kde: sync XWayland keyboard layout with KDE

scripts/default.nix

@@ -146,6 +146,13 @@
       xorg.setxkbmap
       jq
     ];
+    kde-sync-xkbmap = [
+      xorg.setxkbmap
+      dbus
+      gnugrep
+      gnused
+      gawk
+    ];
     print-battery-icon = [ ];
     controller-battery = [ print-battery-icon ];
     mouse-battery = [ print-battery-icon ];

scripts/kde-sync-xkbmap

@@ -0,0 +1,51 @@
+#!/bin/sh
+
+set -euo pipefail
+
+get_layout_display_name() {
+    idx="$1"
+    dbus-send --session --print-reply --dest=org.kde.keyboard /Layouts org.kde.KeyboardLayouts.getLayoutsList 2>/dev/null \
+        | grep 'string "' \
+        | sed 's/.*string "\([^"]*\)".*/\1/' \
+        | awk -v idx="$idx" 'NR%3==0 { if (c++ == idx) { print; exit } }'
+}
+
+get_layout_index() {
+    dbus-send --session --print-reply --dest=org.kde.keyboard /Layouts org.kde.KeyboardLayouts.getLayout 2>/dev/null \
+        | awk '/uint32/ { print $2; exit }'
+}
+
+LAST_LAYOUT=""
+
+apply_layout() {
+    idx="$1"
+    CURRENT_LAYOUT=$(get_layout_display_name "$idx")
+
+    if test "$LAST_LAYOUT" = "$CURRENT_LAYOUT"; then
+        return 0
+    elif test "$CURRENT_LAYOUT" = "English (Colemak)"; then
+        echo "Setting layout to colemak"
+        setxkbmap us colemak
+    elif test "$CURRENT_LAYOUT" = "Portuguese (Brazil)"; then
+        echo "Setting layout to br"
+        setxkbmap br
+    fi
+
+    LAST_LAYOUT="$CURRENT_LAYOUT"
+}
+
+update_layout() {
+    INDEX=$(get_layout_index)
+    apply_layout "$INDEX"
+}
+
+while ! get_layout_index; do
+    sleep 1s
+done
+update_layout
+
+dbus-monitor --session \
+    "type='signal',interface='org.kde.KeyboardLayouts',member='layoutChanged',path='/Layouts'" \
+    | while read -r line; do
+        update_layout
+    done

user/kde.nix

@@ -4,6 +4,9 @@
   config,
   ...
 }:
-lib.mkIf (config.my.desktop == "kde") {
+{
+  imports = [ ./kde/kde-sync-xkbmap.nix ];
+}
+// lib.mkIf (config.my.desktop == "kde") {
   services.gpg-agent.pinentry.package = lib.mkForce pkgs.pinentry-qt;
 }

user/kde/kde-sync-xkbmap.nix

@@ -0,0 +1,22 @@
+{
+  config,
+  pkgs,
+  lib,
+  ...
+}:
+lib.mkIf (config.my.desktop == "kde") {
+  systemd.user.services.kde-sync-xkbmap = {
+    Unit = {
+      Description = "Sync xkbmap with KDE keyboard layout";
+      PartOf = [ "graphical-session.target" ];
+      After = [ "graphical-session.target" ];
+    };
+    Service = {
+      ExecStart = lib.getExe pkgs.kde-sync-xkbmap;
+      Restart = "on-failure";
+    };
+    Install = {
+      WantedBy = [ "plasma-workspace.target" ];
+    };
+  };
+}