/*
 * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
 *           (C) 1999 Antti Koivisto (koivisto@kde.org)
 *           (C) 2007 David Smith (catfish.man@gmail.com)
 * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
 * Copyright (C) Research In Motion Limited 2010. 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 "sky/engine/config.h"
#include "sky/engine/core/rendering/RenderBlock.h"

#include "sky/engine/core/dom/Document.h"
#include "sky/engine/core/dom/Element.h"
#include "sky/engine/core/dom/StyleEngine.h"
#include "sky/engine/core/dom/shadow/ShadowRoot.h"
#include "sky/engine/core/editing/Editor.h"
#include "sky/engine/core/editing/FrameSelection.h"
#include "sky/engine/core/frame/FrameView.h"
#include "sky/engine/core/frame/LocalFrame.h"
#include "sky/engine/core/frame/Settings.h"
#include "sky/engine/core/page/Page.h"
#include "sky/engine/core/rendering/HitTestLocation.h"
#include "sky/engine/core/rendering/HitTestResult.h"
#include "sky/engine/core/rendering/InlineIterator.h"
#include "sky/engine/core/rendering/InlineTextBox.h"
#include "sky/engine/core/rendering/PaintInfo.h"
#include "sky/engine/core/rendering/RenderFlexibleBox.h"
#include "sky/engine/core/rendering/RenderInline.h"
#include "sky/engine/core/rendering/RenderLayer.h"
#include "sky/engine/core/rendering/RenderObjectInlines.h"
#include "sky/engine/core/rendering/RenderParagraph.h"
#include "sky/engine/core/rendering/RenderView.h"
#include "sky/engine/core/rendering/style/RenderStyle.h"
#include "sky/engine/platform/geometry/FloatQuad.h"
#include "sky/engine/platform/geometry/TransformState.h"
#include "sky/engine/platform/graphics/GraphicsContextStateSaver.h"
#include "sky/engine/wtf/StdLibExtras.h"
#include "sky/engine/wtf/TemporaryChange.h"

using namespace WTF;
using namespace Unicode;

namespace blink {

struct SameSizeAsRenderBlock : public RenderBox {
    RenderObjectChildList children;
    RenderLineBoxList lineBoxes;
    int pageLogicalOffset;
    uint32_t bitfields;
};

COMPILE_ASSERT(sizeof(RenderBlock) == sizeof(SameSizeAsRenderBlock), RenderBlock_should_stay_small);

static TrackedDescendantsMap* gPositionedDescendantsMap = 0;
static TrackedDescendantsMap* gPercentHeightDescendantsMap = 0;

static TrackedContainerMap* gPositionedContainerMap = 0;
static TrackedContainerMap* gPercentHeightContainerMap = 0;

RenderBlock::RenderBlock(ContainerNode* node)
    : RenderBox(node)
    , m_hasMarginBeforeQuirk(false)
    , m_hasMarginAfterQuirk(false)
    , m_beingDestroyed(false)
    , m_hasBorderOrPaddingLogicalWidthChanged(false)
{
}

static void removeBlockFromDescendantAndContainerMaps(RenderBlock* block, TrackedDescendantsMap*& descendantMap, TrackedContainerMap*& containerMap)
{
    if (OwnPtr<TrackedRendererListHashSet> descendantSet = descendantMap->take(block)) {
        TrackedRendererListHashSet::iterator end = descendantSet->end();
        for (TrackedRendererListHashSet::iterator descendant = descendantSet->begin(); descendant != end; ++descendant) {
            TrackedContainerMap::iterator it = containerMap->find(*descendant);
            ASSERT(it != containerMap->end());
            if (it == containerMap->end())
                continue;
            HashSet<RenderBlock*>* containerSet = it->value.get();
            ASSERT(containerSet->contains(block));
            containerSet->remove(block);
            if (containerSet->isEmpty())
                containerMap->remove(it);
        }
    }
}

void RenderBlock::removeFromGlobalMaps()
{
    if (gPercentHeightDescendantsMap)
        removeBlockFromDescendantAndContainerMaps(this, gPercentHeightDescendantsMap, gPercentHeightContainerMap);
    if (gPositionedDescendantsMap)
        removeBlockFromDescendantAndContainerMaps(this, gPositionedDescendantsMap, gPositionedContainerMap);
}

RenderBlock::~RenderBlock()
{
#if !ENABLE(OILPAN)
    removeFromGlobalMaps();
#endif
}

void RenderBlock::destroy()
{
    RenderBox::destroy();
#if ENABLE(OILPAN)
    removeFromGlobalMaps();
#endif
}

void RenderBlock::willBeDestroyed()
{
    // Mark as being destroyed to avoid trouble with merges in removeChild().
    m_beingDestroyed = true;

    // Make sure to destroy anonymous children first while they are still connected to the rest of the tree, so that they will
    // properly dirty line boxes that they are removed from. Effects that do :before/:after only on hover could crash otherwise.
    children()->destroyLeftoverChildren();

    if (!documentBeingDestroyed()) {
        if (firstLineBox()) {
            // We can't wait for RenderBox::destroy to clear the selection,
            // because by then we will have nuked the line boxes.
            // FIXME: The FrameSelection should be responsible for this when it
            // is notified of DOM mutations.
            if (isSelectionBorder())
                view()->clearSelection();

            // If we are an anonymous block, then our line boxes might have children
            // that will outlast this block. In the non-anonymous block case those
            // children will be destroyed by the time we return from this function.
            if (isAnonymousBlock()) {
                for (InlineFlowBox* box = firstLineBox(); box; box = box->nextLineBox()) {
                    while (InlineBox* childBox = box->firstChild())
                        childBox->remove();
                }
            }
        } else if (parent())
            parent()->dirtyLinesFromChangedChild(this);
    }

    m_lineBoxes.deleteLineBoxes();

    RenderBox::willBeDestroyed();
}

void RenderBlock::styleWillChange(StyleDifference diff, const RenderStyle& newStyle)
{
    RenderStyle* oldStyle = style();

    setReplaced(newStyle.isDisplayInlineType());

    if (oldStyle && parent()) {
        bool oldStyleIsContainer = oldStyle->position() != StaticPosition || oldStyle->hasTransformRelatedProperty();
        bool newStyleIsContainer = newStyle.position() != StaticPosition || newStyle.hasTransformRelatedProperty();

        if (oldStyleIsContainer && !newStyleIsContainer) {
            // Clear our positioned objects list. Our absolutely positioned descendants will be
            // inserted into our containing block's positioned objects list during layout.
            removePositionedObjects(0, NewContainingBlock);
        } else if (!oldStyleIsContainer && newStyleIsContainer) {
            // Remove our absolutely positioned descendants from their current containing block.
            // They will be inserted into our positioned objects list during layout.
            RenderObject* cb = parent();
            while (cb && (cb->style()->position() == StaticPosition || (cb->isInline() && !cb->isReplaced())) && !cb->isRenderView()) {
                if (cb->style()->position() == RelativePosition && cb->isInline() && !cb->isReplaced()) {
                    cb = cb->containingBlock();
                    break;
                }
                cb = cb->parent();
            }

            if (cb->isRenderBlock())
                toRenderBlock(cb)->removePositionedObjects(this, NewContainingBlock);
        }
    }

    RenderBox::styleWillChange(diff, newStyle);
}

static bool borderOrPaddingLogicalWidthChanged(const RenderStyle* oldStyle, const RenderStyle* newStyle)
{
    return oldStyle->borderLeftWidth() != newStyle->borderLeftWidth()
        || oldStyle->borderRightWidth() != newStyle->borderRightWidth()
        || oldStyle->paddingLeft() != newStyle->paddingLeft()
        || oldStyle->paddingRight() != newStyle->paddingRight();
}

void RenderBlock::styleDidChange(StyleDifference diff, const RenderStyle* oldStyle)
{
    RenderBox::styleDidChange(diff, oldStyle);

    RenderStyle* newStyle = style();
    propagateStyleToAnonymousChildren(true);

    // It's possible for our border/padding to change, but for the overall logical width of the block to
    // end up being the same. We keep track of this change so in layoutBlock, we can know to set relayoutChildren=true.
    m_hasBorderOrPaddingLogicalWidthChanged = oldStyle && diff.needsFullLayout() && needsLayout() && borderOrPaddingLogicalWidthChanged(oldStyle, newStyle);
}

void RenderBlock::addChildIgnoringAnonymousColumnBlocks(RenderObject* newChild, RenderObject* beforeChild)
{
    if (beforeChild && beforeChild->parent() != this) {
        RenderObject* beforeChildContainer = beforeChild->parent();
        ASSERT(beforeChildContainer->parent() == this);
        ASSERT(beforeChildContainer->isAnonymousBlock());
        addChild(newChild, beforeChildContainer);
        return;
    }

    // TODO(ojan): What should we do in this case? For now we insert an anonymous paragraph.
    // This only happens if we have a text node directly inside a non-paragraph.
    if (!isRenderParagraph() && newChild->isInline()) {
        RenderBlock* newBox = createAnonymousBlock();
        ASSERT(newBox->isRenderParagraph());
        RenderBox::addChild(newBox, beforeChild);
        newBox->addChild(newChild);
        return;
    }

    RenderBox::addChild(newChild, beforeChild);
}

void RenderBlock::addChild(RenderObject* newChild, RenderObject* beforeChild)
{
    addChildIgnoringAnonymousColumnBlocks(newChild, beforeChild);
}

void RenderBlock::deleteLineBoxTree()
{
    ASSERT(!m_lineBoxes.firstLineBox());
}

void RenderBlock::removeChild(RenderObject* oldChild)
{
    RenderBox::removeChild(oldChild);

