root/Source/core/rendering/RenderFlowThread.cpp

DEFINITIONS

1. m_pageLogicalSizeChanged
2. createFlowThreadStyle
3. addRegionToThread
4. removeRegionFromThread
5. invalidateRegions
6. m_renderFlowThread
7. validateRegions
8. layout
9. updateLogicalWidth
10. computeLogicalHeight
11. computeRegionClippingRect
12. nodeAtPoint
13. shouldRepaint
14. repaintRectangleInRegions
15. regionAtBlockOffset
16. regionFromAbsolutePointAndBox
17. adjustedPositionRelativeToOffsetParent
18. pageLogicalTopForOffset
19. pageLogicalWidthForOffset
20. pageLogicalHeightForOffset
21. pageRemainingLogicalHeightForOffset
22. mapFromFlowToRegion
23. firstRegion
24. lastRegion
25. setRegionRangeForBox
26. getRegionRangeForBox
27. applyBreakAfterContent
28. regionInRange
29. updateRegionsFlowThreadPortionRect
30. collectLayerFragments
31. fragmentsBoundingBox
32. cachedOffsetFromLogicalTopOfFirstRegion
33. setOffsetFromLogicalTopOfFirstRegion
34. clearOffsetFromLogicalTopOfFirstRegion
35. currentStatePusherRenderBox
36. pushFlowThreadLayoutState
37. popFlowThreadLayoutState
38. offsetFromLogicalTopOfFirstRegion
39. collectIfNeeded
40. mapLocalToContainer
41. m_previousRenderFlowThread

/*
 * Copyright (C) 2011 Adobe Systems Incorporated. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above
 *    copyright notice, this list of conditions and the following
 *    disclaimer.
 * 2. Redistributions in binary form must reproduce the above
 *    copyright notice, this list of conditions and the following
 *    disclaimer in the documentation and/or other materials
 *    provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER "AS IS" AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
 * OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
 * TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
 * THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include "config.h"

#include "core/rendering/RenderFlowThread.h"

#include "core/dom/Node.h"
#include "core/rendering/FlowThreadController.h"
#include "core/rendering/HitTestRequest.h"
#include "core/rendering/HitTestResult.h"
#include "core/rendering/LayoutRectRecorder.h"
#include "core/rendering/PaintInfo.h"
#include "core/rendering/RenderInline.h"
#include "core/rendering/RenderLayer.h"
#include "core/rendering/RenderRegion.h"
#include "core/rendering/RenderView.h"
#include "platform/PODIntervalTree.h"
#include "platform/geometry/TransformState.h"

namespace WebCore {

RenderFlowThread::RenderFlowThread()
    : RenderBlockFlow(0)
    , m_previousRegionCount(0)
    , m_regionsInvalidated(false)
    , m_regionsHaveUniformLogicalHeight(true)
    , m_pageLogicalSizeChanged(false)
{
    setFlowThreadState(InsideOutOfFlowThread);
}

PassRefPtr<RenderStyle> RenderFlowThread::createFlowThreadStyle(RenderStyle* parentStyle)
{
    RefPtr<RenderStyle> newStyle(RenderStyle::create());
    newStyle->inheritFrom(parentStyle);
    newStyle->setDisplay(BLOCK);
    newStyle->setPosition(AbsolutePosition);
    newStyle->setZIndex(0);
    newStyle->setLeft(Length(0, Fixed));
    newStyle->setTop(Length(0, Fixed));
    newStyle->setWidth(Length(100, Percent));
    newStyle->setHeight(Length(100, Percent));
    newStyle->font().update(nullptr);

    return newStyle.release();
}

void RenderFlowThread::addRegionToThread(RenderRegion* renderRegion)
{
    ASSERT(renderRegion);
    m_regionList.add(renderRegion);
    renderRegion->setIsValid(true);
}

void RenderFlowThread::removeRegionFromThread(RenderRegion* renderRegion)
{
    ASSERT(renderRegion);
    m_regionList.remove(renderRegion);
}

void RenderFlowThread::invalidateRegions()
{
    if (m_regionsInvalidated) {
        ASSERT(selfNeedsLayout());
        return;
    }

