Source/WebCore/rendering/FlowThreadController.cpp - WebKit - Git at Google

 /*
  * Copyright (C) 2012 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 "FlowThreadController.h"

 #include "NamedFlowCollection.h"
 #include "RenderFlowThread.h"
 #include "RenderLayer.h"
 #include "RenderNamedFlowThread.h"
 #include "StyleInheritedData.h"
 #include "WebKitNamedFlow.h"
 #include <wtf/text/AtomicString.h>

 namespace WebCore {

 PassOwnPtr<FlowThreadController> FlowThreadController::create(RenderView* view)
 {
     return adoptPtr(new FlowThreadController(view));
 }

 FlowThreadController::FlowThreadController(RenderView* view)
     : m_view(view)
     , m_currentRenderFlowThread(0)
     , m_isRenderNamedFlowThreadOrderDirty(false)
     , m_flowThreadsWithAutoLogicalHeightRegions(0)
 {
 }

 FlowThreadController::~FlowThreadController()
 {
 }

 RenderNamedFlowThread& FlowThreadController::ensureRenderFlowThreadWithName(const AtomicString& name)
 {
     if (!m_renderNamedFlowThreadList)
         m_renderNamedFlowThreadList = adoptPtr(new RenderNamedFlowThreadList());
     else {
         for (auto iter = m_renderNamedFlowThreadList->begin(), end = m_renderNamedFlowThreadList->end(); iter != end; ++iter) {
             RenderNamedFlowThread* flowRenderer = *iter;
             if (flowRenderer->flowThreadName() == name)
                 return *flowRenderer;
         }
     }

     NamedFlowCollection* namedFlows = m_view->document().namedFlows();

     // Sanity check for the absence of a named flow in the "CREATED" state with the same name.
     ASSERT(!namedFlows->flowByName(name));

     auto flowRenderer = new RenderNamedFlowThread(m_view->document(), RenderFlowThread::createFlowThreadStyle(&m_view->style()), namedFlows->ensureFlowWithName(name));
     flowRenderer->initializeStyle();
     m_renderNamedFlowThreadList->add(flowRenderer);

     // Keep the flow renderer as a child of RenderView.
     m_view->addChild(flowRenderer);

     setIsRenderNamedFlowThreadOrderDirty(true);

     return *flowRenderer;
 }

 void FlowThreadController::styleDidChange()
 {
     RenderStyle& viewStyle = m_view->style();
     for (auto iter = m_renderNamedFlowThreadList->begin(), end = m_renderNamedFlowThreadList->end(); iter != end; ++iter) {
         RenderNamedFlowThread* flowRenderer = *iter;
         flowRenderer->setStyle(RenderFlowThread::createFlowThreadStyle(&viewStyle));
     }
 }

 void FlowThreadController::layoutRenderNamedFlowThreads()
 {
     updateFlowThreadsChainIfNecessary();

     for (auto iter = m_renderNamedFlowThreadList->begin(), end = m_renderNamedFlowThreadList->end(); iter != end; ++iter) {
         RenderNamedFlowThread* flowRenderer = *iter;
         flowRenderer->layoutIfNeeded();
     }
 }

 void FlowThreadController::registerNamedFlowContentElement(Element& contentElement, RenderNamedFlowThread& namedFlow)
 {
     ASSERT(!m_mapNamedFlowContentElement.contains(&contentElement));
     ASSERT(!namedFlow.hasContentElement(contentElement));
     m_mapNamedFlowContentElement.add(&contentElement, &namedFlow);
     namedFlow.registerNamedFlowContentElement(contentElement);
 }

 void FlowThreadController::unregisterNamedFlowContentElement(Element& contentElement)
 {
     auto it = m_mapNamedFlowContentElement.find(&contentElement);
     ASSERT(it != m_mapNamedFlowContentElement.end());
     ASSERT(it->value);
     ASSERT(it->value->hasContentElement(contentElement));
     it->value->unregisterNamedFlowContentElement(contentElement);
     m_mapNamedFlowContentElement.remove(&contentElement);
 }

 void FlowThreadController::updateFlowThreadsChainIfNecessary()
 {
     ASSERT(m_renderNamedFlowThreadList);
     ASSERT(isAutoLogicalHeightRegionsCountConsistent());

