LibHTML: Refactor to go from DOM -> styled tree -> layout tree.

Frame::layout() drives everything now, it takes the DOM contained in the
frame and puts it through the tree transformations.

LibHTML/DOM/Document.cpp

@@ -1,3 +1,4 @@
+#include <LibHTML/CSS/StyleResolver.h>
 #include <LibHTML/DOM/Document.h>
 #include <LibHTML/DOM/Element.h>
 #include <LibHTML/Layout/LayoutDocument.h>
@@ -12,31 +13,9 @@ Document::~Document()
 {
 }
 
-static void create_layout_tree_for_node(Node& node)
+StyleResolver& Document::style_resolver()
 {
-    if (auto layout_node = node.create_layout_node()) {
-        node.set_layout_node(*layout_node);
-#ifdef DEBUG_LAYOUT_TREE_BUILD
-        if (node.is_element()) {
-            printf("created layout node for <%s>, parent is %p, parent ln is %p\n", static_cast<const Element&>(node).tag_name().characters(), node.parent_node(), node.parent_node()->layout_node());
-        }
-#endif
-        if (node.parent() && node.parent()->layout_node())
-            node.parent()->layout_node()->append_child(*layout_node);
-    }
-    if (node.is_parent_node()) {
-        static_cast<ParentNode&>(node).for_each_child([&](auto& child) {
-            create_layout_tree_for_node(child);
-        });
-    }
-}
-
-void Document::build_layout_tree()
-{
-    create_layout_tree_for_node(*this);
-}
-
-RefPtr<LayoutNode> Document::create_layout_node()
-{
-    return adopt(*new LayoutDocument(*this));
+    if (!m_style_resolver)
+        m_style_resolver = make<StyleResolver>(*this);
+    return *m_style_resolver;
 }

LibHTML/DOM/Document.h

@@ -1,18 +1,27 @@
 #pragma once
 
 #include <AK/AKString.h>
+#include <AK/NonnullRefPtrVector.h>
+#include <AK/OwnPtr.h>
+#include <LibHTML/CSS/StyleResolver.h>
+#include <LibHTML/CSS/StyleSheet.h>
 #include <LibHTML/DOM/ParentNode.h>
 
 class LayoutNode;
+class StyleResolver;
+class StyleSheet;
 
 class Document : public ParentNode {
 public:
     Document();
     virtual ~Document() override;
 
-    virtual RefPtr<LayoutNode> create_layout_node() override;
+    StyleResolver& style_resolver();
 
-    void build_layout_tree();
+    void add_sheet(const StyleSheet& sheet) { m_sheets.append(sheet); }
+    const NonnullRefPtrVector<StyleSheet>& stylesheets() const { return m_sheets; }
 
 private:
+    OwnPtr<StyleResolver> m_style_resolver;
+    NonnullRefPtrVector<StyleSheet> m_sheets;
 };

LibHTML/DOM/Element.cpp

@@ -62,18 +62,3 @@ bool Element::has_class(const StringView& class_name) const
     }
     return false;
 }
-
-RefPtr<LayoutNode> Element::create_layout_node()
-{
-    if (m_tag_name == "html")
-        return adopt(*new LayoutBlock(*this));
-    if (m_tag_name == "body")
-        return adopt(*new LayoutBlock(*this));
-    if (m_tag_name == "h1")
-        return adopt(*new LayoutBlock(*this));
-    if (m_tag_name == "p")
-        return adopt(*new LayoutBlock(*this));
-    if (m_tag_name == "b")
-        return adopt(*new LayoutInline(*this));
-    return nullptr;
-}

LibHTML/DOM/Element.h

@@ -42,8 +42,6 @@ public:
 
     bool has_class(const StringView&) const;
 
-    virtual RefPtr<LayoutNode> create_layout_node() override;
-
 private:
     Attribute* find_attribute(const String& name);
     const Attribute* find_attribute(const String& name) const;

LibHTML/DOM/Node.cpp

@@ -9,13 +9,3 @@ Node::Node(NodeType type)
 Node::~Node()
 {
 }
-
-RefPtr<LayoutNode> Node::create_layout_node()
-{
-    return nullptr;
-}
-
-void Node::set_layout_node(NonnullRefPtr<LayoutNode> layout_node)
-{
-    m_layout_node = move(layout_node);
-}

LibHTML/DOM/Node.h

@@ -12,7 +12,6 @@ enum class NodeType : unsigned {
     DOCUMENT_NODE = 9,
 };
 
-class LayoutNode;
 class ParentNode;
 
 class Node : public TreeNode<Node> {
@@ -25,16 +24,8 @@ public:
     bool is_document() const { return type() == NodeType::DOCUMENT_NODE; }
     bool is_parent_node() const { return is_element() || is_document(); }
 
-    virtual RefPtr<LayoutNode> create_layout_node();
-
-    const LayoutNode* layout_node() const { return m_layout_node; }
-    LayoutNode* layout_node() { return m_layout_node; }
-
-    void set_layout_node(NonnullRefPtr<LayoutNode>);
-
 protected:
     explicit Node(NodeType);
 
     NodeType m_type { NodeType::INVALID };
-    RefPtr<LayoutNode> m_layout_node;
 };

LibHTML/DOM/Text.cpp

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

LibHTML/DOM/Text.h

@@ -10,8 +10,6 @@ public:
 
     const String& data() const { return m_data; }
 
-    virtual RefPtr<LayoutNode> create_layout_node() override;
-
 private:
     String m_data;
 };