycode) && (keycode <= kb->max_key_code);
+}
+#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\
@@ -11390,34 +11400,19 @@
   kb = XkbGetMap (dpy, XkbAllMapComponentsMask, XkbUseCoreKbd);
   if (kb)
     {
- -      int delete_keycode = 0, backspace_keycode = 0, i;
+      int delete_keycode = XKeysymToKeycode (dpy, XK_Delete);
+      int backspace_keycode = XKeysymToKeycode (dpy, XK_BackSpace);
 
       if (XkbGetNames (dpy, XkbAllNamesMask, kb) == Success)
        {
- -       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;
- -         }
+          if (is_keycode_mapped (kb, delete_keycode) &&
+              is_keycode_mapped (kb, backspace_keycode))
+            have_keys = Qt;
 
          XkbFreeNames (kb, 0, True);
        }
 
       XkbFreeClientMap (kb, 0, 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;

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