WindowServer: Add support for alpha channel based hit testing

This enables implementing non-rectangular window shapes, including
non-rectangular window frames.

2 files changed, 2 insertions, 0 deletions

diff --git a/Userland/Libraries/LibGfx/ClassicWindowTheme.h b/Userland/Libraries/LibGfx/ClassicWindowTheme.h
index 165997bfa4..b0f2c86136 100644
--- a/Userland/Libraries/LibGfx/ClassicWindowTheme.h
+++ b/Userland/Libraries/LibGfx/ClassicWindowTheme.h
@@ -52,6 +52,7 @@ public:
     {
         return compute_frame_colors(state, palette).uses_alpha();
     }
+    virtual float frame_alpha_hit_threshold(WindowState) const override { return 1.0f; }
 
 private:
     struct FrameColors {
diff --git a/Userland/Libraries/LibGfx/WindowTheme.h b/Userland/Libraries/LibGfx/WindowTheme.h
index 383eadcca3..7a18a0b422 100644
--- a/Userland/Libraries/LibGfx/WindowTheme.h
+++ b/Userland/Libraries/LibGfx/WindowTheme.h
@@ -63,6 +63,7 @@ public:
     virtual Vector<IntRect> layout_buttons(WindowType, const IntRect& window_rect, const Palette&, size_t buttons) const = 0;
     virtual bool is_simple_rect_frame() const = 0;
     virtual bool frame_uses_alpha(WindowState, const Palette&) const = 0;
+    virtual float frame_alpha_hit_threshold(WindowState) const = 0;
 
 protected:
     WindowTheme() { }