WindowServer: Fix visibility of WindowSwitcher constructor

Derivatives of Core::Object should be constructed through
ClassName::construct(), to avoid handling ref-counted objects with
refcount zero. Fixing the visibility means that misuses like this are
more difficult.

This commit is separate from the other Servives changes because it
required additional adaption of the code. Note that the old code did
precisely what these changes try to prevent: Create and handle a
ref-counted object with a refcount of zero.

Userland/Services/WindowServer/Compositor.cpp

@@ -1084,10 +1084,10 @@ void Compositor::recompute_overlay_rects()
 void Compositor::recompute_occlusions()
 {
     auto& wm = WindowManager::the();
-    bool is_switcher_visible = wm.m_switcher.is_visible();
+    bool is_switcher_visible = wm.m_switcher->is_visible();
     auto never_occlude = [&](WindowStack& window_stack) {
         if (is_switcher_visible) {
-            switch (wm.m_switcher.mode()) {
+            switch (wm.m_switcher->mode()) {
             case WindowSwitcher::Mode::ShowCurrentDesktop:
                 // Any window on the currently rendered desktop should not be occluded, even if it's behind
                 // another window entirely.
@@ -1540,7 +1540,7 @@ void Compositor::finish_window_stack_switch()
     m_window_stack_transition_animation = nullptr;
 
     auto& wm = WindowManager::the();
-    if (!wm.m_switcher.is_visible())
+    if (!wm.m_switcher->is_visible())
         previous_window_stack->set_all_occluded(true);
     wm.did_switch_window_stack({}, *previous_window_stack, *m_current_window_stack);
 

Userland/Services/WindowServer/WindowManager.cpp

@@ -35,7 +35,8 @@ WindowManager& WindowManager::the()
 }
 
 WindowManager::WindowManager(Gfx::PaletteImpl const& palette)
-    : m_palette(palette)
+    : m_switcher(WindowSwitcher::construct())
+    , m_palette(palette)
 {
     s_the = this;
 
@@ -313,8 +314,8 @@ void WindowManager::add_window(Window& window)
     if (window.type() != WindowType::Desktop || is_first_window)
         set_active_window(&window);
 
-    if (m_switcher.is_visible() && window.type() != WindowType::WindowSwitcher)
-        m_switcher.refresh();
+    if (m_switcher->is_visible() && window.type() != WindowType::WindowSwitcher)
+        m_switcher->refresh();
 
     Compositor::the().invalidate_occlusions();
 
@@ -360,10 +361,10 @@ void WindowManager::do_move_to_front(Window& window, bool make_active, bool make
     if (make_active)
         set_active_window(&window, make_input);
 
-    if (m_switcher.is_visible()) {
-        m_switcher.refresh();
+    if (m_switcher->is_visible()) {
+        m_switcher->refresh();
         if (!window.is_accessory()) {
-            m_switcher.select_window(window);
+            m_switcher->select_window(window);
             set_highlight_window(&window);
         }
     }
@@ -386,8 +387,8 @@ void WindowManager::remove_window(Window& window)
 
     window.invalidate_last_rendered_screen_rects_now();
 
-    if (m_switcher.is_visible() && window.type() != WindowType::WindowSwitcher)
-        m_switcher.refresh();
+    if (m_switcher->is_visible() && window.type() != WindowType::WindowSwitcher)
+        m_switcher->refresh();
 
     Compositor::the().invalidate_occlusions();
 
@@ -543,8 +544,8 @@ static bool window_type_has_title(WindowType type)
 
 void WindowManager::notify_modified_changed(Window& window)
 {
-    if (m_switcher.is_visible())
-        m_switcher.refresh();
+    if (m_switcher->is_visible())
+        m_switcher->refresh();
 
     tell_wms_window_state_changed(window);
 }
@@ -556,8 +557,8 @@ void WindowManager::notify_title_changed(Window& window)
 
     dbgln_if(WINDOWMANAGER_DEBUG, "[WM] Window({}) title set to '{}'", &window, window.title());
 
-    if (m_switcher.is_visible())
-        m_switcher.refresh();
+    if (m_switcher->is_visible())
+        m_switcher->refresh();
 
     tell_wms_window_state_changed(window);
 }
@@ -569,8 +570,8 @@ void WindowManager::notify_modal_unparented(Window& window)
 
     dbgln_if(WINDOWMANAGER_DEBUG, "[WM] Window({}) was unparented", &window);
 
-    if (m_switcher.is_visible())
-        m_switcher.refresh();
+    if (m_switcher->is_visible())
+        m_switcher->refresh();
 
     tell_wms_window_state_changed(window);
 }
@@ -579,8 +580,8 @@ void WindowManager::notify_rect_changed(Window& window, Gfx::IntRect const& old_
 {
     dbgln_if(RESIZE_DEBUG, "[WM] Window({}) rect changed {} -> {}", &window, old_rect, new_rect);
 
-    if (m_switcher.is_visible() && window.type() != WindowType::WindowSwitcher)
-        m_switcher.refresh();
+    if (m_switcher->is_visible() && window.type() != WindowType::WindowSwitcher)
+        m_switcher->refresh();
 
     tell_wms_window_rect_changed(window);
 
@@ -1547,12 +1548,12 @@ void WindowManager::process_key_event(KeyEvent& event)
 
     if (event.type() == Event::KeyDown) {
         if ((event.modifiers() == Mod_Super && event.key() == Key_Tab) || (event.modifiers() == (Mod_Super | Mod_Shift) && event.key() == Key_Tab))
-            m_switcher.show(WindowSwitcher::Mode::ShowAllWindows);
+            m_switcher->show(WindowSwitcher::Mode::ShowAllWindows);
         else if ((event.modifiers() == Mod_Alt && event.key() == Key_Tab) || (event.modifiers() == (Mod_Alt | Mod_Shift) && event.key() == Key_Tab))
-            m_switcher.show(WindowSwitcher::Mode::ShowCurrentDesktop);
+            m_switcher->show(WindowSwitcher::Mode::ShowCurrentDesktop);
     }
-    if (m_switcher.is_visible()) {
-        m_switcher.on_key_event(event);
+    if (m_switcher->is_visible()) {
+        m_switcher->on_key_event(event);
         return;
     }
 

Userland/Services/WindowServer/WindowManager.h

@@ -432,7 +432,7 @@ private:
 
     u8 m_keyboard_modifiers { 0 };
 
-    WindowSwitcher m_switcher;
+    NonnullRefPtr<WindowSwitcher> m_switcher;
 
     WeakPtr<Button> m_cursor_tracking_button;
     WeakPtr<Button> m_hovered_button;

Userland/Services/WindowServer/WindowSwitcher.h

@@ -26,7 +26,6 @@ public:
     };
     static WindowSwitcher& the();
 
-    WindowSwitcher();
     virtual ~WindowSwitcher() override;
 
     bool is_visible() const { return m_visible; }
@@ -49,6 +48,8 @@ public:
     Mode mode() const { return m_mode; }
 
 private:
+    WindowSwitcher();
+
     int thumbnail_width() const { return 40; }
     int thumbnail_height() const { return 40; }
     int item_height() const { return 10 + thumbnail_height(); }