| /* |
| * Copyright (C) 1999 Lars Knoll (knoll@kde.org) |
| * (C) 1999 Antti Koivisto (koivisto@kde.org) |
| * (C) 2001 Dirk Mueller (mueller@kde.org) |
| * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All |
| * rights reserved. |
| * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. |
| * (http://www.torchmobile.com/) |
| * Copyright (C) 2011 Google Inc. All rights reserved. |
| * |
| * This library is free software; you can redistribute it and/or |
| * modify it under the terms of the GNU Library General Public |
| * License as published by the Free Software Foundation; either |
| * version 2 of the License, or (at your option) any later version. |
| * |
| * This library is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| * Library General Public License for more details. |
| * |
| * You should have received a copy of the GNU Library General Public License |
| * along with this library; see the file COPYING.LIB. If not, write to |
| * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, |
| * Boston, MA 02110-1301, USA. |
| * |
| */ |
| |
| #ifndef LayoutTreeBuilder_h |
| #define LayoutTreeBuilder_h |
| |
| #include "base/memory/scoped_refptr.h" |
| #include "core/dom/Document.h" |
| #include "core/dom/LayoutTreeBuilderTraversal.h" |
| #include "core/dom/Node.h" |
| #include "core/dom/Text.h" |
| #include "core/layout/LayoutObject.h" |
| |
| namespace blink { |
| |
| class ComputedStyle; |
| |
| // The LayoutTreeBuilder class uses the DOM tree and CSS style rules as input to |
| // form a LayoutObject Tree which is then used for layout computations in a |
| // later stage. |
| |
| // To construct the LayoutObject tree, the LayoutTreeBuilder does the following: |
| // 1. Starting at the root of the DOM tree, traverse each visible node. |
| // Visibility is determined by |
| // LayoutTreeBuilderFor{Element,Text}::ShouldCreateLayoutObject() functions. |
| // 2. For each visible node, ensure that the style has been resolved (either by |
| // getting the ComputedStyle passed on to the LayoutTreeBuilder or by forcing |
| // style resolution). This is done in LayoutTreeBuilderForElement::Style(). |
| // 3. Emit visible LayoutObjects with content and their computed styles. |
| // This is dealt with by the |
| // LayoutTreeBuilderFor{Element,Text}::CreateLayoutObject() functions. |
| template <typename NodeType> |
| class LayoutTreeBuilder { |
| STACK_ALLOCATED(); |
| |
| protected: |
| LayoutTreeBuilder(NodeType& node, LayoutObject* layout_object_parent) |
| : node_(node), layout_object_parent_(layout_object_parent) { |
| DCHECK(!node.GetLayoutObject()); |
| DCHECK(node.NeedsAttach()); |
| DCHECK(node.GetDocument().InStyleRecalc()); |
| DCHECK(node.InActiveDocument()); |
| } |
| |
| LayoutObject* NextLayoutObject() const { |
| DCHECK(layout_object_parent_); |
| |
| // Avoid an O(N^2) walk over the children when reattaching all children of a |
| // node. |
| if (layout_object_parent_->GetNode() && |
| layout_object_parent_->GetNode()->NeedsAttach()) |
| return nullptr; |
| |
| LayoutObject* next = |
| LayoutTreeBuilderTraversal::NextSiblingLayoutObject(*node_); |
| |
| // If a text node is wrapped in an anonymous inline for display:contents |
| // (see CreateInlineWrapperForDisplayContents()), use the wrapper as the |
| // next layout object. Otherwise we would need to add code to various |
| // AddChild() implementations to walk up the tree to find the correct |
| // layout tree parent/siblings. |
| if (next && next->IsText() && next->Parent()->IsAnonymous() && |
| next->Parent()->IsInline()) { |
| return next->Parent(); |
| } |
| return next; |
| } |
| |
| Member<NodeType> node_; |
| LayoutObject* layout_object_parent_; |
| }; |
| |
| class LayoutTreeBuilderForElement : public LayoutTreeBuilder<Element> { |
| public: |
| LayoutTreeBuilderForElement(Element&, ComputedStyle*); |
| |
| void CreateLayoutObjectIfNeeded() { |
| if (ShouldCreateLayoutObject()) |
| CreateLayoutObject(); |
| } |
| |
| ComputedStyle* ResolvedStyle() const { return style_.get(); } |
| |
| private: |
| LayoutObject* ParentLayoutObject() const; |
| LayoutObject* NextLayoutObject() const; |
| bool ShouldCreateLayoutObject() const; |
| ComputedStyle& Style() const; |
| void CreateLayoutObject(); |
| |
| mutable scoped_refptr<ComputedStyle> style_; |
| }; |
| |
| class LayoutTreeBuilderForText : public LayoutTreeBuilder<Text> { |
| public: |
| LayoutTreeBuilderForText(Text& text, |
| LayoutObject* layout_parent, |
| ComputedStyle* style_from_parent) |
| : LayoutTreeBuilder(text, layout_parent), style_(style_from_parent) {} |
| |
| void CreateLayoutObject(); |
| |
| private: |
| LayoutObject* CreateInlineWrapperForDisplayContentsIfNeeded(); |
| |
| scoped_refptr<ComputedStyle> style_; |
| }; |
| |
| } // namespace blink |
| |
| #endif |