services/surfaceflinger/BufferLayerConsumer.h - platform/frameworks/native - Gitiles

 /*
  * Copyright (C) 2010 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.
  */

 #ifndef ANDROID_BUFFERLAYERCONSUMER_H
 #define ANDROID_BUFFERLAYERCONSUMER_H

 #include <android-base/thread_annotations.h>
 #include <gui/BufferQueueDefs.h>
 #include <gui/ConsumerBase.h>
 #include <gui/HdrMetadata.h>

 #include <ui/FenceTime.h>
 #include <ui/GraphicBuffer.h>
 #include <ui/GraphicTypes.h>
 #include <ui/Region.h>

 #include <utils/String8.h>
 #include <utils/Vector.h>
 #include <utils/threads.h>

 namespace android {
 // ----------------------------------------------------------------------------

 class DispSync;
 class Layer;
 class String8;

 namespace renderengine {
 class RenderEngine;
 class Image;
 } // namespace renderengine

 /*
  * BufferLayerConsumer consumes buffers of graphics data from a BufferQueue,
  * and makes them available to RenderEngine as a texture.
  *
  * A typical usage pattern is to call updateTexImage() when a new frame is
  * desired.  If a new frame is available, the frame is latched.  If not, the
  * previous contents are retained.  The texture is attached and updated after
  * bindTextureImage() is called.
  *
  * All calls to updateTexImage must be made with RenderEngine being current.
  * The texture is attached to the TEXTURE_EXTERNAL texture target.
  */
 class BufferLayerConsumer : public ConsumerBase {
 public:
     static const status_t BUFFER_REJECTED = UNKNOWN_ERROR + 8;

     class BufferRejecter {
         friend class BufferLayerConsumer;
         virtual bool reject(const sp<GraphicBuffer>& buf, const BufferItem& item) = 0;

     protected:
         virtual ~BufferRejecter() {}
     };

     struct ContentsChangedListener : public FrameAvailableListener {
         virtual void onSidebandStreamChanged() = 0;
     };

     // BufferLayerConsumer constructs a new BufferLayerConsumer object.  The
     // tex parameter indicates the name of the RenderEngine texture to which
     // images are to be streamed.
     BufferLayerConsumer(const sp<IGraphicBufferConsumer>& bq, renderengine::RenderEngine& engine,
                         uint32_t tex, Layer* layer);

     // Sets the contents changed listener. This should be used instead of
     // ConsumerBase::setFrameAvailableListener().
     void setContentsChangedListener(const wp<ContentsChangedListener>& listener);

     // updateTexImage acquires the most recently queued buffer, and sets the
     // image contents of the target texture to it.
     //
     // This call may only be made while RenderEngine is current.
     //
     // This calls doFenceWait to ensure proper synchronization unless native
     // fence is supported.
     //
     // Unlike the GLConsumer version, this version takes a functor that may be
     // used to reject the newly acquired buffer.  It also does not bind the
     // RenderEngine texture until bindTextureImage is called.
     status_t updateTexImage(BufferRejecter* rejecter, nsecs_t expectedPresentTime,
                             bool* autoRefresh, bool* queuedBuffer, uint64_t maxFrameNumber);

     // See BufferLayerConsumer::bindTextureImageLocked().
     status_t bindTextureImage();

     // setReleaseFence stores a fence that will signal when the current buffer
     // is no longer being read. This fence will be returned to the producer
     // when the current buffer is released by updateTexImage(). Multiple
     // fences can be set for a given buffer; they will be merged into a single
     // union fence.
     void setReleaseFence(const sp<Fence>& fence);

     bool releasePendingBuffer();

     sp<Fence> getPrevFinalReleaseFence() const;

     // See GLConsumer::getTransformMatrix.
     void getTransformMatrix(float mtx[16]);

     // getTimestamp retrieves the timestamp associated with the texture image
     // set by the most recent call to updateTexImage.
     //
     // The timestamp is in nanoseconds, and is monotonically increasing. Its
     // other semantics (zero point, etc) are source-dependent and should be
     // documented by the source.
     int64_t getTimestamp();