    // No need to waste time deleting the line box tree if we're getting destroyed.
    if (documentBeingDestroyed())
        return;

    // If this was our last child be sure to clear out our line boxes.
    if (!firstChild() && isRenderParagraph())
        deleteLineBoxTree();
}

bool RenderBlock::widthAvailableToChildrenHasChanged()
{
    bool widthAvailableToChildrenHasChanged = m_hasBorderOrPaddingLogicalWidthChanged;
    m_hasBorderOrPaddingLogicalWidthChanged = false;

    // If we use border-box sizing, have percentage padding, and our parent has changed width then the width available to our children has changed even
    // though our own width has remained the same.
    widthAvailableToChildrenHasChanged |= style()->boxSizing() == BORDER_BOX && needsPreferredWidthsRecalculation() && view()->layoutState()->containingBlockLogicalWidthChanged();

    return widthAvailableToChildrenHasChanged;
}

bool RenderBlock::updateLogicalWidthAndColumnWidth()
{
    LayoutUnit oldWidth = logicalWidth();
    updateLogicalWidth();
    return oldWidth != logicalWidth() || widthAvailableToChildrenHasChanged();
}

void RenderBlock::addOverflowFromChildren()
{
    for (RenderBox* child = firstChildBox(); child; child = child->nextSiblingBox()) {
        if (!child->isFloatingOrOutOfFlowPositioned())
            addOverflowFromChild(child);
    }
}

void RenderBlock::computeOverflow(LayoutUnit oldClientAfterEdge, bool)
{
    m_overflow.clear();

    // Add overflow from children.
    addOverflowFromChildren();

    // Add in the overflow from positioned objects.
    addOverflowFromPositionedObjects();

    if (hasOverflowClip()) {
        // When we have overflow clip, propagate the original spillout since it will include collapsed bottom margins
        // and bottom padding.  Set the axis we don't care about to be 1, since we want this overflow to always
        // be considered reachable.
        LayoutRect clientRect(paddingBoxRect());
        LayoutRect rectToApply;
        rectToApply = LayoutRect(clientRect.x(), clientRect.y(), 1, std::max<LayoutUnit>(0, oldClientAfterEdge - clientRect.y()));
        addLayoutOverflow(rectToApply);
        if (hasRenderOverflow())
            m_overflow->setLayoutClientAfterEdge(oldClientAfterEdge);
    }

    addVisualEffectOverflow();
}

void RenderBlock::addOverflowFromPositionedObjects()
{
    TrackedRendererListHashSet* positionedDescendants = positionedObjects();
    if (!positionedDescendants)
        return;

    RenderBox* positionedObject;
    TrackedRendererListHashSet::iterator end = positionedDescendants->end();
    for (TrackedRendererListHashSet::iterator it = positionedDescendants->begin(); it != end; ++it) {
        positionedObject = *it;
        addOverflowFromChild(positionedObject, LayoutSize(positionedObject->x(), positionedObject->y()));
    }
}

bool RenderBlock::createsBlockFormattingContext() const
{
    return isInlineBlock() || isFloatingOrOutOfFlowPositioned() || hasOverflowClip() || isFlexItem() || isDocumentElement();
}

void RenderBlock::updateBlockChildDirtyBitsBeforeLayout(bool relayoutChildren, RenderBox* child)
{
    // FIXME: Technically percentage height objects only need a relayout if their percentage isn't going to be turned into
    // an auto value. Add a method to determine this, so that we can avoid the relayout.
    if (relayoutChildren || (child->hasRelativeLogicalHeight() && !isRenderView()))
        child->setChildNeedsLayout(MarkOnlyThis);

    // If relayoutChildren is set and the child has percentage padding or an embedded content box, we also need to invalidate the childs pref widths.
    if (relayoutChildren && child->needsPreferredWidthsRecalculation())
        child->setPreferredLogicalWidthsDirty(MarkOnlyThis);
}

void RenderBlock::simplifiedNormalFlowLayout()
{
    for (RenderBox* box = firstChildBox(); box; box = box->nextSiblingBox()) {
        if (!box->isOutOfFlowPositioned())
            box->layoutIfNeeded();
    }
}

bool RenderBlock::simplifiedLayout()
{
    // Check if we need to do a full layout.
    if (normalChildNeedsLayout() || selfNeedsLayout())
        return false;

    // Check that we actually need to do a simplified layout.
    if (!posChildNeedsLayout() && !(needsSimplifiedNormalFlowLayout() || needsPositionedMovementLayout()))
        return false;


    {
        // LayoutState needs this deliberate scope to pop before paint invalidation.
        LayoutState state(*this, locationOffset());

        if (needsPositionedMovementLayout() && !tryLayoutDoingPositionedMovementOnly())
            return false;

        // Lay out positioned descendants or objects that just need to recompute overflow.
        if (needsSimplifiedNormalFlowLayout())
            simplifiedNormalFlowLayout();

        if (posChildNeedsLayout() || needsPositionedMovementLayout())
            layoutPositionedObjects(false, needsPositionedMovementLayout() ? ForcedLayoutAfterContainingBlockMoved : DefaultLayout);

        // Recompute our overflow information.
        // FIXME: We could do better here by computing a temporary overflow object from layoutPositionedObjects and only
        // updating our overflow if we either used to have overflow or if the new temporary object has overflow.
        // For now just always recompute overflow. This is no worse performance-wise than the old code that called rightmostPosition and
        // lowestPosition on every relayout so it's not a regression.
        // computeOverflow expects the bottom edge before we clamp our height. Since this information isn't available during
        // simplifiedLayout, we cache the value in m_overflow.
        LayoutUnit oldClientAfterEdge = hasRenderOverflow() ? m_overflow->layoutClientAfterEdge() : clientLogicalBottom();
        computeOverflow(oldClientAfterEdge, true);
    }

    updateLayerTransformAfterLayout();

    clearNeedsLayout();
    return true;
}

LayoutUnit RenderBlock::marginIntrinsicLogicalWidthForChild(RenderBox* child) const
{
    // A margin has three types: fixed, percentage, and auto (variable).
    // Auto and percentage margins become 0 when computing min/max width.
    // Fixed margins can be added in as is.
    Length marginLeft = child->style()->marginStartUsing(style());
    Length marginRight = child->style()->marginEndUsing(style());
    LayoutUnit margin = 0;
    if (marginLeft.isFixed())
        margin += marginLeft.value();
    if (marginRight.isFixed())
        margin += marginRight.value();
    return margin;
}

void RenderBlock::layoutPositionedObjects(bool relayoutChildren, PositionedLayoutBehavior info)
{
    TrackedRendererListHashSet* positionedDescendants = positionedObjects();
    if (!positionedDescendants)
        return;

    RenderBox* r;
    TrackedRendererListHashSet::iterator end = positionedDescendants->end();
    for (TrackedRendererListHashSet::iterator it = positionedDescendants->begin(); it != end; ++it) {
        r = *it;

        SubtreeLayoutScope layoutScope(*r);

        // When a non-positioned block element moves, it may have positioned children that are implicitly positioned relative to the
        // non-positioned block.  Rather than trying to detect all of these movement cases, we just always lay out positioned
        // objects that are positioned implicitly like this.  Such objects are rare, and so in typical DHTML menu usage (where everything is
        // positioned explicitly) this should not incur a performance penalty.
        if (relayoutChildren || (r->style()->hasStaticBlockPosition() && r->parent() != this))
            layoutScope.setChildNeedsLayout(r);

        // If relayoutChildren is set and the child has percentage padding or an embedded content box, we also need to invalidate the childs pref widths.
        if (relayoutChildren && r->needsPreferredWidthsRecalculation())
            r->setPreferredLogicalWidthsDirty(MarkOnlyThis);

        if (info == ForcedLayoutAfterContainingBlockMoved)
            r->setNeedsPositionedMovementLayout();

        r->layoutIfNeeded();
    }
}

void RenderBlock::markPositionedObjectsForLayout()
{
    if (TrackedRendererListHashSet* positionedDescendants = positionedObjects()) {
        TrackedRendererListHashSet::iterator end = positionedDescendants->end();
        for (TrackedRendererListHashSet::iterator it = positionedDescendants->begin(); it != end; ++it)
            (*it)->setChildNeedsLayout();
    }
}

void RenderBlock::paint(PaintInfo& paintInfo, const LayoutPoint& paintOffset)
{
    LayoutPoint adjustedPaintOffset = paintOffset + location();

    LayoutRect overflowBox;
    // Check if we need to do anything at all.
    // FIXME: Could eliminate the isDocumentElement() check if we fix background painting so that the RenderView
    // paints the root's background.
    if (!isDocumentElement()) {
        overflowBox = visualOverflowRect();
        overflowBox.moveBy(adjustedPaintOffset);
        if (!overflowBox.intersects(paintInfo.rect))
            return;
    }

