libs/gui/SurfaceTexture.cpp

/*
 * 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.
 */

#define LOG_TAG "SurfaceTexture"
//#define LOG_NDEBUG 0

#define GL_GLEXT_PROTOTYPES
#define EGL_EGLEXT_PROTOTYPES

#include <EGL/egl.h>
#include <EGL/eglext.h>
#include <GLES2/gl2.h>
#include <GLES2/gl2ext.h>

#include <gui/SurfaceTexture.h>

#include <hardware/hardware.h>

#include <surfaceflinger/ISurfaceComposer.h>
#include <surfaceflinger/SurfaceComposerClient.h>
#include <surfaceflinger/IGraphicBufferAlloc.h>

#include <utils/Log.h>
#include <utils/String8.h>


#define ALLOW_DEQUEUE_CURRENT_BUFFER    false

// Macros for including the SurfaceTexture name in log messages
#define ST_LOGV(x, ...) LOGV("[%s] "x, mName.string(), ##__VA_ARGS__)
#define ST_LOGD(x, ...) LOGD("[%s] "x, mName.string(), ##__VA_ARGS__)
#define ST_LOGI(x, ...) LOGI("[%s] "x, mName.string(), ##__VA_ARGS__)
#define ST_LOGW(x, ...) LOGW("[%s] "x, mName.string(), ##__VA_ARGS__)
#define ST_LOGE(x, ...) LOGE("[%s] "x, mName.string(), ##__VA_ARGS__)

namespace android {

// Transform matrices
static float mtxIdentity[16] = {
    1, 0, 0, 0,
    0, 1, 0, 0,
    0, 0, 1, 0,
    0, 0, 0, 1,
};
static float mtxFlipH[16] = {
    -1, 0, 0, 0,
    0, 1, 0, 0,
    0, 0, 1, 0,
    1, 0, 0, 1,
};
static float mtxFlipV[16] = {
    1, 0, 0, 0,
    0, -1, 0, 0,
    0, 0, 1, 0,
    0, 1, 0, 1,
};
static float mtxRot90[16] = {
    0, 1, 0, 0,
    -1, 0, 0, 0,
    0, 0, 1, 0,
    1, 0, 0, 1,
};
static float mtxRot180[16] = {
    -1, 0, 0, 0,
    0, -1, 0, 0,
    0, 0, 1, 0,
    1, 1, 0, 1,
};
static float mtxRot270[16] = {
    0, -1, 0, 0,
    1, 0, 0, 0,
    0, 0, 1, 0,
    0, 1, 0, 1,
};

static void mtxMul(float out[16], const float a[16], const float b[16]);

// Get an ID that's unique within this process.
static int32_t createProcessUniqueId() {
    static volatile int32_t globalCounter = 0;
    return android_atomic_inc(&globalCounter);
}

SurfaceTexture::SurfaceTexture(GLuint tex, bool allowSynchronousMode,
        GLenum texTarget) :
    mDefaultWidth(1),
    mDefaultHeight(1),
    mPixelFormat(PIXEL_FORMAT_RGBA_8888),
    mBufferCount(MIN_ASYNC_BUFFER_SLOTS),
    mClientBufferCount(0),
    mServerBufferCount(MIN_ASYNC_BUFFER_SLOTS),
    mCurrentTexture(INVALID_BUFFER_SLOT),
    mCurrentTransform(0),
    mCurrentTimestamp(0),
    mNextTransform(0),
    mNextScalingMode(NATIVE_WINDOW_SCALING_MODE_FREEZE),
    mTexName(tex),
    mSynchronousMode(false),
    mAllowSynchronousMode(allowSynchronousMode),
    mConnectedApi(NO_CONNECTED_API),
    mAbandoned(false),
    mTexTarget(texTarget),
    mFrameCounter(0) {
    // Choose a name using the PID and a process-unique ID.
    mName = String8::format("unnamed-%d-%d", getpid(), createProcessUniqueId());

    ST_LOGV("SurfaceTexture");
    sp<ISurfaceComposer> composer(ComposerService::getComposerService());
    mGraphicBufferAlloc = composer->createGraphicBufferAlloc();
    mNextCrop.makeInvalid();
    memcpy(mCurrentTransformMatrix, mtxIdentity,
            sizeof(mCurrentTransformMatrix));
}

SurfaceTexture::~SurfaceTexture() {
    ST_LOGV("~SurfaceTexture");
    freeAllBuffersLocked();
}

status_t SurfaceTexture::setBufferCountServerLocked(int bufferCount) {
    if (bufferCount > NUM_BUFFER_SLOTS)
        return BAD_VALUE;

    // special-case, nothing to do
    if (bufferCount == mBufferCount)
        return OK;

    if (!mClientBufferCount &&
        bufferCount >= mBufferCount) {
        // easy, we just have more buffers
        mBufferCount = bufferCount;
        mServerBufferCount = bufferCount;
        mDequeueCondition.signal();
    } else {
        // we're here because we're either
        // - reducing the number of available buffers
        // - or there is a client-buffer-count in effect

        // less than 2 buffers is never allowed
        if (bufferCount < 2)
            return BAD_VALUE;

        // when there is non client-buffer-count in effect, the client is not
        // allowed to dequeue more than one buffer at a time,
        // so the next time they dequeue a buffer, we know that they don't
        // own one. the actual resizing will happen during the next
        // dequeueBuffer.