    m_regionRangeMap.clear();
    setNeedsLayout();

    m_regionsInvalidated = true;
}

class CurrentRenderFlowThreadDisabler {
    WTF_MAKE_NONCOPYABLE(CurrentRenderFlowThreadDisabler);
public:
    CurrentRenderFlowThreadDisabler(RenderView* view)
        : m_view(view)
        , m_renderFlowThread(0)
    {
        m_renderFlowThread = m_view->flowThreadController()->currentRenderFlowThread();
        if (m_renderFlowThread)
            view->flowThreadController()->setCurrentRenderFlowThread(0);
    }
    ~CurrentRenderFlowThreadDisabler()
    {
        if (m_renderFlowThread)
            m_view->flowThreadController()->setCurrentRenderFlowThread(m_renderFlowThread);
    }
private:
    RenderView* m_view;
    RenderFlowThread* m_renderFlowThread;
};

void RenderFlowThread::validateRegions()
{
    if (m_regionsInvalidated) {
        m_regionsInvalidated = false;
        m_regionsHaveUniformLogicalHeight = true;

        if (hasRegions()) {
            LayoutUnit previousRegionLogicalHeight = 0;
            bool firstRegionVisited = false;

            for (RenderRegionList::iterator iter = m_regionList.begin(); iter != m_regionList.end(); ++iter) {
                RenderRegion* region = *iter;
                LayoutUnit regionLogicalHeight = region->pageLogicalHeight();

                if (!firstRegionVisited) {
                    firstRegionVisited = true;
                } else {
                    if (m_regionsHaveUniformLogicalHeight && previousRegionLogicalHeight != regionLogicalHeight)
                        m_regionsHaveUniformLogicalHeight = false;
                }

                previousRegionLogicalHeight = regionLogicalHeight;
            }
        }
    }

    updateLogicalWidth(); // Called to get the maximum logical width for the region.
    updateRegionsFlowThreadPortionRect();
}

void RenderFlowThread::layout()
{
    LayoutRectRecorder recorder(*this);
    m_pageLogicalSizeChanged = m_regionsInvalidated && everHadLayout();

    validateRegions();

    CurrentRenderFlowThreadMaintainer currentFlowThreadSetter(this);
    RenderBlockFlow::layout();

    m_pageLogicalSizeChanged = false;

    if (lastRegion())
        lastRegion()->expandToEncompassFlowThreadContentsIfNeeded();
}

void RenderFlowThread::updateLogicalWidth()
{
    setLogicalWidth(initialLogicalWidth());
}

void RenderFlowThread::computeLogicalHeight(LayoutUnit, LayoutUnit logicalTop, LogicalExtentComputedValues& computedValues) const
{
    computedValues.m_position = logicalTop;
    computedValues.m_extent = 0;

    for (RenderRegionList::const_iterator iter = m_regionList.begin(); iter != m_regionList.end(); ++iter) {
        RenderRegion* region = *iter;
        computedValues.m_extent += region->logicalHeightOfAllFlowThreadContent();
    }
}

LayoutRect RenderFlowThread::computeRegionClippingRect(const LayoutPoint& offset, const LayoutRect& flowThreadPortionRect, const LayoutRect& flowThreadPortionOverflowRect) const
{
    LayoutRect regionClippingRect(offset + (flowThreadPortionOverflowRect.location() - flowThreadPortionRect.location()), flowThreadPortionOverflowRect.size());
    if (style()->isFlippedBlocksWritingMode())
        regionClippingRect.move(flowThreadPortionRect.size() - flowThreadPortionOverflowRect.size());
    return regionClippingRect;
}

bool RenderFlowThread::nodeAtPoint(const HitTestRequest& request, HitTestResult& result, const HitTestLocation& locationInContainer, const LayoutPoint& accumulatedOffset, HitTestAction hitTestAction)
{
    if (hitTestAction == HitTestBlockBackground)
        return false;
    return RenderBlockFlow::nodeAtPoint(request, result, locationInContainer, accumulatedOffset, hitTestAction);
}

bool RenderFlowThread::shouldRepaint(const LayoutRect& r) const
{
    if (view()->document().printing() || r.isEmpty())
        return false;

    return true;
}

void RenderFlowThread::repaintRectangleInRegions(const LayoutRect& repaintRect) const
{
    if (!shouldRepaint(repaintRect) || !hasValidRegionInfo())
        return;

    LayoutStateDisabler layoutStateDisabler(*this); // We can't use layout state to repaint, since the regions are somewhere else.

