libs/hwui/RenderNode.h - LeafOS-Project/android_frameworks_base - Gitiles

 /*
  * Copyright (C) 2014 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 #pragma once

 #include <SkCamera.h>
 #include <SkMatrix.h>

 #include <utils/LinearAllocator.h>
 #include <utils/RefBase.h>
 #include <utils/String8.h>

 #include <cutils/compiler.h>

 #include <androidfw/ResourceTypes.h>

 #include "AnimatorManager.h"
 #include "Debug.h"
 #include "DisplayList.h"
 #include "Matrix.h"
 #include "RenderProperties.h"
 #include "pipeline/skia/SkiaDisplayList.h"
 #include "pipeline/skia/SkiaLayer.h"
 #include "utils/FatVector.h"

 #include <vector>

 class SkBitmap;
 class SkPaint;
 class SkPath;
 class SkRegion;
 class SkSurface;

 namespace android {
 namespace uirenderer {

 class CanvasState;
 class DisplayListOp;
 class FrameBuilder;
 class OffscreenBuffer;
 class Rect;
 class SkiaShader;
 struct RenderNodeOp;

 class TreeInfo;
 class TreeObserver;

 namespace proto {
 class RenderNode;
 }

 /**
  * Primary class for storing recorded canvas commands, as well as per-View/ViewGroup display properties.
  *
  * Recording of canvas commands is somewhat similar to SkPicture, except the canvas-recording
  * functionality is split between RecordingCanvas (which manages the recording), DisplayList
  * (which holds the actual data), and RenderNode (which holds properties used for render playback).
  *
  * Note that DisplayList is swapped out from beneath an individual RenderNode when a view's
  * recorded stream of canvas operations is refreshed. The RenderNode (and its properties) stay
  * attached.
  */
 class RenderNode : public VirtualLightRefBase {
 friend class TestUtils; // allow TestUtils to access syncDisplayList / syncProperties
 friend class FrameBuilder;
 public:
     enum DirtyPropertyMask {
         GENERIC         = 1 << 1,
         TRANSLATION_X   = 1 << 2,
         TRANSLATION_Y   = 1 << 3,
         TRANSLATION_Z   = 1 << 4,
         SCALE_X         = 1 << 5,
         SCALE_Y         = 1 << 6,
         ROTATION        = 1 << 7,
         ROTATION_X      = 1 << 8,
         ROTATION_Y      = 1 << 9,
         X               = 1 << 10,
         Y               = 1 << 11,
         Z               = 1 << 12,
         ALPHA           = 1 << 13,
         DISPLAY_LIST    = 1 << 14,
     };

     ANDROID_API RenderNode();
     ANDROID_API virtual ~RenderNode();

     // See flags defined in DisplayList.java
     enum ReplayFlag {
         kReplayFlag_ClipChildren = 0x1
     };

     ANDROID_API void setStagingDisplayList(DisplayList* newData);

     void computeOrdering();

     ANDROID_API void output();
     ANDROID_API int getDebugSize();
     void copyTo(proto::RenderNode* node);

     bool isRenderable() const {
         return mDisplayList && !mDisplayList->isEmpty();
     }

     bool hasProjectionReceiver() const {
         return mDisplayList && mDisplayList->projectionReceiveIndex >= 0;
     }

     const char* getName() const {
         return mName.string();
     }

     void setName(const char* name) {
         if (name) {
             const char* lastPeriod = strrchr(name, '.');
             if (lastPeriod) {
                 mName.setTo(lastPeriod + 1);
             } else {
                 mName.setTo(name);
             }
         }
     }

     VirtualLightRefBase* getUserContext() const {
         return mUserContext.get();
     }

     void setUserContext(VirtualLightRefBase* context) {
         mUserContext = context;
     }

     bool isPropertyFieldDirty(DirtyPropertyMask field) const {
         return mDirtyPropertyFields & field;
     }

     void setPropertyFieldsDirty(uint32_t fields) {
         mDirtyPropertyFields |= fields;
     }

     const RenderProperties& properties() const {
         return mProperties;
     }

     RenderProperties& animatorProperties() {
         return mProperties;
     }

     const RenderProperties& stagingProperties() {
         return mStagingProperties;
     }

