Source/WebKit2/WebProcess/WebPage/CoordinatedGraphics/CompositingCoordinator.cpp - third_party/webkit - Git at Google

 /*
  * Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies).
  * Copyright (C) 2013 Company 100, Inc. 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 APPLE INC. AND ITS CONTRIBUTORS ``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 APPLE INC. OR ITS CONTRIBUTORS
  * 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 "CompositingCoordinator.h"

 #if USE(COORDINATED_GRAPHICS)

 #include <WebCore/DOMWindow.h>
 #include <WebCore/Document.h>
 #include <WebCore/FrameView.h>
 #include <WebCore/GraphicsContext.h>
 #include <WebCore/InspectorController.h>
 #include <WebCore/MainFrame.h>
 #include <WebCore/Page.h>
 #include <wtf/TemporaryChange.h>

 using namespace WebCore;

 namespace WebKit {

 CompositingCoordinator::CompositingCoordinator(Page* page, CompositingCoordinator::Client& client)
     : m_page(page)
     , m_client(client)
     , m_releaseInactiveAtlasesTimer(*this, &CompositingCoordinator::releaseInactiveAtlasesTimerFired)
 {
 }

 CompositingCoordinator::~CompositingCoordinator()
 {
     m_isDestructing = true;

     purgeBackingStores();

     for (auto& registeredLayer : m_registeredLayers.values())
         registeredLayer->setCoordinator(nullptr);
 }

 void CompositingCoordinator::invalidate()
 {
     m_rootLayer = nullptr;
     purgeBackingStores();
 }

 void CompositingCoordinator::setRootCompositingLayer(GraphicsLayer* graphicsLayer)
 {
     if (m_rootCompositingLayer == graphicsLayer)
         return;

     if (m_rootCompositingLayer)
         m_rootCompositingLayer->removeFromParent();

     m_rootCompositingLayer = graphicsLayer;
     if (m_rootCompositingLayer)
         m_rootLayer->addChildAtIndex(m_rootCompositingLayer, 0);
 }

 void CompositingCoordinator::setViewOverlayRootLayer(GraphicsLayer* graphicsLayer)
 {
     if (m_overlayCompositingLayer == graphicsLayer)
         return;

     if (m_overlayCompositingLayer)
         m_overlayCompositingLayer->removeFromParent();

     m_overlayCompositingLayer = graphicsLayer;
     if (m_overlayCompositingLayer)
         m_rootLayer->addChild(m_overlayCompositingLayer);
 }

 void CompositingCoordinator::sizeDidChange(const IntSize& newSize)
 {
     m_rootLayer->setSize(newSize);
     notifyFlushRequired(m_rootLayer.get());
 }

 bool CompositingCoordinator::flushPendingLayerChanges()
 {
     TemporaryChange<bool> protector(m_isFlushingLayerChanges, true);

     initializeRootCompositingLayerIfNeeded();

     bool viewportIsStable = m_page->mainFrame().view()->viewportIsStable();
     m_rootLayer->flushCompositingStateForThisLayerOnly(viewportIsStable);
     m_client.didFlushRootLayer(m_visibleContentsRect);

     if (m_overlayCompositingLayer)
         m_overlayCompositingLayer->flushCompositingState(FloatRect(FloatPoint(), m_rootLayer->size()), viewportIsStable);

     bool didSync = m_page->mainFrame().view()->flushCompositingStateIncludingSubframes();

     auto& coordinatedLayer = downcast<CoordinatedGraphicsLayer>(*m_rootLayer);
     coordinatedLayer.updateContentBuffersIncludingSubLayers();
     coordinatedLayer.syncPendingStateChangesIncludingSubLayers();

     flushPendingImageBackingChanges();

     if (m_shouldSyncFrame) {
         didSync = true;

         if (m_rootCompositingLayer) {
             m_state.contentsSize = roundedIntSize(m_rootCompositingLayer->size());
             if (CoordinatedGraphicsLayer* contentsLayer = mainContentsLayer())
                 m_state.coveredRect = contentsLayer->coverRect();
         }
         m_state.scrollPosition = m_visibleContentsRect.location();