    // We can't use currentFlowThread as it is possible to have interleaved flow threads and the wrong one could be used.
    // Let each region figure out the proper enclosing flow thread.
    CurrentRenderFlowThreadDisabler disabler(view());

    for (RenderRegionList::const_iterator iter = m_regionList.begin(); iter != m_regionList.end(); ++iter) {
        RenderRegion* region = *iter;

        region->repaintFlowThreadContent(repaintRect);
    }
}

RenderRegion* RenderFlowThread::regionAtBlockOffset(LayoutUnit offset, bool extendLastRegion, RegionAutoGenerationPolicy autoGenerationPolicy)
{
    ASSERT(!m_regionsInvalidated);

    if (autoGenerationPolicy == AllowRegionAutoGeneration)
        autoGenerateRegionsToBlockOffset(offset);

    if (offset <= 0)
        return m_regionList.isEmpty() ? 0 : m_regionList.first();

    RegionSearchAdapter adapter(offset);
    m_regionIntervalTree.allOverlapsWithAdapter<RegionSearchAdapter>(adapter);

    // If no region was found, the offset is in the flow thread overflow.
    // The last region will contain the offset if extendLastRegion is set or if the last region is a set.
    if (!adapter.result() && !m_regionList.isEmpty())
        return m_regionList.last();

    return adapter.result();
}

RenderRegion* RenderFlowThread::regionFromAbsolutePointAndBox(IntPoint absolutePoint, const RenderBox* flowedBox)
{
    if (!flowedBox)
        return 0;

    RenderRegion* startRegion = 0;
    RenderRegion* endRegion = 0;
    getRegionRangeForBox(flowedBox, startRegion, endRegion);

    if (!startRegion)
        return 0;

    for (RenderRegionList::iterator iter = m_regionList.find(startRegion); iter != m_regionList.end(); ++iter) {
        RenderRegion* region = *iter;
        IntRect regionAbsoluteRect(roundedIntPoint(region->localToAbsolute()), roundedIntSize(region->frameRect().size()));
        if (regionAbsoluteRect.contains(absolutePoint))
            return region;

        if (region == endRegion)
            break;
    }

    return 0;
}

LayoutPoint RenderFlowThread::adjustedPositionRelativeToOffsetParent(const RenderBoxModelObject& boxModelObject, const LayoutPoint& startPoint)
{
    LayoutPoint referencePoint = startPoint;

    // FIXME: This needs to be adapted for different writing modes inside the flow thread.
    RenderRegion* startRegion = regionAtBlockOffset(referencePoint.y());
    if (startRegion) {
        // Take into account the offset coordinates of the region.
        RenderObject* currObject = startRegion;
        RenderObject* currOffsetParentRenderer;
        Element* currOffsetParentElement;
        while ((currOffsetParentElement = currObject->offsetParent()) && (currOffsetParentRenderer = currOffsetParentElement->renderer())) {
            if (currObject->isBoxModelObject())
                referencePoint.move(toRenderBoxModelObject(currObject)->offsetLeft(), toRenderBoxModelObject(currObject)->offsetTop());