     // getDataSpace retrieves the DataSpace associated with the texture image
     // set by the most recent call to updateTexImage.
     ui::Dataspace getCurrentDataSpace();

     // getCurrentHdrMetadata retrieves the HDR metadata associated with the
     // texture image set by the most recent call to updateTexImage.
     const HdrMetadata& getCurrentHdrMetadata() const;

     // getFrameNumber retrieves the frame number associated with the texture
     // image set by the most recent call to updateTexImage.
     //
     // The frame number is an incrementing counter set to 0 at the creation of
     // the BufferQueue associated with this consumer.
     uint64_t getFrameNumber();

     bool getTransformToDisplayInverse() const;

     // must be called from SF main thread
     const Region& getSurfaceDamage() const;

     // Merge the given damage region into the current damage region value.
     void mergeSurfaceDamage(const Region& damage);

     // getCurrentApi retrieves the API which queues the current buffer.
     int getCurrentApi() const;

     // See GLConsumer::setDefaultBufferSize.
     status_t setDefaultBufferSize(uint32_t width, uint32_t height);

     // setFilteringEnabled sets whether the transform matrix should be computed
     // for use with bilinear filtering.
     void setFilteringEnabled(bool enabled);

     // getCurrentBuffer returns the buffer associated with the current image.
     // When outSlot is not nullptr, the current buffer slot index is also
     // returned. Simiarly, when outFence is not nullptr, the current output
     // fence is returned.
     sp<GraphicBuffer> getCurrentBuffer(int* outSlot = nullptr, sp<Fence>* outFence = nullptr) const;

     // getCurrentCrop returns the cropping rectangle of the current buffer.
     Rect getCurrentCrop() const;

     // getCurrentTransform returns the transform of the current buffer.
     uint32_t getCurrentTransform() const;

     // getCurrentScalingMode returns the scaling mode of the current buffer.
     uint32_t getCurrentScalingMode() const;

     // getCurrentFence returns the fence indicating when the current buffer is
     // ready to be read from.
     sp<Fence> getCurrentFence() const;

     // getCurrentFence returns the FenceTime indicating when the current
     // buffer is ready to be read from.
     std::shared_ptr<FenceTime> getCurrentFenceTime() const;

     // setConsumerUsageBits overrides the ConsumerBase method to OR
     // DEFAULT_USAGE_FLAGS to usage.
     status_t setConsumerUsageBits(uint64_t usage);
     void onBufferAvailable(const BufferItem& item) EXCLUDES(mImagesMutex);

 protected:
     // abandonLocked overrides the ConsumerBase method to clear
     // mCurrentTextureImage in addition to the ConsumerBase behavior.
     virtual void abandonLocked() EXCLUDES(mImagesMutex);

     // dumpLocked overrides the ConsumerBase method to dump BufferLayerConsumer-
     // specific info in addition to the ConsumerBase behavior.
     virtual void dumpLocked(String8& result, const char* prefix) const;

     // See ConsumerBase::acquireBufferLocked
     virtual status_t acquireBufferLocked(BufferItem* item, nsecs_t presentWhen,
                                          uint64_t maxFrameNumber = 0) override
             EXCLUDES(mImagesMutex);

     bool canUseImageCrop(const Rect& crop) const;

     struct PendingRelease {
         PendingRelease() : isPending(false), currentTexture(-1), graphicBuffer() {}

         bool isPending;
         int currentTexture;
         sp<GraphicBuffer> graphicBuffer;
     };

     // This releases the buffer in the slot referenced by mCurrentTexture,
     // then updates state to refer to the BufferItem, which must be a
     // newly-acquired buffer. If pendingRelease is not null, the parameters
     // which would have been passed to releaseBufferLocked upon the successful
     // completion of the method will instead be returned to the caller, so that
     // it may call releaseBufferLocked itself later.
     status_t updateAndReleaseLocked(const BufferItem& item,
                                     PendingRelease* pendingRelease = nullptr)
             EXCLUDES(mImagesMutex);

