Attachment 347779 Details for Bug 188693 – Patch for landing

[patch] Patch for landing

bug-188693-20180822140224.patch (text/plain), 72.93 KB, created by Zan Dobersek on 2018-08-22 05:02:26 PDT

(hide)

Description:

Filename:

MIME Type:

Creator: Zan Dobersek

Created: 2018-08-22 05:02:26 PDT

Size: 72.93 KB

patch

obsolete

>Subversion Revision: 235163
>diff --git a/Source/WebCore/ChangeLog b/Source/WebCore/ChangeLog
>index 667cef34549b68236d790d19a5fddcfbf8d302bb..f39d337b6cb696f2505b70d4e062b0e664e10fe8 100644
>--- a/Source/WebCore/ChangeLog
>+++ b/Source/WebCore/ChangeLog
>@@ -1,3 +1,96 @@
>+2018-08-22  Zan Dobersek  <zdobersek@igalia.com>
>+
>+        [CoordGraphics] Switch to Nicosia::CompositionLayer state tracking
>+        https://bugs.webkit.org/show_bug.cgi?id=188693
>+
>+        Reviewed by Carlos Garcia Campos.
>+
>+        Populate Nicosia::CompositionLayer with additional LayerState member
>+        objects. For now we're using pending, staging and committed states,
>+        though it might be possible to narrow down these to just two.
>+
>+        Pending state contains state that will be moved to staging during the
>+        final steps of the next layer flush. flushState() method accumulates all
>+        state changes in the staging state, and also allows the caller to
>+        additionally perform flushing operations that are specific to backing
>+        store, image backing or content layer containers.
>+
>+        commitState() method moves staging state over into the committed state,
>+        again allowing user to pass a functor that receives the just-committed
>+        state and apply it to their composition engine.
>+
>+        Changes in state objects are done under a thread-safe lock. This might
>+        not be completely necessary at this point, but will be useful when
>+        additonal layer state updates will be coming from e.g. the scrolling
>+        thread. It might also make sense to tie in this lock use with the
>+        Nicosia::Scene lock in the future.
>+
>+        Nicosia::ContentLayerTextureMapperImpl is modified slightly to allow
>+        determining during flushes whether an update is pending. This is
>+        necessary for a special case in ThreadedCompositor where content (i.e.
>+        platform) layers like WebGL or video require an additional level of
>+        scene update coordination. This complete special case has to go through
>+        another review to see whether it's still necessary. Ideally we would be
>+        able to remove it.
>+
>+        CoordinatedGraphicsLayer is finally switched over to using
>+        Nicosia layer objects for state updates of any kind. This patch only
>+        adds all the necessary bits, but doesn't yet remove any of the existing
>+        code (but rather disables it temporarily, before it's removed).
>+
>+        Updating of simple state values is already in place. For backing stores,
>+        the flushCompositingStateForThisLayerOnly() method now takes care of
>+        preparing the backing store object if necessary as per layer state,
>+        while the updateContentBuffers() method is switched to operate with
>+        TiledBackingStore objects now kept on the BackingStoreTextureMapperImpl
>+        instance associated with that backing store. Helper methods like
>+        adjustContentsScale() and createBackingStore(), only called from the
>+        updateContentBuffers() method, are removed and the code there inlined.
>+
>+        For image-backed layers, the update is now done directly in
>+        the flushCompositingStateForThisLayerOnly() method, if necessary. The
>+        helper syncImageBacking() method is commented out in order to prevent
>+        double-painting of image buffers for now, but all this (along with the
>+        CoordinatedImageBacking logic in CompositingCoordinator) will be removed
>+        later.
>+
>+        For layers backed by platform layer objects, integration is relatively
>+        simple. setContentsToPlatformLayer() is changed to properly handle any
>+        passed-in platform layer object, and updatePlatformLayer() invokes the
>+        swapBuffersIfNeeded() method on the ContentLayerTextureMapperImpl object
>+        during each flush, if necessary.
>+
>+        In order to ensure any Nicosia-specific state update properly triggers
>+        a composition update, m_nicosia.performLayerUpdate is added and flipped
>+        to true during the flush in case of any state change. This then triggers
>+        a layer sync in the CompositingCoordinator object when the
>+        syncPendingStateChangesIncludingSubLayers() method is called. While no
>+        old-style layer state update is provided, it causes the necessary
>+        synchronization step that properly picks up the Nicosia-provided state
>+        changes. Once the old-style layer state tracking is removed, this method
>+        of update triggering will have to be updated as well.
>+
>+        * platform/graphics/nicosia/NicosiaPlatformLayer.h:
>+        (Nicosia::CompositionLayer::flushState):
>+        (Nicosia::CompositionLayer::commitState):
>+        (Nicosia::CompositionLayer::accessCommitted):
>+        * platform/graphics/nicosia/NicosiaScene.h:
>+        * platform/graphics/nicosia/texmap/NicosiaContentLayerTextureMapperImpl.cpp:
>+        (Nicosia::ContentLayerTextureMapperImpl::flushUpdate):
>+        * platform/graphics/nicosia/texmap/NicosiaContentLayerTextureMapperImpl.h:
>+        * platform/graphics/texmap/coordinated/CoordinatedGraphicsLayer.cpp:
>+        (WebCore::CoordinatedGraphicsLayer::~CoordinatedGraphicsLayer):
>+        (WebCore::CoordinatedGraphicsLayer::setContentsNeedsDisplay):
>+        (WebCore::CoordinatedGraphicsLayer::setContentsToPlatformLayer):
>+        (WebCore::CoordinatedGraphicsLayer::updatePlatformLayer):
>+        (WebCore::CoordinatedGraphicsLayer::flushCompositingStateForThisLayerOnly):
>+        (WebCore::CoordinatedGraphicsLayer::syncPendingStateChangesIncludingSubLayers):
>+        (WebCore::CoordinatedGraphicsLayer::updateContentBuffers):
>+        (WebCore::CoordinatedGraphicsLayer::purgeBackingStores):
>+        (WebCore::CoordinatedGraphicsLayer::adjustContentsScale): Deleted.
>+        (WebCore::CoordinatedGraphicsLayer::createBackingStore): Deleted.
>+        * platform/graphics/texmap/coordinated/CoordinatedGraphicsLayer.h:
>+
> 2018-08-22  Carlos Garcia Campos  <cgarcia@igalia.com>
> 
>         Do not try to update the compositing policy when not in accelerated compositing mode
>diff --git a/Source/WebKit/ChangeLog b/Source/WebKit/ChangeLog
>index 79bf5ede8143744914254805390650332e5d62e9..1e55404ed4cb65ed837f77c4275bc6ce92c4e6a1 100644
>--- a/Source/WebKit/ChangeLog
>+++ b/Source/WebKit/ChangeLog
>@@ -1,3 +1,82 @@
>+2018-08-22  Zan Dobersek  <zdobersek@igalia.com>
>+
>+        [CoordGraphics] Switch to Nicosia::CompositionLayer state tracking
>+        https://bugs.webkit.org/show_bug.cgi?id=188693
>+
>+        Reviewed by Carlos Garcia Campos.
>+
>+        Switch CoordinatedGraphicsScene to utilizing Nicosia::CompositionLayer
>+        objects for state updates of the TextureMapper layer tree.
>+
>+        CoordinatedGraphicsScene::paintToCurrentGLContext() now calls
>+        updateSceneState() at the beginning. This is a new method that manages
>+        all updates for a given Nicosia::Scene instance. Any removed layers
>+        have their composition-side state cleaned up, and the current set of
>+        layers is then iterated to ensure and update the corresponding
>+        TextureMapperLayer objects.
>+
>+        Layers with any backing (painted backing store, platform-layer or image
>+        content) are temporarly stored for updating outside of mutex-controlled
>+        scene update. Performing all other state updates outside of this mutex
>+        area will be investigated at a later point.
>+
>+        We then iterate over vectors for each layer backing, gathering any
>+        affected CoordinatedBackingStore or TextureMapperPlatformLayerProxy
>+        objects that we have to update.
>+
>+        This drops a bunch of member variables and helper methods off the
>+        CoordinatedGraphicsScene class. The applyStateChanges() method will be
>+        further simplified in the future. coordinateUpdateCompletionWithClient
>+        logic in ThreadedCompositor should be checked to see whether it still
>+        addresses any real-life problem, because at the moment it imposes a few
>+        additional operations in terms of scene updates that we could really do
>+        without. This will be checked later and removed if possible.
>+
>+        * Shared/CoordinatedGraphics/CoordinatedGraphicsScene.cpp:
>+        (WebKit::CoordinatedGraphicsScene::applyStateChanges):
>+        (WebKit::CoordinatedGraphicsScene::paintToCurrentGLContext):
>+        (WebKit::compositionLayerImpl):
>+        (WebKit::contentLayerImpl):
>+        (WebKit::backingStoreImpl):
>+        (WebKit::imageBackingImpl):
>+        (WebKit::texmapLayer):
>+        (WebKit::updateBackingStore):
>+        (WebKit::updateImageBacking):
>+        (WebKit::removeLayer):
>+        (WebKit::CoordinatedGraphicsScene::commitSceneState):
>+        (WebKit::CoordinatedGraphicsScene::updateSceneState):
>+        (WebKit::CoordinatedGraphicsScene::purgeGLResources):
>+        (WebKit::CoordinatedGraphicsScene::syncPlatformLayerIfNeeded): Deleted.
>+        (WebKit::CoordinatedGraphicsScene::setLayerChildrenIfNeeded): Deleted.
>+        (WebKit::CoordinatedGraphicsScene::setLayerFiltersIfNeeded): Deleted.
>+        (WebKit::CoordinatedGraphicsScene::setLayerState): Deleted.
>+        (WebKit::CoordinatedGraphicsScene::getLayerByIDIfExists): Deleted.
>+        (WebKit::CoordinatedGraphicsScene::createLayers): Deleted.
>+        (WebKit::CoordinatedGraphicsScene::createLayer): Deleted.
>+        (WebKit::CoordinatedGraphicsScene::deleteLayers): Deleted.
>+        (WebKit::CoordinatedGraphicsScene::deleteLayer): Deleted.
>+        (WebKit::CoordinatedGraphicsScene::setRootLayerID): Deleted.
>+        (WebKit::CoordinatedGraphicsScene::prepareContentBackingStore): Deleted.
>+        (WebKit::CoordinatedGraphicsScene::createBackingStoreIfNeeded): Deleted.
>+        (WebKit::CoordinatedGraphicsScene::removeBackingStoreIfNeeded): Deleted.
>+        (WebKit::CoordinatedGraphicsScene::resetBackingStoreSizeToLayerSize): Deleted.
>+        (WebKit::CoordinatedGraphicsScene::createTilesIfNeeded): Deleted.