         m_client.commitSceneState(m_state);

         clearPendingStateChanges();
         m_shouldSyncFrame = false;
     }

     return didSync;
 }

 double CompositingCoordinator::timestamp() const
 {
     auto* document = m_page->mainFrame().document();
     if (!document)
         return 0;
     return document->domWindow() ? document->domWindow()->nowTimestamp() : document->monotonicTimestamp();
 }

 void CompositingCoordinator::syncDisplayState()
 {
 #if ENABLE(REQUEST_ANIMATION_FRAME) && !USE(REQUEST_ANIMATION_FRAME_TIMER) && !USE(REQUEST_ANIMATION_FRAME_DISPLAY_MONITOR)
     // Make sure that any previously registered animation callbacks are being executed before we flush the layers.
     m_lastAnimationServiceTime = timestamp();
     m_page->mainFrame().view()->serviceScriptedAnimations();
 #endif
     m_page->mainFrame().view()->updateLayoutAndStyleIfNeededRecursive();
 }

 #if ENABLE(REQUEST_ANIMATION_FRAME)
 double CompositingCoordinator::nextAnimationServiceTime() const
 {
     // According to the requestAnimationFrame spec, rAF callbacks should not be faster than 60FPS.
     static const double MinimalTimeoutForAnimations = 1. / 60.;
     return std::max<double>(0., MinimalTimeoutForAnimations - timestamp() + m_lastAnimationServiceTime);
 }
 #endif

 void CompositingCoordinator::clearPendingStateChanges()
 {
     m_state.layersToCreate.clear();
     m_state.layersToUpdate.clear();
     m_state.layersToRemove.clear();

     m_state.imagesToCreate.clear();
     m_state.imagesToRemove.clear();
     m_state.imagesToUpdate.clear();
     m_state.imagesToClear.clear();

     m_state.updateAtlasesToCreate.clear();
     m_state.updateAtlasesToRemove.clear();
 }

 void CompositingCoordinator::initializeRootCompositingLayerIfNeeded()
 {
     if (m_didInitializeRootCompositingLayer)
         return;

     m_state.rootCompositingLayer = downcast<CoordinatedGraphicsLayer>(*m_rootLayer).id();
     m_didInitializeRootCompositingLayer = true;
     m_shouldSyncFrame = true;
 }

 void CompositingCoordinator::createRootLayer(const IntSize& size)
 {
     ASSERT(!m_rootLayer);
     // Create a root layer.
     m_rootLayer = GraphicsLayer::create(this, *this);
 #ifndef NDEBUG
     m_rootLayer->setName("CompositingCoordinator root layer");
 #endif
     m_rootLayer->setDrawsContent(false);
     m_rootLayer->setSize(size);
 }

 void CompositingCoordinator::syncLayerState(CoordinatedLayerID id, CoordinatedGraphicsLayerState& state)
 {
     m_shouldSyncFrame = true;
     m_state.layersToUpdate.append(std::make_pair(id, state));
 }

 Ref<CoordinatedImageBacking> CompositingCoordinator::createImageBackingIfNeeded(Image* image)
 {
     CoordinatedImageBackingID imageID = CoordinatedImageBacking::getCoordinatedImageBackingID(image);
     auto addResult = m_imageBackings.ensure(imageID, [this, image] {
         return CoordinatedImageBacking::create(this, image);
     });
     return *addResult.iterator->value;
 }

 void CompositingCoordinator::createImageBacking(CoordinatedImageBackingID imageID)
 {
     m_state.imagesToCreate.append(imageID);
 }

 void CompositingCoordinator::updateImageBacking(CoordinatedImageBackingID imageID, RefPtr<CoordinatedSurface>&& coordinatedSurface)
 {
     m_shouldSyncFrame = true;
     m_state.imagesToUpdate.append(std::make_pair(imageID, WTFMove(coordinatedSurface)));
 }

 void CompositingCoordinator::clearImageBackingContents(CoordinatedImageBackingID imageID)
 {
     m_shouldSyncFrame = true;
     m_state.imagesToClear.append(imageID);
 }

 void CompositingCoordinator::removeImageBacking(CoordinatedImageBackingID imageID)
 {
     if (m_isPurging)
         return;

