Source/core/rendering/RenderLayerStackingNode.cpp

/*
 * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011, 2012 Apple Inc. All rights reserved.
 *
 * Portions are Copyright (C) 1998 Netscape Communications Corporation.
 *
 * Other contributors:
 *   Robert O'Callahan <roc+@cs.cmu.edu>
 *   David Baron <dbaron@fas.harvard.edu>
 *   Christian Biesinger <cbiesinger@web.de>
 *   Randall Jesup <rjesup@wgate.com>
 *   Roland Mainz <roland.mainz@informatik.med.uni-giessen.de>
 *   Josh Soref <timeless@mac.com>
 *   Boris Zbarsky <bzbarsky@mit.edu>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 *
 * Alternatively, the contents of this file may be used under the terms
 * of either the Mozilla Public License Version 1.1, found at
 * http://www.mozilla.org/MPL/ (the "MPL") or the GNU General Public
 * License Version 2.0, found at http://www.fsf.org/copyleft/gpl.html
 * (the "GPL"), in which case the provisions of the MPL or the GPL are
 * applicable instead of those above.  If you wish to allow use of your
 * version of this file only under the terms of one of those two
 * licenses (the MPL or the GPL) and not to allow others to use your
 * version of this file under the LGPL, indicate your decision by
 * deletingthe provisions above and replace them with the notice and
 * other provisions required by the MPL or the GPL, as the case may be.
 * If you do not delete the provisions above, a recipient may use your
 * version of this file under any of the LGPL, the MPL or the GPL.
 */

#include "config.h"
#include "core/rendering/RenderLayerStackingNode.h"

#include "core/rendering/RenderLayer.h"
#include "core/rendering/RenderView.h"
#include "core/rendering/compositing/RenderLayerCompositor.h"
#include "public/platform/Platform.h"

namespace blink {

// FIXME: This should not require RenderLayer. There is currently a cycle where
// in order to determine if we shoulBeNormalFlowOnly() we have to ask the render
// layer about some of its state.
RenderLayerStackingNode::RenderLayerStackingNode(RenderLayer* layer)
    : m_layer(layer)
    , m_normalFlowListDirty(true)
#if ENABLE(ASSERT)
    , m_layerListMutationAllowed(true)
    , m_stackingParent(0)
#endif
{
    m_isNormalFlowOnly = shouldBeNormalFlowOnly();

    // Non-stacking contexts should have empty z-order lists. As this is already the case,
    // there is no need to dirty / recompute these lists.
    m_zOrderListsDirty = isStackingContext();
}

RenderLayerStackingNode::~RenderLayerStackingNode()
{
#if ENABLE(ASSERT)
    if (!renderer()->documentBeingDestroyed()) {
        ASSERT(!isInStackingParentZOrderLists());
        ASSERT(!isInStackingParentNormalFlowList());

        updateStackingParentForZOrderLists(0);
        updateStackingParentForNormalFlowList(0);
    }
#endif
}

// Helper for the sorting of layers by z-index.
static inline bool compareZIndex(RenderLayerStackingNode* first, RenderLayerStackingNode* second)
{
    return first->zIndex() < second->zIndex();
}

RenderLayerCompositor* RenderLayerStackingNode::compositor() const
{
    ASSERT(renderer()->view());
    return renderer()->view()->compositor();
}

void RenderLayerStackingNode::dirtyZOrderLists()
{
    ASSERT(m_layerListMutationAllowed);
    ASSERT(isStackingContext());

#if ENABLE(ASSERT)
    updateStackingParentForZOrderLists(0);
#endif

    if (m_posZOrderList)
        m_posZOrderList->clear();
    if (m_negZOrderList)
        m_negZOrderList->clear();
    m_zOrderListsDirty = true;

    if (!renderer()->documentBeingDestroyed())
        compositor()->setNeedsCompositingUpdate(CompositingUpdateRebuildTree);
}

void RenderLayerStackingNode::dirtyStackingContextZOrderLists()
{
    if (RenderLayerStackingNode* stackingNode = ancestorStackingContextNode())
        stackingNode->dirtyZOrderLists();
}

void RenderLayerStackingNode::dirtyNormalFlowList()
{
    ASSERT(m_layerListMutationAllowed);

