[AlwaysOnTop] Proof of concept (#14360)

Co-authored-by: Niels Laute <niels.laute@live.nl>

src/modules/alwaysontop/AlwaysOnTop/AlwaysOnTop.h

@@ -0,0 +1,88 @@
+#pragma once
+
+#include <map>
+
+#include <Settings.h>
+#include <SettingsObserver.h>
+#include <Sound.h>
+#include <VirtualDesktopUtils.h>
+#include <WindowBorder.h>
+
+#include <common/hooks/WinHookEvent.h>
+
+class AlwaysOnTop : public SettingsObserver
+{
+public:
+    AlwaysOnTop();
+    ~AlwaysOnTop();
+
+protected:
+    static LRESULT CALLBACK WndProc_Helper(HWND window, UINT message, WPARAM wparam, LPARAM lparam) noexcept
+    {
+        auto thisRef = reinterpret_cast<AlwaysOnTop*>(GetWindowLongPtr(window, GWLP_USERDATA));
+
+        if (!thisRef && (message == WM_CREATE))
+        {
+            const auto createStruct = reinterpret_cast<LPCREATESTRUCT>(lparam);
+            thisRef = reinterpret_cast<AlwaysOnTop*>(createStruct->lpCreateParams);
+            SetWindowLongPtr(window, GWLP_USERDATA, reinterpret_cast<LONG_PTR>(thisRef));
+        }
+
+        return thisRef ? thisRef->WndProc(window, message, wparam, lparam) :
+                         DefWindowProc(window, message, wparam, lparam);
+    }
+
+private:
+    // IDs used to register hot keys (keyboard shortcuts).
+    enum class HotkeyId : int
+    {
+        Pin = 1,
+    };
+
+    static inline AlwaysOnTop* s_instance = nullptr;
+    std::vector<HWINEVENTHOOK> m_staticWinEventHooks{};
+    Sound m_sound;
+    VirtualDesktopUtils m_virtualDesktopUtils;
+
+    HWND m_window{ nullptr };
+    HINSTANCE m_hinstance;
+    std::map<HWND, std::unique_ptr<WindowBorder>> m_topmostWindows{};
+
+    LRESULT WndProc(HWND, UINT, WPARAM, LPARAM) noexcept;
+    void HandleWinHookEvent(WinHookEvent* data) noexcept;
+    
+    bool InitMainWindow();
+    void RegisterHotkey() const;
+    void SubscribeToEvents();
+
+    void ProcessCommand(HWND window);
+    void StartTrackingTopmostWindows();
+    void UnpinAll();
+    void CleanUp();
+
+    void VirtualDesktopSwitchedHandle();
+
+    bool IsTracked(HWND window) const noexcept;
+    bool IsTopmost(HWND window) const noexcept;
+
+    bool PinTopmostWindow(HWND window) const noexcept;
+    bool UnpinTopmostWindow(HWND window) const noexcept;
+    bool AssignBorderTracker(HWND window);
+
+    virtual void SettingsUpdate(SettingId type) override;
+
+    static void CALLBACK WinHookProc(HWINEVENTHOOK winEventHook,
+                                     DWORD event,
+                                     HWND window,
+                                     LONG object,
+                                     LONG child,
+                                     DWORD eventThread,
+                                     DWORD eventTime)
+    {
+        WinHookEvent data{ event, window, object, child, eventThread, eventTime };
+        if (s_instance)
+        {
+            s_instance->HandleWinHookEvent(&data);
+        }
+    }
+};