From 136ac1a6a56a1c2266172d455ef45a432727cf62 Mon Sep 17 00:00:00 2001
From: Andreas Kling <kling@serenityos.org>
Date: Fri, 18 Aug 2023 13:47:52 +0200
Subject: [PATCH] LibWeb: Add virtuals to check if Paintable is PBox or
 PWithLines

Instead of inferring the type of paintables by looking at the type of
their origin in the layout tree, let's ask them directly.
---
 Userland/Libraries/LibWeb/Layout/LayoutState.cpp  | 9 ++++-----
 Userland/Libraries/LibWeb/Painting/Paintable.cpp  | 2 +-
 Userland/Libraries/LibWeb/Painting/Paintable.h    | 8 +++++++-
 Userland/Libraries/LibWeb/Painting/PaintableBox.h | 4 ++++
 4 files changed, 16 insertions(+), 7 deletions(-)

diff --git a/Userland/Libraries/LibWeb/Layout/LayoutState.cpp b/Userland/Libraries/LibWeb/Layout/LayoutState.cpp
index 0df4a9f558..015e1b2d73 100644
--- a/Userland/Libraries/LibWeb/Layout/LayoutState.cpp
+++ b/Userland/Libraries/LibWeb/Layout/LayoutState.cpp
@@ -82,8 +82,8 @@ static CSSPixelRect measure_scrollable_overflow(Box const& box)
     auto scrollable_overflow_rect = paintable_box.absolute_padding_box_rect();
 
     // - All line boxes directly contained by the scroll container.
-    if (box.is_block_container() && box.children_are_inline()) {
-        auto const& line_boxes = verify_cast<Painting::PaintableWithLines>(*box.paintable_box()).line_boxes();
+    if (is<Painting::PaintableWithLines>(box.paintable())) {
+        auto const& line_boxes = static_cast<Painting::PaintableWithLines const&>(*box.paintable()).line_boxes();
         for (auto const& line_box : line_boxes) {
             scrollable_overflow_rect = scrollable_overflow_rect.united(line_box.absolute_rect());
         }
@@ -238,8 +238,7 @@ void LayoutState::commit(Box& root)
         node.set_paintable(paintable);
 
         // For boxes, transfer all the state needed for painting.
-        if (is<Layout::Box>(node)) {
-            auto& box = static_cast<Layout::Box const&>(node);
+        if (paintable && is<Painting::PaintableBox>(*paintable)) {
             auto& paintable_box = static_cast<Painting::PaintableBox&>(*paintable);
             paintable_box.set_offset(used_values.offset);
             paintable_box.set_content_size(used_values.content_width(), used_values.content_height());
@@ -250,7 +249,7 @@ void LayoutState::commit(Box& root)
                 paintable_box.set_table_cell_coordinates(used_values.table_cell_coordinates().value());
             }
 
-            if (is<Layout::BlockContainer>(box)) {
+            if (is<Painting::PaintableWithLines>(paintable_box)) {
                 auto& paintable_with_lines = static_cast<Painting::PaintableWithLines&>(paintable_box);
                 paintable_with_lines.set_line_boxes(move(used_values.line_boxes));
                 paintables_with_lines.append(paintable_with_lines);
diff --git a/Userland/Libraries/LibWeb/Painting/Paintable.cpp b/Userland/Libraries/LibWeb/Painting/Paintable.cpp
index 88d1ec9d5c..87d6dc70df 100644
--- a/Userland/Libraries/LibWeb/Painting/Paintable.cpp
+++ b/Userland/Libraries/LibWeb/Painting/Paintable.cpp
@@ -79,7 +79,7 @@ Optional<HitTestResult> Paintable::hit_test(CSSPixelPoint, HitTestType) const
 
 StackingContext const* Paintable::stacking_context_rooted_here() const
 {
-    if (!layout_node().is_box())
+    if (!is<PaintableBox>(*this))
         return nullptr;
     return static_cast<PaintableBox const&>(*this).stacking_context();
 }
diff --git a/Userland/Libraries/LibWeb/Painting/Paintable.h b/Userland/Libraries/LibWeb/Painting/Paintable.h
index d3f832d1c3..103374b409 100644
--- a/Userland/Libraries/LibWeb/Painting/Paintable.h
+++ b/Userland/Libraries/LibWeb/Painting/Paintable.h
@@ -154,6 +154,9 @@ public:
     template<typename T>
     bool fast_is() const = delete;
 
+    [[nodiscard]] virtual bool is_paintable_box() const { return false; }
+    [[nodiscard]] virtual bool is_paintable_with_lines() const { return false; }
+
     StackingContext const* stacking_context_rooted_here() const;
 
 protected:
@@ -179,6 +182,9 @@ inline DOM::Node const* HitTestResult::dom_node() const
 }
 
 template<>
-inline bool Paintable::fast_is<PaintableBox>() const { return m_layout_node->is_box(); }
+inline bool Paintable::fast_is<PaintableBox>() const { return is_paintable_box(); }
+
+template<>
+inline bool Paintable::fast_is<PaintableWithLines>() const { return is_paintable_with_lines(); }
 
 }
diff --git a/Userland/Libraries/LibWeb/Painting/PaintableBox.h b/Userland/Libraries/LibWeb/Painting/PaintableBox.h
index d3b94ff66d..9d4f9c85b6 100644
--- a/Userland/Libraries/LibWeb/Painting/PaintableBox.h
+++ b/Userland/Libraries/LibWeb/Painting/PaintableBox.h
@@ -197,6 +197,8 @@ protected:
     Vector<ShadowData> resolve_box_shadow_data() const;
 
 private:
+    [[nodiscard]] virtual bool is_paintable_box() const final { return true; }
+
     Optional<OverflowData> m_overflow_data;
 
     CSSPixelPoint m_offset;
@@ -249,6 +251,8 @@ protected:
     PaintableWithLines(Layout::BlockContainer const&);
 
 private:
+    [[nodiscard]] virtual bool is_paintable_with_lines() const final { return true; }
+
     Vector<Layout::LineBox> m_line_boxes;
 };