LibWeb: Move painting logic from Layout::Viewport to ViewportPaintable

Author: https://github.com/awesomekling
Commit: https://github.com/SerenityOS/serenity/commit/8bb275f2ea
Pull-request: https://github.com/SerenityOS/serenity/pull/20661

Userland/Libraries/LibWeb/CSS/ResolvedCSSStyleDeclaration.cpp

@@ -46,6 +46,7 @@
 #include <LibWeb/Layout/Viewport.h>
 #include <LibWeb/Painting/PaintableBox.h>
 #include <LibWeb/Painting/StackingContext.h>
+#include <LibWeb/Painting/ViewportPaintable.h>
 
 namespace Web::CSS {
 
@@ -834,9 +835,9 @@ RefPtr<StyleValue const> ResolvedCSSStyleDeclaration::style_value_for_property(L
             return IdentifierStyleValue::create(ValueID::None);
 
         // The transform matrix is held by the StackingContext, so we need to make sure we have one first.
-        auto const* viewport = layout_node.document().layout_node();
+        auto const* viewport = layout_node.document().paintable_box();
         VERIFY(viewport);
-        const_cast<Layout::Viewport&>(*viewport).build_stacking_context_tree_if_needed();
+        const_cast<Painting::ViewportPaintable&>(verify_cast<Painting::ViewportPaintable>(*viewport)).build_stacking_context_tree_if_needed();
 
         VERIFY(layout_node.paintable());
         auto const& paintable_box = verify_cast<Painting::PaintableBox const>(layout_node.paintable());

Userland/Libraries/LibWeb/Layout/Viewport.cpp

@@ -25,42 +25,6 @@ JS::GCPtr<Selection::Selection> Viewport::selection() const
     return const_cast<DOM::Document&>(document()).get_selection();
 }
 
-void Viewport::build_stacking_context_tree_if_needed()
-{
-    if (paintable_box()->stacking_context())
-        return;
-    build_stacking_context_tree();
-}
-
-void Viewport::build_stacking_context_tree()
-{
-    paintable_box()->set_stacking_context(make<Painting::StackingContext>(*this, nullptr, 0));
-
-    size_t index_in_tree_order = 1;
-    for_each_in_subtree_of_type<Box>([&](Box& box) {
-        if (!box.paintable_box())
-            return IterationDecision::Continue;
-        box.paintable_box()->invalidate_stacking_context();
-        if (!box.establishes_stacking_context()) {
-            VERIFY(!box.paintable_box()->stacking_context());
-            return IterationDecision::Continue;
-        }
-        auto* parent_context = box.paintable_box()->enclosing_stacking_context();
-        VERIFY(parent_context);
-        box.paintable_box()->set_stacking_context(make<Painting::StackingContext>(box, parent_context, index_in_tree_order++));
-        return IterationDecision::Continue;
-    });
-
-    paintable_box()->stacking_context()->sort();
-}
-
-void Viewport::paint_all_phases(PaintContext& context)
-{
-    build_stacking_context_tree_if_needed();
-    context.painter().translate(-context.device_viewport_rect().location().to_type<int>());
-    paintable_box()->stacking_context()->paint(context);
-}
-
 void Viewport::recompute_selection_states()
 {
     // 1. Start by resetting the selection state of all layout nodes to None.

Userland/Libraries/LibWeb/Layout/Viewport.h

@@ -21,17 +21,13 @@ public:
 
     const DOM::Document& dom_node() const { return static_cast<const DOM::Document&>(*Node::dom_node()); }
 
-    void paint_all_phases(PaintContext&);
-
     JS::GCPtr<Selection::Selection> selection() const;
 
-    void build_stacking_context_tree_if_needed();
     void recompute_selection_states();
 
 private:
     virtual JS::GCPtr<Painting::Paintable> create_paintable() const override;
 
-    void build_stacking_context_tree();
     virtual bool is_viewport() const override { return true; }
 };
 

Userland/Libraries/LibWeb/Painting/NestedBrowsingContextPaintable.cpp

@@ -10,6 +10,7 @@
 #include <LibWeb/Layout/Viewport.h>
 #include <LibWeb/Painting/BorderRadiusCornerClipper.h>
 #include <LibWeb/Painting/NestedBrowsingContextPaintable.h>
+#include <LibWeb/Painting/ViewportPaintable.h>
 
 namespace Web::Painting {
 
@@ -43,8 +44,8 @@ void NestedBrowsingContextPaintable::paint(PaintContext& context, PaintPhase pha
         auto* hosted_document = layout_box().dom_node().content_document_without_origin_check();
         if (!hosted_document)
             return;
-        auto* hosted_layout_tree = hosted_document->layout_node();
-        if (!hosted_layout_tree)
+        auto* hosted_paint_tree = hosted_document->paintable_box();
+        if (!hosted_paint_tree)
             return;
 
         context.painter().save();
@@ -56,7 +57,7 @@ void NestedBrowsingContextPaintable::paint(PaintContext& context, PaintPhase pha
         context.painter().translate(absolute_device_rect.x().value(), absolute_device_rect.y().value());
 
         context.set_device_viewport_rect({ {}, context.enclosing_device_size(layout_box().dom_node().nested_browsing_context()->size()) });
-        const_cast<Layout::Viewport*>(hosted_layout_tree)->paint_all_phases(context);
+        const_cast<ViewportPaintable&>(verify_cast<ViewportPaintable>(*hosted_paint_tree)).paint_all_phases(context);
 
         context.set_device_viewport_rect(old_viewport_rect);
         context.painter().restore();

