WindowServer: Add WM_SetActiveWindow client request and use it in Taskbar.

This makes it possible for Taskbar to switch windows. :^)

Applications/Taskbar/WindowList.cpp

@@ -1,4 +1,6 @@
 #include "WindowList.h"
+#include <WindowServer/WSAPITypes.h>
+#include <LibGUI/GEventLoop.h>
 
 Window& WindowList::ensure_window(const WindowIdentifier& identifier)
 {
@@ -7,6 +9,14 @@ Window& WindowList::ensure_window(const WindowIdentifier& identifier)
         return *it->value;
     auto window = make<Window>(identifier);
     window->set_button(aid_create_button());
+    window->button()->on_click = [identifier] (GButton&) {
+        WSAPI_ClientMessage message;
+        message.type = WSAPI_ClientMessage::Type::WM_SetActiveWindow;
+        message.wm.client_id = identifier.client_id();
+        message.wm.window_id = identifier.window_id();
+        bool success = GEventLoop::post_message_to_server(message);
+        ASSERT(success);
+    };
     auto& window_ref = *window;
     m_windows.set(identifier, move(window));
     return window_ref;

Servers/WindowServer/WSAPITypes.h

@@ -185,6 +185,7 @@ struct WSAPI_ClientMessage {
         SetWallpaper,
         GetWallpaper,
         SetWindowOverrideCursor,
+        WM_SetActiveWindow,
     };
     Type type { Invalid };
     int window_id { -1 };
@@ -196,6 +197,10 @@ struct WSAPI_ClientMessage {
         struct {
             int client_pid;
         } greeting;
+        struct {
+            int client_id;
+            int window_id;
+        } wm;
         struct {
             int menubar_id;
             int menu_id;

Servers/WindowServer/WSClientConnection.cpp

@@ -519,6 +519,22 @@ void WSClientConnection::handle_request(const WSAPISetWindowOverrideCursorReques
     window.set_override_cursor(WSCursor::create(request.cursor()));
 }
 
+void WSClientConnection::handle_request(const WSWMAPISetActiveWindowRequest& request)
+{
+    auto* client = WSClientConnection::from_client_id(request.target_client_id());
+    if (!client) {
+        post_error("Bad client ID");
+        return;
+    }
+    auto it = client->m_windows.find(request.target_window_id());
+    if (it == client->m_windows.end()) {
+        post_error("Bad window ID");
+        return;
+    }
+    auto& window = *(*it).value;
+    WSWindowManager::the().set_active_window(&window);
+}
+
 void WSClientConnection::on_request(const WSAPIClientRequest& request)
 {
     switch (request.type()) {
@@ -572,6 +588,8 @@ void WSClientConnection::on_request(const WSAPIClientRequest& request)
         return handle_request(static_cast<const WSAPIGetWallpaperRequest&>(request));
     case WSMessage::APISetWindowOverrideCursorRequest:
         return handle_request(static_cast<const WSAPISetWindowOverrideCursorRequest&>(request));
+    case WSMessage::WMAPISetActiveWindowRequest:
+        return handle_request(static_cast<const WSWMAPISetActiveWindowRequest&>(request));
     default:
         break;
     }

Servers/WindowServer/WSClientConnection.h

@@ -68,6 +68,7 @@ private:
     void handle_request(const WSAPISetWallpaperRequest&);
     void handle_request(const WSAPIGetWallpaperRequest&);
     void handle_request(const WSAPISetWindowOverrideCursorRequest&);
+    void handle_request(const WSWMAPISetActiveWindowRequest&);
 
     void post_error(const String&);
 

Servers/WindowServer/WSMessage.h

@@ -56,6 +56,7 @@ public:
         APISetWallpaperRequest,
         APIGetWallpaperRequest,
         APISetWindowOverrideCursorRequest,
+        WMAPISetActiveWindowRequest,
         __End_API_Client_Requests,
     };
 
@@ -101,6 +102,23 @@ private:
     int m_client_id { 0 };
 };
 
+class WSWMAPISetActiveWindowRequest : public WSAPIClientRequest {
+public:
+    WSWMAPISetActiveWindowRequest(int client_id, int target_client_id, int target_window_id)
+        : WSAPIClientRequest(WSMessage::WMAPISetActiveWindowRequest, client_id)
+        , m_target_client_id(target_client_id)
+        , m_target_window_id(target_window_id)
+    {
+    }
+
+    int target_client_id() const { return m_target_client_id; }
+    int target_window_id() const { return m_target_window_id; }
+
+private:
+    int m_target_client_id;
+    int m_target_window_id;
+};
+
 class WSAPISetGlobalCursorTrackingRequest : public WSAPIClientRequest {
 public:
     WSAPISetGlobalCursorTrackingRequest(int client_id, int window_id, bool value)

Servers/WindowServer/WSMessageLoop.cpp

@@ -346,6 +346,10 @@ void WSMessageLoop::on_receive_from_client(int client_id, const WSAPI_ClientMess
         break;
     case WSAPI_ClientMessage::Type::SetWindowOverrideCursor:
         post_message(client, make<WSAPISetWindowOverrideCursorRequest>(client_id, message.window_id, (WSStandardCursor)message.cursor.cursor));
+        break;
+    case WSAPI_ClientMessage::Type::WM_SetActiveWindow:
+        post_message(client, make<WSWMAPISetActiveWindowRequest>(client_id, message.wm.client_id, message.wm.window_id));
+        break;
     default:
         break;
     }

Servers/WindowServer/WSWindowManager.h

@@ -96,6 +96,8 @@ public:
     const WSCursor& disallowed_cursor() const { return *m_disallowed_cursor; }
     const WSCursor& move_cursor() const { return *m_move_cursor; }
 
+    void set_active_window(WSWindow*);
+
 private:
     void process_mouse_event(const WSMouseEvent&, WSWindow*& event_window);
     bool process_ongoing_window_resize(const WSMouseEvent&, WSWindow*& event_window);
@@ -106,7 +108,6 @@ private:
     void start_window_resize(WSWindow&, const WSMouseEvent&);
     void start_window_drag(WSWindow&, const WSMouseEvent&);
     void handle_client_request(const WSAPIClientRequest&);
-    void set_active_window(WSWindow*);
     void set_hovered_window(WSWindow*);
     template<typename Callback> IterationDecision for_each_visible_window_of_type_from_back_to_front(WSWindowType, Callback);
     template<typename Callback> IterationDecision for_each_visible_window_of_type_from_front_to_back(WSWindowType, Callback);