     // Remove the left-over flow threads.
     RenderNamedFlowThreadList toRemoveList;
     for (auto iter = m_renderNamedFlowThreadList->begin(), end = m_renderNamedFlowThreadList->end(); iter != end; ++iter) {
         RenderNamedFlowThread* flowRenderer = *iter;
         if (flowRenderer->isMarkedForDestruction())
             toRemoveList.add(flowRenderer);
     }

     if (toRemoveList.size() > 0)
         setIsRenderNamedFlowThreadOrderDirty(true);

     for (auto iter = toRemoveList.begin(), end = toRemoveList.end(); iter != end; ++iter) {
         RenderNamedFlowThread* flowRenderer = *iter;
         m_renderNamedFlowThreadList->remove(flowRenderer);
         flowRenderer->destroy();
     }

     if (isRenderNamedFlowThreadOrderDirty()) {
         // Arrange the thread list according to dependencies.
         RenderNamedFlowThreadList sortedList;
         for (auto iter = m_renderNamedFlowThreadList->begin(), end = m_renderNamedFlowThreadList->end(); iter != end; ++iter) {
             RenderNamedFlowThread* flowRenderer = *iter;
             if (sortedList.contains(flowRenderer))
                 continue;
             flowRenderer->pushDependencies(sortedList);
             sortedList.add(flowRenderer);
         }
         m_renderNamedFlowThreadList->swap(sortedList);
         setIsRenderNamedFlowThreadOrderDirty(false);
     }
 }

 bool FlowThreadController::updateFlowThreadsNeedingLayout()
 {
     bool needsTwoPassLayout = false;

     for (auto iter = m_renderNamedFlowThreadList->begin(), end = m_renderNamedFlowThreadList->end(); iter != end; ++iter) {
         RenderNamedFlowThread* flowRenderer = *iter;
         ASSERT(!flowRenderer->needsTwoPhasesLayout());
         ASSERT(flowRenderer->inMeasureContentLayoutPhase());
         if (flowRenderer->needsLayout() && flowRenderer->hasAutoLogicalHeightRegions())
             needsTwoPassLayout = true;
     }

     if (needsTwoPassLayout)
         resetFlowThreadsWithAutoHeightRegions();

     return needsTwoPassLayout;
 }

 bool FlowThreadController::updateFlowThreadsNeedingTwoStepLayout()
 {
     bool needsTwoPassLayout = false;

     for (auto iter = m_renderNamedFlowThreadList->begin(), end = m_renderNamedFlowThreadList->end(); iter != end; ++iter) {
         RenderNamedFlowThread* flowRenderer = *iter;
         if (flowRenderer->needsTwoPhasesLayout()) {
             needsTwoPassLayout = true;
             break;
         }
     }

     if (needsTwoPassLayout)
         resetFlowThreadsWithAutoHeightRegions();

     return needsTwoPassLayout;
 }

 void FlowThreadController::resetFlowThreadsWithAutoHeightRegions()
 {
     for (auto iter = m_renderNamedFlowThreadList->begin(), end = m_renderNamedFlowThreadList->end(); iter != end; ++iter) {
         RenderNamedFlowThread* flowRenderer = *iter;
         if (flowRenderer->hasAutoLogicalHeightRegions()) {
             flowRenderer->markAutoLogicalHeightRegionsForLayout();
             flowRenderer->invalidateRegions();
         }
     }
 }

 void FlowThreadController::updateFlowThreadsIntoConstrainedPhase()
 {
     // Walk the flow chain in reverse order to update the auto-height regions and compute correct sizes for the containing regions. Only after this we can
     // set the flow in the constrained layout phase.
     for (auto iter = m_renderNamedFlowThreadList->rbegin(), end = m_renderNamedFlowThreadList->rend(); iter != end; ++iter) {
         RenderNamedFlowThread* flowRenderer = *iter;
         ASSERT(!flowRenderer->hasRegions() || flowRenderer->hasValidRegionInfo());
         flowRenderer->layoutIfNeeded();
         if (flowRenderer->hasAutoLogicalHeightRegions()) {
             ASSERT(flowRenderer->needsTwoPhasesLayout());
             flowRenderer->markAutoLogicalHeightRegionsForLayout();
         }
         flowRenderer->setLayoutPhase(RenderFlowThread::LayoutPhaseConstrained);
         flowRenderer->clearNeedsTwoPhasesLayout();
     }
 }

 void FlowThreadController::updateFlowThreadsIntoOverflowPhase()
 {
     for (auto iter = m_renderNamedFlowThreadList->rbegin(), end = m_renderNamedFlowThreadList->rend(); iter != end; ++iter) {
         RenderNamedFlowThread* flowRenderer = *iter;
         ASSERT(!flowRenderer->hasRegions() || flowRenderer->hasValidRegionInfo());
         ASSERT(!flowRenderer->needsTwoPhasesLayout());