        mServerBufferCount = bufferCount;
    }
    return OK;
}

status_t SurfaceTexture::setBufferCountServer(int bufferCount) {
    Mutex::Autolock lock(mMutex);
    return setBufferCountServerLocked(bufferCount);
}

status_t SurfaceTexture::setBufferCount(int bufferCount) {
    ST_LOGV("setBufferCount: count=%d", bufferCount);
    Mutex::Autolock lock(mMutex);

    if (mAbandoned) {
        ST_LOGE("setBufferCount: SurfaceTexture has been abandoned!");
        return NO_INIT;
    }
    if (bufferCount > NUM_BUFFER_SLOTS) {
        ST_LOGE("setBufferCount: bufferCount larger than slots available");
        return BAD_VALUE;
    }

    // Error out if the user has dequeued buffers
    for (int i=0 ; i<mBufferCount ; i++) {
        if (mSlots[i].mBufferState == BufferSlot::DEQUEUED) {
            ST_LOGE("setBufferCount: client owns some buffers");
            return -EINVAL;
        }
    }

    const int minBufferSlots = mSynchronousMode ?
            MIN_SYNC_BUFFER_SLOTS : MIN_ASYNC_BUFFER_SLOTS;
    if (bufferCount == 0) {
        mClientBufferCount = 0;
        bufferCount = (mServerBufferCount >= minBufferSlots) ?
                mServerBufferCount : minBufferSlots;
        return setBufferCountServerLocked(bufferCount);
    }

    if (bufferCount < minBufferSlots) {
        ST_LOGE("setBufferCount: requested buffer count (%d) is less than "
                "minimum (%d)", bufferCount, minBufferSlots);
        return BAD_VALUE;
    }

    // here we're guaranteed that the client doesn't have dequeued buffers
    // and will release all of its buffer references.
    freeAllBuffersLocked();
    mBufferCount = bufferCount;
    mClientBufferCount = bufferCount;
    mCurrentTexture = INVALID_BUFFER_SLOT;
    mQueue.clear();
    mDequeueCondition.signal();
    return OK;
}

status_t SurfaceTexture::setDefaultBufferSize(uint32_t w, uint32_t h)
{
    ST_LOGV("setDefaultBufferSize: w=%d, h=%d", w, h);
    if (!w || !h) {
        ST_LOGE("setDefaultBufferSize: dimensions cannot be 0 (w=%d, h=%d)",
                w, h);
        return BAD_VALUE;
    }

    Mutex::Autolock lock(mMutex);
    mDefaultWidth = w;
    mDefaultHeight = h;
    return OK;
}

status_t SurfaceTexture::requestBuffer(int slot, sp<GraphicBuffer>* buf) {
    ST_LOGV("requestBuffer: slot=%d", slot);
    Mutex::Autolock lock(mMutex);
    if (mAbandoned) {
        ST_LOGE("requestBuffer: SurfaceTexture has been abandoned!");
        return NO_INIT;
    }
    if (slot < 0 || mBufferCount <= slot) {
        ST_LOGE("requestBuffer: slot index out of range [0, %d]: %d",
                mBufferCount, slot);
        return BAD_VALUE;
    }
    mSlots[slot].mRequestBufferCalled = true;
    *buf = mSlots[slot].mGraphicBuffer;
    return NO_ERROR;
}

status_t SurfaceTexture::dequeueBuffer(int *outBuf, uint32_t w, uint32_t h,
        uint32_t format, uint32_t usage) {
    ST_LOGV("dequeueBuffer: w=%d h=%d fmt=%#x usage=%#x", w, h, format, usage);

    if ((w && !h) || (!w && h)) {
        ST_LOGE("dequeueBuffer: invalid size: w=%u, h=%u", w, h);
        return BAD_VALUE;
    }

    Mutex::Autolock lock(mMutex);

    status_t returnFlags(OK);

    int found = -1;
    int foundSync = -1;
    int dequeuedCount = 0;
    bool tryAgain = true;
    while (tryAgain) {
        if (mAbandoned) {
            ST_LOGE("dequeueBuffer: SurfaceTexture has been abandoned!");
            return NO_INIT;
        }

        // We need to wait for the FIFO to drain if the number of buffer
        // needs to change.
        //
        // The condition "number of buffers needs to change" is true if
        // - the client doesn't care about how many buffers there are
        // - AND the actual number of buffer is different from what was
        //   set in the last setBufferCountServer()
        //                         - OR -
        //   setBufferCountServer() was set to a value incompatible with
        //   the synchronization mode (for instance because the sync mode
        //   changed since)
        //
        // As long as this condition is true AND the FIFO is not empty, we
        // wait on mDequeueCondition.

        const int minBufferCountNeeded = mSynchronousMode ?
                MIN_SYNC_BUFFER_SLOTS : MIN_ASYNC_BUFFER_SLOTS;

        const bool numberOfBuffersNeedsToChange = !mClientBufferCount &&
                ((mServerBufferCount != mBufferCount) ||
                        (mServerBufferCount < minBufferCountNeeded));

        if (!mQueue.isEmpty() && numberOfBuffersNeedsToChange) {
            // wait for the FIFO to drain
            mDequeueCondition.wait(mMutex);
            // NOTE: we continue here because we need to reevaluate our
            // whole state (eg: we could be abandoned or disconnected)
            continue;
        }

        if (numberOfBuffersNeedsToChange) {
            // here we're guaranteed that mQueue is empty
            freeAllBuffersLocked();
            mBufferCount = mServerBufferCount;
            if (mBufferCount < minBufferCountNeeded)
                mBufferCount = minBufferCountNeeded;
            mCurrentTexture = INVALID_BUFFER_SLOT;
            returnFlags |= ISurfaceTexture::RELEASE_ALL_BUFFERS;
        }