>+        (WebKit::CoordinatedGraphicsScene::removeTilesIfNeeded): Deleted.
>+        (WebKit::CoordinatedGraphicsScene::updateTilesIfNeeded): Deleted.
>+        (WebKit::CoordinatedGraphicsScene::syncImageBackings): Deleted.
>+        (WebKit::CoordinatedGraphicsScene::createImageBacking): Deleted.
>+        (WebKit::CoordinatedGraphicsScene::updateImageBacking): Deleted.
>+        (WebKit::CoordinatedGraphicsScene::clearImageBackingContents): Deleted.
>+        (WebKit::CoordinatedGraphicsScene::removeImageBacking): Deleted.
>+        (WebKit::CoordinatedGraphicsScene::assignImageBackingToLayer): Deleted.
>+        (WebKit::CoordinatedGraphicsScene::setLayerAnimationsIfNeeded): Deleted.
>+        * Shared/CoordinatedGraphics/CoordinatedGraphicsScene.h:
>+        (WebKit::CoordinatedGraphicsScene::layerByID): Deleted.
>+        * Shared/CoordinatedGraphics/threadedcompositor/ThreadedCompositor.cpp:
>+        (WebKit::ThreadedCompositor::renderLayerTree):
>+        * WebProcess/WebPage/CoordinatedGraphics/CompositingCoordinator.cpp:
>+        (WebKit::CompositingCoordinator::flushPendingLayerChanges):
>+
> 2018-08-21  Ryosuke Niwa  <rniwa@webkit.org>
> 
>         Replace booleans for modifier keys in UIEventWithKeyState with OptionSet<Modifier>
>diff --git a/Source/WebCore/platform/graphics/nicosia/NicosiaPlatformLayer.h b/Source/WebCore/platform/graphics/nicosia/NicosiaPlatformLayer.h
>index 780aceb7274447d9e493588e09c843d7200e2994..49f22db4d1d7b9d72126fd3b86d6bacb123a971d 100644
>--- a/Source/WebCore/platform/graphics/nicosia/NicosiaPlatformLayer.h
>+++ b/Source/WebCore/platform/graphics/nicosia/NicosiaPlatformLayer.h
>@@ -180,6 +180,88 @@ public:
>         functor(m_state.pending);
>     }
> 
>+    template<typename T>
>+    void flushState(const T& functor)
>+    {
>+        LockHolder locker(PlatformLayer::m_state.lock);
>+        auto& pending = m_state.pending;
>+        auto& staging = m_state.staging;
>+
>+        staging.delta.value |= pending.delta.value;
>+
>+        if (pending.delta.positionChanged)
>+            staging.position = pending.position;
>+        if (pending.delta.anchorPointChanged)
>+            staging.anchorPoint = pending.anchorPoint;
>+        if (pending.delta.sizeChanged)
>+            staging.size = pending.size;
>+
>+        if (pending.delta.transformChanged)
>+            staging.transform = pending.transform;
>+        if (pending.delta.childrenTransformChanged)
>+            staging.childrenTransform = pending.childrenTransform;
>+
>+        if (pending.delta.contentsRectChanged)
>+            staging.contentsRect = pending.contentsRect;
>+        if (pending.delta.contentsTilingChanged) {
>+            staging.contentsTilePhase = pending.contentsTilePhase;
>+            staging.contentsTileSize = pending.contentsTileSize;
>+        }
>+
>+        if (pending.delta.opacityChanged)
>+            staging.opacity = pending.opacity;
>+        if (pending.delta.solidColorChanged)
>+            staging.solidColor = pending.solidColor;
>+
>+        if (pending.delta.filtersChanged)
>+            staging.filters = pending.filters;
>+        if (pending.delta.animationsChanged)
>+            staging.animations = pending.animations;
>+
>+        if (pending.delta.childrenChanged)
>+            staging.children = pending.children;
>+        if (pending.delta.maskChanged)
>+            staging.mask = pending.mask;
>+        if (pending.delta.replicaChanged)
>+            staging.replica = pending.replica;
>+
>+        if (pending.delta.flagsChanged)
>+            staging.flags.value = pending.flags.value;
>+
>+        if (pending.delta.repaintCounterChanged)
>+            staging.repaintCounter = pending.repaintCounter;
>+        if (pending.delta.debugBorderChanged)
>+            staging.debugBorder = pending.debugBorder;
>+
>+        if (pending.delta.backingStoreChanged)
>+            staging.backingStore = pending.backingStore;
>+        if (pending.delta.contentLayerChanged)
>+            staging.contentLayer = pending.contentLayer;
>+        if (pending.delta.imageBackingChanged)
>+            staging.imageBacking = pending.imageBacking;
>+
>+        pending.delta = { };
>+
>+        functor(staging);
>+    }
>+
>+    template<typename T>
>+    void commitState(const T& functor)
>+    {
>+        LockHolder locker(PlatformLayer::m_state.lock);
>+        m_state.committed = m_state.staging;
>+        m_state.staging.delta = { };
>+
>+        functor(m_state.committed);
>+    }
>+
>+    template<typename T>
>+    void accessCommitted(const T& functor)
>+    {
>+        LockHolder locker(PlatformLayer::m_state.lock);
>+        functor(m_state.committed);
>+    }
>+
> private:
>     CompositionLayer(uint64_t, const Impl::Factory&);
> 
>@@ -187,6 +269,8 @@ private:
> 
>     struct {
>         LayerState pending;
>+        LayerState staging;
>+        LayerState committed;
>     } m_state;
> };
> 
>diff --git a/Source/WebCore/platform/graphics/nicosia/NicosiaScene.h b/Source/WebCore/platform/graphics/nicosia/NicosiaScene.h
>index c3a363372a2953f1d9db4428895384256357d0ac..6f281dcb3c9a49f0b44e48d7a634cde31767e258 100644
>--- a/Source/WebCore/platform/graphics/nicosia/NicosiaScene.h
>+++ b/Source/WebCore/platform/graphics/nicosia/NicosiaScene.h
>@@ -51,6 +51,10 @@ public:
>         ~State();
> 
>         uint32_t id { 0 };
>+        // FIXME: This is needed for a ThreadedCompositor oddity that might not even be
>+        // necessary anymore. It that has to be checked and ideally removed.
>+        // https://bugs.webkit.org/show_bug.cgi?id=188839
>+        bool platformLayerUpdated { false };
>         HashSet<RefPtr<Nicosia::CompositionLayer>> layers;
>         RefPtr<Nicosia::CompositionLayer> rootLayer;
>     };
>diff --git a/Source/WebCore/platform/graphics/nicosia/texmap/NicosiaContentLayerTextureMapperImpl.cpp b/Source/WebCore/platform/graphics/nicosia/texmap/NicosiaContentLayerTextureMapperImpl.cpp
>index 68c4396bc82b697b89bb4d67ec08877efc1bf8cd..561728b5ef1f40d80c535992671066ad874819a7 100644
>--- a/Source/WebCore/platform/graphics/nicosia/texmap/NicosiaContentLayerTextureMapperImpl.cpp
>+++ b/Source/WebCore/platform/graphics/nicosia/texmap/NicosiaContentLayerTextureMapperImpl.cpp
>@@ -63,6 +63,12 @@ void ContentLayerTextureMapperImpl::invalidateClient()
>     m_client.client = nullptr;
> }
> 
>+bool ContentLayerTextureMapperImpl::flushUpdate()
>+{
>+    LockHolder locker(m_client.lock);
>+    return std::exchange(m_client.pendingUpdate, false);
>+}
>+
> void ContentLayerTextureMapperImpl::swapBuffersIfNeeded()
> {
>     LockHolder locker(m_client.lock);
>diff --git a/Source/WebCore/platform/graphics/nicosia/texmap/NicosiaContentLayerTextureMapperImpl.h b/Source/WebCore/platform/graphics/nicosia/texmap/NicosiaContentLayerTextureMapperImpl.h
>index 2ef0da2027d772dfb04f1969c900ce7db862ae36..ef96a6083162de41c27de4bf357b8a4fcaf8d9cf 100644
>--- a/Source/WebCore/platform/graphics/nicosia/texmap/NicosiaContentLayerTextureMapperImpl.h
>+++ b/Source/WebCore/platform/graphics/nicosia/texmap/NicosiaContentLayerTextureMapperImpl.h
>@@ -56,6 +56,8 @@ public:
> 
>     void invalidateClient();
> 
>+    bool flushUpdate();
>+
>     WebCore::TextureMapperPlatformLayerProxy& proxy() const { return m_proxy; }
>     void swapBuffersIfNeeded();
> 
>@@ -64,6 +66,7 @@ private:
>     struct {
>         Lock lock;
>         Client* client { nullptr };
>+        bool pendingUpdate { true }; // Starts off with a pending update.
>     } m_client;
> };
> 
>diff --git a/Source/WebCore/platform/graphics/texmap/coordinated/CoordinatedGraphicsLayer.cpp b/Source/WebCore/platform/graphics/texmap/coordinated/CoordinatedGraphicsLayer.cpp
>index be21680fbd2b191939dae5a0ca5f29f4b69d80d0..59db0f592ad8bb9496412fb9846fdb6cce3f81e6 100644
>--- a/Source/WebCore/platform/graphics/texmap/coordinated/CoordinatedGraphicsLayer.cpp
>+++ b/Source/WebCore/platform/graphics/texmap/coordinated/CoordinatedGraphicsLayer.cpp
>@@ -30,7 +30,11 @@
> #include "GraphicsContext.h"
> #include "GraphicsLayer.h"
> #include "GraphicsLayerFactory.h"
>+#include "NicosiaBackingStoreTextureMapperImpl.h"
> #include "NicosiaCompositionLayerTextureMapperImpl.h"
>+#include "NicosiaContentLayerTextureMapperImpl.h"
>+#include "NicosiaImageBackingTextureMapperImpl.h"
>+#include "NicosiaPaintingContext.h"
> #include "NicosiaPaintingEngine.h"
> #include "ScrollableArea.h"
> #include "TextureMapperPlatformLayerProxyProvider.h"
>@@ -160,6 +164,8 @@ CoordinatedGraphicsLayer::~CoordinatedGraphicsLayer()
>     }
>     ASSERT(!m_coordinatedImageBacking);
>     ASSERT(!m_mainBackingStore);
>+    ASSERT(!m_nicosia.imageBacking);
>+    ASSERT(!m_nicosia.backingStore);
>     willBeDestroyed();
> }
> 
>@@ -421,8 +427,13 @@ bool GraphicsLayer::supportsContentsTiling()
> void CoordinatedGraphicsLayer::setContentsNeedsDisplay()
> {
> #if USE(COORDINATED_GRAPHICS_THREADED)
>+#if USE(NICOSIA)
>+    if (m_nicosia.contentLayer)
>+        m_shouldUpdatePlatformLayer = true;
>+#else
>     if (m_platformLayer)
>         m_shouldUpdatePlatformLayer = true;
>+#endif
> #endif
> 
>     notifyFlushRequired();
>@@ -433,6 +444,12 @@ void CoordinatedGraphicsLayer::setContentsToPlatformLayer(PlatformLayer* platfor
> {
> #if USE(COORDINATED_GRAPHICS_THREADED)
> #if USE(NICOSIA)
>+    auto* contentLayer = downcast<Nicosia::ContentLayer>(platformLayer);
>+    if (m_nicosia.contentLayer != contentLayer) {
>+        m_shouldSyncPlatformLayer = true;
>+        m_nicosia.contentLayer = contentLayer;
>+        m_nicosia.delta.contentLayerChanged = true;
>+    }
> #else
>     if (m_platformLayer != platformLayer)
>         m_shouldSyncPlatformLayer = true;
>@@ -767,6 +784,8 @@ void CoordinatedGraphicsLayer::updatePlatformLayer()
>     m_shouldUpdatePlatformLayer = false;
> #if USE(COORDINATED_GRAPHICS_THREADED)
> #if USE(NICOSIA)
>+    if (m_nicosia.contentLayer)
>+        downcast<Nicosia::ContentLayerTextureMapperImpl>(m_nicosia.contentLayer->impl()).swapBuffersIfNeeded();
> #else
>     m_layerState.platformLayerUpdated = true;
>     if (m_platformLayer)
>@@ -785,7 +804,10 @@ void CoordinatedGraphicsLayer::flushCompositingStateForThisLayerOnly()
>     // Sets the values.