            // Since we're looking for the offset relative to the body, we must also
            // take into consideration the borders of the region's offsetParent.
            if (currOffsetParentRenderer->isBox() && !currOffsetParentRenderer->isBody())
                referencePoint.move(toRenderBox(currOffsetParentRenderer)->borderLeft(), toRenderBox(currOffsetParentRenderer)->borderTop());

            currObject = currOffsetParentRenderer;
        }

        // We need to check if any of this box's containing blocks start in a different region
        // and if so, drop the object's top position (which was computed relative to its containing block
        // and is no longer valid) and recompute it using the region in which it flows as reference.
        bool wasComputedRelativeToOtherRegion = false;
        const RenderBlock* objContainingBlock = boxModelObject.containingBlock();
        while (objContainingBlock) {
            // Check if this object is in a different region.
            RenderRegion* parentStartRegion = 0;
            RenderRegion* parentEndRegion = 0;
            getRegionRangeForBox(objContainingBlock, parentStartRegion, parentEndRegion);
            if (parentStartRegion && parentStartRegion != startRegion) {
                wasComputedRelativeToOtherRegion = true;
                break;
            }
            objContainingBlock = objContainingBlock->containingBlock();
        }

        if (wasComputedRelativeToOtherRegion) {
            // Get the logical top coordinate of the current object.
            LayoutUnit top = 0;
            if (boxModelObject.isRenderBlock()) {
                top = toRenderBlock(&boxModelObject)->offsetFromLogicalTopOfFirstPage();
            } else {
                if (boxModelObject.containingBlock())
                    top = boxModelObject.containingBlock()->offsetFromLogicalTopOfFirstPage();

                if (boxModelObject.isBox())
                    top += toRenderBox(&boxModelObject)->topLeftLocation().y();
                else if (boxModelObject.isRenderInline())
                    top -= toRenderInline(&boxModelObject)->borderTop();
            }

            // Get the logical top of the region this object starts in
            // and compute the object's top, relative to the region's top.
            LayoutUnit regionLogicalTop = startRegion->pageLogicalTopForOffset(top);
            LayoutUnit topRelativeToRegion = top - regionLogicalTop;
            referencePoint.setY(startRegion->offsetTop() + topRelativeToRegion);

            // Since the top has been overriden, check if the
            // relative/sticky positioning must be reconsidered.
            if (boxModelObject.isRelPositioned())
                referencePoint.move(0, boxModelObject.relativePositionOffset().height());
            else if (boxModelObject.isStickyPositioned())
                referencePoint.move(0, boxModelObject.stickyPositionOffset().height());
        }

        // Since we're looking for the offset relative to the body, we must also
        // take into consideration the borders of the region.
        referencePoint.move(startRegion->borderLeft(), startRegion->borderTop());
    }

    return referencePoint;
}

LayoutUnit RenderFlowThread::pageLogicalTopForOffset(LayoutUnit offset)
{
    RenderRegion* region = regionAtBlockOffset(offset);
    return region ? region->pageLogicalTopForOffset(offset) : LayoutUnit();
}

LayoutUnit RenderFlowThread::pageLogicalWidthForOffset(LayoutUnit offset)
{
    RenderRegion* region = regionAtBlockOffset(offset, true);
    return region ? region->pageLogicalWidth() : contentLogicalWidth();
}

LayoutUnit RenderFlowThread::pageLogicalHeightForOffset(LayoutUnit offset)
{
    RenderRegion* region = regionAtBlockOffset(offset);
    if (!region)
        return 0;

    return region->pageLogicalHeight();
}

LayoutUnit RenderFlowThread::pageRemainingLogicalHeightForOffset(LayoutUnit offset, PageBoundaryRule pageBoundaryRule)
{
    RenderRegion* region = regionAtBlockOffset(offset);
    if (!region)
        return 0;

    LayoutUnit pageLogicalTop = region->pageLogicalTopForOffset(offset);
    LayoutUnit pageLogicalHeight = region->pageLogicalHeight();
    LayoutUnit pageLogicalBottom = pageLogicalTop + pageLogicalHeight;
    LayoutUnit remainingHeight = pageLogicalBottom - offset;
    if (pageBoundaryRule == IncludePageBoundary) {
        // If IncludePageBoundary is set, the line exactly on the top edge of a
        // region will act as being part of the previous region.
        remainingHeight = intMod(remainingHeight, pageLogicalHeight);
    }
    return remainingHeight;
}

RenderRegion* RenderFlowThread::mapFromFlowToRegion(TransformState& transformState) const
{
    if (!hasValidRegionInfo())
        return 0;

    LayoutRect boxRect = transformState.mappedQuad().enclosingBoundingBox();
    flipForWritingMode(boxRect);

    // FIXME: We need to refactor RenderObject::absoluteQuads to be able to split the quads across regions,
    // for now we just take the center of the mapped enclosing box and map it to a region.
    // Note: Using the center in order to avoid rounding errors.