     ASSERT(m_imageBackings.contains(imageID));
     m_imageBackings.remove(imageID);

     m_state.imagesToRemove.append(imageID);

     size_t imageIDPosition = m_state.imagesToClear.find(imageID);
     if (imageIDPosition != notFound)
         m_state.imagesToClear.remove(imageIDPosition);
 }

 void CompositingCoordinator::flushPendingImageBackingChanges()
 {
     for (auto& imageBacking : m_imageBackings.values())
         imageBacking->update();
 }

 void CompositingCoordinator::notifyAnimationStarted(const GraphicsLayer*, const String&, double /* time */)
 {
 }

 void CompositingCoordinator::notifyFlushRequired(const GraphicsLayer*)
 {
     if (!m_isDestructing && !isFlushingLayerChanges())
         m_client.notifyFlushRequired();
 }

 void CompositingCoordinator::paintContents(const GraphicsLayer* graphicsLayer, GraphicsContext& graphicsContext, GraphicsLayerPaintingPhase, const FloatRect& clipRect)
 {
     m_client.paintLayerContents(graphicsLayer, graphicsContext, enclosingIntRect(clipRect));
 }

 std::unique_ptr<GraphicsLayer> CompositingCoordinator::createGraphicsLayer(GraphicsLayer::Type layerType, GraphicsLayerClient& client)
 {
     CoordinatedGraphicsLayer* layer = new CoordinatedGraphicsLayer(layerType, client);
     layer->setCoordinator(this);
     m_registeredLayers.add(layer->id(), layer);
     m_state.layersToCreate.append(layer->id());
     layer->setNeedsVisibleRectAdjustment();
     notifyFlushRequired(layer);
     return std::unique_ptr<GraphicsLayer>(layer);
 }

 float CompositingCoordinator::deviceScaleFactor() const
 {
     return m_page->deviceScaleFactor();
 }

 float CompositingCoordinator::pageScaleFactor() const
 {
     return m_page->pageScaleFactor();
 }

 void CompositingCoordinator::createUpdateAtlas(uint32_t atlasID, RefPtr<CoordinatedSurface>&& coordinatedSurface)
 {
     m_state.updateAtlasesToCreate.append(std::make_pair(atlasID, WTFMove(coordinatedSurface)));
 }

 void CompositingCoordinator::removeUpdateAtlas(uint32_t atlasID)
 {
     if (m_isPurging)
         return;
     m_state.updateAtlasesToRemove.append(atlasID);
 }

 FloatRect CompositingCoordinator::visibleContentsRect() const
 {
     return m_visibleContentsRect;
 }

 CoordinatedGraphicsLayer* CompositingCoordinator::mainContentsLayer()
 {
     if (!is<CoordinatedGraphicsLayer>(m_rootCompositingLayer))
         return nullptr;

     return downcast<CoordinatedGraphicsLayer>(*m_rootCompositingLayer).findFirstDescendantWithContentsRecursively();
 }

 void CompositingCoordinator::setVisibleContentsRect(const FloatRect& rect, const FloatPoint& trajectoryVector)
 {
     // A zero trajectoryVector indicates that tiles all around the viewport are requested.
     if (CoordinatedGraphicsLayer* contentsLayer = mainContentsLayer())
         contentsLayer->setVisibleContentRectTrajectoryVector(trajectoryVector);

     bool contentsRectDidChange = rect != m_visibleContentsRect;
     if (contentsRectDidChange) {
         m_visibleContentsRect = rect;

         for (auto& registeredLayer : m_registeredLayers.values())
             registeredLayer->setNeedsVisibleRectAdjustment();
     }