    // There are some cases where not all clipped visual overflow is accounted for.
    // FIXME: reduce the number of such cases.
    ContentsClipBehavior contentsClipBehavior = ForceContentsClip;
    if (hasOverflowClip() && !shouldPaintSelectionGaps() && !hasCaret())
        contentsClipBehavior = SkipContentsClipIfPossible;

    bool pushedClip = pushContentsClip(paintInfo, adjustedPaintOffset, contentsClipBehavior);
    paintObject(paintInfo, adjustedPaintOffset);
    if (pushedClip)
        popContentsClip(paintInfo, adjustedPaintOffset);
}

void RenderBlock::paintChildren(PaintInfo& paintInfo, const LayoutPoint& paintOffset)
{
    for (RenderBox* child = firstChildBox(); child; child = child->nextSiblingBox()) {
        if (!child->hasSelfPaintingLayer())
            child->paint(paintInfo, paintOffset);
    }
}

static inline bool hasCursorCaret(const FrameSelection& selection, const RenderBlock* block)
{
    return selection.caretRenderer() == block && selection.hasEditableStyle();
}

static inline bool hasDragCaret(const DragCaretController& dragCaretController, const RenderBlock* block)
{
    return dragCaretController.caretRenderer() == block && dragCaretController.isContentEditable();
}

bool RenderBlock::hasCaret() const
{
    return hasCursorCaret(frame()->selection(), this)
        || hasDragCaret(frame()->page()->dragCaretController(), this);
}

void RenderBlock::paintCarets(PaintInfo& paintInfo, const LayoutPoint& paintOffset)
{
    FrameSelection& selection = frame()->selection();
    if (hasCursorCaret(selection, this)) {
        selection.paintCaret(paintInfo.context, paintOffset, paintInfo.rect);
    }

    DragCaretController& dragCaretController = frame()->page()->dragCaretController();
    if (hasDragCaret(dragCaretController, this)) {
        dragCaretController.paintDragCaret(frame(), paintInfo.context, paintOffset, paintInfo.rect);
    }
}

void RenderBlock::paintObject(PaintInfo& paintInfo, const LayoutPoint& paintOffset)
{
    if (hasBoxDecorationBackground())
        paintBoxDecorationBackground(paintInfo, paintOffset);

    paintChildren(paintInfo, paintOffset);
    paintSelection(paintInfo, paintOffset); // Fill in gaps in selection on lines and between blocks.

    if (style()->hasOutline() && !style()->outlineStyleIsAuto())
        paintOutline(paintInfo, LayoutRect(paintOffset, size()));

    paintCarets(paintInfo, paintOffset);
}

bool RenderBlock::shouldPaintSelectionGaps() const
{
    return selectionState() != SelectionNone && isSelectionRoot();
}

bool RenderBlock::isSelectionRoot() const
{
    ASSERT(node() || isAnonymous());

    if (isDocumentElement() || hasOverflowClip()
        || isPositioned()
        || isInlineBlock()
        || hasTransform()
        || isFlexItem())
        return true;

    if (view() && view()->selectionStart()) {
        Node* startElement = view()->selectionStart()->node();
        if (startElement && startElement->rootEditableElement() == node())
            return true;
    }

    return false;
}

void RenderBlock::paintSelection(PaintInfo& paintInfo, const LayoutPoint& paintOffset)
{
    if (shouldPaintSelectionGaps()) {
        LayoutUnit lastTop = 0;
        LayoutUnit lastLeft = logicalLeftSelectionOffset(this, lastTop);
        LayoutUnit lastRight = logicalRightSelectionOffset(this, lastTop);
        GraphicsContextStateSaver stateSaver(*paintInfo.context);

        // TODO(ojan): In sky, we don't use the return value, but we
        // need this in order to actually paint selection gaps.
        // We should rename it appropriately.
        selectionGaps(this, paintOffset, LayoutSize(), lastTop, lastLeft, lastRight, &paintInfo);
    }
}

static void clipOutPositionedObjects(const PaintInfo* paintInfo, const LayoutPoint& offset, TrackedRendererListHashSet* positionedObjects)
{
    if (!positionedObjects)
        return;

    TrackedRendererListHashSet::const_iterator end = positionedObjects->end();
    for (TrackedRendererListHashSet::const_iterator it = positionedObjects->begin(); it != end; ++it) {
        RenderBox* r = *it;
        paintInfo->context->clipOut(IntRect(offset.x() + r->x(), offset.y() + r->y(), r->width(), r->height()));
    }
}

LayoutUnit RenderBlock::blockDirectionOffset(const LayoutSize& offsetFromBlock) const
{
    // FIXME(sky): Remove
    return offsetFromBlock.height();
}

LayoutUnit RenderBlock::inlineDirectionOffset(const LayoutSize& offsetFromBlock) const
{
    // FIXME(sky): Remove
    return offsetFromBlock.width();
}

LayoutRect RenderBlock::logicalRectToPhysicalRect(const LayoutPoint& rootBlockPhysicalPosition, const LayoutRect& logicalRect)
{
    LayoutRect result = logicalRect;
    result.moveBy(rootBlockPhysicalPosition);
    return result;
}

GapRects RenderBlock::selectionGaps(RenderBlock* rootBlock, const LayoutPoint& rootBlockPhysicalPosition, const LayoutSize& offsetFromRootBlock,
                                    LayoutUnit& lastLogicalTop, LayoutUnit& lastLogicalLeft, LayoutUnit& lastLogicalRight, const PaintInfo* paintInfo)
{
    // IMPORTANT: Callers of this method that intend for painting to happen need to do a save/restore.
    // Clip out floating and positioned objects when painting selection gaps.
    if (paintInfo) {
        // Note that we don't clip out overflow for positioned objects.  We just stick to the border box.
        LayoutRect blockRect(offsetFromRootBlock.width(), offsetFromRootBlock.height(), width(), height());
        blockRect.moveBy(rootBlockPhysicalPosition);
        clipOutPositionedObjects(paintInfo, blockRect.location(), positionedObjects());
        if (isDocumentElement()) // The <body> must make sure to examine its containingBlock's positioned objects.
            for (RenderBlock* cb = containingBlock(); cb && !cb->isRenderView(); cb = cb->containingBlock())
                clipOutPositionedObjects(paintInfo, LayoutPoint(cb->x(), cb->y()), cb->positionedObjects());
    }

    // FIXME: overflow: auto/scroll regions need more math here, since painting in the border box is different from painting in the padding box (one is scrolled, the other is
    // fixed).
    GapRects result;
    if (!isRenderBlockFlow()) // FIXME: Make multi-column selection gap filling work someday.
        return result;

    if (hasTransform()) {
        // FIXME: We should learn how to gap fill multiple columns and transforms eventually.
        lastLogicalTop = rootBlock->blockDirectionOffset(offsetFromRootBlock) + logicalHeight();
        lastLogicalLeft = logicalLeftSelectionOffset(rootBlock, logicalHeight());
        lastLogicalRight = logicalRightSelectionOffset(rootBlock, logicalHeight());
        return result;
    }

    if (isRenderParagraph())
        result = toRenderParagraph(this)->inlineSelectionGaps(rootBlock, rootBlockPhysicalPosition, offsetFromRootBlock, lastLogicalTop, lastLogicalLeft, lastLogicalRight, paintInfo);
    else
        result = blockSelectionGaps(rootBlock, rootBlockPhysicalPosition, offsetFromRootBlock, lastLogicalTop, lastLogicalLeft, lastLogicalRight, paintInfo);

    // Go ahead and fill the vertical gap all the way to the bottom of our block if the selection extends past our block.
    if (rootBlock == this && (selectionState() != SelectionBoth && selectionState() != SelectionEnd))
        result.uniteCenter(blockSelectionGap(rootBlock, rootBlockPhysicalPosition, offsetFromRootBlock, lastLogicalTop, lastLogicalLeft, lastLogicalRight,
                                             logicalHeight(), paintInfo));
    return result;
}

GapRects RenderBlock::blockSelectionGaps(RenderBlock* rootBlock, const LayoutPoint& rootBlockPhysicalPosition, const LayoutSize& offsetFromRootBlock,
                                         LayoutUnit& lastLogicalTop, LayoutUnit& lastLogicalLeft, LayoutUnit& lastLogicalRight, const PaintInfo* paintInfo)
{
    GapRects result;

    // Go ahead and jump right to the first block child that contains some selected objects.
    RenderBox* curr;
    for (curr = firstChildBox(); curr && curr->selectionState() == SelectionNone; curr = curr->nextSiblingBox()) { }

    for (bool sawSelectionEnd = false; curr && !sawSelectionEnd; curr = curr->nextSiblingBox()) {
        SelectionState childState = curr->selectionState();
        if (childState == SelectionBoth || childState == SelectionEnd)
            sawSelectionEnd = true;

        if (curr->isFloatingOrOutOfFlowPositioned())
            continue; // We must be a normal flow object in order to even be considered.

        if (curr->isRelPositioned() && curr->hasLayer()) {
            // If the relposition offset is anything other than 0, then treat this just like an absolute positioned element.
            // Just disregard it completely.
            LayoutSize relOffset = curr->layer()->offsetForInFlowPosition();
            if (relOffset.width() || relOffset.height())
                continue;
        }

        bool paintsOwnSelection = curr->shouldPaintSelectionGaps();
        bool fillBlockGaps = paintsOwnSelection || (curr->canBeSelectionLeaf() && childState != SelectionNone);
        if (fillBlockGaps) {
            // We need to fill the vertical gap above this object.
            if (childState == SelectionEnd || childState == SelectionInside)
                // Fill the gap above the object.
                result.uniteCenter(blockSelectionGap(rootBlock, rootBlockPhysicalPosition, offsetFromRootBlock, lastLogicalTop, lastLogicalLeft, lastLogicalRight,
                                                     curr->logicalTop(), paintInfo));

            // Only fill side gaps for objects that paint their own selection if we know for sure the selection is going to extend all the way *past*
            // our object.  We know this if the selection did not end inside our object.
            if (paintsOwnSelection && (childState == SelectionStart || sawSelectionEnd))
                childState = SelectionNone;

