LibHTML: Add a Frame class and use it for document layout width

Each HtmlView now has a main_frame(), which represents the main frame
of the web page. Frame inherits from TreeNode<Frame>, which will allow
us to someday implement a Frame tree (to support the <frame> element.)

Libraries/LibHTML/DOM/Document.cpp

@@ -4,6 +4,7 @@
 #include <LibHTML/DOM/HTMLHeadElement.h>
 #include <LibHTML/DOM/HTMLHtmlElement.h>
 #include <LibHTML/DOM/HTMLTitleElement.h>
+#include <LibHTML/Frame.h>
 #include <LibHTML/Layout/LayoutDocument.h>
 #include <stdio.h>
 
@@ -63,3 +64,12 @@ String Document::title() const
 
     return title_element->text_content();
 }
+
+void Document::attach_to_frame(Badge<Frame>, Frame& frame)
+{
+    m_frame = frame.make_weak_ptr();
+}
+
+void Document::detach_from_frame(Badge<Frame>, Frame&)
+{
+}

Libraries/LibHTML/DOM/Document.h

@@ -3,10 +3,12 @@
 #include <AK/NonnullRefPtrVector.h>
 #include <AK/OwnPtr.h>
 #include <AK/String.h>
+#include <AK/WeakPtr.h>
 #include <LibHTML/CSS/StyleResolver.h>
 #include <LibHTML/CSS/StyleSheet.h>
 #include <LibHTML/DOM/ParentNode.h>
 
+class Frame;
 class HTMLHtmlElement;
 class HTMLHeadElement;
 class LayoutNode;
@@ -36,8 +38,15 @@ public:
 
     String title() const;
 
+    void attach_to_frame(Badge<Frame>, Frame&);
+    void detach_from_frame(Badge<Frame>, Frame&);
+
+    Frame* frame() { return m_frame.ptr(); }
+    const Frame* frame() const { return m_frame.ptr(); }
+
 private:
     OwnPtr<StyleResolver> m_style_resolver;
     NonnullRefPtrVector<StyleSheet> m_sheets;
     RefPtr<Node> m_hovered_node;
+    WeakPtr<Frame> m_frame;
 };

Libraries/LibHTML/Frame.cpp

@@ -0,0 +1,31 @@
+#include <LibHTML/DOM/Document.h>
+#include <LibHTML/Frame.h>
+
+Frame::Frame()
+{
+}
+
+Frame::~Frame()
+{
+}
+
+void Frame::set_document(Document* document)
+{
+    if (m_document == document)
+        return;
+
+    if (m_document)
+        m_document->detach_from_frame({}, *this);
+
+    m_document = document;
+
+    if (m_document)
+        m_document->attach_to_frame({}, *this);
+}
+
+void Frame::set_size(const Size& size)
+{
+    if (m_size == size)
+        return;
+    m_size = size;
+}

Libraries/LibHTML/Frame.h

@@ -0,0 +1,31 @@
+#pragma once
+
+#include <AK/Noncopyable.h>
+#include <AK/RefPtr.h>
+#include <AK/Weakable.h>
+#include <LibDraw/Size.h>
+#include <LibHTML/TreeNode.h>
+
+class Document;
+
+class Frame
+    : public TreeNode<Frame>
+    , public Weakable<Frame> {
+public:
+    static NonnullRefPtr<Frame> create() { return adopt(*new Frame); }
+    ~Frame();
+
+    const Document* document() const { return m_document; }
+    Document* document() { return m_document; }
+
+    void set_document(Document*);
+
+    const Size& size() const { return m_size; }
+    void set_size(const Size&);
+
+private:
+    Frame();
+
+    RefPtr<Document> m_document;
+    Size m_size;
+};

Libraries/LibHTML/HtmlView.cpp

@@ -4,6 +4,7 @@
 #include <LibHTML/DOM/Element.h>
 #include <LibHTML/DOM/HTMLAnchorElement.h>
 #include <LibHTML/Dump.h>
+#include <LibHTML/Frame.h>
 #include <LibHTML/HtmlView.h>
 #include <LibHTML/Layout/LayoutNode.h>
 #include <LibHTML/RenderingContext.h>
@@ -11,6 +12,7 @@
 
 HtmlView::HtmlView(GWidget* parent)
     : GScrollableWidget(parent)
+    , m_main_frame(Frame::create())
 {
     set_frame_shape(FrameShape::Container);
     set_frame_shadow(FrameShadow::Sunken);
@@ -19,12 +21,18 @@ HtmlView::HtmlView(GWidget* parent)
     set_background_color(Color::White);
 }
 
+HtmlView::~HtmlView()
+{
+}
+
 void HtmlView::set_document(Document* document)
 {
     if (document == m_document)
         return;
     m_document = document;
 
+    main_frame().set_document(document);
+
     if (document == nullptr)
         m_layout_root = nullptr;
     else
@@ -46,7 +54,7 @@ void HtmlView::layout_and_sync_size()
     if (!m_layout_root)
         return;
 
-    m_layout_root->style().size().set_width(available_size().width());
+    main_frame().set_size(available_size());
     m_layout_root->layout();
     set_content_size(m_layout_root->rect().size());
 

Libraries/LibHTML/HtmlView.h

@@ -3,15 +3,20 @@
 #include <LibGUI/GScrollableWidget.h>
 #include <LibHTML/DOM/Document.h>
 
+class Frame;
+
 class HtmlView : public GScrollableWidget {
     C_OBJECT(HtmlView)
 public:
-    virtual ~HtmlView() override {}
+    virtual ~HtmlView() override;
 
     Document* document() { return m_document; }
     const Document* document() const { return m_document; }
     void set_document(Document*);
 
+    Frame& main_frame() { return *m_main_frame; }
+    const Frame& main_frame() const { return *m_main_frame; }
+
     Function<void(const String&)> on_link_click;
     Function<void(const String&)> on_title_change;
 
@@ -26,6 +31,7 @@ protected:
 private:
     void layout_and_sync_size();
 
+    RefPtr<Frame> m_main_frame;
     RefPtr<Document> m_document;
     RefPtr<LayoutNode> m_layout_root;
 };

Libraries/LibHTML/Layout/ComputedStyle.h

@@ -16,9 +16,6 @@ public:
     const LengthBox& padding() const { return m_padding; }
     const LengthBox& border() const { return m_border; }
 
-    const Size& size() const { return m_size; }
-    Size& size() { return m_size; }
-
     struct PixelBox {
         int top;
         int right;
@@ -32,6 +29,4 @@ private:
     LengthBox m_margin;
     LengthBox m_padding;
     LengthBox m_border;
-
-    Size m_size;
 };

Libraries/LibHTML/Layout/LayoutDocument.cpp

@@ -1,3 +1,4 @@
+#include <LibHTML/Frame.h>
 #include <LibHTML/Layout/LayoutDocument.h>
 
 LayoutDocument::LayoutDocument(const Document& document, NonnullRefPtr<StyleProperties> style_properties)
@@ -11,7 +12,8 @@ LayoutDocument::~LayoutDocument()
 
 void LayoutDocument::layout()
 {
-    rect().set_width(style().size().width());
+    ASSERT(document().frame());
+    rect().set_width(document().frame()->size().width());
 
     LayoutNode::layout();
 

Libraries/LibHTML/Makefile.shared

@@ -31,6 +31,7 @@ LIBHTML_OBJS = \
     Layout/LineBox.o \
     Layout/LineBoxFragment.o \
     HtmlView.o \
+    Frame.o \
     Dump.o
 
 GENERATED_SOURCES = \