fix(osd): handle touchpad hardware keys (#4045)

Port 2.0

core/internal/config/embedded/niri-binds.kdl

@@ -94,6 +94,12 @@ binds {
     XF86TouchpadToggle allow-when-locked=true repeat=false {
         spawn "niri" "msg" "action" "toggle-touchpad";
     }
+    XF86TouchpadOn allow-when-locked=true repeat=false {
+        spawn "dms" "ipc" "call" "niri" "showTouchpadOsd" "true";
+    }
+    XF86TouchpadOff allow-when-locked=true repeat=false {
+        spawn "dms" "ipc" "call" "niri" "showTouchpadOsd" "false";
+    }
 
     // === Window Management ===
     Mod+Q repeat=false { close-window; }

quickshell/Services/NiriService.qml

@@ -462,15 +462,19 @@ Singleton {
         }
     }
 
-    function handleTouchpadToggled(data) {
-        // Each subscription starts with a snapshot; only later changes show the OSD.
-        const showOsd = _touchpadStateInitialized && touchpadEnabled !== data.on;
-        touchpadEnabled = data.on;
+    function updateTouchpadState(enabled, forceOsd) {
+        const showOsd = forceOsd || (_touchpadStateInitialized && touchpadEnabled !== enabled);
+        touchpadEnabled = enabled;
         _touchpadStateInitialized = true;
         if (showOsd)
             touchpadToggled();
     }
 
+    function handleTouchpadToggled(data) {
+        // Each subscription starts with a snapshot; only later changes show the OSD.
+        updateTouchpadState(data.on, false);
+    }
+
     function handleWorkspacesChanged(data) {
         const newWorkspaces = {};
 
@@ -1923,6 +1927,14 @@ window-rule {
     }
 
     IpcHandler {
+        function showTouchpadOsd(enabled: bool): string {
+            if (!CompositorService.isNiri)
+                return "NIRI_NOT_AVAILABLE";
+
+            root.updateTouchpadState(enabled, true);
+            return "TOUCHPAD_OSD_SHOWN";
+        }
+
         function screenshot(): string {
             if (!CompositorService.isNiri) {
                 return "NIRI_NOT_AVAILABLE";