1.00: Init release

README

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+         Simple X11 1-key Keyboard layout switcher
+
+    (c) Alexey Korop, 2014. Mailto: [email protected].
+    This is free software under GNU GPLv3.
+
+                     Installation
+
+  Unpack archive and copy the s1kls file to the any location that is suitable for programs.
+
+                     Command line   
+
+        xkbs1kls keycode1 keycode2 ...
+
+  The key with keycode 'keycode1' sets the layout 1,
+  the key with keycode 'keycode2' sets the layout 2 ...
+
+                     Features
+
+  Only LockGroup switch type supported (each key select the own layout). No layout indicator supported.
+  Key codes you can find out by calling this program in the terminal without parameters.
+
+                     Backgrownd
+
+  Standard X11 layout switcher is activated immediately by pressing the keys and therefore conflicts with the application shortcuts. 
+  This switcher is activated by releasing the keys, but only under the condition that no other key is pressed. For example, You were asked to switch to the layout 2 by RCtrl. Then if You press and release RCtrl, the layout will be switched. But if You pressed in a text editor RCtrl-Right, then the editor performs jump forward a word and layout will not be switched.
+
+  If You need a layout indicator, You can use a standard X11 LED indicator or any tray indicator as xxkb.
+
+                    Example
+
+  I use 3 layouts: (us,ru,ua), LED "ScrollLock" as indicator and keys following: RShift sets "us", RCtrl sets "ru" and RWin sets "ua". On the pc105 keyboard these keys have the keycodes 62, 105 and 134.
+
+  In the X11 keyboard config (in my ArchLinux it is the file /etc/X11/xorg.conf.d/01-keyboard-layout.conf) I define:
+
+        Option "XkbLayout" "us, ru, ua"
+        Option "XkbOptions" "grp_led:scroll"
+
+  In the autostart I call this program:
+
+        xkbs1kls 62 105 134 &
+
+
+https://sourceforge.net/projects/s1kls/

build

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+gcc -lX11 s1kls.c -O2 -o xkbs1kls

s1kls.c

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+/*
+Simple X11 1-key Keyboard layout switcher.
+
+Only LockGroup switch type supported (each key select the own layout).
+No indicator supported.
+
+To switch layout You must press and realease the corresponding key;
+layout will be switched when the key is released,
+but only yf no other key(s) has been pressed.
+
+ Developed by Alexey Korop, 2014
+
+ Compile:
+    gcc -lX11 s1kls.c -o xkbs1kls
+
+ This program is free software, under the GNU General Public License
+ version 3.
+*/
+
+#include <X11/Xlib.h>
+#include <X11/Xutil.h>
+#include <X11/XKBlib.h>
+#include <X11/Xlib.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+//#define TRACE
+
+static int switcher[16];
+/* some keycodes on the pc105 keyboard:
+ 62   rshift
+105   rctrl
+108   ralt
+134   rwin
+ 50   lshift
+ 37   lctrl
+ 64   lalt
+133   lwin
+*/
+
+typedef unsigned char bool;
+
+int main(int argc, char *argv[]) {
+  Display *display;
+  char keys_cur[32], keys_prev[32];
+  unsigned char diff, cur;
+  int n_keys_pressed;
+  int keycode = 0;
+  int i;
+  int byte, bit;
+  int n;
+  bool view_codes = 0;
+  int layout = -1;/*
+    -2 - Awaiting release all keys;
+    -1 - all keys are released;
+    0... - the key that selects this layout is pressed; expect its release */
+
+  for (n=0; n<argc-1; n++){
+    sscanf(argv[n+1], "%d", &switcher[n]);
+    if (switcher[n] <= 0)
+      goto help;
+    }
+  if (n < 2){
+help:
+    printf("Simple X11 1-key Keyboard layout switcher. Version 1.00.\n");
+    printf("(c) Alexey Korop, 2014. Free software under GNU GPLv3\n\n");
+    printf("Command line:   s1kls keycode1 keycode2 ...\n\n");
+    printf("The key with keycode 'keycode1' sets the layout 1, \n");
+    printf("the key with keycode 'keycode2' sets the layout 2 ... \n\n");
+    printf("Now You may press the desired keys and see their keycodes.\n");
+    view_codes = 1;
+    }
+
+  display = XOpenDisplay(NULL);
+  if (display == NULL){
+    fprintf(stderr, "XOpenDisplay error \n");
+    }
+
+  XkbIgnoreExtension(False);
+  XQueryKeymap(display, keys_prev);
+  while(1) {
+    XQueryKeymap(display, keys_cur);
+    n_keys_pressed = 0;
+    for (byte=0; byte<32; byte++) {
+      cur = keys_cur[byte];
+      diff = keys_prev[byte] ^ cur;
+      if (diff | cur) {
+        keys_prev[byte] = cur;
+        for (bit = 0; bit<8; bit++){
+          if (diff & 0x01){
+            if (!view_codes || (cur & 0x01))
+              keycode = byte*8 + bit;
+#ifdef TRACE
+            printf("key %d", keycode);
+            if (cur & 0x01)
+              printf(" press\n");
+            else
+              printf(" release\n");
+#endif
+            }
+          if (cur & 0x01)
+            n_keys_pressed++;
+          diff >>= 1; 
+          cur >>= 1;
+          }
+        }
+      }
+
+    if (view_codes){
+      if (n_keys_pressed == 0){
+        if (keycode){
+          printf(" %4d \n", keycode);
+          keycode = 0;
+          }
+        }
+      }
+    else { // normal work
+      if (n_keys_pressed == 0){
+        if (layout >= 0){
+#ifdef TRACE
+          printf("new layout %d\n", layout);
+#endif
+          if (!XkbLockGroup(display, XkbUseCoreKbd, layout)){
+            fprintf(stderr, "XkbLockGroup error \n");
+            return(1);
+            }
+          }
+        layout = -1;
+        }
+      else if (layout == -2)
+        ;
+      else if ((n_keys_pressed == 1) && (keycode == switcher[layout]))
+        ; //hold the key
+      else if ((n_keys_pressed == 1) && (layout == -1)){
+        layout = -2;
+        for (i=0; i<n; ++i)
+          if (keycode == switcher[i]){
+            layout = i;
+#ifdef TRACE
+            printf("wait for release the key %d\n", switcher[layout]);
+#endif
+            break;
+            }
+          }
+      else{
+#ifdef TRACE
+        if (layout >= 0)
+          printf("reject waiting\n");
+#endif
+        layout = -2;
+        }
+      }
+    usleep(20000);
+    }
+//  XCloseDisplay(display);
+}