        // look for a free buffer to give to the client
        found = INVALID_BUFFER_SLOT;
        foundSync = INVALID_BUFFER_SLOT;
        dequeuedCount = 0;
        for (int i = 0; i < mBufferCount; i++) {
            const int state = mSlots[i].mBufferState;
            if (state == BufferSlot::DEQUEUED) {
                dequeuedCount++;
            }

            // if buffer is FREE it CANNOT be current
            LOGW_IF((state == BufferSlot::FREE) && (mCurrentTexture==i),
                    "dequeueBuffer: buffer %d is both FREE and current!", i);

            if (ALLOW_DEQUEUE_CURRENT_BUFFER) {
                if (state == BufferSlot::FREE || i == mCurrentTexture) {
                    foundSync = i;
                    if (i != mCurrentTexture) {
                        found = i;
                        break;
                    }
                }
            } else {
                if (state == BufferSlot::FREE) {
                    /** For Asynchronous mode, we need to return the oldest of free buffers
                    * There is only one instance when the Framecounter overflows, this logic
                    * might return the earlier buffer to client. Which is a negligible impact
                    **/
                    if (found < 0 || mSlots[i].mFrameNumber < mSlots[found].mFrameNumber) {
                        foundSync = i;
                        found = i;
                    }
                }
            }
        }

        // clients are not allowed to dequeue more than one buffer
        // if they didn't set a buffer count.
        if (!mClientBufferCount && dequeuedCount) {
            ST_LOGE("dequeueBuffer: can't dequeue multiple buffers without "
                    "setting the buffer count");
            return -EINVAL;
        }

        // See whether a buffer has been queued since the last setBufferCount so
        // we know whether to perform the MIN_UNDEQUEUED_BUFFERS check below.
        bool bufferHasBeenQueued = mCurrentTexture != INVALID_BUFFER_SLOT;
        if (bufferHasBeenQueued) {
            // make sure the client is not trying to dequeue more buffers
            // than allowed.
            const int avail = mBufferCount - (dequeuedCount+1);
            if (avail < (MIN_UNDEQUEUED_BUFFERS-int(mSynchronousMode))) {
                ST_LOGE("dequeueBuffer: MIN_UNDEQUEUED_BUFFERS=%d exceeded "
                        "(dequeued=%d)",
                        MIN_UNDEQUEUED_BUFFERS-int(mSynchronousMode),
                        dequeuedCount);
                return -EBUSY;
            }
        }

        // we're in synchronous mode and didn't find a buffer, we need to wait
        // for some buffers to be consumed
        tryAgain = mSynchronousMode && (foundSync == INVALID_BUFFER_SLOT);
        if (tryAgain) {
            mDequeueCondition.wait(mMutex);
        }
    }

    if (mSynchronousMode && found == INVALID_BUFFER_SLOT) {
        // foundSync guaranteed to be != INVALID_BUFFER_SLOT
        found = foundSync;
    }

    if (found == INVALID_BUFFER_SLOT) {
        // This should not happen.
        ST_LOGE("dequeueBuffer: no available buffer slots");
        return -EBUSY;
    }

    const int buf = found;
    *outBuf = found;

    const bool useDefaultSize = !w && !h;
    if (useDefaultSize) {
        // use the default size
        w = mDefaultWidth;
        h = mDefaultHeight;
    }

    const bool updateFormat = (format != 0);
    if (!updateFormat) {
        // keep the current (or default) format
        format = mPixelFormat;
    }

    // buffer is now in DEQUEUED (but can also be current at the same time,
    // if we're in synchronous mode)
    mSlots[buf].mBufferState = BufferSlot::DEQUEUED;

    const sp<GraphicBuffer>& buffer(mSlots[buf].mGraphicBuffer);
    if ((buffer == NULL) ||
        (uint32_t(buffer->width)  != w) ||
        (uint32_t(buffer->height) != h) ||
        (uint32_t(buffer->format) != format) ||
        ((uint32_t(buffer->usage) & usage) != usage))
    {
        usage |= GraphicBuffer::USAGE_HW_TEXTURE;
        status_t error;
        sp<GraphicBuffer> graphicBuffer(
                mGraphicBufferAlloc->createGraphicBuffer(
                        w, h, format, usage, &error));
        if (graphicBuffer == 0) {
            ST_LOGE("dequeueBuffer: SurfaceComposer::createGraphicBuffer "
                    "failed");
            return error;
        }
        if (updateFormat) {
            mPixelFormat = format;
        }
        mSlots[buf].mGraphicBuffer = graphicBuffer;
        mSlots[buf].mRequestBufferCalled = false;
        if (mSlots[buf].mEglImage != EGL_NO_IMAGE_KHR) {
            eglDestroyImageKHR(mSlots[buf].mEglDisplay, mSlots[buf].mEglImage);
            mSlots[buf].mEglImage = EGL_NO_IMAGE_KHR;
            mSlots[buf].mEglDisplay = EGL_NO_DISPLAY;
        }
        returnFlags |= ISurfaceTexture::BUFFER_NEEDS_REALLOCATION;
    }
    ST_LOGV("dequeueBuffer: returning slot=%d buf=%p flags=%#x", buf,
            mSlots[buf].mGraphicBuffer->handle, returnFlags);
    return returnFlags;
}

