WSMenu: Support menu navigation through key presses

Add event handling for key presses for navigating a menu. The currently
hovered menu item is tracked through an index which is either
incremented or decremented on up or down arrow key presses, changing the
hovered item.

Whenever there is a mouse move event, we ensure that the current index
matches the currently hovered item so that the mouse and keyboard do not
get out of sync.

If the right key is pressed, and we are on a submenu menu item, we
'enter' that submenu. While we are currently in a submenu, we forward
all keypress events to that submenu for handling. This allows us to
traverse the heirachy of a menu. While in a submenu, if the left key is
pressed, we leave that submenu and start handling the keypresses
ourselves again.

There is currently a small issue where the mouse hover and key hover can
get out of sync. The mouse can be traversing a submenu, but the parent
menu has no idea that the mouse has 'entered' a submenu, so will handle
the key presses itself, instead of forwarding them to the submenu. One
potential fix for this is for a menu to tell its menu parent that the
submenu is being traversed.

6 files changed, 169 insertions, 29 deletions

diff --git a/Servers/WindowServer/WSMenu.cpp b/Servers/WindowServer/WSMenu.cpp
index 210a247b10..1533a58a5e 100644
--- a/Servers/WindowServer/WSMenu.cpp
+++ b/Servers/WindowServer/WSMenu.cpp
@@ -201,6 +201,42 @@ void WSMenu::draw()
     }
 }
 
+void WSMenu::redraw_for_new_hovered_item()
+{
+    if (m_hovered_item && m_hovered_item->is_submenu()) {
+        ASSERT(m_hovered_item == &m_items.at(m_current_index));
+        WSWindowManager::the().menu_manager().close_everyone_not_in_lineage(*m_hovered_item->submenu());
+        m_hovered_item->submenu()->popup(m_hovered_item->rect().top_right().translated(menu_window()->rect().location()), true);
+    } else {
+        WSWindowManager::the().menu_manager().close_everyone_not_in_lineage(*this);
+    }
+    redraw();
+}
+
+void WSMenu::open_hovered_item()
+{
+    ASSERT(menu_window());
+    ASSERT(menu_window()->is_visible());
+    if (!m_hovered_item)
+        return;
+    ASSERT(m_hovered_item == &m_items.at(m_current_index));
+    if (m_hovered_item->is_enabled())
+        did_activate(*m_hovered_item);
+    clear_hovered_item();
+}
+
+void WSMenu::decend_into_submenu_at_hovered_item()
+{
+    ASSERT(m_hovered_item);
+    ASSERT(m_hovered_item->is_submenu());
+    auto submenu = m_hovered_item->submenu();
+    ASSERT(submenu->m_current_index == 0);
+    submenu->m_hovered_item = &submenu->m_items.at(0);
+    ASSERT(submenu->m_hovered_item->type() != WSMenuItem::Separator);
+    submenu->redraw_for_new_hovered_item();
+    m_in_submenu = true;
+}
+
 void WSMenu::event(CEvent& event)
 {
     if (event.type() == WSEvent::MouseMove) {
@@ -209,26 +245,99 @@ void WSMenu::event(CEvent& event)
         if (m_hovered_item == item)
             return;
         m_hovered_item = item;
-        if (m_hovered_item && m_hovered_item->is_submenu()) {
-            WSWindowManager::the().menu_manager().close_everyone_not_in_lineage(*m_hovered_item->submenu());
-            m_hovered_item->submenu()->popup(m_hovered_item->rect().top_right().translated(menu_window()->rect().location()), true);
-        } else {
-            WSWindowManager::the().menu_manager().close_everyone_not_in_lineage(*this);
+
+        if (m_hovered_item) {
+            // FIXME: Tell parent menu (if it exists) that it is currently in a submenu
+            m_current_index = m_items.find([&](auto& item) { return item.ptr() == m_hovered_item; }).index();
+            ASSERT(m_current_index != m_items.size());
         }
-        redraw();
+
+        m_in_submenu = false;
+        redraw_for_new_hovered_item();
         return;
     }
 
     if (event.type() == WSEvent::MouseUp) {
-        ASSERT(menu_window());
-        if (!m_hovered_item)
-            return;
-        if (m_hovered_item->is_enabled())
-            did_activate(*m_hovered_item);
-        clear_hovered_item();
+        open_hovered_item();
         return;
     }
 
