LibAccelGfx+LibWeb: Discard painting of commands outside of viewport

Userland/Libraries/LibAccelGfx/Painter.cpp

@@ -550,11 +550,13 @@ void Painter::restore()
 
 void Painter::set_clip_rect(Gfx::IntRect rect)
 {
+    state().clip_rect = transform().map(rect);
     GL::enable_scissor_test(transform().map(rect));
 }
 
 void Painter::clear_clip_rect()
 {
+    state().clip_rect = { { 0, 0 }, m_target_canvas->size() };
     GL::disable_scissor_test();
 }
 
@@ -569,6 +571,7 @@ void Painter::set_target_canvas(NonnullRefPtr<Canvas> canvas)
     m_target_canvas = canvas;
     canvas->bind();
     GL::set_viewport({ 0, 0, canvas->size().width(), canvas->size().height() });
+    state().clip_rect = { { 0, 0 }, m_target_canvas->size() };
 }
 
 void Painter::flush(Gfx::Bitmap& bitmap)

Userland/Libraries/LibAccelGfx/Painter.h

@@ -43,6 +43,8 @@ public:
     void set_transform(Gfx::AffineTransform const& transform) { state().transform = transform; }
     void translate(Gfx::FloatPoint translation) { state().transform.translate(translation); }
 
+    Gfx::IntRect const& clip_rect() const { return state().clip_rect; }
+
     void fill_rect(Gfx::FloatRect, Gfx::Color);
     void fill_rect(Gfx::IntRect, Gfx::Color);
 
@@ -88,6 +90,7 @@ private:
 
     struct State {
         Gfx::AffineTransform transform;
+        Gfx::IntRect clip_rect;
     };
 
     [[nodiscard]] State& state() { return m_state_stack.last(); }

Userland/Libraries/LibWeb/Painting/PaintingCommandExecutorGPU.cpp

@@ -306,10 +306,10 @@ CommandResult PaintingCommandExecutorGPU::paint_borders(DevicePixelRect const& b
     return CommandResult::Continue;
 }
 
-bool PaintingCommandExecutorGPU::would_be_fully_clipped_by_painter(Gfx::IntRect) const
+bool PaintingCommandExecutorGPU::would_be_fully_clipped_by_painter(Gfx::IntRect rect) const
 {
-    // FIXME
-    return false;
+    auto translation = painter().transform().translation().to_type<int>();
+    return !painter().clip_rect().intersects(rect.translated(translation));
 }
 
 void PaintingCommandExecutorGPU::prepare_glyph_texture(HashMap<Gfx::Font const*, HashTable<u32>> const& unique_glyphs)