     RenderProperties& mutateStagingProperties() {
         return mStagingProperties;
     }

     bool isValid() {
         return mValid;
     }

     int getWidth() const {
         return properties().getWidth();
     }

     int getHeight() const {
         return properties().getHeight();
     }

     ANDROID_API virtual void prepareTree(TreeInfo& info);
     void destroyHardwareResources(TreeInfo* info = nullptr);
     void destroyLayers();

     // UI thread only!
     ANDROID_API void addAnimator(const sp<BaseRenderNodeAnimator>& animator);
     void removeAnimator(const sp<BaseRenderNodeAnimator>& animator);

     // This can only happen during pushStaging()
     void onAnimatorTargetChanged(BaseRenderNodeAnimator* animator) {
         mAnimatorManager.onAnimatorTargetChanged(animator);
     }

     AnimatorManager& animators() { return mAnimatorManager; }

     void applyViewPropertyTransforms(mat4& matrix, bool true3dTransform = false) const;

     bool nothingToDraw() const {
         const Outline& outline = properties().getOutline();
         return mDisplayList == nullptr
                 || properties().getAlpha() <= 0
                 || (outline.getShouldClip() && outline.isEmpty())
                 || properties().getScaleX() == 0
                 || properties().getScaleY() == 0;
     }

     const DisplayList* getDisplayList() const {
         return mDisplayList;
     }
     OffscreenBuffer* getLayer() const { return mLayer; }
     OffscreenBuffer** getLayerHandle() { return &mLayer; } // ugh...
     void setLayer(OffscreenBuffer* layer) { mLayer = layer; }

     // Note: The position callbacks are relying on the listener using
     // the frameNumber to appropriately batch/synchronize these transactions.
     // There is no other filtering/batching to ensure that only the "final"
     // state called once per frame.
     class ANDROID_API PositionListener : public VirtualLightRefBase {
     public:
         virtual ~PositionListener() {}
         // Called when the RenderNode's position changes
         virtual void onPositionUpdated(RenderNode& node, const TreeInfo& info) = 0;
         // Called when the RenderNode no longer has a position. As in, it's
         // no longer being drawn.
         // Note, tree info might be null
         virtual void onPositionLost(RenderNode& node, const TreeInfo* info) = 0;
     };

     // Note this is not thread safe, this needs to be called
     // before the RenderNode is used for drawing.
     // RenderNode takes ownership of the pointer
     ANDROID_API void setPositionListener(PositionListener* listener) {
         mPositionListener = listener;
     }

     // This is only modified in MODE_FULL, so it can be safely accessed
     // on the UI thread.
     ANDROID_API bool hasParents() {
         return mParentCount;
     }

     void onRemovedFromTree(TreeInfo* info);

     // Called by CanvasContext to promote a RenderNode to be a root node
     void makeRoot() {
         incParentRefCount();
     }

     // Called by CanvasContext when it drops a RenderNode from being a root node
     void clearRoot();

     void output(std::ostream& output, uint32_t level);

 private:
     void computeOrderingImpl(RenderNodeOp* opState,
             std::vector<RenderNodeOp*>* compositedChildrenOfProjectionSurface,
             const mat4* transformFromProjectionSurface);

     void syncProperties();
     void syncDisplayList(TreeObserver& observer, TreeInfo* info);

     void prepareTreeImpl(TreeObserver& observer, TreeInfo& info, bool functorsNeedLayer);
     void pushStagingPropertiesChanges(TreeInfo& info);
     void pushStagingDisplayListChanges(TreeObserver& observer, TreeInfo& info);
     void prepareLayer(TreeInfo& info, uint32_t dirtyMask);
     void pushLayerUpdate(TreeInfo& info);
     void deleteDisplayList(TreeObserver& observer, TreeInfo* info = nullptr);
     void damageSelf(TreeInfo& info);

     void incParentRefCount() { mParentCount++; }
     void decParentRefCount(TreeObserver& observer, TreeInfo* info = nullptr);