#if ENABLE(ASSERT)
    updateStackingParentForNormalFlowList(0);
#endif

    if (m_normalFlowList)
        m_normalFlowList->clear();
    m_normalFlowListDirty = true;

    if (!renderer()->documentBeingDestroyed())
        compositor()->setNeedsCompositingUpdate(CompositingUpdateRebuildTree);
}

void RenderLayerStackingNode::rebuildZOrderLists()
{
    ASSERT(m_layerListMutationAllowed);
    ASSERT(isDirtyStackingContext());

    for (RenderLayer* child = layer()->firstChild(); child; child = child->nextSibling()) {
        if (!layer()->reflectionInfo() || layer()->reflectionInfo()->reflectionLayer() != child)
            child->stackingNode()->collectLayers(m_posZOrderList, m_negZOrderList);
    }

    // Sort the two lists.
    if (m_posZOrderList)
        std::stable_sort(m_posZOrderList->begin(), m_posZOrderList->end(), compareZIndex);

    if (m_negZOrderList)
        std::stable_sort(m_negZOrderList->begin(), m_negZOrderList->end(), compareZIndex);

    // Append layers for top layer elements after normal layer collection, to ensure they are on top regardless of z-indexes.
    // The renderers of top layer elements are children of the view, sorted in top layer stacking order.
    if (layer()->isRootLayer()) {
        RenderView* view = renderer()->view();
        for (RenderObject* child = view->firstChild(); child; child = child->nextSibling()) {
            Element* childElement = (child->node() && child->node()->isElementNode()) ? toElement(child->node()) : 0;
            if (childElement && childElement->isInTopLayer()) {
                RenderLayer* layer = toRenderLayerModelObject(child)->layer();
                // Create the buffer if it doesn't exist yet.
                if (!m_posZOrderList)
                    m_posZOrderList = adoptPtr(new Vector<RenderLayerStackingNode*>);
                m_posZOrderList->append(layer->stackingNode());
            }
        }
    }

#if ENABLE(ASSERT)
    updateStackingParentForZOrderLists(this);
#endif

    m_zOrderListsDirty = false;
}

void RenderLayerStackingNode::updateNormalFlowList()
{
    if (!m_normalFlowListDirty)
        return;

    ASSERT(m_layerListMutationAllowed);

    for (RenderLayer* child = layer()->firstChild(); child; child = child->nextSibling()) {
        if (child->stackingNode()->isNormalFlowOnly() && (!layer()->reflectionInfo() || layer()->reflectionInfo()->reflectionLayer() != child)) {
            if (!m_normalFlowList)
                m_normalFlowList = adoptPtr(new Vector<RenderLayerStackingNode*>);
            m_normalFlowList->append(child->stackingNode());
        }
    }

#if ENABLE(ASSERT)
    updateStackingParentForNormalFlowList(this);
#endif

    m_normalFlowListDirty = false;
}

void RenderLayerStackingNode::collectLayers(OwnPtr<Vector<RenderLayerStackingNode*> >& posBuffer, OwnPtr<Vector<RenderLayerStackingNode*> >& negBuffer)
{
    if (layer()->isInTopLayer())
        return;

    if (!isNormalFlowOnly()) {
        OwnPtr<Vector<RenderLayerStackingNode*> >& buffer = (zIndex() >= 0) ? posBuffer : negBuffer;
        if (!buffer)
            buffer = adoptPtr(new Vector<RenderLayerStackingNode*>);
        buffer->append(this);
    }

    if (!isStackingContext()) {
        for (RenderLayer* child = layer()->firstChild(); child; child = child->nextSibling()) {
            if (!layer()->reflectionInfo() || layer()->reflectionInfo()->reflectionLayer() != child)
                child->stackingNode()->collectLayers(posBuffer, negBuffer);
        }
    }
}

