services/surfaceflinger/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 "RenderEngine/Image.h"

#include <gui/BufferQueueDefs.h>
#include <gui/ConsumerBase.h>

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

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

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

class DispSync;
class Layer;
class RenderEngine;
class String8;

/*
 * 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& 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);

    nsecs_t computeExpectedPresent(const DispSync& dispSync);

    // 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, const DispSync& dispSync, 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.
    android_dataspace getCurrentDataSpace();

    // 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;

    // 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.
    sp<GraphicBuffer> getCurrentBuffer(int* outSlot = 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);

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

    // 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;

    // acquireBufferLocked overrides the ConsumerBase method to update the
    // mImages array in addition to the ConsumerBase behavior.
    virtual status_t acquireBufferLocked(BufferItem* item, nsecs_t presentWhen,
                                         uint64_t maxFrameNumber = 0) override;

    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);

    // Binds mTexName and the current buffer to TEXTURE_EXTERNAL target.  Uses
    // mCurrentTexture if it's set, mCurrentTextureImage if not.  If the
    // bind succeeds, this calls doFenceWait.
    status_t bindTextureImageLocked();

private:
    // Image is a utility class for tracking and creating RE::Images. There
    // is primarily just one image per slot, but there is also special cases:
    //  - After freeBuffer, we must still keep the current image/buffer
    // Reference counting RE::Images lets us handle all these cases easily while
    // also only creating new RE::Images from buffers when required.
    class Image : public LightRefBase<Image> {
    public:
        Image(sp<GraphicBuffer> graphicBuffer, const RenderEngine& engine);

        Image(const Image& rhs) = delete;
        Image& operator=(const Image& rhs) = delete;

        // createIfNeeded creates an RE::Image if required (we haven't created
        // one yet, or the crop-rect has changed).
        status_t createIfNeeded(const Rect& imageCrop);

        const sp<GraphicBuffer>& graphicBuffer() { return mGraphicBuffer; }
        const native_handle* graphicBufferHandle() {
            return mGraphicBuffer == NULL ? NULL : mGraphicBuffer->handle;
        }

        const RE::Image& image() const { return mImage; }

    private:
        // Only allow instantiation using ref counting.
        friend class LightRefBase<Image>;
        virtual ~Image() = default;

        // mGraphicBuffer is the buffer that was used to create this image.
        sp<GraphicBuffer> mGraphicBuffer;

        // mImage is the image created from mGraphicBuffer.
        RE::Image mImage;
        bool mCreated;
        int32_t mCropWidth;
        int32_t mCropHeight;
    };

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

    // 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 NULL.
    void computeCurrentTransformMatrixLocked();

    // doFenceWaitLocked inserts a wait command into the RenderEngine command
    // stream to ensure that it is safe for future RenderEngine commands to
    // access the current texture buffer.
    status_t doFenceWaitLocked() const;

    // syncForReleaseLocked performs the synchronization needed to release the
    // current slot from RenderEngine.  If needed it will set the current
    // slot's fence to guard against a producer accessing the buffer before
    // the outstanding accesses have completed.
    status_t syncForReleaseLocked();

    // 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;

    // mCurrentTextureImage is the Image/buffer of 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.
    sp<Image> mCurrentTextureImage;

    // 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.
    android_dataspace mCurrentDataSpace;

    // 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;

    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& 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
    const wp<Layer> mLayer;

    wp<ContentsChangedListener> mContentsChangedListener;

    // mImages stores the buffers that have been allocated by the BufferQueue
    // for each buffer slot.  It is initialized to null pointers, and gets
    // filled in with the result of BufferQueue::acquire when the
    // client dequeues a buffer from a
    // slot that has not yet been used. The buffer allocated to a slot will also
    // be replaced if the requested buffer usage or geometry differs from that
    // of the buffer allocated to a slot.
    sp<Image> mImages[BufferQueueDefs::NUM_BUFFER_SLOTS];

    // 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;

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

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

#endif // ANDROID_BUFFERLAYERCONSUMER_H