WindowServer: Add an Overlay class for flicker-free overlay rendering

An Overlay is similar to a transparent window, but has less overhead
and does not get rendered within the window stack. Basically, the area
that an Overlay occupies forces transparency rendering for any window
underneath, which allows us to render them flicker-free.

This also adds a new API that allows displaying the screen numbers,
e.g. while the user configures the screen layout in DisplaySettings

Because other things like drag&drop or the window-size label are not
yet converted to use this new mechanism, they will be drawn over the
screen-number currently.

1 files changed, 3 insertions, 0 deletions

diff --git a/Userland/Services/WindowServer/MultiScaleBitmaps.h b/Userland/Services/WindowServer/MultiScaleBitmaps.h
index 830ef97c58..ee0593c44d 100644
--- a/Userland/Services/WindowServer/MultiScaleBitmaps.h
+++ b/Userland/Services/WindowServer/MultiScaleBitmaps.h
@@ -15,12 +15,15 @@ namespace WindowServer {
 
 class MultiScaleBitmaps : public RefCounted<MultiScaleBitmaps> {
 public:
+    static RefPtr<MultiScaleBitmaps> create_empty();
     static RefPtr<MultiScaleBitmaps> create(StringView const& filename, StringView const& default_filename = {});
 
     Gfx::Bitmap const& default_bitmap() const { return bitmap(1); }
     Gfx::Bitmap const& bitmap(int scale_factor) const;
+    Gfx::Bitmap const* find_bitmap(int scale_factor) const;
     Gfx::BitmapFormat format() const { return m_format; }
     bool load(StringView const& filename, StringView const& default_filename = {});
+    void add_bitmap(int scale_factor, NonnullRefPtr<Gfx::Bitmap>&&);
 
 private:
     MultiScaleBitmaps() = default;