         // In the overflow computation phase the flow threads start in the constrained phase even though optimizations didn't set the state before.
         flowRenderer->setLayoutPhase(RenderFlowThread::LayoutPhaseConstrained);

         flowRenderer->layoutIfNeeded();
         flowRenderer->markRegionsForOverflowLayoutIfNeeded();
         flowRenderer->setLayoutPhase(RenderFlowThread::LayoutPhaseOverflow);
     }
 }

 void FlowThreadController::updateFlowThreadsIntoMeasureContentPhase()
 {
     for (auto iter = m_renderNamedFlowThreadList->begin(), end = m_renderNamedFlowThreadList->end(); iter != end; ++iter) {
         RenderNamedFlowThread* flowRenderer = *iter;
         ASSERT(flowRenderer->inFinalLayoutPhase());

         flowRenderer->setLayoutPhase(RenderFlowThread::LayoutPhaseMeasureContent);
     }
 }

 void FlowThreadController::updateFlowThreadsIntoFinalPhase()
 {
     for (auto iter = m_renderNamedFlowThreadList->rbegin(), end = m_renderNamedFlowThreadList->rend(); iter != end; ++iter) {
         RenderNamedFlowThread* flowRenderer = *iter;
         flowRenderer->layoutIfNeeded();
         if (flowRenderer->needsTwoPhasesLayout()) {
             flowRenderer->markRegionsForOverflowLayoutIfNeeded();
             flowRenderer->clearNeedsTwoPhasesLayout();
         }
         flowRenderer->setLayoutPhase(RenderFlowThread::LayoutPhaseFinal);
     }
 }

 #if USE(ACCELERATED_COMPOSITING)
 void FlowThreadController::updateRenderFlowThreadLayersIfNeeded()
 {
     // Walk the flow chain in reverse order because RenderRegions might become RenderLayers for the following flow threads.
     for (auto iter = m_renderNamedFlowThreadList->rbegin(), end = m_renderNamedFlowThreadList->rend(); iter != end; ++iter) {
         RenderNamedFlowThread* flowRenderer = *iter;
         flowRenderer->updateAllLayerToRegionMappingsIfNeeded();
     }
 }
 #endif

 bool FlowThreadController::isContentElementRegisteredWithAnyNamedFlow(const Element& contentElement) const
 {
     return m_mapNamedFlowContentElement.contains(&contentElement);
 }

 // Collect the fixed positioned layers that have the named flows as containing block
 // These layers are painted and hit-tested starting from RenderView not from regions.
 void FlowThreadController::collectFixedPositionedLayers(Vector<RenderLayer*>& fixedPosLayers) const
 {
     for (auto iter = m_renderNamedFlowThreadList->begin(), end = m_renderNamedFlowThreadList->end(); iter != end; ++iter) {
         RenderNamedFlowThread* flowRenderer = *iter;

         // If the named flow does not have any regions attached, a fixed element should not be
         // displayed even if the fixed element is positioned/sized by the viewport.
         if (!flowRenderer->hasRegions())
             continue;

         // Iterate over the fixed positioned elements in the flow thread
         TrackedRendererListHashSet* positionedDescendants = flowRenderer->positionedObjects();
         if (positionedDescendants) {
             for (auto it = positionedDescendants->begin(), end = positionedDescendants->end(); it != end; ++it) {
                 RenderBox* box = *it;
                 if (!box->fixedPositionedWithNamedFlowContainingBlock())
                     continue;
                 fixedPosLayers.append(box->layer());
             }
         }
     }
 }

 #ifndef NDEBUG
 bool FlowThreadController::isAutoLogicalHeightRegionsCountConsistent() const
 {
     if (!hasRenderNamedFlowThreads())
         return !hasFlowThreadsWithAutoLogicalHeightRegions();

     for (auto iter = m_renderNamedFlowThreadList->begin(), end = m_renderNamedFlowThreadList->end(); iter != end; ++iter) {
         if (!(*iter)->isAutoLogicalHeightRegionsCountConsistent())
             return false;
     }

     return true;
 }
 #endif

 } // namespace WebCore
	/*
	* Copyright (C) 2012 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 "FlowThreadController.h"

