WindowServer+LibGUI: Notify GUI clients about menu item enter/leave

We now send out MenuItemEntered and MenuItemLeft messages to the client
when the user hovers/unhovers menu items.

On the client side, these become GUI::ActionEvent, with one of two
types: ActionEnter or ActionLeave. They are sent to the Application.

This will allow GUI applications to react to these events.

Userland/Libraries/LibGUI/Event.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2020, Andreas Kling <kling@serenityos.org>
+ * Copyright (c) 2020-2021, Andreas Kling <kling@serenityos.org>
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -26,6 +26,7 @@
 
 #include <AK/StringBuilder.h>
 #include <LibCore/MimeData.h>
+#include <LibGUI/Action.h>
 #include <LibGUI/Event.h>
 
 namespace GUI {
@@ -69,4 +70,14 @@ String KeyEvent::to_string() const
     return builder.to_string();
 }
 
+ActionEvent::ActionEvent(Type type, Action& action)
+    : Event(type)
+    , m_action(action)
+{
+}
+
+ActionEvent::~ActionEvent()
+{
+}
+
 }

Userland/Libraries/LibGUI/Event.h

@@ -31,6 +31,7 @@
 #include <Kernel/API/KeyCode.h>
 #include <LibCore/Event.h>
 #include <LibGUI/FocusSource.h>
+#include <LibGUI/Forward.h>
 #include <LibGUI/WindowType.h>
 #include <LibGfx/Bitmap.h>
 #include <LibGfx/Point.h>
@@ -72,6 +73,8 @@ public:
         Drop,
         ThemeChange,
         ScreenRectChange,
+        ActionEnter,
+        ActionLeave,
 
         __Begin_WM_Events,
         WM_WindowRemoved,
@@ -428,4 +431,16 @@ private:
     FocusSource m_source { FocusSource::Programmatic };
 };
 
+class ActionEvent final : public Event {
+public:
+    ActionEvent(Type, Action&);
+    ~ActionEvent();
+
+    Action const& action() const { return *m_action; }
+    Action& action() { return *m_action; }
+
+private:
+    NonnullRefPtr<Action> m_action;
+};
+
 }

Userland/Libraries/LibGUI/WindowServerConnection.cpp

@@ -273,6 +273,38 @@ void WindowServerConnection::handle(const Messages::WindowClient::MenuItemActiva
         action->activate(menu);
 }
 
+void WindowServerConnection::handle(Messages::WindowClient::MenuItemEntered const& message)
+{
+    auto* menu = Menu::from_menu_id(message.menu_id());
+    if (!menu) {
+        dbgln("WindowServerConnection received MenuItemEntered for invalid menu ID {}", message.menu_id());
+        return;
+    }
+    auto* action = menu->action_at(message.identifier());
+    if (!action)
+        return;
+    auto* app = Application::the();
+    if (!app)
+        return;
+    Core::EventLoop::current().post_event(*app, make<ActionEvent>(GUI::Event::ActionEnter, *action));
+}
+
+void WindowServerConnection::handle(Messages::WindowClient::MenuItemLeft const& message)
+{
+    auto* menu = Menu::from_menu_id(message.menu_id());
+    if (!menu) {
+        dbgln("WindowServerConnection received MenuItemLeft for invalid menu ID {}", message.menu_id());
+        return;
+    }
+    auto* action = menu->action_at(message.identifier());
+    if (!action)
+        return;
+    auto* app = Application::the();
+    if (!app)
+        return;
+    Core::EventLoop::current().post_event(*app, make<ActionEvent>(GUI::Event::ActionLeave, *action));
+}
+
 void WindowServerConnection::handle(const Messages::WindowClient::ScreenRectChanged& message)
 {
     Desktop::the().did_receive_screen_rect({}, message.rect());

Userland/Libraries/LibGUI/WindowServerConnection.h

@@ -64,6 +64,8 @@ private:
     virtual void handle(const Messages::WindowClient::WindowCloseRequest&) override;
     virtual void handle(const Messages::WindowClient::WindowResized&) override;
     virtual void handle(const Messages::WindowClient::MenuItemActivated&) override;
+    virtual void handle(const Messages::WindowClient::MenuItemEntered&) override;
+    virtual void handle(const Messages::WindowClient::MenuItemLeft&) override;
     virtual void handle(const Messages::WindowClient::MenuVisibilityDidChange&) override;
     virtual void handle(const Messages::WindowClient::ScreenRectChanged&) override;
     virtual void handle(const Messages::WindowClient::AsyncSetWallpaperFinished&) override;

Userland/Services/WindowServer/Menu.cpp

@@ -300,8 +300,8 @@ MenuItem* Menu::hovered_item() const
 
 void Menu::update_for_new_hovered_item(bool make_input)
 {
-    auto* hovered_item = this->hovered_item();
-    if (hovered_item && hovered_item->is_submenu()) {
+    if (auto* hovered_item = this->hovered_item()) {
+        if (hovered_item->is_submenu()) {
             VERIFY(menu_window());
             MenuManager::the().close_everyone_not_in_lineage(*hovered_item->submenu());
             hovered_item->submenu()->do_popup(hovered_item->rect().top_right().translated(menu_window()->rect().location()), make_input, true);
@@ -310,6 +310,7 @@ void Menu::update_for_new_hovered_item(bool make_input)
             ensure_menu_window();
             set_visible(true);
         }
+    }
     redraw();
 }
 
@@ -461,10 +462,7 @@ void Menu::event(Core::Event& event)
 
 void Menu::clear_hovered_item()
 {
-    if (!hovered_item())
-        return;
-    m_hovered_item_index = -1;
-    redraw();
+    set_hovered_index(-1);
 }
 
 void Menu::start_activation_animation(MenuItem& item)
@@ -650,4 +648,20 @@ const Vector<size_t>* Menu::items_with_alt_shortcut(u32 alt_shortcut) const
     return &it->value;
 }
 
+void Menu::set_hovered_index(int index, bool make_input)
+{
+    if (m_hovered_item_index == index)
+        return;
+    if (auto* old_hovered_item = hovered_item()) {
+        if (client())
+            client()->post_message(Messages::WindowClient::MenuItemLeft(m_menu_id, old_hovered_item->identifier()));
+    }
+    m_hovered_item_index = index;
+    update_for_new_hovered_item(make_input);
+    if (auto* new_hovered_item = hovered_item()) {
+        if (client())
+            client()->post_message(Messages::WindowClient::MenuItemEntered(m_menu_id, new_hovered_item->identifier()));
+    }
+}
+
 }

Userland/Services/WindowServer/Menu.h

@@ -101,11 +101,7 @@ public:
 
     MenuItem* hovered_item() const;
 
-    void set_hovered_index(int index, bool make_input = false)
-    {
-        m_hovered_item_index = index;
-        update_for_new_hovered_item(make_input);
-    }
+    void set_hovered_index(int index, bool make_input = false);
 
     void clear_hovered_item();
 

Userland/Services/WindowServer/WindowClient.ipc

@@ -19,6 +19,8 @@ endpoint WindowClient = 4
     WindowResized(i32 window_id, Gfx::IntRect new_rect) =|
 
     MenuItemActivated(i32 menu_id, i32 identifier) =|
+    MenuItemEntered(i32 menu_id, u32 identifier) =|
+    MenuItemLeft(i32 menu_id, u32 identifier) =|
     MenuVisibilityDidChange(i32 menu_id, bool visible) =|
 
     ScreenRectChanged(Gfx::IntRect rect) =|