third_party/WebKit/Source/core/dom/LayoutTreeBuilder.h

   1 /*
   2  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
   3  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
   4  *           (C) 2001 Dirk Mueller (mueller@kde.org)
   5  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
   6  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
   7  * Copyright (C) 2011 Google Inc. All rights reserved.
   8  *
   9  * This library is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU Library General Public
  11  * License as published by the Free Software Foundation; either
  12  * version 2 of the License, or (at your option) any later version.
  13  *
  14  * This library is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  17  * Library General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU Library General Public License
  20  * along with this library; see the file COPYING.LIB.  If not, write to
  21  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  22  * Boston, MA 02110-1301, USA.
  23  *
  24  */
  25
  26 #ifndef LayoutTreeBuilder_h
  27 #define LayoutTreeBuilder_h
  28
  29 #include "core/dom/Document.h"
  30 #include "core/dom/LayoutTreeBuilderTraversal.h"
  31 #include "core/dom/Node.h"
  32 #include "core/dom/Text.h"
  33 #include "core/layout/LayoutObject.h"
  34 #include "wtf/RefPtr.h"
  35
  36 namespace blink {
  37
  38 class ComputedStyle;
  39
  40 template <typename NodeType>
  41 class LayoutTreeBuilder {
  42     STACK_ALLOCATED();
  43 protected:
  44     LayoutTreeBuilder(NodeType& node, LayoutObject* layoutObjectParent)
  45         : m_node(node)
  46         , m_layoutObjectParent(layoutObjectParent)
  47     {
  48         ASSERT(!node.layoutObject());
  49         ASSERT(node.needsAttach());
  50         ASSERT(node.document().inStyleRecalc());
  51         ASSERT(node.inActiveDocument());
  52     }
  53
  54     LayoutObject* nextLayoutObject() const
  55     {
  56         ASSERT(m_layoutObjectParent);
  57
  58         // Avoid an O(N^2) walk over the children when reattaching all children of a node.
  59         if (m_layoutObjectParent->node() && m_layoutObjectParent->node()->needsAttach())
  60             return 0;
  61
  62         return LayoutTreeBuilderTraversal::nextSiblingLayoutObject(*m_node);
  63     }
  64
  65     RawPtrWillBeMember<NodeType> m_node;
  66     LayoutObject* m_layoutObjectParent;
  67 };
  68
  69 class LayoutTreeBuilderForElement : public LayoutTreeBuilder<Element> {
  70 public:
  71     LayoutTreeBuilderForElement(Element&, ComputedStyle*);
  72
  73     void createLayoutObjectIfNeeded()
  74     {
  75         if (shouldCreateLayoutObject())
  76             createLayoutObject();
  77     }
  78
  79 private:
  80     LayoutObject* parentLayoutObject() const;
  81     LayoutObject* nextLayoutObject() const;
  82     bool shouldCreateLayoutObject() const;
  83     ComputedStyle& style() const;
  84     void createLayoutObject();
  85
  86     mutable RefPtr<ComputedStyle> m_style;
  87 };
  88
  89 class LayoutTreeBuilderForText : public LayoutTreeBuilder<Text> {
  90 public:
  91     LayoutTreeBuilderForText(Text& text, LayoutObject* layoutParent)
  92         : LayoutTreeBuilder(text, layoutParent) { }
  93
  94     void createLayoutObject();
  95 };
  96
  97 } // namespace blink
  98
  99 #endif