    LayoutPoint center = boxRect.center();
    RenderRegion* renderRegion = const_cast<RenderFlowThread*>(this)->regionAtBlockOffset(isHorizontalWritingMode() ? center.y() : center.x(), true, DisallowRegionAutoGeneration);
    if (!renderRegion)
        return 0;

    LayoutRect flippedRegionRect(renderRegion->flowThreadPortionRect());
    flipForWritingMode(flippedRegionRect);

    transformState.move(renderRegion->contentBoxRect().location() - flippedRegionRect.location());

    return renderRegion;
}

RenderRegion* RenderFlowThread::firstRegion() const
{
    if (!hasValidRegionInfo())
        return 0;
    return m_regionList.first();
}

RenderRegion* RenderFlowThread::lastRegion() const
{
    if (!hasValidRegionInfo())
        return 0;
    return m_regionList.last();
}

void RenderFlowThread::setRegionRangeForBox(const RenderBox* box, LayoutUnit offsetFromLogicalTopOfFirstPage)
{
    if (!hasRegions())
        return;

    // FIXME: Not right for differing writing-modes.
    RenderRegion* startRegion = regionAtBlockOffset(offsetFromLogicalTopOfFirstPage, true);
    RenderRegion* endRegion = regionAtBlockOffset(offsetFromLogicalTopOfFirstPage + box->logicalHeight(), true);
    RenderRegionRangeMap::iterator it = m_regionRangeMap.find(box);
    if (it == m_regionRangeMap.end()) {
        m_regionRangeMap.set(box, RenderRegionRange(startRegion, endRegion));
        return;
    }

    // If nothing changed, just bail.
    RenderRegionRange& range = it->value;
    if (range.startRegion() == startRegion && range.endRegion() == endRegion)
        return;

    range.setRange(startRegion, endRegion);
}

void RenderFlowThread::getRegionRangeForBox(const RenderBox* box, RenderRegion*& startRegion, RenderRegion*& endRegion) const
{
    startRegion = 0;
    endRegion = 0;
    RenderRegionRangeMap::const_iterator it = m_regionRangeMap.find(box);
    if (it == m_regionRangeMap.end())
        return;

    const RenderRegionRange& range = it->value;
    startRegion = range.startRegion();
    endRegion = range.endRegion();
    ASSERT(m_regionList.contains(startRegion) && m_regionList.contains(endRegion));
}

void RenderFlowThread::applyBreakAfterContent(LayoutUnit clientHeight)
{
    // Simulate a region break at height. If it points inside an auto logical height region,
    // then it may determine the region computed autoheight.
    addForcedRegionBreak(clientHeight, this, false);
}

bool RenderFlowThread::regionInRange(const RenderRegion* targetRegion, const RenderRegion* startRegion, const RenderRegion* endRegion) const
{
    ASSERT(targetRegion);

    for (RenderRegionList::const_iterator it = m_regionList.find(const_cast<RenderRegion*>(startRegion)); it != m_regionList.end(); ++it) {
        const RenderRegion* currRegion = *it;
        if (targetRegion == currRegion)
            return true;
        if (currRegion == endRegion)
            break;
    }

    return false;
}

void RenderFlowThread::updateRegionsFlowThreadPortionRect()
{
    LayoutUnit logicalHeight = 0;
    // FIXME: Optimize not to clear the interval all the time. This implies manually managing the tree nodes lifecycle.
    m_regionIntervalTree.clear();
    m_regionIntervalTree.initIfNeeded();
    for (RenderRegionList::iterator iter = m_regionList.begin(); iter != m_regionList.end(); ++iter) {
        RenderRegion* region = *iter;