#if ENABLE(ASSERT)
bool RenderLayerStackingNode::isInStackingParentZOrderLists() const
{
    if (!m_stackingParent || m_stackingParent->zOrderListsDirty())
        return false;

    if (m_stackingParent->posZOrderList() && m_stackingParent->posZOrderList()->find(this) != kNotFound)
        return true;

    if (m_stackingParent->negZOrderList() && m_stackingParent->negZOrderList()->find(this) != kNotFound)
        return true;

    return false;
}

bool RenderLayerStackingNode::isInStackingParentNormalFlowList() const
{
    if (!m_stackingParent || m_stackingParent->normalFlowListDirty())
        return false;

    return (m_stackingParent->normalFlowList() && m_stackingParent->normalFlowList()->find(this) != kNotFound);
}

void RenderLayerStackingNode::updateStackingParentForZOrderLists(RenderLayerStackingNode* stackingParent)
{
    if (m_posZOrderList) {
        for (size_t i = 0; i < m_posZOrderList->size(); ++i)
            m_posZOrderList->at(i)->setStackingParent(stackingParent);
    }

    if (m_negZOrderList) {
        for (size_t i = 0; i < m_negZOrderList->size(); ++i)
            m_negZOrderList->at(i)->setStackingParent(stackingParent);
    }
}

void RenderLayerStackingNode::updateStackingParentForNormalFlowList(RenderLayerStackingNode* stackingParent)
{
    if (m_normalFlowList) {
        for (size_t i = 0; i < m_normalFlowList->size(); ++i)
            m_normalFlowList->at(i)->setStackingParent(stackingParent);
    }
}
#endif

void RenderLayerStackingNode::updateLayerListsIfNeeded()
{
    updateZOrderLists();
    updateNormalFlowList();

    if (!layer()->reflectionInfo())
        return;

    RenderLayer* reflectionLayer = layer()->reflectionInfo()->reflectionLayer();
    reflectionLayer->stackingNode()->updateZOrderLists();
    reflectionLayer->stackingNode()->updateNormalFlowList();
}

void RenderLayerStackingNode::updateStackingNodesAfterStyleChange(const RenderStyle* oldStyle)
{
    bool wasStackingContext = oldStyle ? !oldStyle->hasAutoZIndex() : false;
    int oldZIndex = oldStyle ? oldStyle->zIndex() : 0;

    bool isStackingContext = this->isStackingContext();
    if (isStackingContext == wasStackingContext && oldZIndex == zIndex())
        return;

    dirtyStackingContextZOrderLists();

    if (isStackingContext)
        dirtyZOrderLists();
    else
        clearZOrderLists();
}

// FIXME: Rename shouldBeNormalFlowOnly to something more accurate now that CSS
// 2.1 defines the term "normal flow".
bool RenderLayerStackingNode::shouldBeNormalFlowOnly() const
{
    return !isStackingContext() && !renderer()->isPositioned();
}

void RenderLayerStackingNode::updateIsNormalFlowOnly()
{
    bool isNormalFlowOnly = shouldBeNormalFlowOnly();
    if (isNormalFlowOnly == this->isNormalFlowOnly())
        return;

    m_isNormalFlowOnly = isNormalFlowOnly;
    if (RenderLayer* p = layer()->parent())
        p->stackingNode()->dirtyNormalFlowList();
    dirtyStackingContextZOrderLists();
}

RenderLayerStackingNode* RenderLayerStackingNode::ancestorStackingContextNode() const
{
    for (RenderLayer* ancestor = layer()->parent(); ancestor; ancestor = ancestor->parent()) {
        RenderLayerStackingNode* stackingNode = ancestor->stackingNode();
        if (stackingNode->isStackingContext())
            return stackingNode;
    }
    return 0;
}

RenderLayerModelObject* RenderLayerStackingNode::renderer() const
{
    return m_layer->renderer();
}

} // namespace blink