kwin: emit window fullscreen info + refactor helper script

The helper script was also refactored to minimize the amount of callbacks added and the memory used. There's no need to keep callbacks attached for non-active windows, which happened before.

Also it should be more efficient and simpler to send info over with just a single DBus call (also if more fields were to be added).

Both the script and the helper app will send/print info only if it changed since the previous one. Otherwise we'd keep spamming fullscreen false update when navigating the desktop and so on.

include/KwinWorkaround.hpp

@@ -5,8 +5,10 @@
 namespace gsr {
     struct ActiveKwinWindow {
         std::string title = "Game";
+        bool fullscreen = false;
     };
 
     void start_kwin_helper_thread();
     std::string get_current_kwin_window_title();
+    bool get_current_kwin_window_fullscreen();
 }

src/KwinWorkaround.cpp

@@ -2,6 +2,7 @@
 
 #include <cstddef>
 #include <iostream>
+#include <string>
 #include <sys/types.h>
 #include <thread>
 #include <cstdlib>
@@ -24,7 +25,8 @@ namespace gsr {
         std::cerr << "Started a KWin helper thread\n";
 
         char buffer[4096];
-        const std::string prefix = "Active window title set to: ";
+        const std::string prefix_title = "Active window title set to: ";
+        const std::string prefix_fullscreen = "Active window fullscreen state set to: ";
 
         std::string line;
         while (fgets(buffer, sizeof(buffer), pipe) != nullptr) {
@@ -34,15 +36,13 @@ namespace gsr {
                 line.pop_back();
             }
 
-            size_t pos = line.find(prefix);
+            size_t pos = std::string::npos;
-            if (pos != std::string::npos) {
+            if ((pos = line.find(prefix_title)) != std::string::npos) {
-                std::string title = line.substr(pos + prefix.length());
+                std::string title = line.substr(pos + prefix_title.length());
-
-                if (title == "gsr ui" || title == "gsr notify") {
-                    continue; // ignore the overlay and notification
-                }
-
                 active_kwin_window.title = std::move(title);
+            } else if ((pos = line.find(prefix_fullscreen)) != std::string::npos) {
+                std::string fullscreen = line.substr(pos + prefix_fullscreen.length());
+                active_kwin_window.fullscreen = fullscreen == "1";
             }
         }
 
@@ -53,6 +53,10 @@ namespace gsr {
         return active_kwin_window.title;
     }
 
+    bool get_current_kwin_window_fullscreen() {
+        return active_kwin_window.fullscreen;
+    }
+
     void start_kwin_helper_thread() {
         if (kwin_helper_thread_started) {
             return;

tools/gsr-kwin-helper/gsrkwinhelper.js

@@ -1,52 +1,51 @@
 const DAEMON_DBUS_NAME = "com.dec05eba.gpu_screen_recorder";
 
-// utils
+function dbusSendUpdateActiveWindow(title, isFullscreen) {
-function sendNewActiveWindowTitle(title) {
     callDBus(
         DAEMON_DBUS_NAME, "/", DAEMON_DBUS_NAME,
-        "setActiveWindowTitle", title
+        "updateActiveWindow",
+        title, isFullscreen,
     );
 }
 
-function sendNewActiveWindowFullscreen(isFullscreen) {
+let prevWindow = null;
-    callDBus(
+let prevEmitActiveWindowUpdate = null;
-        DAEMON_DBUS_NAME, "/", DAEMON_DBUS_NAME,
+
-        "setActiveWindowFullscreen", isFullscreen
+let prevCaption = null;
-    );
+let prevFullScreen = null;
+
+function emitActiveWindowUpdate(window) {
+    if (workspace.activeWindow === window) {
+        let caption = window.caption || "";
+        let fullScreen = window.fullScreen || false;
+        if (caption !== prevCaption || fullScreen !== prevFullScreen) {
+            dbusSendUpdateActiveWindow(caption, fullScreen);
+            prevCaption = caption;
+            prevFullScreen = fullScreen;
+        }
+    }
 }
 
-// track handlers to avoid duplicates
+function subscribeToWindow(window) {
-const windowEventHandlers = new Map();
+    if (!window) return;
-
+    if (prevWindow !== window) {
-function subscribeToClient(client) {
+        if (prevWindow !== null) {
-    if (!client || windowEventHandlers.has(client)) return;
+            prevWindow.captionChanged.disconnect(prevEmitActiveWindowUpdate);
-
+            prevWindow.fullScreenChanged.disconnect(prevEmitActiveWindowUpdate);
-    const emitActiveTitle = () => {
-        if (workspace.activeWindow === client) {
-            sendNewActiveWindowTitle(client.caption || "");
         }
-    };
+        let emitActiveWindowUpdateBound = emitActiveWindowUpdate.bind(null, window);
-
+        window.captionChanged.connect(emitActiveWindowUpdateBound);
-    const emitActiveFullscreen = () => {
+        window.fullScreenChanged.connect(emitActiveWindowUpdateBound);
-        if (workspace.activeWindow === client) {
+        prevWindow = window;
-            sendNewActiveWindowFullscreen(client.fullScreen);
+        prevEmitActiveWindowUpdate = emitActiveWindowUpdateBound;
-        }
+    }
-    };
-
-    windowEventHandlers.set(client, {
-        title: emitActiveTitle,
-        fs: emitActiveFullscreen,
-    });
-
-    client.captionChanged.connect(emitActiveTitle);
-    client.fullScreenChanged.connect(emitActiveFullscreen);
 }
 
