LibHTML: Make Node::create_layout_node() virtual

Instead of branching on the Node type, let subclasses decide how their
layout nodes get constructed.

This will allow elements to create custom layout nodes if they want.

Author: awesomekling

Libraries/LibHTML/DOM/Document.cpp

@@ -125,3 +125,8 @@ URL Document::complete_url(const String& string) const
     url.set_path(fspath.string());
     return url;
 }
+
+RefPtr<LayoutNode> Document::create_layout_node(const StyleResolver&, const StyleProperties*) const
+{
+    return adopt(*new LayoutDocument(*this, StyleProperties::create()));
+}

Libraries/LibHTML/DOM/Document.h

@@ -55,6 +55,8 @@ class Document : public ParentNode {
     Color background_color() const;
 
 private:
+    virtual RefPtr<LayoutNode> create_layout_node(const StyleResolver&, const StyleProperties* parent_properties) const override;
+
     OwnPtr<StyleResolver> m_style_resolver;
     NonnullRefPtrVector<StyleSheet> m_sheets;
     RefPtr<Node> m_hovered_node;

Libraries/LibHTML/DOM/Element.cpp

@@ -1,3 +1,4 @@
+#include <LibHTML/CSS/StyleResolver.h>
 #include <LibHTML/DOM/Element.h>
 #include <LibHTML/Layout/LayoutBlock.h>
 #include <LibHTML/Layout/LayoutInline.h>
@@ -34,7 +35,7 @@ String Element::attribute(const String& name) const
 {
     if (auto* attribute = find_attribute(name))
         return attribute->value();
-    return { };
+    return {};
 }
 
 void Element::set_attribute(const String& name, const String& value)
@@ -62,3 +63,20 @@ bool Element::has_class(const StringView& class_name) const
     }
     return false;
 }
+
+RefPtr<LayoutNode> Element::create_layout_node(const StyleResolver& resolver, const StyleProperties* parent_properties) const
+{
+    auto style_properties = resolver.resolve_style(*this, parent_properties);
+
+    auto display_property = style_properties->property("display");
+    String display = display_property.has_value() ? display_property.release_value()->to_string() : "inline";
+
+    if (display == "none")
+        return nullptr;
+    if (display == "block" || display == "list-item")
+        return adopt(*new LayoutBlock(this, move(style_properties)));
+    if (display == "inline")
+        return adopt(*new LayoutInline(*this, move(style_properties)));
+
+    ASSERT_NOT_REACHED();
+}

Libraries/LibHTML/DOM/Element.h

@@ -45,6 +45,8 @@ class Element : public ParentNode {
     virtual void apply_presentational_hints(StyleProperties&) const {}
 
 private:
+    RefPtr<LayoutNode> create_layout_node(const StyleResolver&, const StyleProperties* parent_properties) const override;
+
     Attribute* find_attribute(const String& name);
     const Attribute* find_attribute(const String& name) const;
 

Libraries/LibHTML/DOM/Node.cpp

@@ -19,31 +19,6 @@ Node::~Node()
 {
 }
 
-RefPtr<LayoutNode> Node::create_layout_node(const StyleResolver& resolver, const StyleProperties* parent_properties) const
-{
-    if (is_document())
-        return adopt(*new LayoutDocument(static_cast<const Document&>(*this), StyleProperties::create()));
-
-    if (is_text())
-        return adopt(*new LayoutText(static_cast<const Text&>(*this)));
-
-    ASSERT(is_element());
-
-    auto style_properties = resolver.resolve_style(static_cast<const Element&>(*this), parent_properties);
-
-    auto display_property = style_properties->property("display");
-    String display = display_property.has_value() ? display_property.release_value()->to_string() : "inline";
-
-    if (display == "none")
-        return nullptr;
-    if (display == "block" || display == "list-item")
-        return adopt(*new LayoutBlock(this, move(style_properties)));
-    if (display == "inline")
-        return adopt(*new LayoutInline(*this, move(style_properties)));
-
-    ASSERT_NOT_REACHED();
-}
-
 RefPtr<LayoutNode> Node::create_layout_tree(const StyleResolver& resolver, const StyleProperties* parent_properties) const
 {
     auto layout_node = create_layout_node(resolver, parent_properties);

Libraries/LibHTML/DOM/Node.h

@@ -31,7 +31,7 @@ class Node : public TreeNode<Node> {
     bool is_document() const { return type() == NodeType::DOCUMENT_NODE; }
     bool is_parent_node() const { return is_element() || is_document(); }
 
-    RefPtr<LayoutNode> create_layout_node(const StyleResolver&, const StyleProperties* parent_properties) const;
+    virtual RefPtr<LayoutNode> create_layout_node(const StyleResolver&, const StyleProperties* parent_properties) const = 0;
     RefPtr<LayoutNode> create_layout_tree(const StyleResolver&, const StyleProperties* parent_properties) const;
 
     virtual String tag_name() const = 0;

Libraries/LibHTML/DOM/Text.cpp

@@ -10,3 +10,8 @@ Text::Text(Document& document, const String& data)
 Text::~Text()
 {
 }
+
+RefPtr<LayoutNode> Text::create_layout_node(const StyleResolver&, const StyleProperties*) const
+{
+    return adopt(*new LayoutText(*this));
+}

Libraries/LibHTML/DOM/Text.h

@@ -15,5 +15,7 @@ class Text final : public Node {
     virtual String text_content() const override { return m_data; }
 
 private:
+    virtual RefPtr<LayoutNode> create_layout_node(const StyleResolver&, const StyleProperties* parent_properties) const override;
+
     String m_data;
 };