            // Fill side gaps on this object based off its state.
            bool leftGap, rightGap;
            getSelectionGapInfo(childState, leftGap, rightGap);

            if (leftGap)
                result.uniteLeft(logicalLeftSelectionGap(rootBlock, rootBlockPhysicalPosition, offsetFromRootBlock, this, curr->logicalLeft(), curr->logicalTop(), curr->logicalHeight(), paintInfo));
            if (rightGap)
                result.uniteRight(logicalRightSelectionGap(rootBlock, rootBlockPhysicalPosition, offsetFromRootBlock, this, curr->logicalRight(), curr->logicalTop(), curr->logicalHeight(), paintInfo));

            // Update lastLogicalTop to be just underneath the object.  lastLogicalLeft and lastLogicalRight extend as far as
            // they can without bumping into floating or positioned objects.  Ideally they will go right up
            // to the border of the root selection block.
            lastLogicalTop = rootBlock->blockDirectionOffset(offsetFromRootBlock) + curr->logicalBottom();
            lastLogicalLeft = logicalLeftSelectionOffset(rootBlock, curr->logicalBottom());
            lastLogicalRight = logicalRightSelectionOffset(rootBlock, curr->logicalBottom());
        } else if (childState != SelectionNone)
            // We must be a block that has some selected object inside it.  Go ahead and recur.
            result.unite(toRenderBlock(curr)->selectionGaps(rootBlock, rootBlockPhysicalPosition, LayoutSize(offsetFromRootBlock.width() + curr->x(), offsetFromRootBlock.height() + curr->y()),
                                                            lastLogicalTop, lastLogicalLeft, lastLogicalRight, paintInfo));
    }
    return result;
}

IntRect alignSelectionRectToDevicePixels(LayoutRect& rect)
{
    LayoutUnit roundedX = rect.x().round();
    return IntRect(roundedX, rect.y().round(),
        (rect.maxX() - roundedX).round(),
        snapSizeToPixel(rect.height(), rect.y()));
}

LayoutRect RenderBlock::blockSelectionGap(RenderBlock* rootBlock, const LayoutPoint& rootBlockPhysicalPosition, const LayoutSize& offsetFromRootBlock,
                                          LayoutUnit lastLogicalTop, LayoutUnit lastLogicalLeft, LayoutUnit lastLogicalRight, LayoutUnit logicalBottom, const PaintInfo* paintInfo)
{
    LayoutUnit logicalTop = lastLogicalTop;
    LayoutUnit logicalHeight = rootBlock->blockDirectionOffset(offsetFromRootBlock) + logicalBottom - logicalTop;
    if (logicalHeight <= 0)
        return LayoutRect();

    // Get the selection offsets for the bottom of the gap
    LayoutUnit logicalLeft = std::max(lastLogicalLeft, logicalLeftSelectionOffset(rootBlock, logicalBottom));
    LayoutUnit logicalRight = std::min(lastLogicalRight, logicalRightSelectionOffset(rootBlock, logicalBottom));
    LayoutUnit logicalWidth = logicalRight - logicalLeft;
    if (logicalWidth <= 0)
        return LayoutRect();

    LayoutRect gapRect = rootBlock->logicalRectToPhysicalRect(rootBlockPhysicalPosition, LayoutRect(logicalLeft, logicalTop, logicalWidth, logicalHeight));
    if (paintInfo)
        paintInfo->context->fillRect(alignSelectionRectToDevicePixels(gapRect), selectionBackgroundColor());
    return gapRect;
}

LayoutRect RenderBlock::logicalLeftSelectionGap(RenderBlock* rootBlock, const LayoutPoint& rootBlockPhysicalPosition, const LayoutSize& offsetFromRootBlock,
                                                RenderObject* selObj, LayoutUnit logicalLeft, LayoutUnit logicalTop, LayoutUnit logicalHeight, const PaintInfo* paintInfo)
{
    LayoutUnit rootBlockLogicalTop = rootBlock->blockDirectionOffset(offsetFromRootBlock) + logicalTop;
    LayoutUnit rootBlockLogicalLeft = std::max(logicalLeftSelectionOffset(rootBlock, logicalTop), logicalLeftSelectionOffset(rootBlock, logicalTop + logicalHeight));
    LayoutUnit rootBlockLogicalRight = std::min(rootBlock->inlineDirectionOffset(offsetFromRootBlock) + logicalLeft, std::min(logicalRightSelectionOffset(rootBlock, logicalTop), logicalRightSelectionOffset(rootBlock, logicalTop + logicalHeight)));
    LayoutUnit rootBlockLogicalWidth = rootBlockLogicalRight - rootBlockLogicalLeft;
    if (rootBlockLogicalWidth <= 0)
        return LayoutRect();

    LayoutRect gapRect = rootBlock->logicalRectToPhysicalRect(rootBlockPhysicalPosition, LayoutRect(rootBlockLogicalLeft, rootBlockLogicalTop, rootBlockLogicalWidth, logicalHeight));
    if (paintInfo)
        paintInfo->context->fillRect(alignSelectionRectToDevicePixels(gapRect), selObj->selectionBackgroundColor());
    return gapRect;
}

LayoutRect RenderBlock::logicalRightSelectionGap(RenderBlock* rootBlock, const LayoutPoint& rootBlockPhysicalPosition, const LayoutSize& offsetFromRootBlock,
                                                 RenderObject* selObj, LayoutUnit logicalRight, LayoutUnit logicalTop, LayoutUnit logicalHeight, const PaintInfo* paintInfo)
{
    LayoutUnit rootBlockLogicalTop = rootBlock->blockDirectionOffset(offsetFromRootBlock) + logicalTop;
    LayoutUnit rootBlockLogicalLeft = std::max(rootBlock->inlineDirectionOffset(offsetFromRootBlock) + logicalRight, max(logicalLeftSelectionOffset(rootBlock, logicalTop), logicalLeftSelectionOffset(rootBlock, logicalTop + logicalHeight)));
    LayoutUnit rootBlockLogicalRight = std::min(logicalRightSelectionOffset(rootBlock, logicalTop), logicalRightSelectionOffset(rootBlock, logicalTop + logicalHeight));
    LayoutUnit rootBlockLogicalWidth = rootBlockLogicalRight - rootBlockLogicalLeft;
    if (rootBlockLogicalWidth <= 0)
        return LayoutRect();

    LayoutRect gapRect = rootBlock->logicalRectToPhysicalRect(rootBlockPhysicalPosition, LayoutRect(rootBlockLogicalLeft, rootBlockLogicalTop, rootBlockLogicalWidth, logicalHeight));
    if (paintInfo)
        paintInfo->context->fillRect(alignSelectionRectToDevicePixels(gapRect), selObj->selectionBackgroundColor());
    return gapRect;
}

void RenderBlock::getSelectionGapInfo(SelectionState state, bool& leftGap, bool& rightGap)
{
    bool ltr = style()->isLeftToRightDirection();
    leftGap = (state == RenderObject::SelectionInside) ||
              (state == RenderObject::SelectionEnd && ltr) ||
              (state == RenderObject::SelectionStart && !ltr);
    rightGap = (state == RenderObject::SelectionInside) ||
               (state == RenderObject::SelectionStart && ltr) ||
               (state == RenderObject::SelectionEnd && !ltr);
}

LayoutUnit RenderBlock::logicalLeftSelectionOffset(RenderBlock* rootBlock, LayoutUnit position)
{
    // The border can potentially be further extended by our containingBlock().
    if (rootBlock != this)
        return containingBlock()->logicalLeftSelectionOffset(rootBlock, position + logicalTop());
    return logicalLeftOffsetForContent();
}

LayoutUnit RenderBlock::logicalRightSelectionOffset(RenderBlock* rootBlock, LayoutUnit position)
{
    // The border can potentially be further extended by our containingBlock().
    if (rootBlock != this)
        return containingBlock()->logicalRightSelectionOffset(rootBlock, position + logicalTop());
    return logicalRightOffsetForContent();
}

RenderBlock* RenderBlock::blockBeforeWithinSelectionRoot(LayoutSize& offset) const
{
    if (isSelectionRoot())
        return 0;

    const RenderObject* object = this;
    RenderObject* sibling;
    do {
        sibling = object->previousSibling();
        while (sibling && (!sibling->isRenderBlock() || toRenderBlock(sibling)->isSelectionRoot()))
            sibling = sibling->previousSibling();

        offset -= LayoutSize(toRenderBlock(object)->logicalLeft(), toRenderBlock(object)->logicalTop());
        object = object->parent();
    } while (!sibling && object && object->isRenderBlock() && !toRenderBlock(object)->isSelectionRoot());

    if (!sibling)
        return 0;

    RenderBlock* beforeBlock = toRenderBlock(sibling);

    offset += LayoutSize(beforeBlock->logicalLeft(), beforeBlock->logicalTop());

    RenderObject* child = beforeBlock->lastChild();
    while (child && child->isRenderBlock()) {
        beforeBlock = toRenderBlock(child);
        offset += LayoutSize(beforeBlock->logicalLeft(), beforeBlock->logicalTop());
        child = beforeBlock->lastChild();
    }
    return beforeBlock;
}

void RenderBlock::setSelectionState(SelectionState state)
{
    RenderBox::setSelectionState(state);

    if (inlineBoxWrapper() && canUpdateSelectionOnRootLineBoxes())
        inlineBoxWrapper()->root().setHasSelectedChildren(state != SelectionNone);
}

void RenderBlock::insertIntoTrackedRendererMaps(RenderBox* descendant, TrackedDescendantsMap*& descendantsMap, TrackedContainerMap*& containerMap)
{
    if (!descendantsMap) {
        descendantsMap = new TrackedDescendantsMap;
        containerMap = new TrackedContainerMap;
    }