+    if (event.type() == WSEvent::KeyDown) {
+        auto key = static_cast<WSKeyEvent&>(event).key();
+
+        if (!(key == Key_Up || key == Key_Down || key == Key_Left || key == Key_Right || key == Key_Return))
+            return;
+
+        ASSERT(menu_window());
+        ASSERT(menu_window()->is_visible());
+
+        // Default to the first item on key press if one has not been selected yet
+        if (!m_hovered_item) {
+            m_hovered_item = &m_items.at(0);
+            redraw_for_new_hovered_item();
+            return;
+        }
+
+        // Pass the event for the submenu that we are currently in to handle
+        if (m_in_submenu && key != Key_Left) {
+            ASSERT(m_hovered_item->is_submenu());
+            m_hovered_item->submenu()->dispatch_event(event);
+            return;
+        }
+
+        if (key == Key_Return) {
+            if (m_hovered_item->is_submenu())
+                decend_into_submenu_at_hovered_item();
+            else
+                open_hovered_item();
+            return;
+        }
+
+        if (key == Key_Up) {
+            ASSERT(m_items.at(0).type() != WSMenuItem::Separator);
+
+            do {
+                m_current_index--;
+                if (m_current_index < 0)
+                    m_current_index = m_items.size() - 1;
+                m_hovered_item = &m_items.at(m_current_index);
+            } while (m_hovered_item->type() == WSMenuItem::Separator);
+
+            redraw_for_new_hovered_item();
+            return;
+        }
+
+        if (key == Key_Down) {
+            ASSERT(m_items.at(0).type() != WSMenuItem::Separator);
+
+            do {
+                m_current_index++;
+                if (m_current_index >= m_items.size())
+                    m_current_index = 0;
+                m_hovered_item = &m_items.at(m_current_index);
+            } while (m_hovered_item->type() == WSMenuItem::Separator);
+
+            redraw_for_new_hovered_item();
+            return;
+        }
+
+        if (key == Key_Left) {
+            if (!m_in_submenu)
+                return;
+
+            m_hovered_item = &m_items.at(m_current_index);
+            ASSERT(m_hovered_item->is_submenu());
+            m_hovered_item->submenu()->clear_hovered_item();
+            m_in_submenu = false;
+            return;
+        }
+
+        if (key == Key_Right) {
+            if (m_hovered_item->is_submenu())
+                decend_into_submenu_at_hovered_item();
+            return;
+        }
+    }
     CObject::event(event);
 }
 
@@ -236,7 +345,9 @@ void WSMenu::clear_hovered_item()
 {
     if (!m_hovered_item)
         return;
+    m_current_index = 0;
     m_hovered_item = nullptr;
+    m_in_submenu = false;
     redraw();
 }
 
diff --git a/Servers/WindowServer/WSMenu.h b/Servers/WindowServer/WSMenu.h
index 0240aaca09..6201871cbd 100644
--- a/Servers/WindowServer/WSMenu.h
+++ b/Servers/WindowServer/WSMenu.h
@@ -92,6 +92,10 @@ private:
 
     int padding_between_text_and_shortcut() const { return 50; }
     void did_activate(WSMenuItem&);
+    void open_hovered_item();
+    void redraw_for_new_hovered_item();
+    void decend_into_submenu_at_hovered_item();
+
     WSClientConnection* m_client { nullptr };
     int m_menu_id { 0 };
     String m_name;
@@ -101,7 +105,11 @@ private:
     WSMenuItem* m_hovered_item { nullptr };
     NonnullOwnPtrVector<WSMenuItem> m_items;
     RefPtr<WSWindow> m_menu_window;
+
     WeakPtr<WSWindow> m_window_menu_of;
     bool m_is_window_menu_open = { false };
+
     int m_theme_index_at_last_paint { -1 };
+    int m_current_index { 0 };
+    bool m_in_submenu { false };
 };
diff --git a/Servers/WindowServer/WSMenuManager.cpp b/Servers/WindowServer/WSMenuManager.cpp
index fe474c7578..0ff230c700 100644
--- a/Servers/WindowServer/WSMenuManager.cpp
+++ b/Servers/WindowServer/WSMenuManager.cpp
@@ -263,6 +263,15 @@ void WSMenuManager::event(CEvent& event)
             applet->event(local_event);
         }
     }
+
+    if (event.type() == WSEvent::KeyDown) {
+        for_each_active_menubar_menu([&](WSMenu& menu) {
+            if (is_open(menu))
+                menu.dispatch_event(event);
+            return IterationDecision::Continue;
+        });
+    }
+
     return CObject::event(event);
 }
 
@@ -270,7 +279,7 @@ void WSMenuManager::handle_menu_mouse_event(WSMenu& menu, const WSMouseEvent& ev
 {
     bool is_hover_with_any_menu_open = event.type() == WSMouseEvent::MouseMove
         && !m_open_menu_stack.is_empty()
-        && (m_open_menu_stack.first()->menubar() || m_open_menu_stack.first() == system_menu());
+        && (m_open_menu_stack.first()->menubar() || m_open_menu_stack.first() == m_system_menu.ptr());
     bool is_mousedown_with_left_button = event.type() == WSMouseEvent::MouseDown && event.button() == MouseButton::Left;
     bool should_open_menu = &menu != m_current_menu && (is_hover_with_any_menu_open || is_mousedown_with_left_button);
 