>     computePixelAlignment(m_adjustedPosition, m_adjustedSize, m_adjustedAnchorPoint, m_pixelAlignmentOffset);
> 
>-    syncImageBacking();
>+    // FIXME: this is commented out to immediately disable any old-way image updates.
>+    // It will soon be removed in a larger cleanup.
>+    // syncImageBacking();
>+
>     syncLayerState();
>     syncAnimations();
>     computeTransformedVisibleRect();
>@@ -798,6 +820,67 @@ void CoordinatedGraphicsLayer::flushCompositingStateForThisLayerOnly()
>     if (!hasActiveTransformAnimation)
>         m_movingVisibleRect = false;
> 
>+    // Determine the backing store presence. Content is painted later, in the updateContentBuffers() traversal.
>+    if (shouldHaveBackingStore()) {
>+        if (!m_nicosia.backingStore) {
>+            m_nicosia.backingStore = Nicosia::BackingStore::create(Nicosia::BackingStoreTextureMapperImpl::createFactory());
>+            m_nicosia.delta.backingStoreChanged = true;
>+        }
>+    } else if (m_nicosia.backingStore) {
>+        auto& layerState = downcast<Nicosia::BackingStoreTextureMapperImpl>(m_nicosia.backingStore->impl()).layerState();
>+        layerState.isPurging = true;
>+        layerState.mainBackingStore = nullptr;
>+        layerState.previousBackingStore = nullptr;
>+
>+        m_nicosia.backingStore = nullptr;
>+        m_nicosia.delta.backingStoreChanged = true;
>+    }
>+
>+    // Determine image backing presence according to the composited image source.
>+    if (m_compositedNativeImagePtr) {
>+        ASSERT(m_compositedImage);
>+        auto& image = *m_compositedImage;
>+        uintptr_t imageID = reinterpret_cast<uintptr_t>(&image);
>+        uintptr_t nativeImageID = reinterpret_cast<uintptr_t>(m_compositedNativeImagePtr.get());
>+
>+        // Respawn the ImageBacking object if the underlying image changed.
>+        if (m_nicosia.imageBacking) {
>+            auto& impl = downcast<Nicosia::ImageBackingTextureMapperImpl>(m_nicosia.imageBacking->impl());
>+            if (impl.layerState().imageID != imageID) {
>+                impl.layerState().update = Nicosia::ImageBackingTextureMapperImpl::Update { };
>+                m_nicosia.imageBacking = nullptr;
>+            }
>+        }
>+        if (!m_nicosia.imageBacking) {
>+            m_nicosia.imageBacking = Nicosia::ImageBacking::create(Nicosia::ImageBackingTextureMapperImpl::createFactory());
>+            m_nicosia.delta.imageBackingChanged = true;
>+        }
>+
>+        // Update the image contents only when the image layer is visible and the native image changed.
>+        auto& impl = downcast<Nicosia::ImageBackingTextureMapperImpl>(m_nicosia.imageBacking->impl());
>+        auto& layerState = impl.layerState();
>+        layerState.imageID = imageID;
>+        layerState.update.isVisible = transformedVisibleRect().intersects(IntRect(contentsRect()));
>+        if (layerState.update.isVisible && layerState.nativeImageID != nativeImageID) {
>+            auto buffer = Nicosia::Buffer::create(IntSize(image.size()),
>+                !image.currentFrameKnownToBeOpaque() ? Nicosia::Buffer::SupportsAlpha : Nicosia::Buffer::NoFlags);
>+            Nicosia::PaintingContext::paint(buffer,
>+                [&image](GraphicsContext& context)
>+                {
>+                    IntRect rect { { }, IntSize { image.size() } };
>+                    context.drawImage(image, rect, rect, ImagePaintingOptions(CompositeCopy));
>+                });
>+            layerState.nativeImageID = nativeImageID;
>+            layerState.update.buffer = WTFMove(buffer);
>+            m_nicosia.delta.imageBackingChanged = true;
>+        }
>+    } else if (m_nicosia.imageBacking) {
>+        auto& layerState = downcast<Nicosia::ImageBackingTextureMapperImpl>(m_nicosia.imageBacking->impl()).layerState();
>+        layerState.update = Nicosia::ImageBackingTextureMapperImpl::Update { };
>+        m_nicosia.imageBacking = nullptr;
>+        m_nicosia.delta.imageBackingChanged = true;
>+    }
>+
>     {
>         m_nicosia.layer->updateState(
>             [this](Nicosia::CompositionLayer::LayerState& state)
>@@ -867,17 +950,29 @@ void CoordinatedGraphicsLayer::flushCompositingStateForThisLayerOnly()
>                     state.repaintCounter = m_nicosia.repaintCounter;
>                 if (localDelta.debugBorderChanged)
>                     state.debugBorder = m_nicosia.debugBorder;
>+
>+                if (localDelta.backingStoreChanged)
>+                    state.backingStore = m_nicosia.backingStore;
>+                if (localDelta.contentLayerChanged)
>+                    state.contentLayer = m_nicosia.contentLayer;
>+                if (localDelta.imageBackingChanged)
>+                    state.imageBacking = m_nicosia.imageBacking;
>             });
>+        m_nicosia.performLayerSync = !!m_nicosia.delta.value;
>         m_nicosia.delta = { };
>     }
> }
> 
> void CoordinatedGraphicsLayer::syncPendingStateChangesIncludingSubLayers()
> {
>-    if (m_layerState.hasPendingChanges()) {
>+    // FIXME: For now the best way for layer state changes to trigger an update is to use
>+    // the CoordinatedGraphicsLayerClient::syncLayerState() method. This should be simplified
>+    // once the m_layerState member object is removed.
>+    if (m_nicosia.performLayerSync || m_layerState.hasPendingChanges()) {
>         m_coordinator->syncLayerState(m_id, m_layerState);
>         resetLayerState();
>     }
>+    m_nicosia.performLayerSync = false;
> 
>     if (maskLayer())
>         downcast<CoordinatedGraphicsLayer>(*maskLayer()).syncPendingStateChangesIncludingSubLayers();
>@@ -923,27 +1018,6 @@ float CoordinatedGraphicsLayer::effectiveContentsScale()
>     return selfOrAncestorHaveNonAffineTransforms() ? 1 : deviceScaleFactor() * pageScaleFactor();
> }
> 
>-void CoordinatedGraphicsLayer::adjustContentsScale()
>-{
>-    ASSERT(shouldHaveBackingStore());
>-    if (!m_mainBackingStore || m_mainBackingStore->contentsScale() == effectiveContentsScale())
>-        return;
>-
>-    // Between creating the new backing store and painting the content,
>-    // we do not want to drop the previous one as that might result in
>-    // briefly seeing flickering as the old tiles may be dropped before
>-    // something replaces them.
>-    m_previousBackingStore = WTFMove(m_mainBackingStore);
>-
>-    // No reason to save the previous backing store for non-visible areas.
>-    m_previousBackingStore->removeAllNonVisibleTiles(transformedVisibleRect(), IntRect(0, 0, size().width(), size().height()));
>-}
>-
>-void CoordinatedGraphicsLayer::createBackingStore()
>-{
>-    m_mainBackingStore = std::make_unique<TiledBackingStore>(*this, effectiveContentsScale());
>-}
>-
> void CoordinatedGraphicsLayer::tiledBackingStoreHasPendingTileCreation()
> {
>     setNeedsVisibleRectAdjustment();
>@@ -1024,44 +1098,70 @@ void CoordinatedGraphicsLayer::updateContentBuffersIncludingSubLayers()
> 
> void CoordinatedGraphicsLayer::updateContentBuffers()
> {
>-    if (!shouldHaveBackingStore()) {
>-        m_mainBackingStore = nullptr;
>-        m_previousBackingStore = nullptr;
>+    if (!m_nicosia.backingStore)
>         return;
>-    }
> 
>+    // Prepare for painting on the impl-contained backing store. isFlushing is used there
>+    // for internal sanity checks.
>+    auto& impl = downcast<Nicosia::BackingStoreTextureMapperImpl>(m_nicosia.backingStore->impl());
>+    auto& layerState = impl.layerState();
>+    layerState.isFlushing = true;
>+
>+    // Helper lambda that finished the flush update and determines layer sync necessity.
>+    auto finishUpdate =
>+        [this, &layerState] {
>+            auto& update = layerState.update;
>+            m_nicosia.performLayerSync = !update.tilesToCreate.isEmpty()
>+                || !update.tilesToRemove.isEmpty() || !update.tilesToUpdate.isEmpty();
>+            layerState.isFlushing = false;
>+        };
>+
>+    // Address the content scale adjustment.
>+    // FIXME: the previousBackingStore logic is likely possible to remove.
>+    // https://bugs.webkit.org/show_bug.cgi?id=188693
>     if (m_pendingContentsScaleAdjustment) {
>-        adjustContentsScale();
>+        if (layerState.mainBackingStore && layerState.mainBackingStore->contentsScale() != effectiveContentsScale()) {
>+            // Between creating the new backing store and painting the content, we do not
>+            // want to drop the previous one as that might result in briefly seeing flickering
>+            // as the old tiles may be dropped before something replaces them.
