third_party/WebKit/Source/core/layout/svg/LayoutSVGTransformableContainer.cpp

/*
 * Copyright (C) 2004, 2005 Nikolas Zimmermann <zimmermann@kde.org>
 * Copyright (C) 2004, 2005, 2006 Rob Buis <buis@kde.org>
 * Copyright (C) 2009 Google, Inc.
 *
 * 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/layout/svg/LayoutSVGTransformableContainer.h"

#include "core/layout/svg/SVGLayoutSupport.h"
#include "core/svg/SVGGElement.h"
#include "core/svg/SVGGraphicsElement.h"
#include "core/svg/SVGUseElement.h"

namespace blink {

LayoutSVGTransformableContainer::LayoutSVGTransformableContainer(
    SVGGraphicsElement* node)
    : LayoutSVGContainer(node), m_needsTransformUpdate(true) {}

static bool hasValidPredecessor(const Node* node) {
  ASSERT(node);
  for (node = node->previousSibling(); node; node = node->previousSibling()) {
    if (node->isSVGElement() && toSVGElement(node)->isValid())
      return true;
  }
  return false;
}

bool LayoutSVGTransformableContainer::isChildAllowed(
    LayoutObject* child,
    const ComputedStyle& style) const {
  ASSERT(element());
  if (isSVGSwitchElement(*element())) {
    Node* node = child->node();
    // Reject non-SVG/non-valid elements.
    if (!node->isSVGElement() || !toSVGElement(node)->isValid())
      return false;
    // Reject this child if it isn't the first valid node.
    if (hasValidPredecessor(node))
      return false;
  } else if (isSVGAElement(*element())) {
    // http://www.w3.org/2003/01/REC-SVG11-20030114-errata#linking-text-environment
    // The 'a' element may contain any element that its parent may contain,
    // except itself.
    if (isSVGAElement(*child->node()))
      return false;
    if (parent() && parent()->isSVG())
      return parent()->isChildAllowed(child, style);
  }
  return LayoutSVGContainer::isChildAllowed(child, style);
}

void LayoutSVGTransformableContainer::setNeedsTransformUpdate() {
  setMayNeedPaintInvalidationSubtree();
  m_needsTransformUpdate = true;
}

SVGTransformChange LayoutSVGTransformableContainer::calculateLocalTransform() {
  SVGGraphicsElement* element = toSVGGraphicsElement(this->element());
  ASSERT(element);

  // If we're either the layoutObject for a <use> element, or for any <g>
  // element inside the shadow tree, that was created during the use/symbol/svg
  // expansion in SVGUseElement. These containers need to respect the
  // translations induced by their corresponding use elements x/y attributes.
  SVGUseElement* useElement = nullptr;
  if (isSVGUseElement(*element)) {
    useElement = toSVGUseElement(element);
  } else if (isSVGGElement(*element) &&
             toSVGGElement(element)->inUseShadowTree()) {
    SVGElement* correspondingElement = element->correspondingElement();
    if (isSVGUseElement(correspondingElement))
      useElement = toSVGUseElement(correspondingElement);
  }

  if (useElement) {
    SVGLengthContext lengthContext(element);
    FloatSize translation(
        useElement->x()->currentValue()->value(lengthContext),
        useElement->y()->currentValue()->value(lengthContext));
    // TODO(fs): Signal this on style update instead. (Since these are
    // suppose to be presentation attributes now, this does feel a bit
    // broken...)
    if (translation != m_additionalTranslation)
      setNeedsTransformUpdate();
    m_additionalTranslation = translation;
  }

  if (!m_needsTransformUpdate)
    return SVGTransformChange::None;

  SVGTransformChangeDetector changeDetector(m_localTransform);
  m_localTransform = element->calculateAnimatedLocalTransform();
  m_localTransform.translate(m_additionalTranslation.width(),
                             m_additionalTranslation.height());
  m_needsTransformUpdate = false;
  return changeDetector.computeChange(m_localTransform);
}

}  // namespace blink