@@ -278,17 +287,7 @@ void WSMenuManager::handle_menu_mouse_event(WSMenu& menu, const WSMouseEvent& ev
         m_bar_open = !m_bar_open;
 
     if (should_open_menu && m_bar_open) {
-        if (m_current_menu == &menu)
-            return;
-        close_everyone();
-        if (!menu.is_empty()) {
-            menu.redraw_if_theme_changed();
-            auto& menu_window = menu.ensure_menu_window();
-            menu_window.move_to({ menu.rect_in_menubar().x(), menu.rect_in_menubar().bottom() + 2 });
-            menu_window.set_visible(true);
-        }
-        set_current_menu(&menu);
-        refresh();
+        open_menu(menu);
         return;
     }
 
@@ -368,6 +367,20 @@ void WSMenuManager::close_menu_and_descendants(WSMenu& menu)
     close_menus(menus_to_close);
 }
 
+void WSMenuManager::open_menu(WSMenu& menu)
+{
+    if (is_open(menu))
+        return;
+    if (!menu.is_empty()) {
+        menu.redraw_if_theme_changed();
+        auto& menu_window = menu.ensure_menu_window();
+        menu_window.move_to({ menu.rect_in_menubar().x(), menu.rect_in_menubar().bottom() + 2 });
+        menu_window.set_visible(true);
+    }
+    set_current_menu(&menu);
+    refresh();
+}
+
 void WSMenuManager::set_current_menu(WSMenu* menu, bool is_submenu)
 {
     if (!is_submenu && m_current_menu)
diff --git a/Servers/WindowServer/WSMenuManager.h b/Servers/WindowServer/WSMenuManager.h
index 26cd609800..c497e740ff 100644
--- a/Servers/WindowServer/WSMenuManager.h
+++ b/Servers/WindowServer/WSMenuManager.h
@@ -30,6 +30,7 @@ public:
 
     WSMenu* current_menu() { return m_current_menu.ptr(); }
     void set_current_menu(WSMenu*, bool is_submenu = false);
+    void open_menu(WSMenu&);
 
     WSMenuBar* current_menubar() { return m_current_menubar.ptr(); }
     void set_current_menubar(WSMenuBar*);
@@ -47,14 +48,14 @@ public:
     void invalidate_applet(const WSWindow&, const Rect&);
 
     Color menu_selection_color() const { return m_menu_selection_color; }
-    WSMenu* system_menu() { return m_system_menu; }
+    WSMenu& system_menu() { return *m_system_menu; }
     WSMenu* find_internal_menu_by_id(int);
     int theme_index() const { return m_theme_index; }
 
     template<typename Callback>
     void for_each_active_menubar_menu(Callback callback)
     {
-        if (callback(*system_menu()) == IterationDecision::Break)
+        if (callback(system_menu()) == IterationDecision::Break)
             return;
         if (m_current_menubar)
             m_current_menubar->for_each_menu(callback);
diff --git a/Servers/WindowServer/WSWindowManager.cpp b/Servers/WindowServer/WSWindowManager.cpp
index 515abb4dcc..adcdce0371 100644
--- a/Servers/WindowServer/WSWindowManager.cpp
+++ b/Servers/WindowServer/WSWindowManager.cpp
@@ -975,10 +975,18 @@ void WSWindowManager::event(CEvent& event)
                     }
                 }
             }
+            m_active_window->dispatch_event(event);
+            return;
+        }
 
-            return m_active_window->dispatch_event(event);
+        // FIXME: I would prefer to be WSEvent::KeyUp, and be at the top of this function
+        // However, the modifier is Invalid of Mod_Logo for a keyup event. Move after a fix is made.
+        if (key_event.type() == WSEvent::KeyDown && key_event.modifiers() == Mod_Logo) {
+            m_menu_manager.open_menu(m_menu_manager.system_menu());
+            return;
         }
-        return;
+
+        m_menu_manager.dispatch_event(event);
     }
 
     CObject::event(event);
diff --git a/Servers/WindowServer/WSWindowManager.h b/Servers/WindowServer/WSWindowManager.h
index f8e01f1361..f02a497a6b 100644
--- a/Servers/WindowServer/WSWindowManager.h
+++ b/Servers/WindowServer/WSWindowManager.h
@@ -258,7 +258,6 @@ private:
 
     u8 m_keyboard_modifiers { 0 };
 
-
     WSWindowSwitcher m_switcher;
     WSMenuManager m_menu_manager;