>+            layerState.previousBackingStore = WTFMove(layerState.mainBackingStore);
>+
>+            // No reason to save the previous backing store for non-visible areas.
>+            layerState.previousBackingStore->removeAllNonVisibleTiles(transformedVisibleRect(), IntRect(0, 0, size().width(), size().height()));
>+        }
>         m_pendingContentsScaleAdjustment = false;
>     }
> 
>-    // This is the only place we (re)create the main tiled backing store, once we
>-    // have a remote client and we are ready to send our data to the UI process.
>-    if (!m_mainBackingStore) {
>-        createBackingStore();
>+    // Ensure the TiledBackingStore object, and enforce a complete repaint if it's not been present yet.
>+    if (!layerState.mainBackingStore) {
>+        layerState.mainBackingStore = std::make_unique<TiledBackingStore>(impl, effectiveContentsScale());
>         m_pendingVisibleRectAdjustment = true;
>     }
> 
>-    if (!m_pendingVisibleRectAdjustment && !m_needsDisplay.completeLayer && m_needsDisplay.rects.isEmpty())
>+    // Bail if there's no painting recorded or enforced.
>+    if (!m_pendingVisibleRectAdjustment && !m_needsDisplay.completeLayer && m_needsDisplay.rects.isEmpty()) {
>+        finishUpdate();
>         return;
>+    }
> 
>     if (!m_needsDisplay.completeLayer) {
>         for (auto& rect : m_needsDisplay.rects)
>-            m_mainBackingStore->invalidate(IntRect { rect });
>+            layerState.mainBackingStore->invalidate(IntRect { rect });
>     } else
>-        m_mainBackingStore->invalidate({ { }, IntSize { m_size } });
>+        layerState.mainBackingStore->invalidate({ { }, IntSize { m_size } });
> 
>     m_needsDisplay.completeLayer = false;
>     m_needsDisplay.rects.clear();
> 
>     if (m_pendingVisibleRectAdjustment) {
>         m_pendingVisibleRectAdjustment = false;
>-        m_mainBackingStore->createTilesIfNeeded(transformedVisibleRect(), IntRect(0, 0, size().width(), size().height()));
>+        layerState.mainBackingStore->createTilesIfNeeded(transformedVisibleRect(), IntRect(0, 0, m_size.width(), m_size.height()));
>     }
> 
>     ASSERT(m_coordinator && m_coordinator->isFlushingLayerChanges());
> 
>-    auto dirtyTiles = m_mainBackingStore->dirtyTiles();
>+    // With all the affected tiles created and/or invalidated, we can finally paint them.
>+    auto dirtyTiles = layerState.mainBackingStore->dirtyTiles();
>     if (!dirtyTiles.isEmpty()) {
>         bool didUpdateTiles = false;
> 
>@@ -1079,11 +1179,11 @@ void CoordinatedGraphicsLayer::updateContentBuffers()
>             updateInfo.buffer = coordinatedBuffer.copyRef();
> 
>             if (!m_coordinator->paintingEngine().paint(*this, WTFMove(coordinatedBuffer),
>-                dirtyRect, m_mainBackingStore->mapToContents(dirtyRect),
>-                IntRect { { 0, 0 }, dirtyRect.size() }, m_mainBackingStore->contentsScale()))
>+                dirtyRect, layerState.mainBackingStore->mapToContents(dirtyRect),
>+                IntRect { { 0, 0 }, dirtyRect.size() }, layerState.mainBackingStore->contentsScale()))
>                 continue;
> 
>-            updateTile(tile.tileID(), updateInfo, tileRect);
>+            impl.updateTile(tile.tileID(), updateInfo, tileRect);
> 
>             tile.markClean();
>             didUpdateTiles |= true;
>@@ -1096,8 +1196,16 @@ void CoordinatedGraphicsLayer::updateContentBuffers()
>     // The previous backing store is kept around to avoid flickering between
>     // removing the existing tiles and painting the new ones. The first time
>     // the visibleRect is full painted we remove the previous backing store.
>-    if (m_previousBackingStore && m_mainBackingStore->visibleAreaIsCovered())
>-        m_previousBackingStore = nullptr;
>+    if (layerState.previousBackingStore && layerState.mainBackingStore->visibleAreaIsCovered())
>+        layerState.previousBackingStore = nullptr;
>+
>+    // Request a second update immediately if some tiles are still pending creation.
>+    if (layerState.hasPendingTileCreation) {
>+        setNeedsVisibleRectAdjustment();
>+        notifyFlushRequired();
>+    }
>+
>+    finishUpdate();
> }
> 
> void CoordinatedGraphicsLayer::purgeBackingStores()
>@@ -1107,6 +1215,14 @@ void CoordinatedGraphicsLayer::purgeBackingStores()
> #endif
>     m_mainBackingStore = nullptr;
>     m_previousBackingStore = nullptr;
>+    if (m_nicosia.backingStore) {
>+        auto& layerState = downcast<Nicosia::BackingStoreTextureMapperImpl>(m_nicosia.backingStore->impl()).layerState();
>+        layerState.isPurging = true;
>+        layerState.mainBackingStore = nullptr;
>+        layerState.previousBackingStore = nullptr;
>+
>+        m_nicosia.backingStore = nullptr;
>+    }
> 
>     releaseImageBackingIfNeeded();
> 
>diff --git a/Source/WebCore/platform/graphics/texmap/coordinated/CoordinatedGraphicsLayer.h b/Source/WebCore/platform/graphics/texmap/coordinated/CoordinatedGraphicsLayer.h
>index 8b9f9a9227884b887f73e33ac3a7868767800171..7d6b66db3d2e19adc3e66c3da947112b8c894746 100644
>--- a/Source/WebCore/platform/graphics/texmap/coordinated/CoordinatedGraphicsLayer.h
>+++ b/Source/WebCore/platform/graphics/texmap/coordinated/CoordinatedGraphicsLayer.h
>@@ -110,7 +110,7 @@ public:
>     void removeAnimation(const String&) override;
>     void suspendAnimations(MonotonicTime) override;
>     void resumeAnimations() override;
>-    bool usesContentsLayer() const override { return m_platformLayer || m_compositedImage; }
>+    bool usesContentsLayer() const override { return m_platformLayer || m_nicosia.contentLayer || m_compositedImage; }
> 
>     void syncPendingStateChangesIncludingSubLayers();
>     void updateContentBuffersIncludingSubLayers();
>@@ -161,7 +161,6 @@ private:
>     void computeTransformedVisibleRect();
>     void updateContentBuffers();
> 
>-    void createBackingStore();
>     void releaseImageBackingIfNeeded();
> 
>     void notifyFlushRequired();
>@@ -171,7 +170,6 @@ private:
>     bool shouldHaveBackingStore() const;
>     bool selfOrAncestorHasActiveTransformAnimation() const;
>     bool selfOrAncestorHaveNonAffineTransforms();
>-    void adjustContentsScale();
> 
>     void setShouldUpdateVisibleRect();
>     float effectiveContentsScale();
>@@ -231,6 +229,11 @@ private:
>         Nicosia::CompositionLayer::LayerState::Delta delta;
>         Nicosia::CompositionLayer::LayerState::RepaintCounter repaintCounter;
>         Nicosia::CompositionLayer::LayerState::DebugBorder debugBorder;
>+        bool performLayerSync { false };
>+
>+        RefPtr<Nicosia::BackingStore> backingStore;
>+        RefPtr<Nicosia::ContentLayer> contentLayer;
>+        RefPtr<Nicosia::ImageBacking> imageBacking;
>     } m_nicosia;
> };
> 
>diff --git a/Source/WebKit/Shared/CoordinatedGraphics/CoordinatedGraphicsScene.cpp b/Source/WebKit/Shared/CoordinatedGraphics/CoordinatedGraphicsScene.cpp
>index fea28ea0b06f58fa38d3916081fcaaa1b3728e3c..56926a2f4b69cd88943bb8e1cb8b09c0da782a82 100644
>--- a/Source/WebKit/Shared/CoordinatedGraphics/CoordinatedGraphicsScene.cpp
>+++ b/Source/WebKit/Shared/CoordinatedGraphics/CoordinatedGraphicsScene.cpp
>@@ -25,7 +25,12 @@
> #if USE(COORDINATED_GRAPHICS)
> 
> #include <WebCore/CoordinatedBackingStore.h>
>+#include <WebCore/NicosiaBackingStoreTextureMapperImpl.h>
> #include <WebCore/NicosiaBuffer.h>
>+#include <WebCore/NicosiaCompositionLayerTextureMapperImpl.h>
>+#include <WebCore/NicosiaContentLayerTextureMapperImpl.h>
>+#include <WebCore/NicosiaImageBackingTextureMapperImpl.h>
>+#include <WebCore/NicosiaScene.h>
> #include <WebCore/TextureMapper.h>
> #include <WebCore/TextureMapperBackingStore.h>
> #include <WebCore/TextureMapperGL.h>
>@@ -57,20 +62,17 @@ void CoordinatedGraphicsScene::applyStateChanges(const Vector<CoordinatedGraphic
>     ensureRootLayer();
> 
>     for (auto& state : states)
>-        commitSceneState(state);
>+        commitSceneState(state.nicosia);
> }
> 
> void CoordinatedGraphicsScene::paintToCurrentGLContext(const TransformationMatrix& matrix, float opacity, const FloatRect& clipRect, const Color& backgroundColor, bool drawsBackground, TextureMapper::PaintFlags PaintFlags)
> {
>+    updateSceneState();
>+
>     TextureMapperLayer* currentRootLayer = rootLayer();
>     if (!currentRootLayer)
>         return;
> 
>-#if USE(COORDINATED_GRAPHICS_THREADED)
>-    for (auto& proxy : m_platformLayerProxies.values())
>-        proxy->swapBuffer();
>-#endif
>-
>     currentRootLayer->setTextureMapper(m_textureMapper.get());
>     bool sceneHasRunningAnimations = currentRootLayer->applyAnimationsRecursively(MonotonicTime::now());
>     m_textureMapper->beginPainting(PaintFlags);
>@@ -104,23 +106,6 @@ void CoordinatedGraphicsScene::updateViewport()
>         m_client->updateViewport();
> }
> 
>-void CoordinatedGraphicsScene::syncPlatformLayerIfNeeded(TextureMapperLayer* layer, const CoordinatedGraphicsLayerState& state)
>-{
>-#if USE(COORDINATED_GRAPHICS_THREADED)
>-    if (!state.platformLayerChanged)
>-        return;
>-
>-    if (state.platformLayerProxy) {
>-        m_platformLayerProxies.set(layer, state.platformLayerProxy);
>-        state.platformLayerProxy->activateOnCompositingThread(this, layer);
>-    } else
>-        m_platformLayerProxies.remove(layer);
>-#else
>-    UNUSED_PARAM(layer);
>-    UNUSED_PARAM(state);
>-#endif
>-}
>-
> #if USE(COORDINATED_GRAPHICS_THREADED)
> void CoordinatedGraphicsScene::onNewBufferAvailable()
> {
>@@ -128,320 +113,305 @@ void CoordinatedGraphicsScene::onNewBufferAvailable()
> }
> #endif
> 
>-void CoordinatedGraphicsScene::setLayerChildrenIfNeeded(TextureMapperLayer* layer, const CoordinatedGraphicsLayerState& state)