	#include "NamedFlowCollection.h"
	#include "RenderFlowThread.h"
	#include "RenderLayer.h"
	#include "RenderNamedFlowThread.h"
	#include "StyleInheritedData.h"
	#include "WebKitNamedFlow.h"
	#include <wtf/text/AtomicString.h>

	namespace WebCore {

	PassOwnPtr<FlowThreadController> FlowThreadController::create(RenderView* view)
	{
	return adoptPtr(new FlowThreadController(view));
	}

	FlowThreadController::FlowThreadController(RenderView* view)
	: m_view(view)
	, m_currentRenderFlowThread(0)
	, m_isRenderNamedFlowThreadOrderDirty(false)
	, m_flowThreadsWithAutoLogicalHeightRegions(0)
	{
	}

	FlowThreadController::~FlowThreadController()
	{
	}

	RenderNamedFlowThread& FlowThreadController::ensureRenderFlowThreadWithName(const AtomicString& name)
	{
	if (!m_renderNamedFlowThreadList)
	m_renderNamedFlowThreadList = adoptPtr(new RenderNamedFlowThreadList());
	else {
	for (auto iter = m_renderNamedFlowThreadList->begin(), end = m_renderNamedFlowThreadList->end(); iter != end; ++iter) {
	RenderNamedFlowThread* flowRenderer = *iter;
	if (flowRenderer->flowThreadName() == name)
	return *flowRenderer;
	}
	}

	NamedFlowCollection* namedFlows = m_view->document().namedFlows();

	// Sanity check for the absence of a named flow in the "CREATED" state with the same name.
	ASSERT(!namedFlows->flowByName(name));

	auto flowRenderer = new RenderNamedFlowThread(m_view->document(), RenderFlowThread::createFlowThreadStyle(&m_view->style()), namedFlows->ensureFlowWithName(name));
	flowRenderer->initializeStyle();
	m_renderNamedFlowThreadList->add(flowRenderer);

	// Keep the flow renderer as a child of RenderView.
	m_view->addChild(flowRenderer);

	setIsRenderNamedFlowThreadOrderDirty(true);

	return *flowRenderer;
	}

	void FlowThreadController::styleDidChange()
	{
	RenderStyle& viewStyle = m_view->style();
	for (auto iter = m_renderNamedFlowThreadList->begin(), end = m_renderNamedFlowThreadList->end(); iter != end; ++iter) {
	RenderNamedFlowThread* flowRenderer = *iter;
	flowRenderer->setStyle(RenderFlowThread::createFlowThreadStyle(&viewStyle));
	}
	}

	void FlowThreadController::layoutRenderNamedFlowThreads()
	{
	updateFlowThreadsChainIfNecessary();

	for (auto iter = m_renderNamedFlowThreadList->begin(), end = m_renderNamedFlowThreadList->end(); iter != end; ++iter) {
	RenderNamedFlowThread* flowRenderer = *iter;
	flowRenderer->layoutIfNeeded();
	}
	}

	void FlowThreadController::registerNamedFlowContentElement(Element& contentElement, RenderNamedFlowThread& namedFlow)
	{
	ASSERT(!m_mapNamedFlowContentElement.contains(&contentElement));
	ASSERT(!namedFlow.hasContentElement(contentElement));
	m_mapNamedFlowContentElement.add(&contentElement, &namedFlow);
	namedFlow.registerNamedFlowContentElement(contentElement);
	}

	void FlowThreadController::unregisterNamedFlowContentElement(Element& contentElement)
	{
	auto it = m_mapNamedFlowContentElement.find(&contentElement);
	ASSERT(it != m_mapNamedFlowContentElement.end());
	ASSERT(it->value);
	ASSERT(it->value->hasContentElement(contentElement));
	it->value->unregisterNamedFlowContentElement(contentElement);
	m_mapNamedFlowContentElement.remove(&contentElement);
	}

	void FlowThreadController::updateFlowThreadsChainIfNecessary()
	{
	ASSERT(m_renderNamedFlowThreadList);
	ASSERT(isAutoLogicalHeightRegionsCountConsistent());

