LibWeb/Painting: Do not clip border radius when it is out of viewport

Painting optimization to do less unnecessary work.

Userland/Libraries/LibWeb/Painting/BorderRadiusCornerClipper.cpp

@@ -53,7 +53,7 @@ ErrorOr<NonnullRefPtr<BorderRadiusCornerClipper>> BorderRadiusCornerClipper::cre
         .corner_bitmap_size = corners_bitmap_size
     };
 
-    return try_make_ref_counted<BorderRadiusCornerClipper>(corner_data, corner_bitmap.release_nonnull(), corner_clip);
+    return try_make_ref_counted<BorderRadiusCornerClipper>(corner_data, corner_bitmap.release_nonnull(), corner_clip, border_rect);
 }
 
 void BorderRadiusCornerClipper::sample_under_corners(Gfx::Painter& page_painter)

Userland/Libraries/LibWeb/Painting/BorderRadiusCornerClipper.h

@@ -41,10 +41,13 @@ public:
         DevicePixelSize corner_bitmap_size;
     } m_data;
 
-    BorderRadiusCornerClipper(CornerData corner_data, NonnullRefPtr<Gfx::Bitmap> corner_bitmap, CornerClip corner_clip)
+    DevicePixelRect border_rect() const { return m_border_rect; }
+
+    BorderRadiusCornerClipper(CornerData corner_data, NonnullRefPtr<Gfx::Bitmap> corner_bitmap, CornerClip corner_clip, DevicePixelRect const& border_rect)
         : m_data(move(corner_data))
         , m_corner_bitmap(corner_bitmap)
         , m_corner_clip(corner_clip)
+        , m_border_rect(border_rect)
     {
     }
 
@@ -52,6 +55,7 @@ private:
     NonnullRefPtr<Gfx::Bitmap> m_corner_bitmap;
     bool m_has_sampled { false };
     CornerClip m_corner_clip { false };
+    DevicePixelRect m_border_rect;
 };
 
 struct ScopedCornerRadiusClip {

Userland/Libraries/LibWeb/Painting/RecordingPainter.cpp

@@ -482,6 +482,8 @@ CommandResult DrawTriangleWave::execute(CommandExecutionState& state) const
 
 CommandResult SampleUnderCorners::execute(CommandExecutionState& state) const
 {
+    if (state.would_be_fully_clipped_by_painter(corner_clipper->border_rect().to_type<int>()))
+        return CommandResult::Continue;
     auto& painter = state.painter();
     corner_clipper->sample_under_corners(painter);
     return CommandResult::Continue;
@@ -489,6 +491,8 @@ CommandResult SampleUnderCorners::execute(CommandExecutionState& state) const
 
 CommandResult BlitCornerClipping::execute(CommandExecutionState& state) const
 {
+    if (state.would_be_fully_clipped_by_painter(corner_clipper->border_rect().to_type<int>()))
+        return CommandResult::Continue;
     auto& painter = state.painter();
     corner_clipper->blit_corner_clipping(painter);
     return CommandResult::Continue;