>+Nicosia::CompositionLayerTextureMapperImpl& compositionLayerImpl(Nicosia::CompositionLayer& compositionLayer)
> {
>-    if (!state.childrenChanged)
>-        return;
>-
>-    Vector<TextureMapperLayer*> children;
>-    children.reserveCapacity(state.children.size());
>-    for (auto& child : state.children)
>-        children.append(layerByID(child));
>-
>-    layer->setChildren(children);
>+    return downcast<Nicosia::CompositionLayerTextureMapperImpl>(compositionLayer.impl());
> }
> 
>-void CoordinatedGraphicsScene::setLayerFiltersIfNeeded(TextureMapperLayer* layer, const CoordinatedGraphicsLayerState& state)
>+Nicosia::ContentLayerTextureMapperImpl& contentLayerImpl(Nicosia::ContentLayer& contentLayer)
> {
>-    if (!state.filtersChanged)
>-        return;
>-
>-    layer->setFilters(state.filters);
>+    return downcast<Nicosia::ContentLayerTextureMapperImpl>(contentLayer.impl());
> }
> 
>-void CoordinatedGraphicsScene::setLayerState(CoordinatedLayerID id, const CoordinatedGraphicsLayerState& layerState, CommitScope& commitScope)
>+Nicosia::BackingStoreTextureMapperImpl& backingStoreImpl(Nicosia::BackingStore& backingStore)
> {
>-    ASSERT(m_rootLayerID != InvalidCoordinatedLayerID);
>-    TextureMapperLayer* layer = layerByID(id);
>-
>-    if (layerState.positionChanged)
>-        layer->setPosition(layerState.pos);
>-
>-    if (layerState.anchorPointChanged)
>-        layer->setAnchorPoint(layerState.anchorPoint);
>-
>-    if (layerState.sizeChanged)
>-        layer->setSize(layerState.size);
>-
>-    if (layerState.transformChanged)
>-        layer->setTransform(layerState.transform);
>-
>-    if (layerState.childrenTransformChanged)
>-        layer->setChildrenTransform(layerState.childrenTransform);
>-
>-    if (layerState.contentsRectChanged)
>-        layer->setContentsRect(layerState.contentsRect);
>-
>-    if (layerState.contentsTilingChanged) {
>-        layer->setContentsTilePhase(layerState.contentsTilePhase);
>-        layer->setContentsTileSize(layerState.contentsTileSize);
>-    }
>-
>-    if (layerState.opacityChanged)
>-        layer->setOpacity(layerState.opacity);
>-
>-    if (layerState.solidColorChanged)
>-        layer->setSolidColor(layerState.solidColor);
>-
>-    if (layerState.debugVisualsChanged)
>-        layer->setDebugVisuals(layerState.debugVisuals.showDebugBorders, layerState.debugVisuals.debugBorderColor, layerState.debugVisuals.debugBorderWidth);
>-    if (layerState.repaintCountChanged)
>-        layer->setRepaintCounter(layerState.repaintCount.showRepaintCounter, layerState.repaintCount.count);
>-
>-    if (layerState.replicaChanged)
>-        layer->setReplicaLayer(getLayerByIDIfExists(layerState.replica));
>-
>-    if (layerState.maskChanged)
>-        layer->setMaskLayer(getLayerByIDIfExists(layerState.mask));
>-
>-    if (layerState.imageChanged)
>-        assignImageBackingToLayer(layer, layerState.imageID);
>-
>-    if (layerState.flagsChanged) {
>-        layer->setContentsOpaque(layerState.contentsOpaque);
>-        layer->setDrawsContent(layerState.drawsContent);
>-        layer->setContentsVisible(layerState.contentsVisible);
>-        layer->setBackfaceVisibility(layerState.backfaceVisible);
>-
>-        // Never clip the root layer.
>-        layer->setMasksToBounds(id == m_rootLayerID ? false : layerState.masksToBounds);
>-        layer->setPreserves3D(layerState.preserves3D);
>-    }
>-
>-    // Apply Operations.
>-    setLayerChildrenIfNeeded(layer, layerState);
>-    setLayerFiltersIfNeeded(layer, layerState);
>-    setLayerAnimationsIfNeeded(layer, layerState);
>-    prepareContentBackingStore(layer, commitScope);
>-    createTilesIfNeeded(layer, layerState);
>-    removeTilesIfNeeded(layer, layerState, commitScope);
>-    updateTilesIfNeeded(layer, layerState, commitScope);
>-    syncPlatformLayerIfNeeded(layer, layerState);
>+    return downcast<Nicosia::BackingStoreTextureMapperImpl>(backingStore.impl());
> }
> 
>-TextureMapperLayer* CoordinatedGraphicsScene::getLayerByIDIfExists(CoordinatedLayerID id)
>+Nicosia::ImageBackingTextureMapperImpl& imageBackingImpl(Nicosia::ImageBacking& imageBacking)
> {
>-    return (id != InvalidCoordinatedLayerID) ? layerByID(id) : 0;
>+    return downcast<Nicosia::ImageBackingTextureMapperImpl>(imageBacking.impl());
> }
> 
>-void CoordinatedGraphicsScene::createLayers(const Vector<CoordinatedLayerID>& layerIDs)
>+TextureMapperLayer& texmapLayer(Nicosia::CompositionLayer& compositionLayer)
> {
>-    for (auto& layerID : layerIDs)
>-        createLayer(layerID);
>-}
>-
>-void CoordinatedGraphicsScene::createLayer(CoordinatedLayerID id)
>-{
>-    std::unique_ptr<TextureMapperLayer> newLayer = std::make_unique<TextureMapperLayer>();
>-    newLayer->setID(id);
>-    m_layers.add(id, WTFMove(newLayer));
>-}
>-
>-void CoordinatedGraphicsScene::deleteLayers(const Vector<CoordinatedLayerID>& layerIDs)
>-{
>-    for (auto& layerID : layerIDs)
>-        deleteLayer(layerID);
>+    auto& compositionState = compositionLayerImpl(compositionLayer).compositionState();
>+    if (!compositionState.layer) {
>+        compositionState.layer = std::make_unique<TextureMapperLayer>();
>+        compositionState.layer->setID(compositionLayer.id());
>+    }
>+    return *compositionState.layer;
> }
> 
>-void CoordinatedGraphicsScene::deleteLayer(CoordinatedLayerID layerID)
>+void updateBackingStore(TextureMapperLayer& layer,
>+    Nicosia::BackingStoreTextureMapperImpl::CompositionState& compositionState,
>+    const Nicosia::BackingStoreTextureMapperImpl::TileUpdate& update)
> {
>-    std::unique_ptr<TextureMapperLayer> layer = m_layers.take(layerID);
>-    ASSERT(layer);
>-
>-    m_backingStores.remove(layer.get());
>-#if USE(COORDINATED_GRAPHICS_THREADED)
>-    if (auto platformLayerProxy = m_platformLayerProxies.take(layer.get()))
>-        platformLayerProxy->invalidate();
>-#endif
>-}
>+    if (!layerShouldHaveBackingStore(&layer)) {
>+        layer.setBackingStore(nullptr);
>+        compositionState.backingStore = nullptr;
>+        return;
>+    }
> 
>-void CoordinatedGraphicsScene::setRootLayerID(CoordinatedLayerID layerID)
>-{
>-    ASSERT(layerID != InvalidCoordinatedLayerID);
>-    ASSERT(m_rootLayerID == InvalidCoordinatedLayerID);
>+    if (!compositionState.backingStore)
>+        compositionState.backingStore = CoordinatedBackingStore::create();
>+    auto& backingStore = *compositionState.backingStore;
> 
>-    m_rootLayerID = layerID;
>+    layer.setBackingStore(&backingStore);
>+    backingStore.setSize(layer.size());
> 
>-    TextureMapperLayer* layer = layerByID(layerID);
>-    ASSERT(m_rootLayer->children().isEmpty());
>-    m_rootLayer->addChild(layer);
>+    for (auto& tile : update.tilesToCreate)
>+        backingStore.createTile(tile.tileID, tile.scale);
>+    for (auto& tile : update.tilesToRemove)
>+        backingStore.removeTile(tile.tileID);
>+    for (auto& tile : update.tilesToUpdate) {
>+        backingStore.updateTile(tile.tileID, tile.updateInfo.updateRect,
>+            tile.tileRect, tile.updateInfo.buffer.copyRef(), { 0, 0 });
>+    }
> }
> 
>-void CoordinatedGraphicsScene::prepareContentBackingStore(TextureMapperLayer* layer, CommitScope& commitScope)
>+void updateImageBacking(TextureMapperLayer& layer,
>+    Nicosia::ImageBackingTextureMapperImpl::CompositionState& compositionState,
>+    Nicosia::ImageBackingTextureMapperImpl::Update& update)
> {
>-    if (!layerShouldHaveBackingStore(layer)) {
>-        removeBackingStoreIfNeeded(layer);
>+    if (!update.isVisible) {
>+        layer.setBackingStore(nullptr);
>         return;
>     }
> 
>-    createBackingStoreIfNeeded(layer);
>-    resetBackingStoreSizeToLayerSize(layer, commitScope);
>-}
>+    if (!compositionState.backingStore)
>+        compositionState.backingStore = CoordinatedBackingStore::create();
>+    auto& backingStore = *compositionState.backingStore;
>+    layer.setContentsLayer(&backingStore);
> 
>-void CoordinatedGraphicsScene::createBackingStoreIfNeeded(TextureMapperLayer* layer)
>-{
>-    if (m_backingStores.contains(layer))
>+    if (!update.buffer)
>         return;
> 
>-    auto backingStore = CoordinatedBackingStore::create();
>-    m_backingStores.add(layer, backingStore.copyRef());
>-    layer->setBackingStore(backingStore.ptr());
>-}
>-
>-void CoordinatedGraphicsScene::removeBackingStoreIfNeeded(TextureMapperLayer* layer)
>-{
>-    RefPtr<CoordinatedBackingStore> backingStore = m_backingStores.take(layer);
>-    if (!backingStore)
>-        return;
>-
>-    layer->setBackingStore(nullptr);
>+    backingStore.createTile(1, 1.0);
>+    WebCore::IntRect rect { { }, update.buffer->size() };
>+    ASSERT(2000 >= std::max(rect.width(), rect.height()));
>+    backingStore.setSize(rect.size());
>+    backingStore.updateTile(1, rect, rect, WTFMove(update.buffer), rect.location());
> }
> 
>-void CoordinatedGraphicsScene::resetBackingStoreSizeToLayerSize(TextureMapperLayer* layer, CommitScope& commitScope)
>+void removeLayer(Nicosia::CompositionLayer& layer)
> {
>-    RefPtr<CoordinatedBackingStore> backingStore = m_backingStores.get(layer);
>-    ASSERT(backingStore);
>-    backingStore->setSize(layer->size());
>-    commitScope.backingStoresWithPendingBuffers.add(backingStore);
>-}
>+    layer.accessCommitted(
>+        [](const Nicosia::CompositionLayer::LayerState& committed)
>+        {
>+            if (committed.backingStore) {
>+                auto& compositionState = backingStoreImpl(*committed.backingStore).compositionState();
>+                compositionState.backingStore = nullptr;
>+            }
> 
>-void CoordinatedGraphicsScene::createTilesIfNeeded(TextureMapperLayer* layer, const CoordinatedGraphicsLayerState& state)
>-{
>-    if (state.tilesToCreate.isEmpty())
>-        return;