	// Remove the left-over flow threads.
	RenderNamedFlowThreadList toRemoveList;
	for (auto iter = m_renderNamedFlowThreadList->begin(), end = m_renderNamedFlowThreadList->end(); iter != end; ++iter) {
	RenderNamedFlowThread* flowRenderer = *iter;
	if (flowRenderer->isMarkedForDestruction())
	toRemoveList.add(flowRenderer);
	}

	if (toRemoveList.size() > 0)
	setIsRenderNamedFlowThreadOrderDirty(true);

	for (auto iter = toRemoveList.begin(), end = toRemoveList.end(); iter != end; ++iter) {
	RenderNamedFlowThread* flowRenderer = *iter;
	m_renderNamedFlowThreadList->remove(flowRenderer);
	flowRenderer->destroy();
	}

	if (isRenderNamedFlowThreadOrderDirty()) {
	// Arrange the thread list according to dependencies.
	RenderNamedFlowThreadList sortedList;
	for (auto iter = m_renderNamedFlowThreadList->begin(), end = m_renderNamedFlowThreadList->end(); iter != end; ++iter) {
	RenderNamedFlowThread* flowRenderer = *iter;
	if (sortedList.contains(flowRenderer))
	continue;
	flowRenderer->pushDependencies(sortedList);
	sortedList.add(flowRenderer);
	}
	m_renderNamedFlowThreadList->swap(sortedList);
	setIsRenderNamedFlowThreadOrderDirty(false);
	}
	}

	bool FlowThreadController::updateFlowThreadsNeedingLayout()
	{
	bool needsTwoPassLayout = false;

	for (auto iter = m_renderNamedFlowThreadList->begin(), end = m_renderNamedFlowThreadList->end(); iter != end; ++iter) {
	RenderNamedFlowThread* flowRenderer = *iter;
	ASSERT(!flowRenderer->needsTwoPhasesLayout());
	ASSERT(flowRenderer->inMeasureContentLayoutPhase());
	if (flowRenderer->needsLayout() && flowRenderer->hasAutoLogicalHeightRegions())
	needsTwoPassLayout = true;
	}

	if (needsTwoPassLayout)
	resetFlowThreadsWithAutoHeightRegions();

	return needsTwoPassLayout;
	}

	bool FlowThreadController::updateFlowThreadsNeedingTwoStepLayout()
	{
	bool needsTwoPassLayout = false;

	for (auto iter = m_renderNamedFlowThreadList->begin(), end = m_renderNamedFlowThreadList->end(); iter != end; ++iter) {
	RenderNamedFlowThread* flowRenderer = *iter;
	if (flowRenderer->needsTwoPhasesLayout()) {
	needsTwoPassLayout = true;
	break;
	}
	}

	if (needsTwoPassLayout)
	resetFlowThreadsWithAutoHeightRegions();

	return needsTwoPassLayout;
	}

	void FlowThreadController::resetFlowThreadsWithAutoHeightRegions()
	{
	for (auto iter = m_renderNamedFlowThreadList->begin(), end = m_renderNamedFlowThreadList->end(); iter != end; ++iter) {
	RenderNamedFlowThread* flowRenderer = *iter;
	if (flowRenderer->hasAutoLogicalHeightRegions()) {
	flowRenderer->markAutoLogicalHeightRegionsForLayout();
	flowRenderer->invalidateRegions();
	}
	}
	}

	void FlowThreadController::updateFlowThreadsIntoConstrainedPhase()
	{
	// Walk the flow chain in reverse order to update the auto-height regions and compute correct sizes for the containing regions. Only after this we can
	// set the flow in the constrained layout phase.
	for (auto iter = m_renderNamedFlowThreadList->rbegin(), end = m_renderNamedFlowThreadList->rend(); iter != end; ++iter) {
	RenderNamedFlowThread* flowRenderer = *iter;
	ASSERT(!flowRenderer->hasRegions() \|\| flowRenderer->hasValidRegionInfo());
	flowRenderer->layoutIfNeeded();
	if (flowRenderer->hasAutoLogicalHeightRegions()) {
	ASSERT(flowRenderer->needsTwoPhasesLayout());
	flowRenderer->markAutoLogicalHeightRegionsForLayout();
	}
	flowRenderer->setLayoutPhase(RenderFlowThread::LayoutPhaseConstrained);
	flowRenderer->clearNeedsTwoPhasesLayout();
	}
	}

	void FlowThreadController::updateFlowThreadsIntoOverflowPhase()
	{
	for (auto iter = m_renderNamedFlowThreadList->rbegin(), end = m_renderNamedFlowThreadList->rend(); iter != end; ++iter) {
	RenderNamedFlowThread* flowRenderer = *iter;
	ASSERT(!flowRenderer->hasRegions() \|\| flowRenderer->hasValidRegionInfo());
	ASSERT(!flowRenderer->needsTwoPhasesLayout());