     String8 mName;
     sp<VirtualLightRefBase> mUserContext;

     uint32_t mDirtyPropertyFields;
     RenderProperties mProperties;
     RenderProperties mStagingProperties;

     // Owned by UI. Set when DL is set, cleared when DL cleared or when node detached
     // (likely by parent re-record/removal)
     bool mValid = false;

     bool mNeedsDisplayListSync;
     // WARNING: Do not delete this directly, you must go through deleteDisplayList()!
     DisplayList* mDisplayList;
     DisplayList* mStagingDisplayList;

     friend class AnimatorManager;
     AnimatorManager mAnimatorManager;

     // Owned by RT. Lifecycle is managed by prepareTree(), with the exception
     // being in ~RenderNode() which may happen on any thread.
     OffscreenBuffer* mLayer = nullptr;

     /**
      * Draw time state - these properties are only set and used during rendering
      */

     // for projection surfaces, contains a list of all children items
     std::vector<RenderNodeOp*> mProjectedNodes;

     // How many references our parent(s) have to us. Typically this should alternate
     // between 2 and 1 (when a staging push happens we inc first then dec)
     // When this hits 0 we are no longer in the tree, so any hardware resources
     // (specifically Layers) should be released.
     // This is *NOT* thread-safe, and should therefore only be tracking
     // mDisplayList, not mStagingDisplayList.
     uint32_t mParentCount;

     sp<PositionListener> mPositionListener;

 // METHODS & FIELDS ONLY USED BY THE SKIA RENDERER
 public:
     /**
      * Detach and transfer ownership of an already allocated displayList for use
      * in recording updated content for this renderNode
      */
     std::unique_ptr<skiapipeline::SkiaDisplayList> detachAvailableList() {
         return std::move(mAvailableDisplayList);
     }

     /**
      * Attach unused displayList to this node for potential future reuse.
      */
     void attachAvailableList(skiapipeline::SkiaDisplayList* skiaDisplayList) {
         mAvailableDisplayList.reset(skiaDisplayList);
     }

     /**
      * Returns true if an offscreen layer from any renderPipeline is attached
      * to this node.
      */
     bool hasLayer() const { return mLayer || mSkiaLayer.get(); }

     /**
      * Used by the RenderPipeline to attach an offscreen surface to the RenderNode.
      * The surface is then will be used to store the contents of a layer.
      */
     void setLayerSurface(sk_sp<SkSurface> layer) {
         if (layer.get()) {
             if (!mSkiaLayer.get()) {
                 mSkiaLayer = std::make_unique<skiapipeline::SkiaLayer>();
             }
             mSkiaLayer->layerSurface = std::move(layer);
             mSkiaLayer->inverseTransformInWindow.loadIdentity();
         } else {
             mSkiaLayer.reset();
         }
     }

     /**
      * If the RenderNode is of type LayerType::RenderLayer then this method will
      * return the an offscreen rendering surface that is used to both render into
      * the layer and composite the layer into its parent.  If the type is not
      * LayerType::RenderLayer then it will return a nullptr.
      *
      * NOTE: this function is only guaranteed to return accurate results after
      *       prepareTree has been run for this RenderNode
      */
     SkSurface* getLayerSurface() const {
         return mSkiaLayer.get() ? mSkiaLayer->layerSurface.get() : nullptr;
     }

     skiapipeline::SkiaLayer* getSkiaLayer() const {
         return mSkiaLayer.get();
     }