        LayoutUnit regionLogicalWidth = region->pageLogicalWidth();
        LayoutUnit regionLogicalHeight = std::min<LayoutUnit>(RenderFlowThread::maxLogicalHeight() - logicalHeight, region->logicalHeightOfAllFlowThreadContent());

        LayoutRect regionRect(style()->direction() == LTR ? LayoutUnit() : logicalWidth() - regionLogicalWidth, logicalHeight, regionLogicalWidth, regionLogicalHeight);

        region->setFlowThreadPortionRect(isHorizontalWritingMode() ? regionRect : regionRect.transposedRect());

        m_regionIntervalTree.add(RegionIntervalTree::createInterval(logicalHeight, logicalHeight + regionLogicalHeight, region));

        logicalHeight += regionLogicalHeight;
    }
}

void RenderFlowThread::collectLayerFragments(LayerFragments& layerFragments, const LayoutRect& layerBoundingBox, const LayoutRect& dirtyRect)
{
    ASSERT(!m_regionsInvalidated);

    for (RenderRegionList::const_iterator iter = m_regionList.begin(); iter != m_regionList.end(); ++iter) {
        RenderRegion* region = *iter;
        region->collectLayerFragments(layerFragments, layerBoundingBox, dirtyRect);
    }
}

LayoutRect RenderFlowThread::fragmentsBoundingBox(const LayoutRect& layerBoundingBox)
{
    ASSERT(!m_regionsInvalidated);

    LayoutRect result;
    for (RenderRegionList::const_iterator iter = m_regionList.begin(); iter != m_regionList.end(); ++iter) {
        RenderRegion* region = *iter;
        LayerFragments fragments;
        region->collectLayerFragments(fragments, layerBoundingBox, PaintInfo::infiniteRect());
        for (size_t i = 0; i < fragments.size(); ++i) {
            const LayerFragment& fragment = fragments.at(i);
            LayoutRect fragmentRect(layerBoundingBox);
            fragmentRect.intersect(fragment.paginationClip);
            fragmentRect.moveBy(fragment.paginationOffset);
            result.unite(fragmentRect);
        }
    }

    return result;
}

bool RenderFlowThread::cachedOffsetFromLogicalTopOfFirstRegion(const RenderBox* box, LayoutUnit& result) const
{
    RenderBoxToOffsetMap::const_iterator offsetIterator = m_boxesToOffsetMap.find(box);
    if (offsetIterator == m_boxesToOffsetMap.end())
        return false;

    result = offsetIterator->value;
    return true;
}

void RenderFlowThread::setOffsetFromLogicalTopOfFirstRegion(const RenderBox* box, LayoutUnit offset)
{
    m_boxesToOffsetMap.set(box, offset);
}

void RenderFlowThread::clearOffsetFromLogicalTopOfFirstRegion(const RenderBox* box)
{
    ASSERT(m_boxesToOffsetMap.contains(box));
    m_boxesToOffsetMap.remove(box);
}

const RenderBox* RenderFlowThread::currentStatePusherRenderBox() const
{
    const RenderObject* currentObject = m_statePusherObjectsStack.isEmpty() ? 0 : m_statePusherObjectsStack.last();
    if (currentObject && currentObject->isBox())
        return toRenderBox(currentObject);

    return 0;
}

void RenderFlowThread::pushFlowThreadLayoutState(const RenderObject& object)
{
    if (const RenderBox* currentBoxDescendant = currentStatePusherRenderBox()) {
        LayoutState* layoutState = currentBoxDescendant->view()->layoutState();
        if (layoutState && layoutState->isPaginated()) {
            ASSERT(layoutState->renderer() == currentBoxDescendant);
            LayoutSize offsetDelta = layoutState->layoutOffset() - layoutState->pageOffset();
            setOffsetFromLogicalTopOfFirstRegion(currentBoxDescendant, currentBoxDescendant->isHorizontalWritingMode() ? offsetDelta.height() : offsetDelta.width());
        }
    }

    m_statePusherObjectsStack.add(&object);
}

void RenderFlowThread::popFlowThreadLayoutState()
{
    m_statePusherObjectsStack.removeLast();

    if (const RenderBox* currentBoxDescendant = currentStatePusherRenderBox()) {
        LayoutState* layoutState = currentBoxDescendant->view()->layoutState();
        if (layoutState && layoutState->isPaginated())
            clearOffsetFromLogicalTopOfFirstRegion(currentBoxDescendant);
    }
}