    TrackedRendererListHashSet* descendantSet = descendantsMap->get(this);
    if (!descendantSet) {
        descendantSet = new TrackedRendererListHashSet;
        descendantsMap->set(this, adoptPtr(descendantSet));
    }
    bool added = descendantSet->add(descendant).isNewEntry;
    if (!added) {
        ASSERT(containerMap->get(descendant));
        ASSERT(containerMap->get(descendant)->contains(this));
        return;
    }

    HashSet<RenderBlock*>* containerSet = containerMap->get(descendant);
    if (!containerSet) {
        containerSet = new HashSet<RenderBlock*>;
        containerMap->set(descendant, adoptPtr(containerSet));
    }
    ASSERT(!containerSet->contains(this));
    containerSet->add(this);
}

void RenderBlock::removeFromTrackedRendererMaps(RenderBox* descendant, TrackedDescendantsMap*& descendantsMap, TrackedContainerMap*& containerMap)
{
    if (!descendantsMap)
        return;

    OwnPtr<HashSet<RenderBlock*> > containerSet = containerMap->take(descendant);
    if (!containerSet)
        return;

    HashSet<RenderBlock*>::iterator end = containerSet->end();
    for (HashSet<RenderBlock*>::iterator it = containerSet->begin(); it != end; ++it) {
        RenderBlock* container = *it;

        // FIXME: Disabling this assert temporarily until we fix the layout
        // bugs associated with positioned objects not properly cleared from
        // their ancestor chain before being moved. See webkit bug 93766.
        // ASSERT(descendant->isDescendantOf(container));

        TrackedDescendantsMap::iterator descendantsMapIterator = descendantsMap->find(container);
        ASSERT(descendantsMapIterator != descendantsMap->end());
        if (descendantsMapIterator == descendantsMap->end())
            continue;
        TrackedRendererListHashSet* descendantSet = descendantsMapIterator->value.get();
        ASSERT(descendantSet->contains(descendant));
        descendantSet->remove(descendant);
        if (descendantSet->isEmpty())
            descendantsMap->remove(descendantsMapIterator);
    }
}

TrackedRendererListHashSet* RenderBlock::positionedObjects() const
{
    if (gPositionedDescendantsMap)
        return gPositionedDescendantsMap->get(this);
    return 0;
}

void RenderBlock::insertPositionedObject(RenderBox* o)
{
    ASSERT(!isAnonymousBlock());
    insertIntoTrackedRendererMaps(o, gPositionedDescendantsMap, gPositionedContainerMap);
}

void RenderBlock::removePositionedObject(RenderBox* o)
{
    removeFromTrackedRendererMaps(o, gPositionedDescendantsMap, gPositionedContainerMap);
}

void RenderBlock::removePositionedObjects(RenderBlock* o, ContainingBlockState containingBlockState)
{
    TrackedRendererListHashSet* positionedDescendants = positionedObjects();
    if (!positionedDescendants)
        return;

    RenderBox* r;

    TrackedRendererListHashSet::iterator end = positionedDescendants->end();

    Vector<RenderBox*, 16> deadObjects;

    for (TrackedRendererListHashSet::iterator it = positionedDescendants->begin(); it != end; ++it) {
        r = *it;
        if (!o || r->isDescendantOf(o)) {
            if (containingBlockState == NewContainingBlock)
                r->setChildNeedsLayout(MarkOnlyThis);

            // It is parent blocks job to add positioned child to positioned objects list of its containing block
            // Parent layout needs to be invalidated to ensure this happens.
            RenderObject* p = r->parent();
            while (p && !p->isRenderBlock())
                p = p->parent();
            if (p)
                p->setChildNeedsLayout();

            deadObjects.append(r);
        }
    }

    for (unsigned i = 0; i < deadObjects.size(); i++)
        removePositionedObject(deadObjects.at(i));
}

void RenderBlock::addPercentHeightDescendant(RenderBox* descendant)
{
    insertIntoTrackedRendererMaps(descendant, gPercentHeightDescendantsMap, gPercentHeightContainerMap);
}

void RenderBlock::removePercentHeightDescendant(RenderBox* descendant)
{
    removeFromTrackedRendererMaps(descendant, gPercentHeightDescendantsMap, gPercentHeightContainerMap);
}

TrackedRendererListHashSet* RenderBlock::percentHeightDescendants() const
{
    return gPercentHeightDescendantsMap ? gPercentHeightDescendantsMap->get(this) : 0;
}

bool RenderBlock::hasPercentHeightContainerMap()
{
    return gPercentHeightContainerMap;
}

bool RenderBlock::hasPercentHeightDescendant(RenderBox* descendant)
{
    // We don't null check gPercentHeightContainerMap since the caller
    // already ensures this and we need to call this function on every
    // descendant in clearPercentHeightDescendantsFrom().
    ASSERT(gPercentHeightContainerMap);
    return gPercentHeightContainerMap->contains(descendant);
}

void RenderBlock::dirtyForLayoutFromPercentageHeightDescendants(SubtreeLayoutScope& layoutScope)
{
    if (!gPercentHeightDescendantsMap)
        return;

    TrackedRendererListHashSet* descendants = gPercentHeightDescendantsMap->get(this);
    if (!descendants)
        return;

    TrackedRendererListHashSet::iterator end = descendants->end();
    for (TrackedRendererListHashSet::iterator it = descendants->begin(); it != end; ++it) {
        RenderBox* box = *it;
        while (box != this) {
            if (box->normalChildNeedsLayout())
                break;
            layoutScope.setChildNeedsLayout(box);
            box = box->containingBlock();
            ASSERT(box);
            if (!box)
                break;
        }
    }
}

void RenderBlock::removePercentHeightDescendantIfNeeded(RenderBox* descendant)
{
    // We query the map directly, rather than looking at style's
    // logicalHeight()/logicalMinHeight()/logicalMaxHeight() since those
    // can change with writing mode/directional changes.
    if (!hasPercentHeightContainerMap())
        return;

    if (!hasPercentHeightDescendant(descendant))
        return;

    removePercentHeightDescendant(descendant);
}

void RenderBlock::clearPercentHeightDescendantsFrom(RenderBox* parent)
{
    ASSERT(gPercentHeightContainerMap);
    for (RenderObject* curr = parent->slowFirstChild(); curr; curr = curr->nextInPreOrder(parent)) {
        if (!curr->isBox())
            continue;

        RenderBox* box = toRenderBox(curr);
        if (!hasPercentHeightDescendant(box))
            continue;

        removePercentHeightDescendant(box);
    }
}

LayoutUnit RenderBlock::textIndentOffset() const
{
    LayoutUnit cw = 0;
    if (style()->textIndent().isPercent())
        cw = containingBlock()->availableLogicalWidth();
    return minimumValueForLength(style()->textIndent(), cw);
}

bool RenderBlock::nodeAtPoint(const HitTestRequest& request, HitTestResult& result, const HitTestLocation& locationInContainer, const LayoutPoint& accumulatedOffset, HitTestAction hitTestAction)
{
    LayoutPoint adjustedLocation(accumulatedOffset + location());
    LayoutSize localOffset = toLayoutSize(adjustedLocation);

    if (!isRenderView()) {
        // Check if we need to do anything at all.
        // If we have clipping, then we can't have any spillout.
        LayoutRect overflowBox = hasOverflowClip() ? borderBoxRect() : visualOverflowRect();
        overflowBox.moveBy(adjustedLocation);
        if (!locationInContainer.intersects(overflowBox))
            return false;
    }

    if (style()->clipPath()) {
        switch (style()->clipPath()->type()) {
        case ClipPathOperation::SHAPE: {
            ShapeClipPathOperation* clipPath = toShapeClipPathOperation(style()->clipPath());
            // FIXME: handle marginBox etc.
            if (!clipPath->path(borderBoxRect()).contains(locationInContainer.point() - localOffset, clipPath->windRule()))
                return false;
            break;
        }
        case ClipPathOperation::REFERENCE:
            break;
        }
    }

    // If we have clipping, then we can't have any spillout.
    bool useOverflowClip = hasOverflowClip() && !hasSelfPaintingLayer();
    bool checkChildren = !useOverflowClip;
    if (!checkChildren) {
        LayoutRect clipRect = overflowClipRect(adjustedLocation);
        if (style()->hasBorderRadius())
            checkChildren = locationInContainer.intersects(style()->getRoundedBorderFor(clipRect));
        else
            checkChildren = locationInContainer.intersects(clipRect);
    }
    if (checkChildren) {
        if (hitTestContents(request, result, locationInContainer, toLayoutPoint(localOffset), hitTestAction)) {
            updateHitTestResult(result, locationInContainer.point() - localOffset);
            return true;
        }
    }

    // Check if the point is outside radii.
    if (style()->hasBorderRadius()) {
        LayoutRect borderRect = borderBoxRect();
        borderRect.moveBy(adjustedLocation);
        RoundedRect border = style()->getRoundedBorderFor(borderRect);
        if (!locationInContainer.intersects(border))
            return false;
    }