     /**
      * Returns the path that represents the outline of RenderNode intersected with
      * the provided rect.  This call will internally cache the resulting path in
      * order to potentially return that path for subsequent calls to this method.
      * By reusing the same path we get better performance on the GPU backends since
      * those resources are cached in the hardware based on the path's genID.
      *
      * The returned path is only guaranteed to be valid until this function is called
      * again or the RenderNode's outline is mutated.
      */
     const SkPath* getClippedOutline(const SkRect& clipRect) const;
 private:
     /**
      * If this RenderNode has been used in a previous frame then the SkiaDisplayList
      * from that frame is cached here until one of the following conditions is met:
      *  1) The RenderNode is deleted (causing this to be deleted)
      *  2) It is replaced with the displayList from the next completed frame
      *  3) It is detached and used to to record a new displayList for a later frame
      */
     std::unique_ptr<skiapipeline::SkiaDisplayList> mAvailableDisplayList;

     /**
      * An offscreen rendering target used to contain the contents this RenderNode
      * when it has been set to draw as a LayerType::RenderLayer.
      */
     std::unique_ptr<skiapipeline::SkiaLayer> mSkiaLayer;

     struct ClippedOutlineCache {
         // keys
         uint32_t outlineID = 0;
         SkRect clipRect;

         // value
         SkPath clippedOutline;
     };
     mutable ClippedOutlineCache mClippedOutlineCache;
 }; // class RenderNode

 class MarkAndSweepRemoved : public TreeObserver {
 PREVENT_COPY_AND_ASSIGN(MarkAndSweepRemoved);

 public:
     explicit MarkAndSweepRemoved(TreeInfo* info) : mTreeInfo(info) {}

     void onMaybeRemovedFromTree(RenderNode* node) override {
         mMarked.emplace_back(node);
     }

     ~MarkAndSweepRemoved() {
         for (auto& node : mMarked) {
             if (!node->hasParents()) {
                 node->onRemovedFromTree(mTreeInfo);
             }
         }
     }

 private:
     FatVector<sp<RenderNode>, 10> mMarked;
     TreeInfo* mTreeInfo;
 };

 } /* namespace uirenderer */
 } /* namespace android */
	/*
	* Copyright (C) 2014 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	#pragma once

	#include <SkCamera.h>
	#include <SkMatrix.h>

	#include <utils/LinearAllocator.h>
	#include <utils/RefBase.h>
	#include <utils/String8.h>

	#include <cutils/compiler.h>

	#include <androidfw/ResourceTypes.h>

	#include "AnimatorManager.h"
	#include "Debug.h"
	#include "DisplayList.h"
	#include "Matrix.h"
	#include "RenderProperties.h"
	#include "pipeline/skia/SkiaDisplayList.h"
	#include "pipeline/skia/SkiaLayer.h"
	#include "utils/FatVector.h"

	#include <vector>

	class SkBitmap;
	class SkPaint;
	class SkPath;
	class SkRegion;
	class SkSurface;

	namespace android {
	namespace uirenderer {

	class CanvasState;
	class DisplayListOp;
	class FrameBuilder;
	class OffscreenBuffer;
	class Rect;
	class SkiaShader;
	struct RenderNodeOp;

	class TreeInfo;
	class TreeObserver;

	namespace proto {
	class RenderNode;
	}

	/**
	* Primary class for storing recorded canvas commands, as well as per-View/ViewGroup display properties.
	*
	* Recording of canvas commands is somewhat similar to SkPicture, except the canvas-recording
	* functionality is split between RecordingCanvas (which manages the recording), DisplayList
	* (which holds the actual data), and RenderNode (which holds properties used for render playback).
	*
	* Note that DisplayList is swapped out from beneath an individual RenderNode when a view's
	* recorded stream of canvas operations is refreshed. The RenderNode (and its properties) stay
	* attached.
	*/
	class RenderNode : public VirtualLightRefBase {
	friend class TestUtils; // allow TestUtils to access syncDisplayList / syncProperties
	friend class FrameBuilder;
	public:
	enum DirtyPropertyMask {
	GENERIC = 1 << 1,
	TRANSLATION_X = 1 << 2,
	TRANSLATION_Y = 1 << 3,
	TRANSLATION_Z = 1 << 4,
	SCALE_X = 1 << 5,
	SCALE_Y = 1 << 6,
	ROTATION = 1 << 7,
	ROTATION_X = 1 << 8,
	ROTATION_Y = 1 << 9,
	X = 1 << 10,
	Y = 1 << 11,
	Z = 1 << 12,
	ALPHA = 1 << 13,
	DISPLAY_LIST = 1 << 14,
	};

