[KBM] Do not register low level hook if there're no remappings (#29708)

* [KBM] Do not register low level hook if there're no remappings

* f: typo

* f: address review comment

src/modules/keyboardmanager/KeyboardManagerEngine/main.cpp

@@ -61,9 +61,14 @@ int WINAPI wWinMain(_In_ HINSTANCE /*hInstance*/,
     }
 
     auto kbm = KeyboardManager();
-    kbm.StartLowlevelKeyboardHook();
+    if (kbm.HasRegisteredRemappings())
+        kbm.StartLowlevelKeyboardHook();
 
-    run_message_loop();
+    auto StartHookFunc = [&kbm]() {
+        kbm.StartLowlevelKeyboardHook();
+    };
+
+    run_message_loop({}, {}, { { KeyboardManager::StartHookMessageID, StartHookFunc } });
 
     kbm.StopLowlevelKeyboardHook();
     Trace::UnregisterProvider();

src/modules/keyboardmanager/KeyboardManagerEngineLibrary/KeyboardManager.cpp

@@ -21,8 +21,15 @@ HHOOK KeyboardManager::hookHandleCopy;
 HHOOK KeyboardManager::hookHandle;
 KeyboardManager* KeyboardManager::keyboardManagerObjectPtr;
 
+namespace
+{
+    DWORD mainThreadId = {};
+}
+
 KeyboardManager::KeyboardManager()
 {
+    mainThreadId = GetCurrentThreadId();
+
     // Load the initial settings.
     LoadSettings();
 
@@ -38,9 +45,11 @@ KeyboardManager::KeyboardManager()
         }
 
         loadingSettings = true;
+        bool loadedSuccessfully = false;
         try
         {
             LoadSettings();
+            loadedSuccessfully = true;
         }
         catch (...)
         {
@@ -48,6 +57,18 @@ KeyboardManager::KeyboardManager()
         }
 
         loadingSettings = false;
+
+        if (!loadedSuccessfully)
+            return;
+
+        const bool newHasRemappings = HasRegisteredRemappingsUnchecked();
+        // We didn't have any bindings before and we have now
+        if (newHasRemappings && !hookHandle)
+            PostThreadMessageW(mainThreadId, StartHookMessageID, 0, 0);
+
+        // All bindings were removed
+        if (!newHasRemappings && hookHandle)
+            StopLowlevelKeyboardHook();
     };
 
     editorIsRunningEvent = CreateEvent(nullptr, true, false, KeyboardManagerConstants::EditorWindowEventName.c_str());
@@ -121,6 +142,32 @@ void KeyboardManager::StopLowlevelKeyboardHook()
     }
 }
 
+bool KeyboardManager::HasRegisteredRemappings() const
+{
+    constexpr int MaxAttempts = 5;
+
+    if (loadingSettings)
+    {
+        for (int currentAttempt = 0; currentAttempt < MaxAttempts; ++currentAttempt)
+        {
+            std::this_thread::sleep_for(std::chrono::milliseconds(500));
+            if (!loadingSettings)
+                break;
+        }
+    }
+
+    // Assume that we have registered remappings to be on the safe side if we couldn't check
+    if (loadingSettings)
+        return true;
+
+    return HasRegisteredRemappingsUnchecked();
+}
+
+bool KeyboardManager::HasRegisteredRemappingsUnchecked() const
+{
+    return !(state.appSpecificShortcutReMap.empty() && state.appSpecificShortcutReMapSortedKeys.empty() && state.osLevelShortcutReMap.empty() && state.osLevelShortcutReMapSortedKeys.empty() && state.singleKeyReMap.empty() && state.singleKeyToTextReMap.empty());
+}
+
 intptr_t KeyboardManager::HandleKeyboardHookEvent(LowlevelKeyboardEvent* data) noexcept
 {
     if (loadingSettings)

src/modules/keyboardmanager/KeyboardManagerEngineLibrary/KeyboardManager.h

@@ -7,6 +7,8 @@
 class KeyboardManager
 {
 public:
+    static const inline DWORD StartHookMessageID = WM_APP + 1;
+
     // Constructor
     KeyboardManager();
     
@@ -21,7 +23,12 @@ public:
     void StartLowlevelKeyboardHook();
     void StopLowlevelKeyboardHook();
 
+    bool HasRegisteredRemappings() const;
+
 private:
+    // Returns whether there are any remappings available without waiting for settings to load
+    bool HasRegisteredRemappingsUnchecked() const;
+
     // Contains the non localized module name
     std::wstring moduleName = KeyboardManagerConstants::ModuleName;