    // Now hit test our background
    if (hitTestAction == HitTestBlockBackground || hitTestAction == HitTestChildBlockBackground) {
        LayoutRect boundsRect(adjustedLocation, size());
        if (visibleToHitTestRequest(request) && locationInContainer.intersects(boundsRect)) {
            updateHitTestResult(result, locationInContainer.point() - localOffset);
            if (!result.addNodeToRectBasedTestResult(node(), request, locationInContainer, boundsRect))
                return true;
        }
    }

    return false;
}

bool RenderBlock::hitTestContents(const HitTestRequest& request, HitTestResult& result, const HitTestLocation& locationInContainer, const LayoutPoint& accumulatedOffset, HitTestAction hitTestAction)
{
    // Hit test our children.
    HitTestAction childHitTest = hitTestAction;
    if (hitTestAction == HitTestChildBlockBackgrounds)
        childHitTest = HitTestChildBlockBackground;
    for (RenderBox* child = lastChildBox(); child; child = child->previousSiblingBox()) {
        if (!child->hasSelfPaintingLayer() && child->nodeAtPoint(request, result, locationInContainer, accumulatedOffset, childHitTest))
            return true;
    }

    return false;
}

Position RenderBlock::positionForBox(InlineBox *box, bool start) const
{
    if (!box)
        return Position();

    if (!box->renderer().node())
        return createLegacyEditingPosition(node(), start ? caretMinOffset() : caretMaxOffset());

    if (!box->isInlineTextBox())
        return createLegacyEditingPosition(box->renderer().node(), start ? box->renderer().caretMinOffset() : box->renderer().caretMaxOffset());

    InlineTextBox* textBox = toInlineTextBox(box);
    return createLegacyEditingPosition(box->renderer().node(), start ? textBox->start() : textBox->start() + textBox->len());
}

static inline bool isEditingBoundary(RenderObject* ancestor, RenderObject* child)
{
    ASSERT(!ancestor || ancestor->node());
    ASSERT(child && child->node());
    return !ancestor || !ancestor->parent() || (ancestor->hasLayer() && ancestor->parent()->isRenderView())
        || ancestor->node()->hasEditableStyle() == child->node()->hasEditableStyle();
}

// FIXME: This function should go on RenderObject as an instance method. Then
// all cases in which positionForPoint recurs could call this instead to
// prevent crossing editable boundaries. This would require many tests.
static PositionWithAffinity positionForPointRespectingEditingBoundaries(RenderBlock* parent, RenderBox* child, const LayoutPoint& pointInParentCoordinates)
{
    LayoutPoint childLocation = child->location();
    if (child->isRelPositioned())
        childLocation += child->offsetForInFlowPosition();

    // FIXME: This is wrong if the child's writing-mode is different from the parent's.
    LayoutPoint pointInChildCoordinates(toLayoutPoint(pointInParentCoordinates - childLocation));

    // If this is an anonymous renderer, we just recur normally
    Node* childNode = child->node();
    if (!childNode)
        return child->positionForPoint(pointInChildCoordinates);

    // Otherwise, first make sure that the editability of the parent and child agree.
    // If they don't agree, then we return a visible position just before or after the child
    RenderObject* ancestor = parent;
    while (ancestor && !ancestor->node())
        ancestor = ancestor->parent();

    // If we can't find an ancestor to check editability on, or editability is unchanged, we recur like normal
    if (isEditingBoundary(ancestor, child))
        return child->positionForPoint(pointInChildCoordinates);

    // Otherwise return before or after the child, depending on if the click was to the logical left or logical right of the child
    LayoutUnit childMiddle = parent->logicalWidthForChild(child) / 2;
    LayoutUnit logicalLeft = pointInChildCoordinates.x();
    if (logicalLeft < childMiddle)
        return ancestor->createPositionWithAffinity(childNode->nodeIndex(), DOWNSTREAM);
    return ancestor->createPositionWithAffinity(childNode->nodeIndex() + 1, UPSTREAM);
}

PositionWithAffinity RenderBlock::positionForPointWithInlineChildren(const LayoutPoint& pointInLogicalContents)
{
    ASSERT(isRenderParagraph());

    if (!firstRootBox())
        return createPositionWithAffinity(0, DOWNSTREAM);

    // look for the closest line box in the root box which is at the passed-in y coordinate
    InlineBox* closestBox = 0;
    RootInlineBox* firstRootBoxWithChildren = 0;
    RootInlineBox* lastRootBoxWithChildren = 0;
    for (RootInlineBox* root = firstRootBox(); root; root = root->nextRootBox()) {
        if (!root->firstLeafChild())
            continue;
        if (!firstRootBoxWithChildren)
            firstRootBoxWithChildren = root;

        if (root->isFirstAfterPageBreak() && (pointInLogicalContents.y() < root->lineTopWithLeading()))
            break;

        lastRootBoxWithChildren = root;

        // check if this root line box is located at this y coordinate
        if (pointInLogicalContents.y() < root->selectionBottom()) {
            closestBox = root->closestLeafChildForLogicalLeftPosition(pointInLogicalContents.x());
            if (closestBox)
                break;
        }
    }

    bool moveCaretToBoundary = document().frame()->editor().behavior().shouldMoveCaretToHorizontalBoundaryWhenPastTopOrBottom();

    if (!moveCaretToBoundary && !closestBox && lastRootBoxWithChildren) {
        // y coordinate is below last root line box, pretend we hit it
        closestBox = lastRootBoxWithChildren->closestLeafChildForLogicalLeftPosition(pointInLogicalContents.x());
    }

    if (closestBox) {
        if (moveCaretToBoundary) {
            LayoutUnit firstRootBoxWithChildrenTop = std::min<LayoutUnit>(firstRootBoxWithChildren->selectionTop(), firstRootBoxWithChildren->logicalTop());
            if (pointInLogicalContents.y() < firstRootBoxWithChildrenTop) {
                InlineBox* box = firstRootBoxWithChildren->firstLeafChild();
                if (box->isLineBreak()) {
                    if (InlineBox* newBox = box->nextLeafChildIgnoringLineBreak())
                        box = newBox;
                }
                // y coordinate is above first root line box, so return the start of the first
                return PositionWithAffinity(positionForBox(box, true), DOWNSTREAM);
            }
        }

        // pass the box a top position that is inside it
        LayoutPoint point(pointInLogicalContents.x(), closestBox->root().blockDirectionPointInLine());
        if (closestBox->renderer().isReplaced())
            return positionForPointRespectingEditingBoundaries(this, &toRenderBox(closestBox->renderer()), point);
        return closestBox->renderer().positionForPoint(point);
    }

    if (lastRootBoxWithChildren) {
        // We hit this case for Mac behavior when the Y coordinate is below the last box.
        ASSERT(moveCaretToBoundary);
        InlineBox* logicallyLastBox;
        if (lastRootBoxWithChildren->getLogicalEndBoxWithNode(logicallyLastBox))
            return PositionWithAffinity(positionForBox(logicallyLastBox, false), DOWNSTREAM);
    }

    // Can't reach this. We have a root line box, but it has no kids.
    // FIXME: This should ASSERT_NOT_REACHED(), but clicking on placeholder text
    // seems to hit this code path.
    return createPositionWithAffinity(0, DOWNSTREAM);
}

static inline bool isChildHitTestCandidate(RenderBox* box)
{
    return box->height() && !box->isFloatingOrOutOfFlowPositioned();
}

PositionWithAffinity RenderBlock::positionForPoint(const LayoutPoint& point)
{
    if (isReplaced()) {
        // FIXME: This seems wrong when the object's writing-mode doesn't match the line's writing-mode.
        LayoutUnit pointLogicalLeft = point.x();
        LayoutUnit pointLogicalTop = point.y();

        if (pointLogicalLeft < 0)
            return createPositionWithAffinity(caretMinOffset(), DOWNSTREAM);
        if (pointLogicalLeft >= logicalWidth())
            return createPositionWithAffinity(caretMaxOffset(), DOWNSTREAM);
        if (pointLogicalTop < 0)
            return createPositionWithAffinity(caretMinOffset(), DOWNSTREAM);
        if (pointLogicalTop >= logicalHeight())
            return createPositionWithAffinity(caretMaxOffset(), DOWNSTREAM);
    }

    LayoutPoint pointInContents = point;
    LayoutPoint pointInLogicalContents(pointInContents);

    if (isRenderParagraph())
        return positionForPointWithInlineChildren(pointInLogicalContents);

    RenderBox* lastCandidateBox = lastChildBox();
    while (lastCandidateBox && !isChildHitTestCandidate(lastCandidateBox))
        lastCandidateBox = lastCandidateBox->previousSiblingBox();

    if (lastCandidateBox) {
        if (pointInLogicalContents.y() > logicalTopForChild(lastCandidateBox)
            || (pointInLogicalContents.y() == logicalTopForChild(lastCandidateBox)))
            return positionForPointRespectingEditingBoundaries(this, lastCandidateBox, pointInContents);

        for (RenderBox* childBox = firstChildBox(); childBox; childBox = childBox->nextSiblingBox()) {
            if (!isChildHitTestCandidate(childBox))
                continue;
            LayoutUnit childLogicalBottom = logicalTopForChild(childBox) + logicalHeightForChild(childBox);
            // We hit child if our click is above the bottom of its padding box (like IE6/7 and FF3).
            if (isChildHitTestCandidate(childBox) && (pointInLogicalContents.y() < childLogicalBottom))
                return positionForPointRespectingEditingBoundaries(this, childBox, pointInContents);
        }
    }

    // We only get here if there are no hit test candidate children below the click.
    return RenderBox::positionForPoint(point);
}

LayoutUnit RenderBlock::availableLogicalWidth() const
{
    return RenderBox::availableLogicalWidth();
}

void RenderBlock::computePreferredLogicalWidths()
{
    ASSERT(preferredLogicalWidthsDirty());

    m_minPreferredLogicalWidth = 0;
    m_maxPreferredLogicalWidth = 0;