>+            if (committed.contentLayer)
>+                contentLayerImpl(*committed.contentLayer).proxy().invalidate();
> 
>-    RefPtr<CoordinatedBackingStore> backingStore = m_backingStores.get(layer);
>-    ASSERT(backingStore || !layerShouldHaveBackingStore(layer));
>-    if (!backingStore)
>-        return;
>+            if (committed.imageBacking) {
>+                auto& compositionState = imageBackingImpl(*committed.imageBacking).compositionState();
>+                compositionState.backingStore = nullptr;
>+            }
>+        });
> 
>-    for (auto& tile : state.tilesToCreate)
>-        backingStore->createTile(tile.tileID, tile.scale);
>+    auto& compositionState = compositionLayerImpl(layer).compositionState();
>+    compositionState.layer = nullptr;
> }
> 
>-void CoordinatedGraphicsScene::removeTilesIfNeeded(TextureMapperLayer* layer, const CoordinatedGraphicsLayerState& state, CommitScope& commitScope)
>+void CoordinatedGraphicsScene::commitSceneState(const CoordinatedGraphicsState::NicosiaState& state)
> {
>-    if (state.tilesToRemove.isEmpty())
>-        return;
>-
>-    RefPtr<CoordinatedBackingStore> backingStore = m_backingStores.get(layer);
>-    if (!backingStore)
>+    if (!m_client)
>         return;
> 
>-    for (auto& tile : state.tilesToRemove)
>-        backingStore->removeTile(tile);
>-
>-    commitScope.backingStoresWithPendingBuffers.add(backingStore);
>+    m_nicosia.scene = state.scene;
> }
> 
>-void CoordinatedGraphicsScene::updateTilesIfNeeded(TextureMapperLayer* layer, const CoordinatedGraphicsLayerState& state, CommitScope& commitScope)
>+void CoordinatedGraphicsScene::updateSceneState()
> {
>-    if (state.tilesToUpdate.isEmpty())
>+    if (!m_nicosia.scene)
>         return;
> 
>-    RefPtr<CoordinatedBackingStore> backingStore = m_backingStores.get(layer);
>-    ASSERT(backingStore || !layerShouldHaveBackingStore(layer));
>-    if (!backingStore)
>-        return;
>-
>-    for (auto& tile : state.tilesToUpdate) {
>-        const SurfaceUpdateInfo& surfaceUpdateInfo = tile.updateInfo;
>-
>-        backingStore->updateTile(tile.tileID, surfaceUpdateInfo.updateRect, tile.tileRect, surfaceUpdateInfo.buffer.copyRef(), { 0, 0 });
>-        commitScope.backingStoresWithPendingBuffers.add(backingStore);
>+    // Store layer and impl references along with the corresponding update
>+    // for each type of possible layer backing.
>+    struct {
>+        struct BackingStore {
>+            std::reference_wrapper<TextureMapperLayer> layer;
>+            std::reference_wrapper<Nicosia::BackingStoreTextureMapperImpl> backingStore;
>+            Nicosia::BackingStoreTextureMapperImpl::TileUpdate update;
>+        };
>+        Vector<BackingStore> backingStore;
>+
>+        struct ContentLayer {
>+            std::reference_wrapper<TextureMapperLayer> layer;
>+            std::reference_wrapper<TextureMapperPlatformLayerProxy> proxy;
>+            bool needsActivation { false };
>+        };
>+        Vector<ContentLayer> contentLayer;
>+
>+        struct ImageBacking {
>+            std::reference_wrapper<TextureMapperLayer> layer;
>+            std::reference_wrapper<Nicosia::ImageBackingTextureMapperImpl> imageBacking;
>+            Nicosia::ImageBackingTextureMapperImpl::Update update;
>+        };
>+        Vector<ImageBacking> imageBacking;
>+    } layersByBacking;
>+
>+    // Access the scene state and perform state update for each layer.
>+    m_nicosia.scene->accessState(
>+        [this, &layersByBacking](Nicosia::Scene::State& state)
>+        {
>+            // Bail if the scene didn't change.
>+            if (state.id == m_nicosia.state.id)
>+                return;
>+
>+            // Handle the root layer, adding it to the TextureMapperLayer tree
>+            // on the first update. No such change is expected later.
>+            {
>+                auto& rootLayer = texmapLayer(*state.rootLayer);
>+                if (rootLayer.id() != m_rootLayerID) {
>+                    m_rootLayerID = rootLayer.id();
>+                    RELEASE_ASSERT(m_rootLayer->children().isEmpty());
>+                    m_rootLayer->addChild(&rootLayer);
>+                }
>+            }
>+
>+            // Gather all the to-be-removed layers so that composition-side state
>+            // can be properly purged after the current state's set of layers is adopted.
>+            HashSet<RefPtr<Nicosia::CompositionLayer>> removedLayers;
>+            for (auto& layer : m_nicosia.state.layers) {
>+                if (!state.layers.contains(layer))
>+                    removedLayers.add(layer);
>+            }
>+
>+            m_nicosia.state = state;
>+
>+            for (auto& layer : removedLayers)
>+                removeLayer(*layer);
>+            removedLayers = { };
>+
>+            // Iterate the current state's set of layers, updating state values according to
>+            // the incoming state changes. Layer backings are stored so that the updates
>+            // (possibly time-consuming) can be done outside of this scene update.
>+            for (auto& compositionLayer : m_nicosia.state.layers) {
>+                auto& layer = texmapLayer(*compositionLayer);
>+                compositionLayer->commitState(
>+                    [this, &layer, &compositionLayer, &layersByBacking]
>+                    (const Nicosia::CompositionLayer::LayerState& layerState)
>+                    {
>+                        if (layerState.delta.positionChanged)
>+                            layer.setPosition(layerState.position);
>+                        if (layerState.delta.anchorPointChanged)
>+                            layer.setAnchorPoint(layerState.anchorPoint);
>+                        if (layerState.delta.sizeChanged)
>+                            layer.setSize(layerState.size);
>+
>+                        if (layerState.delta.transformChanged)
>+                            layer.setTransform(layerState.transform);
>+                        if (layerState.delta.childrenTransformChanged)
>+                            layer.setChildrenTransform(layerState.childrenTransform);
>+
>+                        if (layerState.delta.contentsRectChanged)
>+                            layer.setContentsRect(layerState.contentsRect);
>+                        if (layerState.delta.contentsTilingChanged) {
>+                            layer.setContentsTilePhase(layerState.contentsTilePhase);
>+                            layer.setContentsTileSize(layerState.contentsTileSize);
>+                        }
>+
>+                        if (layerState.delta.opacityChanged)
>+                            layer.setOpacity(layerState.opacity);
>+                        if (layerState.delta.solidColorChanged)
>+                            layer.setSolidColor(layerState.solidColor);
>+
>+                        if (layerState.delta.filtersChanged)
>+                            layer.setFilters(layerState.filters);
>+                        if (layerState.delta.animationsChanged)
>+                            layer.setAnimations(layerState.animations);
>+
>+                        if (layerState.delta.childrenChanged) {
>+                            layer.setChildren(WTF::map(layerState.children,
>+                                [](auto& child) { return &texmapLayer(*child); }));
>+                        }
>+
>+                        if (layerState.delta.maskChanged)
>+                            layer.setMaskLayer(layerState.mask ? &texmapLayer(*layerState.mask) : nullptr);
>+                        if (layerState.delta.replicaChanged)
>+                            layer.setReplicaLayer(layerState.replica ? &texmapLayer(*layerState.replica) : nullptr);
>+
>+                        if (layerState.delta.flagsChanged) {
>+                            layer.setContentsOpaque(layerState.flags.contentsOpaque);
>+                            layer.setDrawsContent(layerState.flags.drawsContent);
>+                            layer.setContentsVisible(layerState.flags.contentsVisible);
>+                            layer.setBackfaceVisibility(layerState.flags.backfaceVisible);
>+                            layer.setMasksToBounds(layerState.flags.masksToBounds);
>+                            layer.setPreserves3D(layerState.flags.preserves3D);
>+                        }
>+
>+                        if (layerState.backingStore) {
>+                            auto& impl = backingStoreImpl(*layerState.backingStore);
>+                            layersByBacking.backingStore.append(
>+                                { std::ref(layer), std::ref(impl), impl.takeUpdate() });
>+                        } else
>+                            layer.setBackingStore(nullptr);
>+
>+                        if (layerState.contentLayer) {
>+                            auto& impl = contentLayerImpl(*layerState.contentLayer);
>+                            layersByBacking.contentLayer.append(
>+                                { std::ref(layer), std::ref(impl.proxy()), layerState.delta.contentLayerChanged });
>+                        } else if (layerState.imageBacking) {
>+                            auto& impl = imageBackingImpl(*layerState.imageBacking);
>+                            layersByBacking.imageBacking.append(
>+                                { std::ref(layer), std::ref(impl), impl.takeUpdate() });
>+                        } else
>+                            layer.setContentsLayer(nullptr);
>+                    });
>+            }
>+        });
>+
>+    // Iterate through each backing type of layers and gather backing store
>+    // or proxy objects that need an update.
>+    // FIXME: HashSet<std::reference_wrapper<>> would be ideal, but doesn't work (yet).
