1 files changed, 34 insertions, 1 deletions

diff --git a/Userland/Services/WindowServer/Compositor.h b/Userland/Services/WindowServer/Compositor.h
index 3d9e719cb6..f869d9d51f 100644
--- a/Userland/Services/WindowServer/Compositor.h
+++ b/Userland/Services/WindowServer/Compositor.h
@@ -22,6 +22,7 @@ class Cursor;
 class MultiScaleBitmaps;
 class Window;
 class WindowManager;
+class WindowStack;
 
 enum class WallpaperMode {
     Tile,
@@ -92,6 +93,27 @@ public:
         return IterationDecision::Continue;
     }
 
+    template<typename F>
+    IterationDecision for_each_rendering_window_stack(F f)
+    {
+        VERIFY(m_current_window_stack);
+        IterationDecision decision = f(*m_current_window_stack);
+        if (decision != IterationDecision::Continue)
+            return decision;
+        if (m_transitioning_to_window_stack)
+            decision = f(*m_transitioning_to_window_stack);
+        return decision;
+    }
+
+    [[nodiscard]] WindowStack& get_rendering_window_stacks(WindowStack*& transitioning_window_stack)
+    {
+        transitioning_window_stack = m_transitioning_to_window_stack;
+        return *m_current_window_stack;
+    }
+
+    bool is_switching_window_stacks() const { return m_transitioning_to_window_stack != nullptr; }
+    void switch_to_window_stack(WindowStack&);
+
     void did_construct_window_manager(Badge<WindowManager>);
 
     const Gfx::Bitmap* cursor_bitmap_for_screenshot(Badge<ClientConnection>, Screen&) const;
@@ -114,10 +136,14 @@ private:
     void start_compose_async_timer();
     void recompute_overlay_rects();
     void recompute_occlusions();
-    bool any_opaque_window_above_this_one_contains_rect(const Window&, const Gfx::IntRect&);
+    bool any_opaque_window_above_this_one_contains_rect(Window&, const Gfx::IntRect&);
     void change_cursor(const Cursor*);
     void flush(Screen&);
+    Gfx::IntPoint window_transition_offset(Window&);
     void update_animations(Screen&, Gfx::DisjointRectSet& flush_rects);
+    void create_window_stack_switch_overlay(WindowStack&);
+    void start_window_stack_switch_overlay_timer();
+    void finish_window_stack_switch();
 
     RefPtr<Core::Timer> m_compose_timer;
     RefPtr<Core::Timer> m_immediate_compose_timer;
@@ -139,6 +165,7 @@ private:
         OwnPtr<Gfx::Painter> m_cursor_back_painter;
         Gfx::IntRect m_last_cursor_rect;
         OwnPtr<ScreenNumberOverlay> m_screen_number_overlay;
+        OwnPtr<WindowStackSwitchOverlay> m_window_stack_switch_overlay;
         bool m_buffers_are_flipped { false };
         bool m_screen_can_set_buffer { false };
         bool m_cursor_back_is_valid { false };
@@ -197,6 +224,12 @@ private:
     RefPtr<Core::Timer> m_display_link_notify_timer;
     size_t m_display_link_count { 0 };
 
+    WindowStack* m_current_window_stack { nullptr };
+    WindowStack* m_transitioning_to_window_stack { nullptr };
+    RefPtr<Animation> m_window_stack_transition_animation;
+    OwnPtr<WindowStackSwitchOverlay> m_stack_switch_overlay;
+    RefPtr<Core::Timer> m_stack_switch_overlay_timer;
+
     size_t m_show_screen_number_count { 0 };
     Optional<Gfx::Color> m_custom_background_color;