Userland/Libraries/LibWeb/Painting/PaintableBox.cpp

@@ -15,6 +15,7 @@
 #include <LibWeb/Painting/FilterPainting.h>
 #include <LibWeb/Painting/PaintableBox.h>
 #include <LibWeb/Painting/StackingContext.h>
+#include <LibWeb/Painting/ViewportPaintable.h>
 #include <LibWeb/Platform/FontPlugin.h>
 
 namespace Web::Painting {
@@ -739,7 +740,7 @@ Optional<HitTestResult> PaintableBox::hit_test(CSSPixelPoint position, HitTestTy
         return {};
 
     if (layout_box().is_viewport()) {
-        const_cast<Layout::Viewport&>(static_cast<Layout::Viewport const&>(layout_box())).build_stacking_context_tree_if_needed();
+        const_cast<ViewportPaintable&>(static_cast<ViewportPaintable const&>(*this)).build_stacking_context_tree_if_needed();
         return stacking_context()->hit_test(position, type);
     }
 

Userland/Libraries/LibWeb/Painting/ViewportPaintable.cpp

@@ -5,6 +5,7 @@
  */
 
 #include <LibWeb/Layout/Viewport.h>
+#include <LibWeb/Painting/StackingContext.h>
 #include <LibWeb/Painting/ViewportPaintable.h>
 
 namespace Web::Painting {
@@ -21,4 +22,39 @@ ViewportPaintable::ViewportPaintable(Layout::Viewport const& layout_viewport)
 
 ViewportPaintable::~ViewportPaintable() = default;
 
+void ViewportPaintable::build_stacking_context_tree_if_needed()
+{
+    if (stacking_context())
+        return;
+    build_stacking_context_tree();
+}
+
+void ViewportPaintable::build_stacking_context_tree()
+{
+    set_stacking_context(make<StackingContext>(layout_box(), nullptr, 0));
+
+    size_t index_in_tree_order = 1;
+    for_each_in_subtree_of_type<PaintableBox>([&](PaintableBox const& paintable) {
+        auto& paintable_box = const_cast<PaintableBox&>(paintable);
+        paintable_box.invalidate_stacking_context();
+        if (!paintable_box.layout_box().establishes_stacking_context()) {
+            VERIFY(!paintable_box.stacking_context());
+            return TraversalDecision::Continue;
+        }
+        auto* parent_context = paintable_box.enclosing_stacking_context();
+        VERIFY(parent_context);
+        paintable_box.set_stacking_context(make<Painting::StackingContext>(paintable_box.layout_box(), parent_context, index_in_tree_order++));
+        return TraversalDecision::Continue;
+    });
+
+    stacking_context()->sort();
+}
+
+void ViewportPaintable::paint_all_phases(PaintContext& context)
+{
+    build_stacking_context_tree_if_needed();
+    context.painter().translate(-context.device_viewport_rect().location().to_type<int>());
+    stacking_context()->paint(context);
+}
+
 }

Userland/Libraries/LibWeb/Painting/ViewportPaintable.h

@@ -17,7 +17,12 @@ public:
     static JS::NonnullGCPtr<ViewportPaintable> create(Layout::Viewport const&);
     virtual ~ViewportPaintable() override;
 
+    void paint_all_phases(PaintContext&);
+    void build_stacking_context_tree_if_needed();
+
 private:
+    void build_stacking_context_tree();
+
     explicit ViewportPaintable(Layout::Viewport const&);
 };
 

Userland/Libraries/LibWeb/SVG/SVGDecodedImageData.cpp

@@ -12,6 +12,7 @@
 #include <LibWeb/HTML/Parser/HTMLParser.h>
 #include <LibWeb/Layout/Viewport.h>
 #include <LibWeb/Painting/PaintContext.h>
+#include <LibWeb/Painting/ViewportPaintable.h>
 #include <LibWeb/SVG/SVGDecodedImageData.h>
 #include <LibWeb/SVG/SVGSVGElement.h>
 
@@ -99,7 +100,7 @@ void SVGDecodedImageData::render(Gfx::IntSize size) const
     Gfx::Painter painter(*m_bitmap);
     PaintContext context(painter, m_page_client->palette(), m_page_client->device_pixels_per_css_pixel());
 
-    m_document->layout_node()->paint_all_phases(context);
+    verify_cast<Painting::ViewportPaintable>(*m_document->paintable_box()).paint_all_phases(context);
 }
 
 RefPtr<Gfx::Bitmap const> SVGDecodedImageData::bitmap(size_t, Gfx::IntSize size) const

Userland/Services/WebContent/PageHost.cpp

@@ -14,6 +14,7 @@
 #include <LibWeb/HTML/BrowsingContext.h>
 #include <LibWeb/Layout/Viewport.h>
 #include <LibWeb/Painting/PaintableBox.h>
+#include <LibWeb/Painting/ViewportPaintable.h>
 #include <LibWeb/Platform/Timer.h>
 #include <WebContent/WebContentClientEndpoint.h>
 #include <WebContent/WebDriverConnection.h>
@@ -139,7 +140,7 @@ void PageHost::paint(Web::DevicePixelRect const& content_rect, Gfx::Bitmap& targ
     context.set_should_show_line_box_borders(m_should_show_line_box_borders);
     context.set_device_viewport_rect(content_rect);
     context.set_has_focus(m_has_focus);
-    layout_root->paint_all_phases(context);
+    verify_cast<Web::Painting::ViewportPaintable>(*layout_root->paintable_box()).paint_all_phases(context);
 }
 
 void PageHost::set_viewport_rect(Web::DevicePixelRect const& rect)