     // Binds mTexName and the current buffer to TEXTURE_EXTERNAL target.
     // If the bind succeeds, this calls doFenceWait.
     status_t bindTextureImageLocked();

 private:
     // Utility class for managing GraphicBuffer references into renderengine
     class Image {
     public:
         Image(const sp<GraphicBuffer>& graphicBuffer, renderengine::RenderEngine& engine);
         virtual ~Image();
         const sp<GraphicBuffer>& graphicBuffer() { return mGraphicBuffer; }

     private:
         // mGraphicBuffer is the buffer that was used to create this image.
         sp<GraphicBuffer> mGraphicBuffer;
         // Back-reference into renderengine to initiate cleanup.
         renderengine::RenderEngine& mRE;
         DISALLOW_COPY_AND_ASSIGN(Image);
     };

     // freeBufferLocked frees up the given buffer slot. If the slot has been
     // initialized this will release the reference to the GraphicBuffer in
     // that slot.  Otherwise it has no effect.
     //
     // This method must be called with mMutex locked.
     virtual void freeBufferLocked(int slotIndex) EXCLUDES(mImagesMutex);

     // IConsumerListener interface
     void onDisconnect() override;
     void onSidebandStreamChanged() override;
     void addAndGetFrameTimestamps(const NewFrameEventsEntry* newTimestamps,
                                   FrameEventHistoryDelta* outDelta) override;

     // computeCurrentTransformMatrixLocked computes the transform matrix for the
     // current texture.  It uses mCurrentTransform and the current GraphicBuffer
     // to compute this matrix and stores it in mCurrentTransformMatrix.
     // mCurrentTextureImage must not be nullptr.
     void computeCurrentTransformMatrixLocked();

     // getCurrentCropLocked returns the cropping rectangle of the current buffer.
     Rect getCurrentCropLocked() const;

     // The default consumer usage flags that BufferLayerConsumer always sets on its
     // BufferQueue instance; these will be OR:d with any additional flags passed
     // from the BufferLayerConsumer user. In particular, BufferLayerConsumer will always
     // consume buffers as hardware textures.
     static const uint64_t DEFAULT_USAGE_FLAGS = GraphicBuffer::USAGE_HW_TEXTURE;

     // mCurrentTextureBuffer is the buffer containing the current texture. It's
     // possible that this buffer is not associated with any buffer slot, so we
     // must track it separately in order to support the getCurrentBuffer method.
     std::shared_ptr<Image> mCurrentTextureBuffer;

     // mCurrentCrop is the crop rectangle that applies to the current texture.
     // It gets set each time updateTexImage is called.
     Rect mCurrentCrop;

     // mCurrentTransform is the transform identifier for the current texture. It
     // gets set each time updateTexImage is called.
     uint32_t mCurrentTransform;

     // mCurrentScalingMode is the scaling mode for the current texture. It gets
     // set each time updateTexImage is called.
     uint32_t mCurrentScalingMode;

     // mCurrentFence is the fence received from BufferQueue in updateTexImage.
     sp<Fence> mCurrentFence;

     // The FenceTime wrapper around mCurrentFence.
     std::shared_ptr<FenceTime> mCurrentFenceTime{FenceTime::NO_FENCE};

     // mCurrentTransformMatrix is the transform matrix for the current texture.
     // It gets computed by computeTransformMatrix each time updateTexImage is
     // called.
     float mCurrentTransformMatrix[16];

     // mCurrentTimestamp is the timestamp for the current texture. It
     // gets set each time updateTexImage is called.
     int64_t mCurrentTimestamp;

     // mCurrentDataSpace is the dataspace for the current texture. It
     // gets set each time updateTexImage is called.
     ui::Dataspace mCurrentDataSpace;

     // mCurrentHdrMetadata is the HDR metadata for the current texture. It
     // gets set each time updateTexImage is called.
     HdrMetadata mCurrentHdrMetadata;

     // mCurrentFrameNumber is the frame counter for the current texture.
     // It gets set each time updateTexImage is called.
     uint64_t mCurrentFrameNumber;

     // Indicates this buffer must be transformed by the inverse transform of the screen
     // it is displayed onto. This is applied after BufferLayerConsumer::mCurrentTransform.
     // This must be set/read from SurfaceFlinger's main thread.
     bool mCurrentTransformToDisplayInverse;