     FrameView* view = m_page->mainFrame().view();
     if (view->useFixedLayout() && contentsRectDidChange) {
         // Round the rect instead of enclosing it to make sure that its size stays
         // the same while panning. This can have nasty effects on layout.
         view->setFixedVisibleContentRect(roundedIntRect(rect));
     }
 }

 void CompositingCoordinator::deviceOrPageScaleFactorChanged()
 {
     m_rootLayer->deviceOrPageScaleFactorChanged();
 }

 void CompositingCoordinator::detachLayer(CoordinatedGraphicsLayer* layer)
 {
     if (m_isPurging)
         return;

     m_registeredLayers.remove(layer->id());

     size_t index = m_state.layersToCreate.find(layer->id());
     if (index != notFound) {
         m_state.layersToCreate.remove(index);
         return;
     }

     m_state.layersToRemove.append(layer->id());
     notifyFlushRequired(layer);
 }

 void CompositingCoordinator::commitScrollOffset(uint32_t layerID, const WebCore::IntSize& offset)
 {
     if (auto* layer = m_registeredLayers.get(layerID))
         layer->commitScrollOffset(offset);
 }

 void CompositingCoordinator::renderNextFrame()
 {
     for (auto& atlas : m_updateAtlases)
         atlas->didSwapBuffers();
 }

 void CompositingCoordinator::purgeBackingStores()
 {
     TemporaryChange<bool> purgingToggle(m_isPurging, true);

     for (auto& registeredLayer : m_registeredLayers.values())
         registeredLayer->purgeBackingStores();

     m_imageBackings.clear();
     m_updateAtlases.clear();
 }

 bool CompositingCoordinator::paintToSurface(const IntSize& size, CoordinatedSurface::Flags flags, uint32_t& atlasID, IntPoint& offset, CoordinatedSurface::Client& client)
 {
     for (auto& updateAtlas : m_updateAtlases) {
         UpdateAtlas* atlas = updateAtlas.get();
         if (atlas->supportsAlpha() == (flags & CoordinatedSurface::SupportsAlpha)) {
             // This will be false if there is no available buffer space.
             if (atlas->paintOnAvailableBuffer(size, atlasID, offset, client))
                 return true;
         }
     }

     static const int ScratchBufferDimension = 1024; // Should be a power of two.
     m_updateAtlases.append(std::make_unique<UpdateAtlas>(*this, ScratchBufferDimension, flags));
     scheduleReleaseInactiveAtlases();
     return m_updateAtlases.last()->paintOnAvailableBuffer(size, atlasID, offset, client);
 }

 const double ReleaseInactiveAtlasesTimerInterval = 0.5;

 void CompositingCoordinator::scheduleReleaseInactiveAtlases()
 {
     if (!m_releaseInactiveAtlasesTimer.isActive())
         m_releaseInactiveAtlasesTimer.startRepeating(ReleaseInactiveAtlasesTimerInterval);
 }

 void CompositingCoordinator::releaseInactiveAtlasesTimerFired()
 {
     // We always want to keep one atlas for root contents layer.
     std::unique_ptr<UpdateAtlas> atlasToKeepAnyway;
     bool foundActiveAtlasForRootContentsLayer = false;
     for (int i = m_updateAtlases.size() - 1;  i >= 0; --i) {
         UpdateAtlas* atlas = m_updateAtlases[i].get();
         if (!atlas->isInUse())
             atlas->addTimeInactive(ReleaseInactiveAtlasesTimerInterval);
         bool usableForRootContentsLayer = !atlas->supportsAlpha();
         if (atlas->isInactive()) {
             if (!foundActiveAtlasForRootContentsLayer && !atlasToKeepAnyway && usableForRootContentsLayer)
                 atlasToKeepAnyway = WTFMove(m_updateAtlases[i]);
             m_updateAtlases.remove(i);
         } else if (usableForRootContentsLayer)
             foundActiveAtlasForRootContentsLayer = true;
     }

     if (!foundActiveAtlasForRootContentsLayer && atlasToKeepAnyway)
         m_updateAtlases.append(atlasToKeepAnyway.release());

     m_updateAtlases.shrinkToFit();

     if (m_updateAtlases.size() <= 1)
         m_releaseInactiveAtlasesTimer.stop();
 }