status_t SurfaceTexture::setSynchronousMode(bool enabled) {
    ST_LOGV("setSynchronousMode: enabled=%d", enabled);
    Mutex::Autolock lock(mMutex);

    if (mAbandoned) {
        ST_LOGE("setSynchronousMode: SurfaceTexture has been abandoned!");
        return NO_INIT;
    }

    status_t err = OK;
    if (!mAllowSynchronousMode && enabled)
        return err;

    if (!enabled) {
        // going to asynchronous mode, drain the queue
        err = drainQueueLocked();
        if (err != NO_ERROR)
            return err;
    }

    if (mSynchronousMode != enabled) {
        // - if we're going to asynchronous mode, the queue is guaranteed to be
        // empty here
        // - if the client set the number of buffers, we're guaranteed that
        // we have at least 3 (because we don't allow less)
        mSynchronousMode = enabled;
        mDequeueCondition.signal();
    }
    return err;
}

status_t SurfaceTexture::queueBuffer(int buf, int64_t timestamp,
        uint32_t* outWidth, uint32_t* outHeight, uint32_t* outTransform) {
    ST_LOGV("queueBuffer: slot=%d time=%lld", buf, timestamp);

    sp<FrameAvailableListener> listener;

    { // scope for the lock
        Mutex::Autolock lock(mMutex);
        if (mAbandoned) {
            ST_LOGE("queueBuffer: SurfaceTexture has been abandoned!");
            return NO_INIT;
        }
        if (buf < 0 || buf >= mBufferCount) {
            ST_LOGE("queueBuffer: slot index out of range [0, %d]: %d",
                    mBufferCount, buf);
            return -EINVAL;
        } else if (mSlots[buf].mBufferState != BufferSlot::DEQUEUED) {
            ST_LOGE("queueBuffer: slot %d is not owned by the client "
                    "(state=%d)", buf, mSlots[buf].mBufferState);
            return -EINVAL;
        } else if (buf == mCurrentTexture) {
            ST_LOGE("queueBuffer: slot %d is current!", buf);
            return -EINVAL;
        } else if (!mSlots[buf].mRequestBufferCalled) {
            ST_LOGE("queueBuffer: slot %d was enqueued without requesting a "
                    "buffer", buf);
            return -EINVAL;
        }

        if (mSynchronousMode) {
            // In synchronous mode we queue all buffers in a FIFO.
            mQueue.push_back(buf);

            // Synchronous mode always signals that an additional frame should
            // be consumed.
            listener = mFrameAvailableListener;
        } else {
            // In asynchronous mode we only keep the most recent buffer.
            if (mQueue.empty()) {
                mQueue.push_back(buf);

                // Asynchronous mode only signals that a frame should be
                // consumed if no previous frame was pending. If a frame were
                // pending then the consumer would have already been notified.
                listener = mFrameAvailableListener;
            } else {
                Fifo::iterator front(mQueue.begin());
                // buffer currently queued is freed
                mSlots[*front].mBufferState = BufferSlot::FREE;
                // and we record the new buffer index in the queued list
                *front = buf;
            }
        }

        mSlots[buf].mBufferState = BufferSlot::QUEUED;
        mSlots[buf].mCrop = mNextCrop;
        mSlots[buf].mTransform = mNextTransform;
        mSlots[buf].mScalingMode = mNextScalingMode;
        mSlots[buf].mTimestamp = timestamp;
        mFrameCounter++;
        mSlots[buf].mFrameNumber = mFrameCounter;

        mDequeueCondition.signal();

        *outWidth = mDefaultWidth;
        *outHeight = mDefaultHeight;
        *outTransform = 0;
    } // scope for the lock

    // call back without lock held
    if (listener != 0) {
        listener->onFrameAvailable();
    }
    return OK;
}

void SurfaceTexture::cancelBuffer(int buf) {
    ST_LOGV("cancelBuffer: slot=%d", buf);
    Mutex::Autolock lock(mMutex);

    if (mAbandoned) {
        ST_LOGW("cancelBuffer: SurfaceTexture has been abandoned!");
        return;
    }

    if (buf < 0 || buf >= mBufferCount) {
        ST_LOGE("cancelBuffer: slot index out of range [0, %d]: %d",
                mBufferCount, buf);
        return;
    } else if (mSlots[buf].mBufferState != BufferSlot::DEQUEUED) {
        ST_LOGE("cancelBuffer: slot %d is not owned by the client (state=%d)",
                buf, mSlots[buf].mBufferState);
        return;
    }
    mSlots[buf].mBufferState = BufferSlot::FREE;
    mSlots[buf].mFrameNumber = 0;
    mDequeueCondition.signal();
}

status_t SurfaceTexture::setCrop(const Rect& crop) {
    ST_LOGV("setCrop: crop=[%d,%d,%d,%d]", crop.left, crop.top, crop.right,
            crop.bottom);

