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 <android-base/thread_annotations.h>
#include <gui/BufferQueueDefs.h>
#include <gui/ConsumerBase.h>
#include <gui/HdrMetadata.h>
#include <renderengine/ExternalTexture.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 Layer;
class String8;

namespace renderengine {
class RenderEngine;
} // 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);

    // 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.
    std::shared_ptr<renderengine::ExternalTexture> 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);

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<renderengine::ExternalTexture> 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<renderengine::ExternalTexture>
            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