    // FIXME: The isFixed() calls here should probably be checking for isSpecified since you
    // should be able to use percentage, calc or viewport relative values for width.
    RenderStyle* styleToUse = style();
    if (styleToUse->logicalWidth().isFixed() && styleToUse->logicalWidth().value() >= 0)
        m_minPreferredLogicalWidth = m_maxPreferredLogicalWidth = adjustContentBoxLogicalWidthForBoxSizing(styleToUse->logicalWidth().value());
    else
        computeIntrinsicLogicalWidths(m_minPreferredLogicalWidth, m_maxPreferredLogicalWidth);

    if (styleToUse->logicalMinWidth().isFixed() && styleToUse->logicalMinWidth().value() > 0) {
        m_maxPreferredLogicalWidth = std::max(m_maxPreferredLogicalWidth, adjustContentBoxLogicalWidthForBoxSizing(styleToUse->logicalMinWidth().value()));
        m_minPreferredLogicalWidth = std::max(m_minPreferredLogicalWidth, adjustContentBoxLogicalWidthForBoxSizing(styleToUse->logicalMinWidth().value()));
    }

    if (styleToUse->logicalMaxWidth().isFixed()) {
        m_maxPreferredLogicalWidth = std::min(m_maxPreferredLogicalWidth, adjustContentBoxLogicalWidthForBoxSizing(styleToUse->logicalMaxWidth().value()));
        m_minPreferredLogicalWidth = std::min(m_minPreferredLogicalWidth, adjustContentBoxLogicalWidthForBoxSizing(styleToUse->logicalMaxWidth().value()));
    }

    LayoutUnit borderAndPadding = borderAndPaddingLogicalWidth();
    m_minPreferredLogicalWidth += borderAndPadding;
    m_maxPreferredLogicalWidth += borderAndPadding;

    clearPreferredLogicalWidthsDirty();
}

void RenderBlock::computeIntrinsicLogicalWidths(LayoutUnit& minLogicalWidth, LayoutUnit& maxLogicalWidth) const
{
    RenderStyle* styleToUse = style();
    bool nowrap = styleToUse->whiteSpace() == NOWRAP;

    RenderObject* child = firstChild();
    while (child) {
        // Positioned children don't affect the min/max width
        if (child->isOutOfFlowPositioned()) {
            child = child->nextSibling();
            continue;
        }

        RefPtr<RenderStyle> childStyle = child->style();

        // A margin basically has three types: fixed, percentage, and auto (variable).
        // Auto and percentage margins simply become 0 when computing min/max width.
        // Fixed margins can be added in as is.
        Length startMarginLength = childStyle->marginStartUsing(styleToUse);
        Length endMarginLength = childStyle->marginEndUsing(styleToUse);
        LayoutUnit margin = 0;
        LayoutUnit marginStart = 0;
        LayoutUnit marginEnd = 0;
        if (startMarginLength.isFixed())
            marginStart += startMarginLength.value();
        if (endMarginLength.isFixed())
            marginEnd += endMarginLength.value();
        margin = marginStart + marginEnd;

        LayoutUnit childMinPreferredLogicalWidth = child->minPreferredLogicalWidth();
        LayoutUnit childMaxPreferredLogicalWidth = child->maxPreferredLogicalWidth();

        LayoutUnit w = childMinPreferredLogicalWidth + margin;
        minLogicalWidth = std::max(w, minLogicalWidth);

        // IE ignores tables for calculation of nowrap. Makes some sense.
        if (nowrap)
            maxLogicalWidth = std::max(w, maxLogicalWidth);

        w = childMaxPreferredLogicalWidth + margin;

        maxLogicalWidth = std::max(w, maxLogicalWidth);

        child = child->nextSibling();
    }

    // Always make sure these values are non-negative.
    minLogicalWidth = std::max<LayoutUnit>(0, minLogicalWidth);
    maxLogicalWidth = std::max<LayoutUnit>(minLogicalWidth, maxLogicalWidth);
}

bool RenderBlock::hasLineIfEmpty() const
{
    return node() && node()->isRootEditableElement();
}

LayoutUnit RenderBlock::lineHeight(bool firstLine, LineDirectionMode direction, LinePositionMode linePositionMode) const
{
    // Inline blocks are replaced elements. Otherwise, just pass off to
    // the base class.  If we're being queried as though we're the root line
    // box, then the fact that we're an inline-block is irrelevant, and we behave
    // just like a block.
    if (isReplaced() && linePositionMode == PositionOnContainingLine)
        return RenderBox::lineHeight(firstLine, direction, linePositionMode);
    return style()->computedLineHeight();
}

int RenderBlock::beforeMarginInLineDirection(LineDirectionMode direction) const
{
    return direction == HorizontalLine ? marginTop() : marginRight();
}

int RenderBlock::baselinePosition(FontBaseline baselineType, bool firstLine, LineDirectionMode direction, LinePositionMode linePositionMode) const
{
    // Inline blocks are replaced elements. Otherwise, just pass off to
    // the base class.  If we're being queried as though we're the root line
    // box, then the fact that we're an inline-block is irrelevant, and we behave
    // just like a block.
    if (isInline() && linePositionMode == PositionOnContainingLine) {
        // CSS2.1 states that the baseline of an inline block is the baseline of the last line box in
        // the normal flow.  We make an exception for marquees, since their baselines are meaningless
        // (the content inside them moves).  This matches WinIE as well, which just bottom-aligns them.
        // We also give up on finding a baseline if we have a vertical scrollbar, or if we are scrolled
        // vertically (e.g., an overflow:hidden block that has had scrollTop moved).
        int baselinePos = inlineBlockBaseline(direction);
        if (baselinePos != -1)
            return beforeMarginInLineDirection(direction) + baselinePos;

        return RenderBox::baselinePosition(baselineType, firstLine, direction, linePositionMode);
    }

    // If we're not replaced, we'll only get called with PositionOfInteriorLineBoxes.
    // Note that inline-block counts as replaced here.
    ASSERT(linePositionMode == PositionOfInteriorLineBoxes);

    const FontMetrics& fontMetrics = style(firstLine)->fontMetrics();
    return fontMetrics.ascent(baselineType) + (lineHeight(firstLine, direction, linePositionMode) - fontMetrics.height()) / 2;
}

LayoutUnit RenderBlock::minLineHeightForReplacedRenderer(bool isFirstLine, LayoutUnit replacedHeight) const
{
    if (!(style(isFirstLine)->lineBoxContain() & LineBoxContainBlock))
        return 0;

    return std::max<LayoutUnit>(replacedHeight, lineHeight(isFirstLine, HorizontalLine, PositionOfInteriorLineBoxes));
}

int RenderBlock::firstLineBoxBaseline() const
{
    for (RenderBox* curr = firstChildBox(); curr; curr = curr->nextSiblingBox()) {
        if (!curr->isFloatingOrOutOfFlowPositioned()) {
            int result = curr->firstLineBoxBaseline();
            if (result != -1)
                return curr->logicalTop() + result; // Translate to our coordinate space.
        }
    }

    return -1;
}

int RenderBlock::inlineBlockBaseline(LineDirectionMode direction) const
{
    if (!style()->isOverflowVisible()) {
        // We are not calling RenderBox::baselinePosition here because the caller should add the margin-top/margin-right, not us.
        return direction == HorizontalLine ? height() + m_marginBox.bottom() : width() + m_marginBox.left();
    }

    return lastLineBoxBaseline(direction);
}

int RenderBlock::lastLineBoxBaseline(LineDirectionMode lineDirection) const
{
    bool haveNormalFlowChild = false;
    for (RenderBox* curr = lastChildBox(); curr; curr = curr->previousSiblingBox()) {
        if (!curr->isFloatingOrOutOfFlowPositioned()) {
            haveNormalFlowChild = true;
            int result = curr->inlineBlockBaseline(lineDirection);
            if (result != -1)
                return curr->logicalTop() + result; // Translate to our coordinate space.
        }
    }
    if (!haveNormalFlowChild && hasLineIfEmpty()) {
        const FontMetrics& fontMetrics = firstLineStyle()->fontMetrics();
        return fontMetrics.ascent()
             + (lineHeight(true, lineDirection, PositionOfInteriorLineBoxes) - fontMetrics.height()) / 2
             + (lineDirection == HorizontalLine ? borderTop() + paddingTop() : borderRight() + paddingRight());
    }

    return -1;
}

RenderBlock* RenderBlock::firstLineBlock() const
{
    RenderBlock* firstLineBlock = const_cast<RenderBlock*>(this);
    bool hasPseudo = false;
    while (true) {
        // FIXME(sky): Remove all this.
        hasPseudo = false;
        if (hasPseudo)
            break;
        RenderObject* parentBlock = firstLineBlock->parent();
        if (firstLineBlock->isReplaced()
            || !parentBlock
            || !parentBlock->isRenderBlockFlow())
            break;
        ASSERT_WITH_SECURITY_IMPLICATION(parentBlock->isRenderBlock());
        if (toRenderBlock(parentBlock)->firstChild() != firstLineBlock)
            break;
        firstLineBlock = toRenderBlock(parentBlock);
    }

    if (!hasPseudo)
        return 0;

    return firstLineBlock;
}

// Helper methods for obtaining the last line, computing line counts and heights for line counts
// (crawling into blocks).
static bool shouldCheckLines(RenderObject* obj)
{
    return !obj->isFloatingOrOutOfFlowPositioned()
        && obj->isRenderBlock() && obj->style()->height().isAuto();
}

static int getHeightForLineCount(RenderBlock* block, int l, bool includeBottom, int& count)
{
    RenderBox* normalFlowChildWithoutLines = 0;
    for (RenderBox* obj = block->firstChildBox(); obj; obj = obj->nextSiblingBox()) {
        if (shouldCheckLines(obj)) {
            int result = getHeightForLineCount(toRenderBlock(obj), l, false, count);
            if (result != -1)
                return result + obj->y() + (includeBottom ? (block->borderBottom() + block->paddingBottom()) : LayoutUnit());
        } else if (!obj->isFloatingOrOutOfFlowPositioned()) {
            normalFlowChildWithoutLines = obj;
        }
    }
    if (normalFlowChildWithoutLines && l == 0)
        return normalFlowChildWithoutLines->y() + normalFlowChildWithoutLines->height();