    Mutex::Autolock lock(mMutex);
    if (mAbandoned) {
        ST_LOGE("setCrop: SurfaceTexture has been abandoned!");
        return NO_INIT;
    }
    mNextCrop = crop;
    return OK;
}

status_t SurfaceTexture::setTransform(uint32_t transform) {
    ST_LOGV("setTransform: xform=%#x", transform);
    Mutex::Autolock lock(mMutex);
    if (mAbandoned) {
        ST_LOGE("setTransform: SurfaceTexture has been abandoned!");
        return NO_INIT;
    }
    mNextTransform = transform;
    return OK;
}

status_t SurfaceTexture::connect(int api,
        uint32_t* outWidth, uint32_t* outHeight, uint32_t* outTransform) {
    ST_LOGV("connect: api=%d", api);
    Mutex::Autolock lock(mMutex);

    if (mAbandoned) {
        ST_LOGE("connect: SurfaceTexture has been abandoned!");
        return NO_INIT;
    }

    int err = NO_ERROR;
    switch (api) {
        case NATIVE_WINDOW_API_EGL:
        case NATIVE_WINDOW_API_CPU:
        case NATIVE_WINDOW_API_MEDIA:
        case NATIVE_WINDOW_API_CAMERA:
            if (mConnectedApi != NO_CONNECTED_API) {
                ST_LOGE("connect: already connected (cur=%d, req=%d)",
                        mConnectedApi, api);
                err = -EINVAL;
            } else {
                mConnectedApi = api;
                *outWidth = mDefaultWidth;
                *outHeight = mDefaultHeight;
                *outTransform = 0;
            }
            break;
        default:
            err = -EINVAL;
            break;
    }
    return err;
}

status_t SurfaceTexture::disconnect(int api) {
    ST_LOGV("disconnect: api=%d", api);
    Mutex::Autolock lock(mMutex);

    if (mAbandoned) {
        ST_LOGE("disconnect: SurfaceTexture has been abandoned!");
        return NO_INIT;
    }

    int err = NO_ERROR;
    switch (api) {
        case NATIVE_WINDOW_API_EGL:
        case NATIVE_WINDOW_API_CPU:
        case NATIVE_WINDOW_API_MEDIA:
        case NATIVE_WINDOW_API_CAMERA:
            if (mConnectedApi == api) {
                drainQueueAndFreeBuffersLocked();
                mConnectedApi = NO_CONNECTED_API;
                mNextCrop.makeInvalid();
                mNextScalingMode = NATIVE_WINDOW_SCALING_MODE_FREEZE;
                mNextTransform = 0;
                mDequeueCondition.signal();
            } else {
                ST_LOGE("disconnect: connected to another api (cur=%d, req=%d)",
                        mConnectedApi, api);
                err = -EINVAL;
            }
            break;
        default:
            ST_LOGE("disconnect: unknown API %d", api);
            err = -EINVAL;
            break;
    }
    return err;
}

status_t SurfaceTexture::setScalingMode(int mode) {
    ST_LOGV("setScalingMode: mode=%d", mode);

    switch (mode) {
        case NATIVE_WINDOW_SCALING_MODE_FREEZE:
        case NATIVE_WINDOW_SCALING_MODE_SCALE_TO_WINDOW:
            break;
        default:
            ST_LOGE("unknown scaling mode: %d", mode);
            return BAD_VALUE;
    }

    Mutex::Autolock lock(mMutex);
    mNextScalingMode = mode;
    return OK;
}

status_t SurfaceTexture::updateTexImage() {
    ST_LOGV("updateTexImage");
    Mutex::Autolock lock(mMutex);

    if (mAbandoned) {
        ST_LOGE("calling updateTexImage() on an abandoned SurfaceTexture");
        return NO_INIT;
    }

    // In asynchronous mode the list is guaranteed to be one buffer
    // deep, while in synchronous mode we use the oldest buffer.
    if (!mQueue.empty()) {
        Fifo::iterator front(mQueue.begin());
        int buf = *front;

        // Update the GL texture object.
        EGLImageKHR image = mSlots[buf].mEglImage;
        if (image == EGL_NO_IMAGE_KHR) {
            EGLDisplay dpy = eglGetCurrentDisplay();
            if (mSlots[buf].mGraphicBuffer == 0) {
                ST_LOGE("buffer at slot %d is null", buf);
                return BAD_VALUE;
            }
            image = createImage(dpy, mSlots[buf].mGraphicBuffer);
            mSlots[buf].mEglImage = image;
            mSlots[buf].mEglDisplay = dpy;
            if (image == EGL_NO_IMAGE_KHR) {
                // NOTE: if dpy was invalid, createImage() is guaranteed to
                // fail. so we'd end up here.
                return -EINVAL;
            }
        }

        GLint error;
        while ((error = glGetError()) != GL_NO_ERROR) {
            ST_LOGW("updateTexImage: clearing GL error: %#04x", error);
        }

        glBindTexture(mTexTarget, mTexName);
        glEGLImageTargetTexture2DOES(mTexTarget, (GLeglImageOES)image);

        bool failed = false;
        while ((error = glGetError()) != GL_NO_ERROR) {
            ST_LOGE("error binding external texture image %p (slot %d): %#04x",
                    image, buf, error);
            failed = true;
        }
        if (failed) {
            return -EINVAL;
        }

