LibHTML: Start fleshing out a basic layout tree.

Author: https://github.com/awesomekling
Commit: https://github.com/SerenityOS/serenity/commit/8a0e21b22bc

LibHTML/Document.cpp

@@ -1,4 +1,7 @@
 #include <LibHTML/Document.h>
+#include <LibHTML/Element.h>
+#include <LibHTML/LayoutDocument.h>
+#include <stdio.h>
 
 Document::Document()
     : ParentNode(NodeType::DOCUMENT_NODE)
@@ -9,3 +12,31 @@ Document::~Document()
 {
 }
 
+static void create_layout_tree_for_node(Node& node)
+{
+    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() && node.parent_node()->layout_node())
+            node.parent_node()->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);
+}
+
+RetainPtr<LayoutNode> Document::create_layout_node()
+{
+    return adopt(*new LayoutDocument(*this));
+}

LibHTML/Document.h

@@ -3,11 +3,16 @@
 #include <AK/AKString.h>
 #include <LibHTML/ParentNode.h>
 
+class LayoutNode;
+
 class Document : public ParentNode {
 public:
     Document();
     virtual ~Document() override;
 
+    virtual RetainPtr<LayoutNode> create_layout_node() override;
+
+    void build_layout_tree();
+
 private:
 };
-

LibHTML/Dump.cpp

@@ -1,10 +1,12 @@
 #include <LibHTML/Document.h>
 #include <LibHTML/Dump.h>
 #include <LibHTML/Element.h>
+#include <LibHTML/LayoutNode.h>
+#include <LibHTML/LayoutText.h>
 #include <LibHTML/Text.h>
 #include <stdio.h>
 
-void dump_tree(Node& node)
+void dump_tree(const Node& node)
 {
     static int indent = 0;
     for (int i = 0; i < indent; ++i)
@@ -12,19 +14,35 @@ void dump_tree(Node& node)
     if (node.is_document()) {
         printf("*Document*\n");
     } else if (node.is_element()) {
-        printf("<%s", static_cast<Element&>(node).tag_name().characters());
-        static_cast<Element&>(node).for_each_attribute([](auto& name, auto& value) {
+        printf("<%s", static_cast<const Element&>(node).tag_name().characters());
+        static_cast<const Element&>(node).for_each_attribute([](auto& name, auto& value) {
             printf(" %s=%s", name.characters(), value.characters());
         });
         printf(">\n");
     } else if (node.is_text()) {
-        printf("\"%s\"\n", static_cast<Text&>(node).data().characters());
+        printf("\"%s\"\n", static_cast<const Text&>(node).data().characters());
     }
     ++indent;
     if (node.is_parent_node()) {
-        static_cast<ParentNode&>(node).for_each_child([](Node& child) {
+        static_cast<const ParentNode&>(node).for_each_child([](auto& child) {
             dump_tree(child);
         });
     }
     --indent;
 }
+
+void dump_tree(const LayoutNode& node)
+{
+    static int indent = 0;
+    for (int i = 0; i < indent; ++i)
+        printf("   ");
+    printf("%s{%p}", node.class_name(), &node);
+    if (node.is_text())
+        printf(" \"%s\"", static_cast<const LayoutText&>(node).node().data().characters());
+    printf("\n");
+    ++indent;
+    node.for_each_child([](auto& child) {
+        dump_tree(child);
+    });
+    --indent;
+}

LibHTML/Dump.h

@@ -1,5 +1,7 @@
 #pragma once
 
 class Node;
+class LayoutNode;
 
-void dump_tree(Node&);
+void dump_tree(const Node&);
+void dump_tree(const LayoutNode&);

LibHTML/Element.cpp

@@ -1,4 +1,6 @@
 #include <LibHTML/Element.h>
+#include <LibHTML/LayoutBlock.h>
+#include <LibHTML/LayoutInline.h>
 
 Element::Element(const String& tag_name)
     : ParentNode(NodeType::ELEMENT_NODE)
@@ -47,3 +49,18 @@ void Element::set_attributes(Vector<Attribute>&& attributes)
 {
     m_attributes = move(attributes);
 }
+
+RetainPtr<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/Element.h