    return -1;
}

RootInlineBox* RenderBlock::lineAtIndex(int i) const
{
    ASSERT(i >= 0);

    for (RenderObject* child = firstChild(); child; child = child->nextSibling()) {
        if (!shouldCheckLines(child))
            continue;
        if (RootInlineBox* box = toRenderBlock(child)->lineAtIndex(i))
            return box;
    }

    return 0;
}

int RenderBlock::lineCount(const RootInlineBox* stopRootInlineBox, bool* found) const
{
    int count = 0;
    for (RenderObject* obj = firstChild(); obj; obj = obj->nextSibling()) {
        if (shouldCheckLines(obj)) {
            bool recursiveFound = false;
            count += toRenderBlock(obj)->lineCount(stopRootInlineBox, &recursiveFound);
            if (recursiveFound) {
                if (found)
                    *found = true;
                break;
            }
        }
    }

    return count;
}

void RenderBlock::clearTruncation()
{
    for (RenderObject* obj = firstChild(); obj; obj = obj->nextSibling()) {
        if (shouldCheckLines(obj))
            toRenderBlock(obj)->clearTruncation();
    }
}

void RenderBlock::absoluteQuads(Vector<FloatQuad>& quads) const
{
    quads.append(RenderBox::localToAbsoluteQuad(FloatRect(0, 0, width().toFloat(), height().toFloat()), 0 /* mode */));
}

void RenderBlock::updateHitTestResult(HitTestResult& result, const LayoutPoint& point)
{
    if (result.innerNode())
        return;

    if (Node* n = node()) {
        result.setInnerNode(n);
        if (!result.innerNonSharedNode())
            result.setInnerNonSharedNode(n);
        result.setLocalPoint(point);
    }
}

LayoutRect RenderBlock::localCaretRect(InlineBox* inlineBox, int caretOffset, LayoutUnit* extraWidthToEndOfLine)
{
    // Do the normal calculation in most cases.
    if (firstChild())
        return RenderBox::localCaretRect(inlineBox, caretOffset, extraWidthToEndOfLine);

    LayoutRect caretRect = localCaretRectForEmptyElement(width(), textIndentOffset());

    if (extraWidthToEndOfLine)
        *extraWidthToEndOfLine = width() - caretRect.maxX();

    return caretRect;
}

void RenderBlock::addFocusRingRects(Vector<IntRect>& rects, const LayoutPoint& additionalOffset, const RenderLayerModelObject* paintContainer) const
{
    if (width() && height())
        rects.append(pixelSnappedIntRect(additionalOffset, size()));

    if (!hasOverflowClip()) {
        for (RootInlineBox* curr = firstRootBox(); curr; curr = curr->nextRootBox()) {
            LayoutUnit top = std::max<LayoutUnit>(curr->lineTop(), curr->top());
            LayoutUnit bottom = std::min<LayoutUnit>(curr->lineBottom(), curr->top() + curr->height());
            LayoutRect rect(additionalOffset.x() + curr->x(), additionalOffset.y() + top, curr->width(), bottom - top);
            if (!rect.isEmpty())
                rects.append(pixelSnappedIntRect(rect));
        }

        addChildFocusRingRects(rects, additionalOffset, paintContainer);
    }
}

LayoutUnit RenderBlock::marginBeforeForChild(const RenderBox* child) const
{
    // FIXME(sky): Remove
    return child->marginBefore();
}

LayoutUnit RenderBlock::marginAfterForChild(const  RenderBox* child) const
{
    // FIXME(sky): Remove
    return child->marginAfter();
}

bool RenderBlock::hasMarginBeforeQuirk(const RenderBox* child) const
{
    return child->isRenderBlock() ? toRenderBlock(child)->hasMarginBeforeQuirk() : child->style()->hasMarginBeforeQuirk();
}

bool RenderBlock::hasMarginAfterQuirk(const RenderBox* child) const
{
    return child->isRenderBlock() ? toRenderBlock(child)->hasMarginAfterQuirk() : child->style()->hasMarginAfterQuirk();
}

const char* RenderBlock::renderName() const
{
    if (isInlineBlock())
        return "RenderBlock (inline-block)";
    if (isOutOfFlowPositioned())
        return "RenderBlock (positioned)";
    if (isAnonymousBlock())
        return "RenderBlock (anonymous)";
    if (isAnonymous())
        return "RenderBlock (generated)";
    if (isRelPositioned())
        return "RenderBlock (relative positioned)";
    return "RenderBlock";
}

// FIXME(sky): Clean up callers now that we no longer use the EDisplay argument.
RenderBlock* RenderBlock::createAnonymousWithParentRendererAndDisplay(const RenderObject* parent, EDisplay)
{
    RenderBlock* newBox = RenderParagraph::createAnonymous(parent->document());
    RefPtr<RenderStyle> newStyle = RenderStyle::createAnonymousStyleWithDisplay(parent->style(), PARAGRAPH);
    parent->updateAnonymousChildStyle(newBox, newStyle.get());
    newBox->setStyle(newStyle.release());
    return newBox;
}

static bool recalcNormalFlowChildOverflowIfNeeded(RenderObject* renderer)
{
    if (renderer->isOutOfFlowPositioned() || !renderer->needsOverflowRecalcAfterStyleChange())
        return false;

    ASSERT(renderer->isRenderBlock());
    return toRenderBlock(renderer)->recalcOverflowAfterStyleChange();
}

bool RenderBlock::recalcChildOverflowAfterStyleChange()
{
    ASSERT(childNeedsOverflowRecalcAfterStyleChange());
    setChildNeedsOverflowRecalcAfterStyleChange(false);

    bool childrenOverflowChanged = false;

    if (isRenderParagraph()) {
        ListHashSet<RootInlineBox*> lineBoxes;
        for (InlineWalker walker(this); !walker.atEnd(); walker.advance()) {
            RenderObject* renderer = walker.current();
            if (recalcNormalFlowChildOverflowIfNeeded(renderer)) {
                childrenOverflowChanged = true;
                if (InlineBox* inlineBoxWrapper = toRenderBlock(renderer)->inlineBoxWrapper())
                    lineBoxes.add(&inlineBoxWrapper->root());
            }
        }

        // FIXME: Glyph overflow will get lost in this case, but not really a big deal.
        GlyphOverflowAndFallbackFontsMap textBoxDataMap;
        for (ListHashSet<RootInlineBox*>::const_iterator it = lineBoxes.begin(); it != lineBoxes.end(); ++it) {
            RootInlineBox* box = *it;
            box->computeOverflow(box->lineTop(), box->lineBottom(), textBoxDataMap);
        }
    } else {
        for (RenderBox* box = firstChildBox(); box; box = box->nextSiblingBox()) {
            if (recalcNormalFlowChildOverflowIfNeeded(box))
                childrenOverflowChanged = true;
        }
    }

    TrackedRendererListHashSet* positionedDescendants = positionedObjects();
    if (!positionedDescendants)
        return childrenOverflowChanged;

    TrackedRendererListHashSet::iterator end = positionedDescendants->end();
    for (TrackedRendererListHashSet::iterator it = positionedDescendants->begin(); it != end; ++it) {
        RenderBox* box = *it;

        if (!box->needsOverflowRecalcAfterStyleChange())
            continue;
        RenderBlock* block = toRenderBlock(box);
        if (!block->recalcOverflowAfterStyleChange())
            continue;

        childrenOverflowChanged = true;
    }
    return childrenOverflowChanged;
}

bool RenderBlock::recalcOverflowAfterStyleChange()
{
    ASSERT(needsOverflowRecalcAfterStyleChange());

    bool childrenOverflowChanged = false;
    if (childNeedsOverflowRecalcAfterStyleChange())
        childrenOverflowChanged = recalcChildOverflowAfterStyleChange();

    if (!selfNeedsOverflowRecalcAfterStyleChange() && !childrenOverflowChanged)
        return false;

    setSelfNeedsOverflowRecalcAfterStyleChange(false);
    // If the current block needs layout, overflow will be recalculated during
    // layout time anyway. We can safely exit here.
    if (needsLayout())
        return false;

    LayoutUnit oldClientAfterEdge = hasRenderOverflow() ? m_overflow->layoutClientAfterEdge() : clientLogicalBottom();
    computeOverflow(oldClientAfterEdge, true);

    return !hasOverflowClip();
}

#if ENABLE(ASSERT)
void RenderBlock::checkPositionedObjectsNeedLayout()
{
    if (!gPositionedDescendantsMap)
        return;

    if (TrackedRendererListHashSet* positionedDescendantSet = positionedObjects()) {
        TrackedRendererListHashSet::const_iterator end = positionedDescendantSet->end();
        for (TrackedRendererListHashSet::const_iterator it = positionedDescendantSet->begin(); it != end; ++it) {
            RenderBox* currBox = *it;
            ASSERT(!currBox->needsLayout());
        }
    }
}

#endif

#ifndef NDEBUG

void RenderBlock::showLineTreeAndMark(const InlineBox* markedBox1, const char* markedLabel1, const InlineBox* markedBox2, const char* markedLabel2, const RenderObject* obj) const
{
    showRenderObject();
    for (const RootInlineBox* root = firstRootBox(); root; root = root->nextRootBox())
        root->showLineTreeAndMark(markedBox1, markedLabel1, markedBox2, markedLabel2, obj, 1);
}

#endif

} // namespace blink