        ST_LOGV("updateTexImage: (slot=%d buf=%p) -> (slot=%d buf=%p)", mCurrentTexture,
                mCurrentTextureBuf != NULL ? mCurrentTextureBuf->handle : 0, buf,
                mSlots[buf].mGraphicBuffer->handle);

        if (mCurrentTexture != INVALID_BUFFER_SLOT) {
            // The current buffer becomes FREE if it was still in the queued
            // state. If it has already been given to the client
            // (synchronous mode), then it stays in DEQUEUED state.
            if (mSlots[mCurrentTexture].mBufferState == BufferSlot::QUEUED)
                mSlots[mCurrentTexture].mBufferState = BufferSlot::FREE;
        }

        // Update the SurfaceTexture state.
        mCurrentTexture = buf;
        mCurrentTextureBuf = mSlots[buf].mGraphicBuffer;
        mCurrentCrop = mSlots[buf].mCrop;
        mCurrentTransform = mSlots[buf].mTransform;
        mCurrentScalingMode = mSlots[buf].mScalingMode;
        mCurrentTimestamp = mSlots[buf].mTimestamp;
        computeCurrentTransformMatrix();

        // Now that we've passed the point at which failures can happen,
        // it's safe to remove the buffer from the front of the queue.
        mQueue.erase(front);
        mDequeueCondition.signal();
    } else {
        // We always bind the texture even if we don't update its contents.
        glBindTexture(mTexTarget, mTexName);
    }

    return OK;
}

bool SurfaceTexture::isExternalFormat(uint32_t format)
{
    switch (format) {
    // supported YUV formats
    case HAL_PIXEL_FORMAT_YV12:
    // Legacy/deprecated YUV formats
    case HAL_PIXEL_FORMAT_YCbCr_422_SP:
    case HAL_PIXEL_FORMAT_YCrCb_420_SP:
    case HAL_PIXEL_FORMAT_YCbCr_422_I:
        return true;
    }

    // Any OEM format needs to be considered
    if (format>=0x100 && format<=0x1FF)
        return true;

    return false;
}

GLenum SurfaceTexture::getCurrentTextureTarget() const {
    return mTexTarget;
}

void SurfaceTexture::getTransformMatrix(float mtx[16]) {
    Mutex::Autolock lock(mMutex);
    memcpy(mtx, mCurrentTransformMatrix, sizeof(mCurrentTransformMatrix));
}

void SurfaceTexture::computeCurrentTransformMatrix() {
    ST_LOGV("computeCurrentTransformMatrix");

    float xform[16];
    for (int i = 0; i < 16; i++) {
        xform[i] = mtxIdentity[i];
    }
    if (mCurrentTransform & NATIVE_WINDOW_TRANSFORM_FLIP_H) {
        float result[16];
        mtxMul(result, xform, mtxFlipH);
        for (int i = 0; i < 16; i++) {
            xform[i] = result[i];
        }
    }
    if (mCurrentTransform & NATIVE_WINDOW_TRANSFORM_FLIP_V) {
        float result[16];
        mtxMul(result, xform, mtxFlipV);
        for (int i = 0; i < 16; i++) {
            xform[i] = result[i];
        }
    }
    if (mCurrentTransform & NATIVE_WINDOW_TRANSFORM_ROT_90) {
        float result[16];
        mtxMul(result, xform, mtxRot90);
        for (int i = 0; i < 16; i++) {
            xform[i] = result[i];
        }
    }

    sp<GraphicBuffer>& buf(mSlots[mCurrentTexture].mGraphicBuffer);
    float tx, ty, sx, sy;
    if (!mCurrentCrop.isEmpty()) {
        // In order to prevent bilinear sampling at the of the crop rectangle we
        // may need to shrink it by 2 texels in each direction.  Normally this
        // would just need to take 1/2 a texel off each end, but because the
        // chroma channels will likely be subsampled we need to chop off a whole
        // texel.  This will cause artifacts if someone does nearest sampling
        // with 1:1 pixel:texel ratio, but it's impossible to simultaneously
        // accomodate the bilinear and nearest sampling uses.
        //
        // If nearest sampling turns out to be a desirable usage of these
        // textures then we could add the ability to switch a SurfaceTexture to
        // nearest-mode.  Preferably, however, the image producers (video
        // decoder, camera, etc.) would simply not use a crop rectangle (or at
        // least not tell the framework about it) so that the GPU can do the
        // correct edge behavior.
        int xshrink = 0, yshrink = 0;
        if (mCurrentCrop.left > 0) {
            tx = float(mCurrentCrop.left + 1) / float(buf->getWidth());
            xshrink++;
        } else {
            tx = 0.0f;
        }
        if (mCurrentCrop.right < int32_t(buf->getWidth())) {
            xshrink++;
        }
        if (mCurrentCrop.bottom < int32_t(buf->getHeight())) {
            ty = (float(buf->getHeight() - mCurrentCrop.bottom) + 1.0f) /
                    float(buf->getHeight());
            yshrink++;
        } else {
            ty = 0.0f;
        }
        if (mCurrentCrop.top > 0) {
            yshrink++;
        }
        sx = float(mCurrentCrop.width() - xshrink) / float(buf->getWidth());
        sy = float(mCurrentCrop.height() - yshrink) / float(buf->getHeight());
    } else {
        tx = 0.0f;
        ty = 0.0f;
        sx = 1.0f;
        sy = 1.0f;
    }
    float crop[16] = {
        sx, 0, 0, 0,
        0, sy, 0, 0,
        0, 0, 1, 0,
        tx, ty, 0, 1,
    };

    float mtxBeforeFlipV[16];
    mtxMul(mtxBeforeFlipV, crop, xform);