@@ -34,12 +34,14 @@ public:
     void set_attributes(Vector<Attribute>&&);
 
     template<typename Callback>
-    void for_each_attribute(Callback callback)
+    void for_each_attribute(Callback callback) const
     {
         for (auto& attribute : m_attributes)
             callback(attribute.name(), attribute.value());
     }
 
+    virtual RetainPtr<LayoutNode> create_layout_node() override;
+
 private:
     Attribute* find_attribute(const String& name);
     const Attribute* find_attribute(const String& name) const;

LibHTML/LayoutBlock.cpp

@@ -0,0 +1,11 @@
+#include <LibHTML/Element.h>
+#include <LibHTML/LayoutBlock.h>
+
+LayoutBlock::LayoutBlock(Element& element)
+    : LayoutNode(&element)
+{
+}
+
+LayoutBlock::~LayoutBlock()
+{
+}

LibHTML/LayoutBlock.h

@@ -0,0 +1,15 @@
+#pragma once
+
+#include <LibHTML/LayoutNode.h>
+
+class Element;
+
+class LayoutBlock : public LayoutNode {
+public:
+    explicit LayoutBlock(Element&);
+    virtual ~LayoutBlock() override;
+
+    virtual const char* class_name() const override { return "LayoutBlock"; }
+
+private:
+};

LibHTML/LayoutDocument.cpp

@@ -0,0 +1,10 @@
+#include <LibHTML/LayoutDocument.h>
+
+LayoutDocument::LayoutDocument(const Document& document)
+    : LayoutNode(&document)
+{
+}
+
+LayoutDocument::~LayoutDocument()
+{
+}

LibHTML/LayoutDocument.h

@@ -0,0 +1,16 @@
+#pragma once
+
+#include <LibHTML/LayoutNode.h>
+#include <LibHTML/Document.h>
+
+class LayoutDocument : public LayoutNode {
+public:
+    explicit LayoutDocument(const Document&);
+    virtual ~LayoutDocument() override;
+
+    const Document& node() const { return static_cast<const Document&>(*LayoutNode::node()); }
+
+    virtual const char* class_name() const override { return "LayoutDocument"; }
+
+private:
+};

LibHTML/LayoutInline.cpp

@@ -0,0 +1,11 @@
+#include <LibHTML/Element.h>
+#include <LibHTML/LayoutInline.h>
+
+LayoutInline::LayoutInline(Element& element)
+    : LayoutNode(&element)
+{
+}
+
+LayoutInline::~LayoutInline()
+{
+}

LibHTML/LayoutInline.h

@@ -0,0 +1,15 @@
+#pragma once
+
+#include <LibHTML/LayoutNode.h>
+
+class Element;
+
+class LayoutInline : public LayoutNode {
+public:
+    explicit LayoutInline(Element&);
+    virtual ~LayoutInline() override;
+
+    virtual const char* class_name() const override { return "LayoutInline"; }
+
+private:
+};

LibHTML/LayoutNode.cpp

@@ -0,0 +1,33 @@
+#include <LibHTML/LayoutNode.h>
+
+LayoutNode::LayoutNode(const Node* node)
+    : m_node(node)
+{
+}
+
+LayoutNode::~LayoutNode()
+{
+}
+
+void LayoutNode::retain()
+{
+    ASSERT(m_retain_count);
+    ++m_retain_count;
+}
+
+void LayoutNode::release()
+{
+    ASSERT(m_retain_count);
+    if (!--m_retain_count)
+        delete this;
+}
+
+void LayoutNode::append_child(Retained<LayoutNode> node)
+{
+    if (m_last_child)
+        m_last_child->set_next_sibling(node.ptr());
+    node->m_parent_node = this;
+    m_last_child = &node.leak_ref();
+    if (!m_first_child)
+        m_first_child = m_last_child;
+}