     // The portion of this surface that has changed since the previous frame
     Region mCurrentSurfaceDamage;

     int mCurrentApi;

     uint32_t mDefaultWidth, mDefaultHeight;

     // mFilteringEnabled indicates whether the transform matrix is computed for
     // use with bilinear filtering. It defaults to true and is changed by
     // setFilteringEnabled().
     bool mFilteringEnabled;

     renderengine::RenderEngine& mRE;

     // mTexName is the name of the RenderEngine texture to which streamed
     // images will be bound when bindTexImage is called. It is set at
     // construction time.
     const uint32_t mTexName;

     // The layer for this BufferLayerConsumer. Always check mAbandoned before accessing.
     Layer* mLayer GUARDED_BY(mMutex);

     wp<ContentsChangedListener> mContentsChangedListener;

     // mCurrentTexture is the buffer slot index of the buffer that is currently
     // bound to the RenderEngine texture. It is initialized to INVALID_BUFFER_SLOT,
     // indicating that no buffer slot is currently bound to the texture. Note,
     // however, that a value of INVALID_BUFFER_SLOT does not necessarily mean
     // that no buffer is bound to the texture. A call to setBufferCount will
     // reset mCurrentTexture to INVALID_BUFFER_SLOT.
     int mCurrentTexture;

     // Shadow buffer cache for cleaning up renderengine references.
     std::shared_ptr<Image> mImages[BufferQueueDefs::NUM_BUFFER_SLOTS] GUARDED_BY(mImagesMutex);

     // Separate mutex guarding the shadow buffer cache.
     // mImagesMutex can be manipulated with binder threads (e.g. onBuffersAllocated)
     // which is contentious enough that we can't just use mMutex.
     mutable std::mutex mImagesMutex;

     // A release that is pending on the receipt of a new release fence from
     // presentDisplay
     PendingRelease mPendingRelease;
 };

 // ----------------------------------------------------------------------------
 }; // namespace android

 #endif // ANDROID_BUFFERLAYERCONSUMER_H
	/*
	* Copyright (C) 2010 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.
	*/

	#ifndef ANDROID_BUFFERLAYERCONSUMER_H
	#define ANDROID_BUFFERLAYERCONSUMER_H

	#include <android-base/thread_annotations.h>
	#include <gui/BufferQueueDefs.h>
	#include <gui/ConsumerBase.h>
	#include <gui/HdrMetadata.h>

	#include <ui/FenceTime.h>
	#include <ui/GraphicBuffer.h>
	#include <ui/GraphicTypes.h>
	#include <ui/Region.h>

	#include <utils/String8.h>
	#include <utils/Vector.h>
	#include <utils/threads.h>

	namespace android {
	// ----------------------------------------------------------------------------

	class DispSync;
	class Layer;
	class String8;

	namespace renderengine {
	class RenderEngine;
	class Image;
	} // namespace renderengine

	/*
	* BufferLayerConsumer consumes buffers of graphics data from a BufferQueue,
	* and makes them available to RenderEngine as a texture.
	*
	* A typical usage pattern is to call updateTexImage() when a new frame is
	* desired. If a new frame is available, the frame is latched. If not, the
	* previous contents are retained. The texture is attached and updated after
	* bindTextureImage() is called.
	*
	* All calls to updateTexImage must be made with RenderEngine being current.
	* The texture is attached to the TEXTURE_EXTERNAL texture target.
	*/
	class BufferLayerConsumer : public ConsumerBase {
	public:
	static const status_t BUFFER_REJECTED = UNKNOWN_ERROR + 8;

	class BufferRejecter {
	friend class BufferLayerConsumer;
	virtual bool reject(const sp<GraphicBuffer>& buf, const BufferItem& item) = 0;

	protected:
	virtual ~BufferRejecter() {}
	};

	struct ContentsChangedListener : public FrameAvailableListener {
	virtual void onSidebandStreamChanged() = 0;
	};