    // SurfaceFlinger expects the top of its window textures to be at a Y
    // coordinate of 0, so SurfaceTexture must behave the same way.  We don't
    // want to expose this to applications, however, so we must add an
    // additional vertical flip to the transform after all the other transforms.
    mtxMul(mCurrentTransformMatrix, mtxFlipV, mtxBeforeFlipV);
}

nsecs_t SurfaceTexture::getTimestamp() {
    ST_LOGV("getTimestamp");
    Mutex::Autolock lock(mMutex);
    return mCurrentTimestamp;
}

void SurfaceTexture::setFrameAvailableListener(
        const sp<FrameAvailableListener>& listener) {
    ST_LOGV("setFrameAvailableListener");
    Mutex::Autolock lock(mMutex);
    mFrameAvailableListener = listener;
}

void SurfaceTexture::freeBufferLocked(int i) {
    mSlots[i].mGraphicBuffer = 0;
    mSlots[i].mBufferState = BufferSlot::FREE;
    mSlots[i].mFrameNumber = 0;
    if (mSlots[i].mEglImage != EGL_NO_IMAGE_KHR) {
        eglDestroyImageKHR(mSlots[i].mEglDisplay, mSlots[i].mEglImage);
        mSlots[i].mEglImage = EGL_NO_IMAGE_KHR;
        mSlots[i].mEglDisplay = EGL_NO_DISPLAY;
    }
}

void SurfaceTexture::freeAllBuffersLocked() {
    LOGW_IF(!mQueue.isEmpty(),
            "freeAllBuffersLocked called but mQueue is not empty");
    mCurrentTexture = INVALID_BUFFER_SLOT;
    for (int i = 0; i < NUM_BUFFER_SLOTS; i++) {
        freeBufferLocked(i);
    }
}

void SurfaceTexture::freeAllBuffersExceptHeadLocked() {
    LOGW_IF(!mQueue.isEmpty(),
            "freeAllBuffersExceptCurrentLocked called but mQueue is not empty");
    int head = -1;
    if (!mQueue.empty()) {
        Fifo::iterator front(mQueue.begin());
        head = *front;
    }
    mCurrentTexture = INVALID_BUFFER_SLOT;
    for (int i = 0; i < NUM_BUFFER_SLOTS; i++) {
        if (i != head) {
            freeBufferLocked(i);
        }
    }
}

status_t SurfaceTexture::drainQueueLocked() {
    while (mSynchronousMode && !mQueue.isEmpty()) {
        mDequeueCondition.wait(mMutex);
        if (mAbandoned) {
            ST_LOGE("drainQueueLocked: SurfaceTexture has been abandoned!");
            return NO_INIT;
        }
        if (mConnectedApi == NO_CONNECTED_API) {
            ST_LOGE("drainQueueLocked: SurfaceTexture is not connected!");
            return NO_INIT;
        }
    }
    return NO_ERROR;
}

status_t SurfaceTexture::drainQueueAndFreeBuffersLocked() {
    status_t err = drainQueueLocked();
    if (err == NO_ERROR) {
        if (mSynchronousMode) {
            freeAllBuffersLocked();
        } else {
            freeAllBuffersExceptHeadLocked();
        }
    }
    return err;
}

EGLImageKHR SurfaceTexture::createImage(EGLDisplay dpy,
        const sp<GraphicBuffer>& graphicBuffer) {
    EGLClientBuffer cbuf = (EGLClientBuffer)graphicBuffer->getNativeBuffer();
    EGLint attrs[] = {
        EGL_IMAGE_PRESERVED_KHR,    EGL_TRUE,
        EGL_NONE,
    };
    EGLImageKHR image = eglCreateImageKHR(dpy, EGL_NO_CONTEXT,
            EGL_NATIVE_BUFFER_ANDROID, cbuf, attrs);
    if (image == EGL_NO_IMAGE_KHR) {
        EGLint error = eglGetError();
        ST_LOGE("error creating EGLImage: %#x", error);
    }
    return image;
}

sp<GraphicBuffer> SurfaceTexture::getCurrentBuffer() const {
    Mutex::Autolock lock(mMutex);
    return mCurrentTextureBuf;
}

Rect SurfaceTexture::getCurrentCrop() const {
    Mutex::Autolock lock(mMutex);
    return mCurrentCrop;
}

uint32_t SurfaceTexture::getCurrentTransform() const {
    Mutex::Autolock lock(mMutex);
    return mCurrentTransform;
}

uint32_t SurfaceTexture::getCurrentScalingMode() const {
    Mutex::Autolock lock(mMutex);
    return mCurrentScalingMode;
}

int SurfaceTexture::query(int what, int* outValue)
{
    Mutex::Autolock lock(mMutex);

    if (mAbandoned) {
        ST_LOGE("query: SurfaceTexture has been abandoned!");
        return NO_INIT;
    }

    int value;
    switch (what) {
    case NATIVE_WINDOW_WIDTH:
        value = mDefaultWidth;
        break;
    case NATIVE_WINDOW_HEIGHT:
        value = mDefaultHeight;
        break;
    case NATIVE_WINDOW_FORMAT:
        value = mPixelFormat;
        break;
    case NATIVE_WINDOW_MIN_UNDEQUEUED_BUFFERS:
        value = mSynchronousMode ?
                (MIN_UNDEQUEUED_BUFFERS-1) : MIN_UNDEQUEUED_BUFFERS;
        break;
    default:
        return BAD_VALUE;
    }
    outValue[0] = value;
    return NO_ERROR;
}