-function updateActiveWindow(client) {
+function updateActiveWindow(window) {
-    if (!client) return;
+    if (!window) return;
-    sendNewActiveWindowTitle(client.caption || "");
+    if (window.resourceName === "gsr-ui" || window.resourceName === "gsr-notify") return; // ignore the overlay and notification
-    sendNewActiveWindowFullscreen(client.fullScreen);
+    emitActiveWindowUpdate(window);
-    subscribeToClient(client);
+    subscribeToWindow(window);
 }
 
 // handle window focus changes
@@ -55,4 +54,4 @@ workspace.windowActivated.connect(updateActiveWindow);
 // handle initial state
 if (workspace.activeWindow) {
     updateActiveWindow(workspace.activeWindow);
-}
+}

tools/gsr-kwin-helper/main.cpp

@@ -8,8 +8,9 @@ static const char* INTROSPECTION_XML =
     "\"http://www.freedesktop.org/standards/dbus/1.0/introspect.dtd\">\n"
     "<node>\n"
     "  <interface name='com.dec05eba.gpu_screen_recorder'>\n"
-    "    <method name='setActiveWindowTitle'>\n"
+    "    <method name='updateActiveWindow'>\n"
     "      <arg type='s' name='title' direction='in'/>\n"
+    "      <arg type='b' name='fullscreen' direction='in'/>\n"
     "    </method>\n"
     "  </interface>\n"
     "  <interface name='org.freedesktop.DBus.Introspectable'>\n"
@@ -23,6 +24,7 @@ static const char* INTROSPECTION_XML =
 class GsrKwinHelper {
 public:
     std::string active_window_title;
+    bool active_window_fullscreen;
     DBusConnection* connection = nullptr;
     DBusError err;
 
@@ -83,8 +85,8 @@ public:
 
             if (dbus_message_is_method_call(msg, "org.freedesktop.DBus.Introspectable", "Introspect")) {
                 handle_introspect(msg);
-            } else if (dbus_message_is_method_call(msg, "com.dec05eba.gpu_screen_recorder", "setActiveWindowTitle")) {
+            } else if (dbus_message_is_method_call(msg, "com.dec05eba.gpu_screen_recorder", "updateActiveWindow")) {
-                handle_set_title(msg);
+                handle_update_active_window(msg);
             }
 
             dbus_message_unref(msg);
@@ -108,9 +110,10 @@ public:
         dbus_message_unref(reply);
     }
 
-    void handle_set_title(DBusMessage* msg) {
+    void handle_update_active_window(DBusMessage* msg) {
         DBusMessageIter args;
-        const char* title = nullptr;
+        DBusBasicValue title;
+        DBusBasicValue fullscreen;
 
         if (!dbus_message_iter_init(msg, &args)) {
             send_error_reply(msg, "No arguments provided");
@@ -123,15 +126,37 @@ public:
         }
 
         dbus_message_iter_get_basic(&args, &title);
+
+        if (!dbus_message_iter_next(&args)) {
+            send_error_reply(msg, "Not enough arguments provided");
+            return;
+        }
+
+        if (dbus_message_iter_get_arg_type(&args) != DBUS_TYPE_BOOLEAN) {
+            send_error_reply(msg, "Expected boolean argument");
+            return;
+        }
+
+        dbus_message_iter_get_basic(&args, &fullscreen);
         
-        if (title) {
+        if (title.str) {
-            active_window_title = title;
+            if (active_window_title != title.str) {
-            std::cout << "Active window title set to: " << active_window_title << "\n";
+                active_window_title = title.str;
-            std::cout.flush();
+                std::cout << "Active window title set to: " << active_window_title << "\n";
-            send_success_reply(msg);
+                std::cout.flush();
+            }
         } else {
             send_error_reply(msg, "Failed to read string");
+            return;
         }
+
+        if (active_window_fullscreen != fullscreen.bool_val) {
+            active_window_fullscreen = fullscreen.bool_val;
+            std::cout << "Active window fullscreen state set to: " << active_window_fullscreen << "\n";
+            std::cout.flush();
+        }
+
+        send_success_reply(msg);
     }
 
     void send_success_reply(DBusMessage* msg) {