	// BufferLayerConsumer constructs a new BufferLayerConsumer object. The
	// tex parameter indicates the name of the RenderEngine texture to which
	// images are to be streamed.
	BufferLayerConsumer(const sp<IGraphicBufferConsumer>& bq, renderengine::RenderEngine& engine,
	uint32_t tex, Layer* layer);

	// Sets the contents changed listener. This should be used instead of
	// ConsumerBase::setFrameAvailableListener().
	void setContentsChangedListener(const wp<ContentsChangedListener>& listener);

	// updateTexImage acquires the most recently queued buffer, and sets the
	// image contents of the target texture to it.
	//
	// This call may only be made while RenderEngine is current.
	//
	// This calls doFenceWait to ensure proper synchronization unless native
	// fence is supported.
	//
	// Unlike the GLConsumer version, this version takes a functor that may be
	// used to reject the newly acquired buffer. It also does not bind the
	// RenderEngine texture until bindTextureImage is called.
	status_t updateTexImage(BufferRejecter* rejecter, nsecs_t expectedPresentTime,
	bool* autoRefresh, bool* queuedBuffer, uint64_t maxFrameNumber);

	// See BufferLayerConsumer::bindTextureImageLocked().
	status_t bindTextureImage();

	// setReleaseFence stores a fence that will signal when the current buffer
	// is no longer being read. This fence will be returned to the producer
	// when the current buffer is released by updateTexImage(). Multiple
	// fences can be set for a given buffer; they will be merged into a single
	// union fence.
	void setReleaseFence(const sp<Fence>& fence);

	bool releasePendingBuffer();

	sp<Fence> getPrevFinalReleaseFence() const;

	// See GLConsumer::getTransformMatrix.
	void getTransformMatrix(float mtx[16]);

	// getTimestamp retrieves the timestamp associated with the texture image
	// set by the most recent call to updateTexImage.
	//
	// The timestamp is in nanoseconds, and is monotonically increasing. Its
	// other semantics (zero point, etc) are source-dependent and should be
	// documented by the source.
	int64_t getTimestamp();

	// getDataSpace retrieves the DataSpace associated with the texture image
	// set by the most recent call to updateTexImage.
	ui::Dataspace getCurrentDataSpace();

	// getCurrentHdrMetadata retrieves the HDR metadata associated with the
	// texture image set by the most recent call to updateTexImage.
	const HdrMetadata& getCurrentHdrMetadata() const;

	// getFrameNumber retrieves the frame number associated with the texture
	// image set by the most recent call to updateTexImage.
	//
	// The frame number is an incrementing counter set to 0 at the creation of
	// the BufferQueue associated with this consumer.
	uint64_t getFrameNumber();

	bool getTransformToDisplayInverse() const;

	// must be called from SF main thread
	const Region& getSurfaceDamage() const;

	// Merge the given damage region into the current damage region value.
	void mergeSurfaceDamage(const Region& damage);

	// getCurrentApi retrieves the API which queues the current buffer.
	int getCurrentApi() const;

	// See GLConsumer::setDefaultBufferSize.
	status_t setDefaultBufferSize(uint32_t width, uint32_t height);

	// setFilteringEnabled sets whether the transform matrix should be computed
	// for use with bilinear filtering.
	void setFilteringEnabled(bool enabled);

	// getCurrentBuffer returns the buffer associated with the current image.
	// When outSlot is not nullptr, the current buffer slot index is also
	// returned. Simiarly, when outFence is not nullptr, the current output
	// fence is returned.
	sp<GraphicBuffer> getCurrentBuffer(int* outSlot = nullptr, sp<Fence>* outFence = nullptr) const;

	// getCurrentCrop returns the cropping rectangle of the current buffer.
	Rect getCurrentCrop() const;

	// getCurrentTransform returns the transform of the current buffer.
	uint32_t getCurrentTransform() const;

	// getCurrentScalingMode returns the scaling mode of the current buffer.
	uint32_t getCurrentScalingMode() const;

	// getCurrentFence returns the fence indicating when the current buffer is
	// ready to be read from.
	sp<Fence> getCurrentFence() const;