>+    HashSet<Ref<WebCore::CoordinatedBackingStore>> backingStoresWithPendingBuffers;
>+    HashSet<Ref<WebCore::TextureMapperPlatformLayerProxy>> proxiesForSwapping;
>+
>+    {
>+        for (auto& entry : layersByBacking.backingStore) {
>+            auto& compositionState = entry.backingStore.get().compositionState();
>+            updateBackingStore(entry.layer.get(), compositionState, entry.update);
>+
>+            if (compositionState.backingStore)
>+                backingStoresWithPendingBuffers.add(makeRef(*compositionState.backingStore));
>+        }
>+
>+        layersByBacking.backingStore = { };
>     }
>-}
>-
>-void CoordinatedGraphicsScene::syncImageBackings(const CoordinatedGraphicsState& state, CommitScope& commitScope)
>-{
>-    for (auto& image : state.imagesToRemove)
>-        removeImageBacking(image, commitScope);
>-
>-    for (auto& image : state.imagesToCreate)
>-        createImageBacking(image);
>-
>-    for (auto& image : state.imagesToUpdate)
>-        updateImageBacking(image.first, image.second.copyRef(), commitScope);
>-
>-    for (auto& image : state.imagesToClear)
>-        clearImageBackingContents(image, commitScope);
>-}
>-
>-void CoordinatedGraphicsScene::createImageBacking(CoordinatedImageBackingID imageID)
>-{
>-    ASSERT(!m_imageBackings.contains(imageID));
>-    m_imageBackings.add(imageID, CoordinatedBackingStore::create());
>-}
>-
>-void CoordinatedGraphicsScene::updateImageBacking(CoordinatedImageBackingID imageID, RefPtr<Nicosia::Buffer>&& buffer, CommitScope& commitScope)
>-{
>-    ASSERT(m_imageBackings.contains(imageID));
>-    auto it = m_imageBackings.find(imageID);
>-    RefPtr<CoordinatedBackingStore> backingStore = it->value;
>-
>-    // CoordinatedImageBacking is realized to CoordinatedBackingStore with only one tile in UI Process.
>-    backingStore->createTile(1 /* id */, 1 /* scale */);
>-    IntRect rect(IntPoint::zero(), buffer->size());
>-    // See CoordinatedGraphicsLayer::shouldDirectlyCompositeImage()
>-    ASSERT(2000 >= std::max(rect.width(), rect.height()));
>-    backingStore->setSize(rect.size());
>-    backingStore->updateTile(1 /* id */, rect, rect, WTFMove(buffer), rect.location());
>-
>-    commitScope.backingStoresWithPendingBuffers.add(backingStore);
>-}
> 
>-void CoordinatedGraphicsScene::clearImageBackingContents(CoordinatedImageBackingID imageID, CommitScope& commitScope)
>-{
>-    ASSERT(m_imageBackings.contains(imageID));
>-    auto it = m_imageBackings.find(imageID);
>-    RefPtr<CoordinatedBackingStore> backingStore = it->value;
>-    backingStore->removeAllTiles();
>-    commitScope.backingStoresWithPendingBuffers.add(backingStore);
>-}
>-
>-void CoordinatedGraphicsScene::removeImageBacking(CoordinatedImageBackingID imageID, CommitScope& commitScope)
>-{
>-    ASSERT(m_imageBackings.contains(imageID));
>+    {
>+        for (auto& entry : layersByBacking.contentLayer) {
>+            auto& proxy = entry.proxy.get();
>+            if (entry.needsActivation)
>+                proxy.activateOnCompositingThread(this, &entry.layer.get());
>+            proxiesForSwapping.add(makeRef(proxy));
>+        }
> 
>-    // We don't want TextureMapperLayer refers a dangling pointer.
>-    commitScope.releasedImageBackings.append(m_imageBackings.take(imageID));
>-}
>-
>-void CoordinatedGraphicsScene::assignImageBackingToLayer(TextureMapperLayer* layer, CoordinatedImageBackingID imageID)
>-{
>-    if (imageID == InvalidCoordinatedImageBackingID) {
>-        layer->setContentsLayer(0);
>-        return;
>+        layersByBacking.contentLayer = { };
>     }
> 
>-    auto it = m_imageBackings.find(imageID);
>-    ASSERT(it != m_imageBackings.end());
>-    layer->setContentsLayer(it->value.get());
>-}
>-
>-void CoordinatedGraphicsScene::commitSceneState(const CoordinatedGraphicsState& state)
>-{
>-    if (!m_client)
>-        return;
>-
>-    m_nicosia = state.nicosia;
>-    // FIXME: Start using the Nicosia layer state for updates.
>+    {
>+        for (auto& entry : layersByBacking.imageBacking) {
>+            auto& compositionState = entry.imageBacking.get().compositionState();
>+            updateImageBacking(entry.layer.get(), compositionState, entry.update);
> 
>-    CommitScope commitScope;
>+            if (compositionState.backingStore)
>+                backingStoresWithPendingBuffers.add(makeRef(*compositionState.backingStore));
>+        }
> 
>-    createLayers(state.layersToCreate);
>-    deleteLayers(state.layersToRemove);
>-
>-    if (state.rootCompositingLayer != m_rootLayerID)
>-        setRootLayerID(state.rootCompositingLayer);
>-
>-    syncImageBackings(state, commitScope);
>-
>-    for (auto& layer : state.layersToUpdate)
>-        setLayerState(layer.first, layer.second, commitScope);
>+        layersByBacking.imageBacking = { };
>+    }
> 
>-    for (auto& backingStore : commitScope.backingStoresWithPendingBuffers)
>+    for (auto& backingStore : backingStoresWithPendingBuffers)
>         backingStore->commitTileOperations(*m_textureMapper);
>+
>+    for (auto& proxy : proxiesForSwapping)
>+        proxy->swapBuffer();
> }
> 
> void CoordinatedGraphicsScene::ensureRootLayer()
>@@ -465,26 +435,22 @@ void CoordinatedGraphicsScene::purgeGLResources()
> {
>     ASSERT(!m_client);
> 
>-    m_imageBackings.clear();
>-#if USE(COORDINATED_GRAPHICS_THREADED)
>-    for (auto& proxy : m_platformLayerProxies.values())
>-        proxy->invalidate();
>-    m_platformLayerProxies.clear();
>-#endif
>+    if (m_nicosia.scene) {
>+        m_nicosia.scene->accessState(
>+            [this](const Nicosia::Scene::State& state)
>+            {
>+                ASSERT(state.id == m_nicosia.state.id);
>+                for (auto& layer : m_nicosia.state.layers)
>+                    removeLayer(*layer);
>+                m_nicosia.state.layers = { };
>+                m_nicosia.state.rootLayer = nullptr;
>+            });
>+        m_nicosia.scene = nullptr;
>+    }
> 
>     m_rootLayer = nullptr;
>     m_rootLayerID = InvalidCoordinatedLayerID;
>-    m_layers.clear();
>     m_textureMapper = nullptr;
>-    m_backingStores.clear();
>-}
>-
>-void CoordinatedGraphicsScene::setLayerAnimationsIfNeeded(TextureMapperLayer* layer, const CoordinatedGraphicsLayerState& state)
>-{
>-    if (!state.animationsChanged)
>-        return;
>-
>-    layer->setAnimations(state.animations);
> }
> 
> void CoordinatedGraphicsScene::detach()
>diff --git a/Source/WebKit/Shared/CoordinatedGraphics/CoordinatedGraphicsScene.h b/Source/WebKit/Shared/CoordinatedGraphics/CoordinatedGraphicsScene.h
>index 2f3b4f339753fdc7ddcb711020396002a1a92afb..40b8b63110e99fb24e30749bceaa029cf0f3b98e 100644
>--- a/Source/WebKit/Shared/CoordinatedGraphics/CoordinatedGraphicsScene.h
>+++ b/Source/WebKit/Shared/CoordinatedGraphics/CoordinatedGraphicsScene.h
>@@ -81,83 +81,36 @@ public:
>     bool isActive() const { return m_isActive; }
>     void setActive(bool active) { m_isActive = active; }
> 
>-    void commitSceneState(const WebCore::CoordinatedGraphicsState&);
>-
>     void setViewBackgroundColor(const WebCore::Color& color) { m_viewBackgroundColor = color; }
>     WebCore::Color viewBackgroundColor() const { return m_viewBackgroundColor; }
> 
> private:
>-    struct CommitScope {
>-        CommitScope() = default;
>-        CommitScope(CommitScope&) = delete;
>-        CommitScope& operator=(const CommitScope&) = delete;
>-
>-        Vector<RefPtr<WebCore::CoordinatedBackingStore>> releasedImageBackings;
>-        HashSet<RefPtr<WebCore::CoordinatedBackingStore>> backingStoresWithPendingBuffers;
>-    };
>-
>-    void setRootLayerID(WebCore::CoordinatedLayerID);
>-    void createLayers(const Vector<WebCore::CoordinatedLayerID>&);
>-    void deleteLayers(const Vector<WebCore::CoordinatedLayerID>&);
>-    void setLayerState(WebCore::CoordinatedLayerID, const WebCore::CoordinatedGraphicsLayerState&, CommitScope&);
>-    void setLayerChildrenIfNeeded(WebCore::TextureMapperLayer*, const WebCore::CoordinatedGraphicsLayerState&);
>-    void updateTilesIfNeeded(WebCore::TextureMapperLayer*, const WebCore::CoordinatedGraphicsLayerState&, CommitScope&);
>-    void createTilesIfNeeded(WebCore::TextureMapperLayer*, const WebCore::CoordinatedGraphicsLayerState&);
>-    void removeTilesIfNeeded(WebCore::TextureMapperLayer*, const WebCore::CoordinatedGraphicsLayerState&, CommitScope&);
>-    void setLayerFiltersIfNeeded(WebCore::TextureMapperLayer*, const WebCore::CoordinatedGraphicsLayerState&);
>-    void setLayerAnimationsIfNeeded(WebCore::TextureMapperLayer*, const WebCore::CoordinatedGraphicsLayerState&);
>-    void syncPlatformLayerIfNeeded(WebCore::TextureMapperLayer*, const WebCore::CoordinatedGraphicsLayerState&);
>-
>-    void syncImageBackings(const WebCore::CoordinatedGraphicsState&, CommitScope&);
>-    void createImageBacking(WebCore::CoordinatedImageBackingID);
>-    void updateImageBacking(WebCore::CoordinatedImageBackingID, RefPtr<Nicosia::Buffer>&&, CommitScope&);
>-    void clearImageBackingContents(WebCore::CoordinatedImageBackingID, CommitScope&);
>-    void removeImageBacking(WebCore::CoordinatedImageBackingID, CommitScope&);
>-
>-    WebCore::TextureMapperLayer* layerByID(WebCore::CoordinatedLayerID id)
>-    {
>-        ASSERT(m_layers.contains(id));
>-        ASSERT(id != WebCore::InvalidCoordinatedLayerID);
>-        return m_layers.get(id);
>-    }
>-    WebCore::TextureMapperLayer* getLayerByIDIfExists(WebCore::CoordinatedLayerID);
>+    void commitSceneState(const WebCore::CoordinatedGraphicsState::NicosiaState&);
>+    void updateSceneState();
>+
>     WebCore::TextureMapperLayer* rootLayer() { return m_rootLayer.get(); }
> 
>     void updateViewport();
> 
>-    void createLayer(WebCore::CoordinatedLayerID);
>-    void deleteLayer(WebCore::CoordinatedLayerID);
>-
>-    void assignImageBackingToLayer(WebCore::TextureMapperLayer*, WebCore::CoordinatedImageBackingID);
>     void ensureRootLayer();
> 
>-    void prepareContentBackingStore(WebCore::TextureMapperLayer*, CommitScope&);
>-    void createBackingStoreIfNeeded(WebCore::TextureMapperLayer*);
>-    void removeBackingStoreIfNeeded(WebCore::TextureMapperLayer*);
>-    void resetBackingStoreSizeToLayerSize(WebCore::TextureMapperLayer*, CommitScope&);
>-
> #if USE(COORDINATED_GRAPHICS_THREADED)
>     void onNewBufferAvailable() override;
> #endif
> 
>-    WebCore::CoordinatedGraphicsState::NicosiaState m_nicosia;
>+    struct {
>+        RefPtr<Nicosia::Scene> scene;
>+        Nicosia::Scene::State state;
>+    } m_nicosia;
> 
>     std::unique_ptr<WebCore::TextureMapper> m_textureMapper;
> 
>-    HashMap<WebCore::CoordinatedImageBackingID, RefPtr<WebCore::CoordinatedBackingStore>> m_imageBackings;
>-    HashMap<WebCore::TextureMapperLayer*, RefPtr<WebCore::CoordinatedBackingStore>> m_backingStores;
>-
>-#if USE(COORDINATED_GRAPHICS_THREADED)
>-    HashMap<WebCore::TextureMapperLayer*, RefPtr<WebCore::TextureMapperPlatformLayerProxy>> m_platformLayerProxies;
>-#endif
>-
>     // Below two members are accessed by only the main thread. The painting thread must lock the main thread to access both members.