LibHTML/LayoutNode.h

@@ -0,0 +1,54 @@
+#pragma once
+
+#include <AK/Retained.h>
+#include <AK/Vector.h>
+
+class Node;
+
+class LayoutNode {
+public:
+    virtual ~LayoutNode();
+
+    void retain();
+    void release();
+    int retain_count() const { return m_retain_count; }
+
+    const Node* node() const { return m_node; }
+
+    LayoutNode* next_sibling() { return m_next_sibling; }
+    LayoutNode* previous_sibling() { return m_previous_sibling; }
+    LayoutNode* first_child() { return m_first_child; }
+    LayoutNode* last_child() { return m_last_child; }
+    const LayoutNode* next_sibling() const { return m_next_sibling; }
+    const LayoutNode* previous_sibling() const { return m_previous_sibling; }
+    const LayoutNode* first_child() const { return m_first_child; }
+    const LayoutNode* last_child() const { return m_last_child; }
+
+    void append_child(Retained<LayoutNode>);
+
+    void set_next_sibling(LayoutNode* node) { m_next_sibling = node; }
+    void set_previous_sibling(LayoutNode* node) { m_previous_sibling = node; }
+
+    template<typename Callback>
+    inline void for_each_child(Callback callback) const
+    {
+        for (auto* node = first_child(); node; node = node->next_sibling())
+            callback(*node);
+    }
+
+    virtual const char* class_name() const { return "LayoutNode"; }
+    virtual bool is_text() const { return false; }
+
+protected:
+    explicit LayoutNode(const Node*);
+
+private:
+    int m_retain_count { 1 };
+    const Node* m_node { nullptr };
+    LayoutNode* m_parent_node { nullptr };
+    LayoutNode* m_first_child { nullptr };
+    LayoutNode* m_last_child { nullptr };
+    LayoutNode* m_next_sibling { nullptr };
+    LayoutNode* m_previous_sibling { nullptr };
+};
+

LibHTML/LayoutText.cpp

@@ -0,0 +1,10 @@
+#include <LibHTML/LayoutText.h>
+
+LayoutText::LayoutText(const Text& text)
+    : LayoutNode(&text)
+{
+}
+
+LayoutText::~LayoutText()
+{
+}

LibHTML/LayoutText.h

@@ -0,0 +1,17 @@
+#pragma once
+
+#include <LibHTML/LayoutNode.h>
+#include <LibHTML/Text.h>
+
+class LayoutText : public LayoutNode {
+public:
+    explicit LayoutText(const Text&);
+    virtual ~LayoutText() override;
+
+    const Text& node() const { return static_cast<const Text&>(*LayoutNode::node()); }
+
+    virtual const char* class_name() const override { return "LayoutText"; }
+    virtual bool is_text() const final { return true; }
+
+private:
+};

LibHTML/Makefile

@@ -7,6 +7,11 @@ LIBHTML_OBJS = \
     Document.o \
     Text.o \
     Parser.o \
+    LayoutNode.o \
+    LayoutText.o \
+    LayoutBlock.o \
+    LayoutInline.o \
+    LayoutDocument.o \
     Dump.o
 
 TEST_OBJS = test.o

LibHTML/Node.cpp

@@ -1,5 +1,5 @@
-#include <AK/Retained.h>
 #include <LibHTML/Node.h>
+#include <LibHTML/LayoutNode.h>
 
 Node::Node(NodeType type)
     : m_type(type)
@@ -22,3 +22,13 @@ void Node::release()
     if (!--m_retain_count)
         delete this;
 }
+
+RetainPtr<LayoutNode> Node::create_layout_node()
+{
+    return nullptr;
+}
+
+void Node::set_layout_node(Retained<LayoutNode> layout_node)
+{
+    m_layout_node = move(layout_node);
+}

LibHTML/Node.h

@@ -1,6 +1,7 @@
 #pragma once
 
-#include <AK/Retained.h>
+#include <AK/Badge.h>
+#include <AK/RetainPtr.h>
 #include <AK/Vector.h>
 
 enum class NodeType : unsigned {
@@ -10,6 +11,9 @@ enum class NodeType : unsigned {
     DOCUMENT_NODE = 9,
 };
 