LayoutUnit RenderFlowThread::offsetFromLogicalTopOfFirstRegion(const RenderBlock* currentBlock) const
{
    // First check if we cached the offset for the block if it's an ancestor containing block of the box
    // being currently laid out.
    LayoutUnit offset;
    if (cachedOffsetFromLogicalTopOfFirstRegion(currentBlock, offset))
        return offset;

    // If it's the current box being laid out, use the layout state.
    const RenderBox* currentBoxDescendant = currentStatePusherRenderBox();
    if (currentBlock == currentBoxDescendant) {
        LayoutState* layoutState = view()->layoutState();
        ASSERT(layoutState->renderer() == currentBlock);
        ASSERT(layoutState && layoutState->isPaginated());
        LayoutSize offsetDelta = layoutState->layoutOffset() - layoutState->pageOffset();
        return currentBoxDescendant->isHorizontalWritingMode() ? offsetDelta.height() : offsetDelta.width();
    }

    // As a last resort, take the slow path.
    LayoutRect blockRect(0, 0, currentBlock->width(), currentBlock->height());
    while (currentBlock && !currentBlock->isRenderFlowThread()) {
        RenderBlock* containerBlock = currentBlock->containingBlock();
        ASSERT(containerBlock);
        if (!containerBlock)
            return 0;
        LayoutPoint currentBlockLocation = currentBlock->location();

        if (containerBlock->style()->writingMode() != currentBlock->style()->writingMode()) {
            // We have to put the block rect in container coordinates
            // and we have to take into account both the container and current block flipping modes
            if (containerBlock->style()->isFlippedBlocksWritingMode()) {
                if (containerBlock->isHorizontalWritingMode())
                    blockRect.setY(currentBlock->height() - blockRect.maxY());
                else
                    blockRect.setX(currentBlock->width() - blockRect.maxX());
            }
            currentBlock->flipForWritingMode(blockRect);
        }
        blockRect.moveBy(currentBlockLocation);
        currentBlock = containerBlock;
    }

    return currentBlock->isHorizontalWritingMode() ? blockRect.y() : blockRect.x();
}

void RenderFlowThread::RegionSearchAdapter::collectIfNeeded(const RegionInterval& interval)
{
    if (m_result)
        return;
    if (interval.low() <= m_offset && interval.high() > m_offset)
        m_result = interval.data();
}

void RenderFlowThread::mapLocalToContainer(const RenderLayerModelObject* repaintContainer, TransformState& transformState, MapCoordinatesFlags mode, bool* wasFixed) const
{
    if (this == repaintContainer)
        return;

    if (RenderRegion* region = mapFromFlowToRegion(transformState)) {
        // FIXME: The cast below is probably not the best solution, we may need to find a better way.
        static_cast<const RenderObject*>(region)->mapLocalToContainer(region->containerForRepaint(), transformState, mode, wasFixed);
    }
}

CurrentRenderFlowThreadMaintainer::CurrentRenderFlowThreadMaintainer(RenderFlowThread* renderFlowThread)
    : m_renderFlowThread(renderFlowThread)
    , m_previousRenderFlowThread(0)
{
    if (!m_renderFlowThread)
        return;
    RenderView* view = m_renderFlowThread->view();
    m_previousRenderFlowThread = view->flowThreadController()->currentRenderFlowThread();
    view->flowThreadController()->setCurrentRenderFlowThread(m_renderFlowThread);
}

CurrentRenderFlowThreadMaintainer::~CurrentRenderFlowThreadMaintainer()
{
    if (!m_renderFlowThread)
        return;
    RenderView* view = m_renderFlowThread->view();
    ASSERT(view->flowThreadController()->currentRenderFlowThread() == m_renderFlowThread);
    view->flowThreadController()->setCurrentRenderFlowThread(m_previousRenderFlowThread);
}


} // namespace WebCore