>     CoordinatedGraphicsSceneClient* m_client;
>     bool m_isActive { false };
> 
>     std::unique_ptr<WebCore::TextureMapperLayer> m_rootLayer;
> 
>-    HashMap<WebCore::CoordinatedLayerID, std::unique_ptr<WebCore::TextureMapperLayer>> m_layers;
>     WebCore::CoordinatedLayerID m_rootLayerID { WebCore::InvalidCoordinatedLayerID };
>     WebCore::Color m_viewBackgroundColor { WebCore::Color::white };
> 
>diff --git a/Source/WebKit/Shared/CoordinatedGraphics/threadedcompositor/ThreadedCompositor.cpp b/Source/WebKit/Shared/CoordinatedGraphics/threadedcompositor/ThreadedCompositor.cpp
>index 2cdc1ffb9a375aa65063d8ec5d6f5d0d9b781c0e..0b2b68ae11e9ebd6bee5008741b5a9895fda0de6 100644
>--- a/Source/WebKit/Shared/CoordinatedGraphics/threadedcompositor/ThreadedCompositor.cpp
>+++ b/Source/WebKit/Shared/CoordinatedGraphics/threadedcompositor/ThreadedCompositor.cpp
>@@ -215,11 +215,21 @@ void ThreadedCompositor::renderLayerTree()
>             // Coordinate scene update completion with the client in case of changed or updated platform layers.
>             // But do not change coordinateUpdateCompletionWithClient while in force repaint because that
>             // demands immediate scene update completion regardless of platform layers.
>+            // FIXME: Check whether we still need all this coordinateUpdateCompletionWithClient logic.
>+            // https://bugs.webkit.org/show_bug.cgi?id=188839
>+            // Relatedly, we should only ever operate with a single Nicosia::Scene object, not with a Vector
>+            // of CoordinatedGraphicsState instances (which at this time will all contain RefPtr to the same
>+            // Nicosia::State object anyway).
>             if (!m_inForceRepaint) {
>                 bool coordinateUpdate = false;
>-                for (auto& state : states)
>-                    coordinateUpdate |= std::any_of(state.layersToUpdate.begin(), state.layersToUpdate.end(),
>-                        [](auto& it) { return it.second.platformLayerChanged || it.second.platformLayerUpdated; });
>+                for (auto& state : states) {
>+                    state.nicosia.scene->accessState(
>+                        [&coordinateUpdate](Nicosia::Scene::State& state)
>+                        {
>+                            coordinateUpdate |= state.platformLayerUpdated;
>+                            state.platformLayerUpdated = false;
>+                        });
>+                }
>                 m_attributes.coordinateUpdateCompletionWithClient = coordinateUpdate;
>             }
>         }
>diff --git a/Source/WebKit/WebProcess/WebPage/CoordinatedGraphics/CompositingCoordinator.cpp b/Source/WebKit/WebProcess/WebPage/CoordinatedGraphics/CompositingCoordinator.cpp
>index 4ec0f5ea1a318c18c8ade2cd9b82c3fd75bfb7b2..6ba95758c09d9d5a94d2e23ac2e891290b61d886 100644
>--- a/Source/WebKit/WebProcess/WebPage/CoordinatedGraphics/CompositingCoordinator.cpp
>+++ b/Source/WebKit/WebProcess/WebPage/CoordinatedGraphics/CompositingCoordinator.cpp
>@@ -35,6 +35,9 @@
> #include <WebCore/FrameView.h>
> #include <WebCore/GraphicsContext.h>
> #include <WebCore/InspectorController.h>
>+#include <WebCore/NicosiaBackingStoreTextureMapperImpl.h>
>+#include <WebCore/NicosiaContentLayerTextureMapperImpl.h>
>+#include <WebCore/NicosiaImageBackingTextureMapperImpl.h>
> #include <WebCore/NicosiaPaintingEngine.h>
> #include <WebCore/Page.h>
> #include <wtf/MemoryPressureHandler.h>
>@@ -130,7 +133,31 @@ bool CompositingCoordinator::flushPendingLayerChanges()
>         m_state.nicosia.scene->accessState(
>             [this](Nicosia::Scene::State& state)
>             {
>+                bool platformLayerUpdated = false;
>+                for (auto& compositionLayer : m_nicosia.state.layers) {
>+                    compositionLayer->flushState(
>+                        [&platformLayerUpdated]
>+                        (const Nicosia::CompositionLayer::LayerState& state)
>+                        {
>+                            if (state.backingStore) {
>+                                auto& impl = downcast<Nicosia::BackingStoreTextureMapperImpl>(state.backingStore->impl());
>+                                impl.flushUpdate();
>+                            }
>+
>+                            if (state.imageBacking) {
>+                                auto& impl = downcast<Nicosia::ImageBackingTextureMapperImpl>(state.imageBacking->impl());
>+                                impl.flushUpdate();
>+                            }
>+
>+                            if (state.contentLayer) {
>+                                auto& impl = downcast<Nicosia::ContentLayerTextureMapperImpl>(state.contentLayer->impl());
>+                                platformLayerUpdated |= impl.flushUpdate();
>+                            }
>+                        });
>+                }
>+
>                 ++state.id;
>+                state.platformLayerUpdated = platformLayerUpdated;
>                 state.layers = m_nicosia.state.layers;
>                 state.rootLayer = m_nicosia.state.rootLayer;
>             });
>diff --git a/Source/cmake/OptionsGTK.cmake b/Source/cmake/OptionsGTK.cmake
>index 945dedec22eff04197728abd5a6e501a950d507f..452451084ebb154583376c2358b49ab9b29a8a67 100644
>--- a/Source/cmake/OptionsGTK.cmake
>+++ b/Source/cmake/OptionsGTK.cmake
>@@ -277,6 +277,7 @@ if (ENABLE_OPENGL)
> 
>     SET_AND_EXPOSE_TO_BUILD(USE_COORDINATED_GRAPHICS TRUE)
>     SET_AND_EXPOSE_TO_BUILD(USE_COORDINATED_GRAPHICS_THREADED TRUE)
>+    SET_AND_EXPOSE_TO_BUILD(USE_NICOSIA TRUE)
> endif ()
> 
> if (ENABLE_PLUGIN_PROCESS_GTK2)
>diff --git a/Source/cmake/OptionsWPE.cmake b/Source/cmake/OptionsWPE.cmake
>index 1cf47c8bf82c48a922937223c92a6290e94df2d4..5ae17a8fdfcc9249e1fa13ec3539ccd41df013a9 100644
>--- a/Source/cmake/OptionsWPE.cmake
>+++ b/Source/cmake/OptionsWPE.cmake
>@@ -134,6 +134,7 @@ SET_AND_EXPOSE_TO_BUILD(USE_TEXTURE_MAPPER_GL TRUE)
> SET_AND_EXPOSE_TO_BUILD(USE_TILED_BACKING_STORE TRUE)
> SET_AND_EXPOSE_TO_BUILD(USE_COORDINATED_GRAPHICS TRUE)
> SET_AND_EXPOSE_TO_BUILD(USE_COORDINATED_GRAPHICS_THREADED TRUE)
>+SET_AND_EXPOSE_TO_BUILD(USE_NICOSIA TRUE)
> 
> set(FORWARDING_HEADERS_DIR ${DERIVED_SOURCES_DIR}/ForwardingHeaders)
> set(FORWARDING_HEADERS_WPE_DIR ${FORWARDING_HEADERS_DIR}/wpe)
>diff --git a/ChangeLog b/ChangeLog
>index 15dbf0afc9aa3d072cbabe77bc253afe338ee88a..62930f80ca5ca12f5349ebcfd9e086d44e11256f 100644
>--- a/ChangeLog
>+++ b/ChangeLog
>@@ -1,3 +1,14 @@
>+2018-08-22  Zan Dobersek  <zdobersek@igalia.com>
>+
>+        [CoordGraphics] Switch to Nicosia::CompositionLayer state tracking
>+        https://bugs.webkit.org/show_bug.cgi?id=188693
>+
>+        Reviewed by Carlos Garcia Campos.
>+
>+        * Source/cmake/OptionsGTK.cmake: Enable USE_NICOSIA alongside
>+        USE_COORDINATED_GRAPHICS and USE_COORDINATED_GRAPHICS_THREADED.
>+        * Source/cmake/OptionsWPE.cmake: Ditto.
>+
> 2018-08-21  Adrian Perez de Castro  <aperez@igalia.com>
> 
>         Unreviewed. Update OptionsWPE.cmake and NEWS for 2.21.91 release.

Actions: View | Formatted Diff | Diff

Attachments on bug 188693: 347355 | 347444 | 347483 | 347487 | 347494 | 347502 | 347514 | 347616 | 347627 | 347678 | 347779