	// getCurrentFence returns the FenceTime indicating when the current
	// buffer is ready to be read from.
	std::shared_ptr<FenceTime> getCurrentFenceTime() const;

	// setConsumerUsageBits overrides the ConsumerBase method to OR
	// DEFAULT_USAGE_FLAGS to usage.
	status_t setConsumerUsageBits(uint64_t usage);
	void onBufferAvailable(const BufferItem& item) EXCLUDES(mImagesMutex);

	protected:
	// abandonLocked overrides the ConsumerBase method to clear
	// mCurrentTextureImage in addition to the ConsumerBase behavior.
	virtual void abandonLocked() EXCLUDES(mImagesMutex);

	// dumpLocked overrides the ConsumerBase method to dump BufferLayerConsumer-
	// specific info in addition to the ConsumerBase behavior.
	virtual void dumpLocked(String8& result, const char* prefix) const;

	// See ConsumerBase::acquireBufferLocked
	virtual status_t acquireBufferLocked(BufferItem* item, nsecs_t presentWhen,
	uint64_t maxFrameNumber = 0) override
	EXCLUDES(mImagesMutex);

	bool canUseImageCrop(const Rect& crop) const;

	struct PendingRelease {
	PendingRelease() : isPending(false), currentTexture(-1), graphicBuffer() {}

	bool isPending;
	int currentTexture;
	sp<GraphicBuffer> graphicBuffer;
	};

	// This releases the buffer in the slot referenced by mCurrentTexture,
	// then updates state to refer to the BufferItem, which must be a
	// newly-acquired buffer. If pendingRelease is not null, the parameters
	// which would have been passed to releaseBufferLocked upon the successful
	// completion of the method will instead be returned to the caller, so that
	// it may call releaseBufferLocked itself later.
	status_t updateAndReleaseLocked(const BufferItem& item,
	PendingRelease* pendingRelease = nullptr)
	EXCLUDES(mImagesMutex);

	// Binds mTexName and the current buffer to TEXTURE_EXTERNAL target.
	// If the bind succeeds, this calls doFenceWait.
	status_t bindTextureImageLocked();

	private:
	// Utility class for managing GraphicBuffer references into renderengine
	class Image {
	public:
	Image(const sp<GraphicBuffer>& graphicBuffer, renderengine::RenderEngine& engine);
	virtual ~Image();
	const sp<GraphicBuffer>& graphicBuffer() { return mGraphicBuffer; }

	private:
	// mGraphicBuffer is the buffer that was used to create this image.
	sp<GraphicBuffer> mGraphicBuffer;
	// Back-reference into renderengine to initiate cleanup.
	renderengine::RenderEngine& mRE;
	DISALLOW_COPY_AND_ASSIGN(Image);
	};

	// freeBufferLocked frees up the given buffer slot. If the slot has been
	// initialized this will release the reference to the GraphicBuffer in
	// that slot. Otherwise it has no effect.
	//
	// This method must be called with mMutex locked.
	virtual void freeBufferLocked(int slotIndex) EXCLUDES(mImagesMutex);

	// IConsumerListener interface
	void onDisconnect() override;
	void onSidebandStreamChanged() override;
	void addAndGetFrameTimestamps(const NewFrameEventsEntry* newTimestamps,
	FrameEventHistoryDelta* outDelta) override;

	// computeCurrentTransformMatrixLocked computes the transform matrix for the
	// current texture. It uses mCurrentTransform and the current GraphicBuffer
	// to compute this matrix and stores it in mCurrentTransformMatrix.
	// mCurrentTextureImage must not be nullptr.
	void computeCurrentTransformMatrixLocked();

	// getCurrentCropLocked returns the cropping rectangle of the current buffer.
	Rect getCurrentCropLocked() const;

	// The default consumer usage flags that BufferLayerConsumer always sets on its
	// BufferQueue instance; these will be OR:d with any additional flags passed
	// from the BufferLayerConsumer user. In particular, BufferLayerConsumer will always
	// consume buffers as hardware textures.
	static const uint64_t DEFAULT_USAGE_FLAGS = GraphicBuffer::USAGE_HW_TEXTURE;