 } // namespace WebKit

 #endif // USE(COORDINATED_GRAPHICS)
	/*
	* Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies).
	* Copyright (C) 2013 Company 100, Inc. 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 APPLE INC. AND ITS CONTRIBUTORS ``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 APPLE INC. OR ITS CONTRIBUTORS
	* 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 "CompositingCoordinator.h"

	#if USE(COORDINATED_GRAPHICS)

	#include <WebCore/DOMWindow.h>
	#include <WebCore/Document.h>
	#include <WebCore/FrameView.h>
	#include <WebCore/GraphicsContext.h>
	#include <WebCore/InspectorController.h>
	#include <WebCore/MainFrame.h>
	#include <WebCore/Page.h>
	#include <wtf/TemporaryChange.h>

	using namespace WebCore;

	namespace WebKit {

	CompositingCoordinator::CompositingCoordinator(Page* page, CompositingCoordinator::Client& client)
	: m_page(page)
	, m_client(client)
	, m_releaseInactiveAtlasesTimer(*this, &CompositingCoordinator::releaseInactiveAtlasesTimerFired)
	{
	}

	CompositingCoordinator::~CompositingCoordinator()
	{
	m_isDestructing = true;

	purgeBackingStores();

	for (auto& registeredLayer : m_registeredLayers.values())
	registeredLayer->setCoordinator(nullptr);
	}

	void CompositingCoordinator::invalidate()
	{
	m_rootLayer = nullptr;
	purgeBackingStores();
	}

	void CompositingCoordinator::setRootCompositingLayer(GraphicsLayer* graphicsLayer)
	{
	if (m_rootCompositingLayer == graphicsLayer)
	return;

	if (m_rootCompositingLayer)
	m_rootCompositingLayer->removeFromParent();

	m_rootCompositingLayer = graphicsLayer;
	if (m_rootCompositingLayer)
	m_rootLayer->addChildAtIndex(m_rootCompositingLayer, 0);
	}

	void CompositingCoordinator::setViewOverlayRootLayer(GraphicsLayer* graphicsLayer)
	{
	if (m_overlayCompositingLayer == graphicsLayer)
	return;

	if (m_overlayCompositingLayer)
	m_overlayCompositingLayer->removeFromParent();

	m_overlayCompositingLayer = graphicsLayer;
	if (m_overlayCompositingLayer)
	m_rootLayer->addChild(m_overlayCompositingLayer);
	}

	void CompositingCoordinator::sizeDidChange(const IntSize& newSize)
	{
	m_rootLayer->setSize(newSize);
	notifyFlushRequired(m_rootLayer.get());
	}

	bool CompositingCoordinator::flushPendingLayerChanges()
	{
	TemporaryChange<bool> protector(m_isFlushingLayerChanges, true);

	initializeRootCompositingLayerIfNeeded();

	bool viewportIsStable = m_page->mainFrame().view()->viewportIsStable();
	m_rootLayer->flushCompositingStateForThisLayerOnly(viewportIsStable);
	m_client.didFlushRootLayer(m_visibleContentsRect);

	if (m_overlayCompositingLayer)
	m_overlayCompositingLayer->flushCompositingState(FloatRect(FloatPoint(), m_rootLayer->size()), viewportIsStable);

	bool didSync = m_page->mainFrame().view()->flushCompositingStateIncludingSubframes();

	auto& coordinatedLayer = downcast<CoordinatedGraphicsLayer>(*m_rootLayer);
	coordinatedLayer.updateContentBuffersIncludingSubLayers();
	coordinatedLayer.syncPendingStateChangesIncludingSubLayers();

	flushPendingImageBackingChanges();

	if (m_shouldSyncFrame) {
	didSync = true;

	if (m_rootCompositingLayer) {
	m_state.contentsSize = roundedIntSize(m_rootCompositingLayer->size());
	if (CoordinatedGraphicsLayer* contentsLayer = mainContentsLayer())
	m_state.coveredRect = contentsLayer->coverRect();
	}
	m_state.scrollPosition = m_visibleContentsRect.location();