	// In the overflow computation phase the flow threads start in the constrained phase even though optimizations didn't set the state before.
	flowRenderer->setLayoutPhase(RenderFlowThread::LayoutPhaseConstrained);

	flowRenderer->layoutIfNeeded();
	flowRenderer->markRegionsForOverflowLayoutIfNeeded();
	flowRenderer->setLayoutPhase(RenderFlowThread::LayoutPhaseOverflow);
	}
	}

	void FlowThreadController::updateFlowThreadsIntoMeasureContentPhase()
	{
	for (auto iter = m_renderNamedFlowThreadList->begin(), end = m_renderNamedFlowThreadList->end(); iter != end; ++iter) {
	RenderNamedFlowThread* flowRenderer = *iter;
	ASSERT(flowRenderer->inFinalLayoutPhase());

	flowRenderer->setLayoutPhase(RenderFlowThread::LayoutPhaseMeasureContent);
	}
	}

	void FlowThreadController::updateFlowThreadsIntoFinalPhase()
	{
	for (auto iter = m_renderNamedFlowThreadList->rbegin(), end = m_renderNamedFlowThreadList->rend(); iter != end; ++iter) {
	RenderNamedFlowThread* flowRenderer = *iter;
	flowRenderer->layoutIfNeeded();
	if (flowRenderer->needsTwoPhasesLayout()) {
	flowRenderer->markRegionsForOverflowLayoutIfNeeded();
	flowRenderer->clearNeedsTwoPhasesLayout();
	}
	flowRenderer->setLayoutPhase(RenderFlowThread::LayoutPhaseFinal);
	}
	}

	#if USE(ACCELERATED_COMPOSITING)
	void FlowThreadController::updateRenderFlowThreadLayersIfNeeded()
	{
	// Walk the flow chain in reverse order because RenderRegions might become RenderLayers for the following flow threads.
	for (auto iter = m_renderNamedFlowThreadList->rbegin(), end = m_renderNamedFlowThreadList->rend(); iter != end; ++iter) {
	RenderNamedFlowThread* flowRenderer = *iter;
	flowRenderer->updateAllLayerToRegionMappingsIfNeeded();
	}
	}
	#endif

	bool FlowThreadController::isContentElementRegisteredWithAnyNamedFlow(const Element& contentElement) const
	{
	return m_mapNamedFlowContentElement.contains(&contentElement);
	}

	// Collect the fixed positioned layers that have the named flows as containing block
	// These layers are painted and hit-tested starting from RenderView not from regions.
	void FlowThreadController::collectFixedPositionedLayers(Vector<RenderLayer*>& fixedPosLayers) const
	{
	for (auto iter = m_renderNamedFlowThreadList->begin(), end = m_renderNamedFlowThreadList->end(); iter != end; ++iter) {
	RenderNamedFlowThread* flowRenderer = *iter;

	// If the named flow does not have any regions attached, a fixed element should not be
	// displayed even if the fixed element is positioned/sized by the viewport.
	if (!flowRenderer->hasRegions())
	continue;

	// Iterate over the fixed positioned elements in the flow thread
	TrackedRendererListHashSet* positionedDescendants = flowRenderer->positionedObjects();
	if (positionedDescendants) {
	for (auto it = positionedDescendants->begin(), end = positionedDescendants->end(); it != end; ++it) {
	RenderBox* box = *it;
	if (!box->fixedPositionedWithNamedFlowContainingBlock())
	continue;
	fixedPosLayers.append(box->layer());
	}
	}
	}
	}

	#ifndef NDEBUG
	bool FlowThreadController::isAutoLogicalHeightRegionsCountConsistent() const
	{
	if (!hasRenderNamedFlowThreads())
	return !hasFlowThreadsWithAutoLogicalHeightRegions();

	for (auto iter = m_renderNamedFlowThreadList->begin(), end = m_renderNamedFlowThreadList->end(); iter != end; ++iter) {
	if (!(*iter)->isAutoLogicalHeightRegionsCountConsistent())
	return false;
	}

	return true;
	}
	#endif

	} // namespace WebCore