	// mCurrentTextureBuffer is the buffer containing the current texture. It's
	// possible that this buffer is not associated with any buffer slot, so we
	// must track it separately in order to support the getCurrentBuffer method.
	std::shared_ptr<Image> mCurrentTextureBuffer;

	// mCurrentCrop is the crop rectangle that applies to the current texture.
	// It gets set each time updateTexImage is called.
	Rect mCurrentCrop;

	// mCurrentTransform is the transform identifier for the current texture. It
	// gets set each time updateTexImage is called.
	uint32_t mCurrentTransform;

	// mCurrentScalingMode is the scaling mode for the current texture. It gets
	// set each time updateTexImage is called.
	uint32_t mCurrentScalingMode;

	// mCurrentFence is the fence received from BufferQueue in updateTexImage.
	sp<Fence> mCurrentFence;

	// The FenceTime wrapper around mCurrentFence.
	std::shared_ptr<FenceTime> mCurrentFenceTime{FenceTime::NO_FENCE};

	// mCurrentTransformMatrix is the transform matrix for the current texture.
	// It gets computed by computeTransformMatrix each time updateTexImage is
	// called.
	float mCurrentTransformMatrix[16];

	// mCurrentTimestamp is the timestamp for the current texture. It
	// gets set each time updateTexImage is called.
	int64_t mCurrentTimestamp;

	// mCurrentDataSpace is the dataspace for the current texture. It
	// gets set each time updateTexImage is called.
	ui::Dataspace mCurrentDataSpace;

	// mCurrentHdrMetadata is the HDR metadata for the current texture. It
	// gets set each time updateTexImage is called.
	HdrMetadata mCurrentHdrMetadata;

	// mCurrentFrameNumber is the frame counter for the current texture.
	// It gets set each time updateTexImage is called.
	uint64_t mCurrentFrameNumber;

	// Indicates this buffer must be transformed by the inverse transform of the screen
	// it is displayed onto. This is applied after BufferLayerConsumer::mCurrentTransform.
	// This must be set/read from SurfaceFlinger's main thread.
	bool mCurrentTransformToDisplayInverse;

	// The portion of this surface that has changed since the previous frame
	Region mCurrentSurfaceDamage;

	int mCurrentApi;

	uint32_t mDefaultWidth, mDefaultHeight;

	// mFilteringEnabled indicates whether the transform matrix is computed for
	// use with bilinear filtering. It defaults to true and is changed by
	// setFilteringEnabled().
	bool mFilteringEnabled;

	renderengine::RenderEngine& mRE;

	// mTexName is the name of the RenderEngine texture to which streamed
	// images will be bound when bindTexImage is called. It is set at
	// construction time.
	const uint32_t mTexName;

	// The layer for this BufferLayerConsumer. Always check mAbandoned before accessing.
	Layer* mLayer GUARDED_BY(mMutex);

	wp<ContentsChangedListener> mContentsChangedListener;

	// mCurrentTexture is the buffer slot index of the buffer that is currently
	// bound to the RenderEngine texture. It is initialized to INVALID_BUFFER_SLOT,
	// indicating that no buffer slot is currently bound to the texture. Note,
	// however, that a value of INVALID_BUFFER_SLOT does not necessarily mean
	// that no buffer is bound to the texture. A call to setBufferCount will
	// reset mCurrentTexture to INVALID_BUFFER_SLOT.
	int mCurrentTexture;

	// Shadow buffer cache for cleaning up renderengine references.
	std::shared_ptr<Image> mImages[BufferQueueDefs::NUM_BUFFER_SLOTS] GUARDED_BY(mImagesMutex);

	// Separate mutex guarding the shadow buffer cache.
	// mImagesMutex can be manipulated with binder threads (e.g. onBuffersAllocated)
	// which is contentious enough that we can't just use mMutex.
	mutable std::mutex mImagesMutex;

	// A release that is pending on the receipt of a new release fence from
	// presentDisplay
	PendingRelease mPendingRelease;
	};

	// ----------------------------------------------------------------------------
	}; // namespace android

	#endif // ANDROID_BUFFERLAYERCONSUMER_H