	ANDROID_API RenderNode();
	ANDROID_API virtual ~RenderNode();

	// See flags defined in DisplayList.java
	enum ReplayFlag {
	kReplayFlag_ClipChildren = 0x1
	};

	ANDROID_API void setStagingDisplayList(DisplayList* newData);

	void computeOrdering();

	ANDROID_API void output();
	ANDROID_API int getDebugSize();
	void copyTo(proto::RenderNode* node);

	bool isRenderable() const {
	return mDisplayList && !mDisplayList->isEmpty();
	}

	bool hasProjectionReceiver() const {
	return mDisplayList && mDisplayList->projectionReceiveIndex >= 0;
	}

	const char* getName() const {
	return mName.string();
	}

	void setName(const char* name) {
	if (name) {
	const char* lastPeriod = strrchr(name, '.');
	if (lastPeriod) {
	mName.setTo(lastPeriod + 1);
	} else {
	mName.setTo(name);
	}
	}
	}

	VirtualLightRefBase* getUserContext() const {
	return mUserContext.get();
	}

	void setUserContext(VirtualLightRefBase* context) {
	mUserContext = context;
	}

	bool isPropertyFieldDirty(DirtyPropertyMask field) const {
	return mDirtyPropertyFields & field;
	}

	void setPropertyFieldsDirty(uint32_t fields) {
	mDirtyPropertyFields \|= fields;
	}

	const RenderProperties& properties() const {
	return mProperties;
	}

	RenderProperties& animatorProperties() {
	return mProperties;
	}

	const RenderProperties& stagingProperties() {
	return mStagingProperties;
	}

	RenderProperties& mutateStagingProperties() {
	return mStagingProperties;
	}

	bool isValid() {
	return mValid;
	}

	int getWidth() const {
	return properties().getWidth();
	}

	int getHeight() const {
	return properties().getHeight();
	}

	ANDROID_API virtual void prepareTree(TreeInfo& info);
	void destroyHardwareResources(TreeInfo* info = nullptr);
	void destroyLayers();

	// UI thread only!
	ANDROID_API void addAnimator(const sp<BaseRenderNodeAnimator>& animator);
	void removeAnimator(const sp<BaseRenderNodeAnimator>& animator);

	// This can only happen during pushStaging()
	void onAnimatorTargetChanged(BaseRenderNodeAnimator* animator) {
	mAnimatorManager.onAnimatorTargetChanged(animator);
	}

	AnimatorManager& animators() { return mAnimatorManager; }

	void applyViewPropertyTransforms(mat4& matrix, bool true3dTransform = false) const;

	bool nothingToDraw() const {
	const Outline& outline = properties().getOutline();
	return mDisplayList == nullptr
	\|\| properties().getAlpha() <= 0
	\|\| (outline.getShouldClip() && outline.isEmpty())
	\|\| properties().getScaleX() == 0
	\|\| properties().getScaleY() == 0;
	}

	const DisplayList* getDisplayList() const {
	return mDisplayList;
	}
	OffscreenBuffer* getLayer() const { return mLayer; }
	OffscreenBuffer** getLayerHandle() { return &mLayer; } // ugh...
	void setLayer(OffscreenBuffer* layer) { mLayer = layer; }