	m_client.commitSceneState(m_state);

	clearPendingStateChanges();
	m_shouldSyncFrame = false;
	}

	return didSync;
	}

	double CompositingCoordinator::timestamp() const
	{
	auto* document = m_page->mainFrame().document();
	if (!document)
	return 0;
	return document->domWindow() ? document->domWindow()->nowTimestamp() : document->monotonicTimestamp();
	}

	void CompositingCoordinator::syncDisplayState()
	{
	#if ENABLE(REQUEST_ANIMATION_FRAME) && !USE(REQUEST_ANIMATION_FRAME_TIMER) && !USE(REQUEST_ANIMATION_FRAME_DISPLAY_MONITOR)
	// Make sure that any previously registered animation callbacks are being executed before we flush the layers.
	m_lastAnimationServiceTime = timestamp();
	m_page->mainFrame().view()->serviceScriptedAnimations();
	#endif
	m_page->mainFrame().view()->updateLayoutAndStyleIfNeededRecursive();
	}

	#if ENABLE(REQUEST_ANIMATION_FRAME)
	double CompositingCoordinator::nextAnimationServiceTime() const
	{
	// According to the requestAnimationFrame spec, rAF callbacks should not be faster than 60FPS.
	static const double MinimalTimeoutForAnimations = 1. / 60.;
	return std::max<double>(0., MinimalTimeoutForAnimations - timestamp() + m_lastAnimationServiceTime);
	}
	#endif

	void CompositingCoordinator::clearPendingStateChanges()
	{
	m_state.layersToCreate.clear();
	m_state.layersToUpdate.clear();
	m_state.layersToRemove.clear();

	m_state.imagesToCreate.clear();
	m_state.imagesToRemove.clear();
	m_state.imagesToUpdate.clear();
	m_state.imagesToClear.clear();

	m_state.updateAtlasesToCreate.clear();
	m_state.updateAtlasesToRemove.clear();
	}

	void CompositingCoordinator::initializeRootCompositingLayerIfNeeded()
	{
	if (m_didInitializeRootCompositingLayer)
	return;

	m_state.rootCompositingLayer = downcast<CoordinatedGraphicsLayer>(*m_rootLayer).id();
	m_didInitializeRootCompositingLayer = true;
	m_shouldSyncFrame = true;
	}

	void CompositingCoordinator::createRootLayer(const IntSize& size)
	{
	ASSERT(!m_rootLayer);
	// Create a root layer.
	m_rootLayer = GraphicsLayer::create(this, *this);
	#ifndef NDEBUG
	m_rootLayer->setName("CompositingCoordinator root layer");
	#endif
	m_rootLayer->setDrawsContent(false);
	m_rootLayer->setSize(size);
	}

	void CompositingCoordinator::syncLayerState(CoordinatedLayerID id, CoordinatedGraphicsLayerState& state)
	{
	m_shouldSyncFrame = true;
	m_state.layersToUpdate.append(std::make_pair(id, state));
	}

	Ref<CoordinatedImageBacking> CompositingCoordinator::createImageBackingIfNeeded(Image* image)
	{
	CoordinatedImageBackingID imageID = CoordinatedImageBacking::getCoordinatedImageBackingID(image);
	auto addResult = m_imageBackings.ensure(imageID, [this, image] {
	return CoordinatedImageBacking::create(this, image);
	});
	return *addResult.iterator->value;
	}

	void CompositingCoordinator::createImageBacking(CoordinatedImageBackingID imageID)
	{
	m_state.imagesToCreate.append(imageID);
	}

	void CompositingCoordinator::updateImageBacking(CoordinatedImageBackingID imageID, RefPtr<CoordinatedSurface>&& coordinatedSurface)
	{
	m_shouldSyncFrame = true;
	m_state.imagesToUpdate.append(std::make_pair(imageID, WTFMove(coordinatedSurface)));
	}

	void CompositingCoordinator::clearImageBackingContents(CoordinatedImageBackingID imageID)
	{
	m_shouldSyncFrame = true;
	m_state.imagesToClear.append(imageID);
	}

	void CompositingCoordinator::removeImageBacking(CoordinatedImageBackingID imageID)
	{
	if (m_isPurging)
	return;

