WindowServer: Give menu items an identifier field and add a simple callback.

Eventually these identifiers will be sent to the userspace client who created
the menu. None of that is hooked up yet though.

WindowServer/WSMenu.cpp

@@ -107,7 +107,23 @@ void WSMenu::on_window_message(WSMessage& message)
             return;
         m_hovered_item = item;
         redraw();
+        return;
     }
+
+    if (message.type() == WSMessage::MouseUp) {
+        if (!m_hovered_item)
+            return;
+        did_activate(*m_hovered_item);
+        m_hovered_item = nullptr;
+        redraw();
+        return;
+    }
+}
+
+void WSMenu::did_activate(WSMenuItem& item)
+{
+    if (on_item_activation)
+        on_item_activation(item);
 }
 
 WSMenuItem* WSMenu::item_at(const Point& position)

WindowServer/WSMenu.h

@@ -57,7 +57,11 @@ public:
     WSMenuItem* item_at(const Point&);
     void redraw();
 
+    Function<void(WSMenuItem&)> on_item_activation;
+
 private:
+    void did_activate(WSMenuItem&);
+
     String m_name;
     Rect m_rect_in_menubar;
     Rect m_text_rect_in_menubar;

WindowServer/WSMenuItem.cpp

@@ -1,7 +1,8 @@
 #include "WSMenuItem.h"
 
-WSMenuItem::WSMenuItem(const String& text)
+WSMenuItem::WSMenuItem(unsigned identifier, const String& text)
     : m_type(Text)
+    , m_identifier(identifier)
     , m_text(text)
 {
 }

WindowServer/WSMenuItem.h

@@ -1,6 +1,7 @@
 #pragma once
 
 #include <AK/AKString.h>
+#include <AK/Function.h>
 #include <SharedGraphics/Rect.h>
 
 class WSMenuItem {
@@ -11,7 +12,7 @@ public:
         Separator,
     };
 
-    explicit WSMenuItem(const String& text);
+    explicit WSMenuItem(unsigned identifier, const String& text);
     explicit WSMenuItem(Type);
     ~WSMenuItem();
 
@@ -23,9 +24,12 @@ public:
     void set_rect(const Rect& rect) { m_rect = rect; }
     Rect rect() const { return m_rect; }
 
+    unsigned identifier() const { return m_identifier; }
+
 private:
     Type m_type { None };
     bool m_enabled { true };
+    unsigned m_identifier { 0 };
     String m_text;
     Rect m_rect;
 };

WindowServer/WSWindowManager.cpp

@@ -185,19 +185,26 @@ WSWindowManager::WSWindowManager()
 
         {
             auto menu = make<WSMenu>("Serenity");
-            menu->add_item(make<WSMenuItem>("Launch Terminal"));
+            menu->add_item(make<WSMenuItem>(0, "Launch Terminal"));
             menu->add_item(make<WSMenuItem>(WSMenuItem::Separator));
-            menu->add_item(make<WSMenuItem>("Hello again"));
-            menu->add_item(make<WSMenuItem>("To all my friends"));
-            menu->add_item(make<WSMenuItem>("Together we can play some rock&roll"));
+            menu->add_item(make<WSMenuItem>(1, "Hello again"));
+            menu->add_item(make<WSMenuItem>(2, "To all my friends"));
+            menu->add_item(make<WSMenuItem>(3, "Together we can play some rock&roll"));
             menu->add_item(make<WSMenuItem>(WSMenuItem::Separator));
-            menu->add_item(make<WSMenuItem>("About..."));
+            menu->add_item(make<WSMenuItem>(4, "About..."));
+            menu->on_item_activation = [] (WSMenuItem& item) {
+                kprintf("WSMenu 1 item activated: '%s'\n", item.text().characters());
+            };
             menubar->add_menu(move(menu));
         }
         {
             auto menu = make<WSMenu>("Application");
-            menu->add_item(make<WSMenuItem>("Bar!"));
-            menu->add_item(make<WSMenuItem>("Foo!"));
+            menu->add_item(make<WSMenuItem>(5, "Foo."));
+            menu->add_item(make<WSMenuItem>(6, "Bar?"));
+            menu->add_item(make<WSMenuItem>(7, "Baz!"));
+            menu->on_item_activation = [] (WSMenuItem& item) {
+                kprintf("WSMenu 2 item activated: '%s'\n", item.text().characters());
+            };
             menubar->add_menu(move(menu));
         }