	// Note: The position callbacks are relying on the listener using
	// the frameNumber to appropriately batch/synchronize these transactions.
	// There is no other filtering/batching to ensure that only the "final"
	// state called once per frame.
	class ANDROID_API PositionListener : public VirtualLightRefBase {
	public:
	virtual ~PositionListener() {}
	// Called when the RenderNode's position changes
	virtual void onPositionUpdated(RenderNode& node, const TreeInfo& info) = 0;
	// Called when the RenderNode no longer has a position. As in, it's
	// no longer being drawn.
	// Note, tree info might be null
	virtual void onPositionLost(RenderNode& node, const TreeInfo* info) = 0;
	};

	// Note this is not thread safe, this needs to be called
	// before the RenderNode is used for drawing.
	// RenderNode takes ownership of the pointer
	ANDROID_API void setPositionListener(PositionListener* listener) {
	mPositionListener = listener;
	}

	// This is only modified in MODE_FULL, so it can be safely accessed
	// on the UI thread.
	ANDROID_API bool hasParents() {
	return mParentCount;
	}

	void onRemovedFromTree(TreeInfo* info);

	// Called by CanvasContext to promote a RenderNode to be a root node
	void makeRoot() {
	incParentRefCount();
	}

	// Called by CanvasContext when it drops a RenderNode from being a root node
	void clearRoot();

	void output(std::ostream& output, uint32_t level);

	private:
	void computeOrderingImpl(RenderNodeOp* opState,
	std::vector<RenderNodeOp> compositedChildrenOfProjectionSurface,
	const mat4* transformFromProjectionSurface);

	void syncProperties();
	void syncDisplayList(TreeObserver& observer, TreeInfo* info);

	void prepareTreeImpl(TreeObserver& observer, TreeInfo& info, bool functorsNeedLayer);
	void pushStagingPropertiesChanges(TreeInfo& info);
	void pushStagingDisplayListChanges(TreeObserver& observer, TreeInfo& info);
	void prepareLayer(TreeInfo& info, uint32_t dirtyMask);
	void pushLayerUpdate(TreeInfo& info);
	void deleteDisplayList(TreeObserver& observer, TreeInfo* info = nullptr);
	void damageSelf(TreeInfo& info);

	void incParentRefCount() { mParentCount++; }
	void decParentRefCount(TreeObserver& observer, TreeInfo* info = nullptr);

	String8 mName;
	sp<VirtualLightRefBase> mUserContext;

	uint32_t mDirtyPropertyFields;
	RenderProperties mProperties;
	RenderProperties mStagingProperties;

	// Owned by UI. Set when DL is set, cleared when DL cleared or when node detached
	// (likely by parent re-record/removal)
	bool mValid = false;

	bool mNeedsDisplayListSync;
	// WARNING: Do not delete this directly, you must go through deleteDisplayList()!
	DisplayList* mDisplayList;
	DisplayList* mStagingDisplayList;

	friend class AnimatorManager;
	AnimatorManager mAnimatorManager;

	// Owned by RT. Lifecycle is managed by prepareTree(), with the exception
	// being in ~RenderNode() which may happen on any thread.
	OffscreenBuffer* mLayer = nullptr;

	/**
	* Draw time state - these properties are only set and used during rendering
	*/

	// for projection surfaces, contains a list of all children items
	std::vector<RenderNodeOp*> mProjectedNodes;

	// How many references our parent(s) have to us. Typically this should alternate
	// between 2 and 1 (when a staging push happens we inc first then dec)
	// When this hits 0 we are no longer in the tree, so any hardware resources
	// (specifically Layers) should be released.
	// This is NOT thread-safe, and should therefore only be tracking
	// mDisplayList, not mStagingDisplayList.
	uint32_t mParentCount;

	sp<PositionListener> mPositionListener;

	// METHODS & FIELDS ONLY USED BY THE SKIA RENDERER
	public:
	/**
	* Detach and transfer ownership of an already allocated displayList for use
	* in recording updated content for this renderNode
	*/
	std::unique_ptr<skiapipeline::SkiaDisplayList> detachAvailableList() {
	return std::move(mAvailableDisplayList);
	}