	ASSERT(m_imageBackings.contains(imageID));
	m_imageBackings.remove(imageID);

	m_state.imagesToRemove.append(imageID);

	size_t imageIDPosition = m_state.imagesToClear.find(imageID);
	if (imageIDPosition != notFound)
	m_state.imagesToClear.remove(imageIDPosition);
	}

	void CompositingCoordinator::flushPendingImageBackingChanges()
	{
	for (auto& imageBacking : m_imageBackings.values())
	imageBacking->update();
	}

	void CompositingCoordinator::notifyAnimationStarted(const GraphicsLayer, const String&, double / time */)
	{
	}

	void CompositingCoordinator::notifyFlushRequired(const GraphicsLayer*)
	{
	if (!m_isDestructing && !isFlushingLayerChanges())
	m_client.notifyFlushRequired();
	}

	void CompositingCoordinator::paintContents(const GraphicsLayer* graphicsLayer, GraphicsContext& graphicsContext, GraphicsLayerPaintingPhase, const FloatRect& clipRect)
	{
	m_client.paintLayerContents(graphicsLayer, graphicsContext, enclosingIntRect(clipRect));
	}

	std::unique_ptr<GraphicsLayer> CompositingCoordinator::createGraphicsLayer(GraphicsLayer::Type layerType, GraphicsLayerClient& client)
	{
	CoordinatedGraphicsLayer* layer = new CoordinatedGraphicsLayer(layerType, client);
	layer->setCoordinator(this);
	m_registeredLayers.add(layer->id(), layer);
	m_state.layersToCreate.append(layer->id());
	layer->setNeedsVisibleRectAdjustment();
	notifyFlushRequired(layer);
	return std::unique_ptr<GraphicsLayer>(layer);
	}

	float CompositingCoordinator::deviceScaleFactor() const
	{
	return m_page->deviceScaleFactor();
	}

	float CompositingCoordinator::pageScaleFactor() const
	{
	return m_page->pageScaleFactor();
	}

	void CompositingCoordinator::createUpdateAtlas(uint32_t atlasID, RefPtr<CoordinatedSurface>&& coordinatedSurface)
	{
	m_state.updateAtlasesToCreate.append(std::make_pair(atlasID, WTFMove(coordinatedSurface)));
	}

	void CompositingCoordinator::removeUpdateAtlas(uint32_t atlasID)
	{
	if (m_isPurging)
	return;
	m_state.updateAtlasesToRemove.append(atlasID);
	}

	FloatRect CompositingCoordinator::visibleContentsRect() const
	{
	return m_visibleContentsRect;
	}

	CoordinatedGraphicsLayer* CompositingCoordinator::mainContentsLayer()
	{
	if (!is<CoordinatedGraphicsLayer>(m_rootCompositingLayer))
	return nullptr;

	return downcast<CoordinatedGraphicsLayer>(*m_rootCompositingLayer).findFirstDescendantWithContentsRecursively();
	}

	void CompositingCoordinator::setVisibleContentsRect(const FloatRect& rect, const FloatPoint& trajectoryVector)
	{
	// A zero trajectoryVector indicates that tiles all around the viewport are requested.
	if (CoordinatedGraphicsLayer* contentsLayer = mainContentsLayer())
	contentsLayer->setVisibleContentRectTrajectoryVector(trajectoryVector);

	bool contentsRectDidChange = rect != m_visibleContentsRect;
	if (contentsRectDidChange) {
	m_visibleContentsRect = rect;

	for (auto& registeredLayer : m_registeredLayers.values())
	registeredLayer->setNeedsVisibleRectAdjustment();
	}

