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

/*
 * 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.
 *
 */

#include "core/dom/LayoutTreeBuilder.h"

#include "core/HTMLNames.h"
#include "core/SVGNames.h"
#include "core/css/resolver/StyleResolver.h"
#include "core/dom/FirstLetterPseudoElement.h"
#include "core/dom/Fullscreen.h"
#include "core/dom/Node.h"
#include "core/dom/PseudoElement.h"
#include "core/dom/Text.h"
#include "core/dom/shadow/InsertionPoint.h"
#include "core/layout/LayoutFullScreen.h"
#include "core/layout/LayoutObject.h"
#include "core/layout/LayoutText.h"
#include "core/layout/LayoutView.h"
#include "core/svg/SVGElement.h"
#include "platform/RuntimeEnabledFeatures.h"

namespace blink {

LayoutTreeBuilderForElement::LayoutTreeBuilderForElement(Element& element,
                                                         ComputedStyle* style)
    : LayoutTreeBuilder(element, nullptr), m_style(style) {
  DCHECK(!element.isActiveSlotOrActiveInsertionPoint());
  // TODO(ecobos): Move the first-letter logic inside parentLayoutObject too?
  // It's an extra (unnecessary) check for text nodes, though.
  if (element.isFirstLetterPseudoElement()) {
    if (LayoutObject* nextLayoutObject =
            FirstLetterPseudoElement::firstLetterTextLayoutObject(element))
      m_layoutObjectParent = nextLayoutObject->parent();
  } else {
    m_layoutObjectParent =
        LayoutTreeBuilderTraversal::parentLayoutObject(element);
  }
}

LayoutObject* LayoutTreeBuilderForElement::nextLayoutObject() const {
  DCHECK(m_layoutObjectParent);

  if (m_node->isInTopLayer())
    return LayoutTreeBuilderTraversal::nextInTopLayer(*m_node);

  if (m_node->isFirstLetterPseudoElement())
    return FirstLetterPseudoElement::firstLetterTextLayoutObject(*m_node);

  return LayoutTreeBuilder::nextLayoutObject();
}

LayoutObject* LayoutTreeBuilderForElement::parentLayoutObject() const {
  if (m_layoutObjectParent) {
    // FIXME: Guarding this by parentLayoutObject isn't quite right as the spec
    // for top layer only talks about display: none ancestors so putting a
    // <dialog> inside an <optgroup> seems like it should still work even though
    // this check will prevent it.
    if (m_node->isInTopLayer())
      return m_node->document().layoutView();
  }

  return m_layoutObjectParent;
}

DISABLE_CFI_PERF
bool LayoutTreeBuilderForElement::shouldCreateLayoutObject() const {
  if (!m_layoutObjectParent)
    return false;

  LayoutObject* parentLayoutObject = this->parentLayoutObject();
  if (!parentLayoutObject)
    return false;
  if (!parentLayoutObject->canHaveChildren())
    return false;
  return m_node->layoutObjectIsNeeded(style());
}

ComputedStyle& LayoutTreeBuilderForElement::style() const {
  if (!m_style)
    m_style = m_node->styleForLayoutObject();
  return *m_style;
}

DISABLE_CFI_PERF
void LayoutTreeBuilderForElement::createLayoutObject() {
  ComputedStyle& style = this->style();

  LayoutObject* newLayoutObject = m_node->createLayoutObject(style);
  if (!newLayoutObject)
    return;

  LayoutObject* parentLayoutObject = this->parentLayoutObject();

  if (!parentLayoutObject->isChildAllowed(newLayoutObject, style)) {
    newLayoutObject->destroy();
    return;
  }

  // Make sure the LayoutObject already knows it is going to be added to a
  // LayoutFlowThread before we set the style for the first time. Otherwise code
  // using inLayoutFlowThread() in the styleWillChange and styleDidChange will
  // fail.
  newLayoutObject->setIsInsideFlowThread(
      parentLayoutObject->isInsideFlowThread());

  LayoutObject* nextLayoutObject = this->nextLayoutObject();
  m_node->setLayoutObject(newLayoutObject);
  newLayoutObject->setStyle(
      &style);  // setStyle() can depend on layoutObject() already being set.

  if (Fullscreen::isCurrentFullScreenElement(*m_node)) {
    newLayoutObject = LayoutFullScreen::wrapLayoutObject(
        newLayoutObject, parentLayoutObject, &m_node->document());
    if (!newLayoutObject)
      return;
  }

  // Note: Adding newLayoutObject instead of layoutObject(). layoutObject() may
  // be a child of newLayoutObject.
  parentLayoutObject->addChild(newLayoutObject, nextLayoutObject);
}

void LayoutTreeBuilderForText::createLayoutObject() {
  ComputedStyle& style = *m_style;

  DCHECK(m_style == m_layoutObjectParent->style() ||
         toElement(LayoutTreeBuilderTraversal::parent(*m_node))
             ->hasDisplayContentsStyle());

  DCHECK(m_node->textLayoutObjectIsNeeded(style, *m_layoutObjectParent));

  LayoutText* newLayoutObject = m_node->createTextLayoutObject(style);
  if (!m_layoutObjectParent->isChildAllowed(newLayoutObject, style)) {
    newLayoutObject->destroy();
    return;
  }

  // Make sure the LayoutObject already knows it is going to be added to a
  // LayoutFlowThread before we set the style for the first time. Otherwise code
  // using inLayoutFlowThread() in the styleWillChange and styleDidChange will
  // fail.
  newLayoutObject->setIsInsideFlowThread(
      m_layoutObjectParent->isInsideFlowThread());

  LayoutObject* nextLayoutObject = this->nextLayoutObject();
  m_node->setLayoutObject(newLayoutObject);
  // Parent takes care of the animations, no need to call setAnimatableStyle.
  newLayoutObject->setStyle(&style);
  m_layoutObjectParent->addChild(newLayoutObject, nextLayoutObject);
}

}  // namespace blink