	/**
	* Attach unused displayList to this node for potential future reuse.
	*/
	void attachAvailableList(skiapipeline::SkiaDisplayList* skiaDisplayList) {
	mAvailableDisplayList.reset(skiaDisplayList);
	}

	/**
	* Returns true if an offscreen layer from any renderPipeline is attached
	* to this node.
	*/
	bool hasLayer() const { return mLayer \|\| mSkiaLayer.get(); }

	/**
	* Used by the RenderPipeline to attach an offscreen surface to the RenderNode.
	* The surface is then will be used to store the contents of a layer.
	*/
	void setLayerSurface(sk_sp<SkSurface> layer) {
	if (layer.get()) {
	if (!mSkiaLayer.get()) {
	mSkiaLayer = std::make_unique<skiapipeline::SkiaLayer>();
	}
	mSkiaLayer->layerSurface = std::move(layer);
	mSkiaLayer->inverseTransformInWindow.loadIdentity();
	} else {
	mSkiaLayer.reset();
	}
	}

	/**
	* If the RenderNode is of type LayerType::RenderLayer then this method will
	* return the an offscreen rendering surface that is used to both render into
	* the layer and composite the layer into its parent. If the type is not
	* LayerType::RenderLayer then it will return a nullptr.
	*
	* NOTE: this function is only guaranteed to return accurate results after
	* prepareTree has been run for this RenderNode
	*/
	SkSurface* getLayerSurface() const {
	return mSkiaLayer.get() ? mSkiaLayer->layerSurface.get() : nullptr;
	}

	skiapipeline::SkiaLayer* getSkiaLayer() const {
	return mSkiaLayer.get();
	}

	/**
	* Returns the path that represents the outline of RenderNode intersected with
	* the provided rect. This call will internally cache the resulting path in
	* order to potentially return that path for subsequent calls to this method.
	* By reusing the same path we get better performance on the GPU backends since
	* those resources are cached in the hardware based on the path's genID.
	*
	* The returned path is only guaranteed to be valid until this function is called
	* again or the RenderNode's outline is mutated.
	*/
	const SkPath* getClippedOutline(const SkRect& clipRect) const;
	private:
	/**
	* If this RenderNode has been used in a previous frame then the SkiaDisplayList
	* from that frame is cached here until one of the following conditions is met:
	* 1) The RenderNode is deleted (causing this to be deleted)
	* 2) It is replaced with the displayList from the next completed frame
	* 3) It is detached and used to to record a new displayList for a later frame
	*/
	std::unique_ptr<skiapipeline::SkiaDisplayList> mAvailableDisplayList;

	/**
	* An offscreen rendering target used to contain the contents this RenderNode
	* when it has been set to draw as a LayerType::RenderLayer.
	*/
	std::unique_ptr<skiapipeline::SkiaLayer> mSkiaLayer;

	struct ClippedOutlineCache {
	// keys
	uint32_t outlineID = 0;
	SkRect clipRect;

	// value
	SkPath clippedOutline;
	};
	mutable ClippedOutlineCache mClippedOutlineCache;
	}; // class RenderNode

	class MarkAndSweepRemoved : public TreeObserver {
	PREVENT_COPY_AND_ASSIGN(MarkAndSweepRemoved);

	public:
	explicit MarkAndSweepRemoved(TreeInfo* info) : mTreeInfo(info) {}

	void onMaybeRemovedFromTree(RenderNode* node) override {
	mMarked.emplace_back(node);
	}

	~MarkAndSweepRemoved() {
	for (auto& node : mMarked) {
	if (!node->hasParents()) {
	node->onRemovedFromTree(mTreeInfo);
	}
	}
	}

	private:
	FatVector<sp<RenderNode>, 10> mMarked;
	TreeInfo* mTreeInfo;
	};

	} /* namespace uirenderer */
	} /* namespace android */