	FrameView* view = m_page->mainFrame().view();
	if (view->useFixedLayout() && contentsRectDidChange) {
	// Round the rect instead of enclosing it to make sure that its size stays
	// the same while panning. This can have nasty effects on layout.
	view->setFixedVisibleContentRect(roundedIntRect(rect));
	}
	}

	void CompositingCoordinator::deviceOrPageScaleFactorChanged()
	{
	m_rootLayer->deviceOrPageScaleFactorChanged();
	}

	void CompositingCoordinator::detachLayer(CoordinatedGraphicsLayer* layer)
	{
	if (m_isPurging)
	return;

	m_registeredLayers.remove(layer->id());

	size_t index = m_state.layersToCreate.find(layer->id());
	if (index != notFound) {
	m_state.layersToCreate.remove(index);
	return;
	}

	m_state.layersToRemove.append(layer->id());
	notifyFlushRequired(layer);
	}

	void CompositingCoordinator::commitScrollOffset(uint32_t layerID, const WebCore::IntSize& offset)
	{
	if (auto* layer = m_registeredLayers.get(layerID))
	layer->commitScrollOffset(offset);
	}

	void CompositingCoordinator::renderNextFrame()
	{
	for (auto& atlas : m_updateAtlases)
	atlas->didSwapBuffers();
	}

	void CompositingCoordinator::purgeBackingStores()
	{
	TemporaryChange<bool> purgingToggle(m_isPurging, true);

	for (auto& registeredLayer : m_registeredLayers.values())
	registeredLayer->purgeBackingStores();

	m_imageBackings.clear();
	m_updateAtlases.clear();
	}

	bool CompositingCoordinator::paintToSurface(const IntSize& size, CoordinatedSurface::Flags flags, uint32_t& atlasID, IntPoint& offset, CoordinatedSurface::Client& client)
	{
	for (auto& updateAtlas : m_updateAtlases) {
	UpdateAtlas* atlas = updateAtlas.get();
	if (atlas->supportsAlpha() == (flags & CoordinatedSurface::SupportsAlpha)) {
	// This will be false if there is no available buffer space.
	if (atlas->paintOnAvailableBuffer(size, atlasID, offset, client))
	return true;
	}
	}

	static const int ScratchBufferDimension = 1024; // Should be a power of two.
	m_updateAtlases.append(std::make_unique<UpdateAtlas>(*this, ScratchBufferDimension, flags));
	scheduleReleaseInactiveAtlases();
	return m_updateAtlases.last()->paintOnAvailableBuffer(size, atlasID, offset, client);
	}

	const double ReleaseInactiveAtlasesTimerInterval = 0.5;

	void CompositingCoordinator::scheduleReleaseInactiveAtlases()
	{
	if (!m_releaseInactiveAtlasesTimer.isActive())
	m_releaseInactiveAtlasesTimer.startRepeating(ReleaseInactiveAtlasesTimerInterval);
	}

	void CompositingCoordinator::releaseInactiveAtlasesTimerFired()
	{
	// We always want to keep one atlas for root contents layer.
	std::unique_ptr<UpdateAtlas> atlasToKeepAnyway;
	bool foundActiveAtlasForRootContentsLayer = false;
	for (int i = m_updateAtlases.size() - 1; i >= 0; --i) {
	UpdateAtlas* atlas = m_updateAtlases[i].get();
	if (!atlas->isInUse())
	atlas->addTimeInactive(ReleaseInactiveAtlasesTimerInterval);
	bool usableForRootContentsLayer = !atlas->supportsAlpha();
	if (atlas->isInactive()) {
	if (!foundActiveAtlasForRootContentsLayer && !atlasToKeepAnyway && usableForRootContentsLayer)
	atlasToKeepAnyway = WTFMove(m_updateAtlases[i]);
	m_updateAtlases.remove(i);
	} else if (usableForRootContentsLayer)
	foundActiveAtlasForRootContentsLayer = true;
	}

	if (!foundActiveAtlasForRootContentsLayer && atlasToKeepAnyway)
	m_updateAtlases.append(atlasToKeepAnyway.release());

	m_updateAtlases.shrinkToFit();

	if (m_updateAtlases.size() <= 1)
	m_releaseInactiveAtlasesTimer.stop();
	}

	} // namespace WebKit

	#endif // USE(COORDINATED_GRAPHICS)