+class LayoutNode;
+class ParentNode;
+
 class Node {
 public:
     virtual ~Node();
@@ -18,6 +22,11 @@ public:
     void release();
     int retain_count() const { return m_retain_count; }
 
+    ParentNode* parent_node() { return m_parent_node; }
+    const ParentNode* parent_node() const { return m_parent_node; }
+
+    void set_parent_node(Badge<ParentNode>, ParentNode* parent_node) { m_parent_node = parent_node; }
+
     NodeType type() const { return m_type; }
     bool is_element() const { return type() == NodeType::ELEMENT_NODE; }
     bool is_text() const { return type() == NodeType::TEXT_NODE; }
@@ -26,16 +35,26 @@ public:
 
     Node* next_sibling() { return m_next_sibling; }
     Node* previous_sibling() { return m_previous_sibling; }
+    const Node* next_sibling() const { return m_next_sibling; }
+    const Node* previous_sibling() const { return m_previous_sibling; }
+
     void set_next_sibling(Node* node) { m_next_sibling = node; }
     void set_previous_sibling(Node* node) { m_previous_sibling = node; }
 
+    virtual RetainPtr<LayoutNode> create_layout_node();
+
+    const LayoutNode* layout_node() const { return m_layout_node; }
+    LayoutNode* layout_node() { return m_layout_node; }
+
+    void set_layout_node(Retained<LayoutNode>);
+
 protected:
     explicit Node(NodeType);
 
     int m_retain_count { 1 };
     NodeType m_type { NodeType::INVALID };
-    Vector<Node*> m_children;
+    ParentNode* m_parent_node { nullptr };
     Node* m_next_sibling { nullptr };
     Node* m_previous_sibling { nullptr };
+    RetainPtr<LayoutNode> m_layout_node;
 };
-

LibHTML/ParentNode.cpp

@@ -4,6 +4,7 @@ void ParentNode::append_child(Retained<Node> node)
 {
     if (m_last_child)
         m_last_child->set_next_sibling(node.ptr());
+    node->set_parent_node({}, this);
     m_last_child = &node.leak_ref();
     if (!m_first_child)
         m_first_child = m_last_child;

LibHTML/ParentNode.h

@@ -8,7 +8,10 @@ public:
 
     Node* first_child() { return m_first_child; }
     Node* last_child() { return m_last_child; }
+    const Node* first_child() const { return m_first_child; }
+    const Node* last_child() const { return m_last_child; }
 
+    template<typename F> void for_each_child(F) const;
     template<typename F> void for_each_child(F);
 
 protected:
@@ -22,11 +25,16 @@ private:
     Node* m_last_child { nullptr };
 };
 
-template<typename F>
-inline void ParentNode::for_each_child(F func)
+template<typename Callback>
+inline void ParentNode::for_each_child(Callback callback) const
 {
-    for (auto* node = first_child(); node; node = node->next_sibling()) {
-        func(*node);
-    }
+    for (auto* node = first_child(); node; node = node->next_sibling())
+        callback(*node);
 }
 
+template<typename Callback>
+inline void ParentNode::for_each_child(Callback callback)
+{
+    for (auto* node = first_child(); node; node = node->next_sibling())
+        callback(*node);
+}

LibHTML/Text.cpp

@@ -1,4 +1,5 @@
 #include <LibHTML/Text.h>
+#include <LibHTML/LayoutText.h>
 
 Text::Text(const String& data)
     : Node(NodeType::TEXT_NODE)
@@ -10,4 +11,7 @@ Text::~Text()
 {
 }
 
-
+RetainPtr<LayoutNode> Text::create_layout_node()
+{
+    return adopt(*new LayoutText(*this));
+}

LibHTML/Text.h

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

LibHTML/test.cpp

@@ -14,5 +14,9 @@ int main(int argc, char** argv)
     String html = String::copy(f.read_all());
     auto doc = parse(html);
     dump_tree(doc);
+
+    doc->build_layout_tree();
+    ASSERT(doc->layout_node());
+    dump_tree(*doc->layout_node());
     return 0;
 }