void SurfaceTexture::abandon() {
    Mutex::Autolock lock(mMutex);
    mQueue.clear();
    mAbandoned = true;
    mCurrentTextureBuf.clear();
    freeAllBuffersLocked();
    mDequeueCondition.signal();
}

void SurfaceTexture::setName(const String8& name) {
    mName = name;
}

void SurfaceTexture::dump(String8& result) const
{
    char buffer[1024];
    dump(result, "", buffer, 1024);
}

void SurfaceTexture::dump(String8& result, const char* prefix,
        char* buffer, size_t SIZE) const
{
    Mutex::Autolock _l(mMutex);
    snprintf(buffer, SIZE,
            "%smBufferCount=%d, mSynchronousMode=%d, default-size=[%dx%d], "
            "mPixelFormat=%d, mTexName=%d\n",
            prefix, mBufferCount, mSynchronousMode, mDefaultWidth,
            mDefaultHeight, mPixelFormat, mTexName);
    result.append(buffer);

    String8 fifo;
    int fifoSize = 0;
    Fifo::const_iterator i(mQueue.begin());
    while (i != mQueue.end()) {
        snprintf(buffer, SIZE, "%02d ", *i++);
        fifoSize++;
        fifo.append(buffer);
    }

    snprintf(buffer, SIZE,
            "%scurrent: {crop=[%d,%d,%d,%d], transform=0x%02x, current=%d}\n"
            "%snext   : {crop=[%d,%d,%d,%d], transform=0x%02x, FIFO(%d)={%s}}\n"
            ,
            prefix, mCurrentCrop.left,
            mCurrentCrop.top, mCurrentCrop.right, mCurrentCrop.bottom,
            mCurrentTransform, mCurrentTexture,
            prefix, mNextCrop.left, mNextCrop.top, mNextCrop.right,
            mNextCrop.bottom, mNextTransform, fifoSize, fifo.string()
    );
    result.append(buffer);

    struct {
        const char * operator()(int state) const {
            switch (state) {
                case BufferSlot::DEQUEUED: return "DEQUEUED";
                case BufferSlot::QUEUED: return "QUEUED";
                case BufferSlot::FREE: return "FREE";
                default: return "Unknown";
            }
        }
    } stateName;

    for (int i=0 ; i<mBufferCount ; i++) {
        const BufferSlot& slot(mSlots[i]);
        snprintf(buffer, SIZE,
                "%s%s[%02d] "
                "state=%-8s, crop=[%d,%d,%d,%d], "
                "transform=0x%02x, timestamp=%lld",
                prefix, (i==mCurrentTexture)?">":" ", i,
                stateName(slot.mBufferState),
                slot.mCrop.left, slot.mCrop.top, slot.mCrop.right,
                slot.mCrop.bottom, slot.mTransform, slot.mTimestamp
        );
        result.append(buffer);

        const sp<GraphicBuffer>& buf(slot.mGraphicBuffer);
        if (buf != NULL) {
            snprintf(buffer, SIZE,
                    ", %p [%4ux%4u:%4u,%3X]",
                    buf->handle, buf->width, buf->height, buf->stride,
                    buf->format);
            result.append(buffer);
        }
        result.append("\n");
    }
}

static void mtxMul(float out[16], const float a[16], const float b[16]) {
    out[0] = a[0]*b[0] + a[4]*b[1] + a[8]*b[2] + a[12]*b[3];
    out[1] = a[1]*b[0] + a[5]*b[1] + a[9]*b[2] + a[13]*b[3];
    out[2] = a[2]*b[0] + a[6]*b[1] + a[10]*b[2] + a[14]*b[3];
    out[3] = a[3]*b[0] + a[7]*b[1] + a[11]*b[2] + a[15]*b[3];

    out[4] = a[0]*b[4] + a[4]*b[5] + a[8]*b[6] + a[12]*b[7];
    out[5] = a[1]*b[4] + a[5]*b[5] + a[9]*b[6] + a[13]*b[7];
    out[6] = a[2]*b[4] + a[6]*b[5] + a[10]*b[6] + a[14]*b[7];
    out[7] = a[3]*b[4] + a[7]*b[5] + a[11]*b[6] + a[15]*b[7];

    out[8] = a[0]*b[8] + a[4]*b[9] + a[8]*b[10] + a[12]*b[11];
    out[9] = a[1]*b[8] + a[5]*b[9] + a[9]*b[10] + a[13]*b[11];
    out[10] = a[2]*b[8] + a[6]*b[9] + a[10]*b[10] + a[14]*b[11];
    out[11] = a[3]*b[8] + a[7]*b[9] + a[11]*b[10] + a[15]*b[11];

    out[12] = a[0]*b[12] + a[4]*b[13] + a[8]*b[14] + a[12]*b[15];
    out[13] = a[1]*b[12] + a[5]*b[13] + a[9]*b[14] + a[13]*b[15];
    out[14] = a[2]*b[12] + a[6]*b[13] + a[10]*b[14] + a[14]*b[15];
    out[15] = a[3]*b[12] + a[7]*b[13] + a[11]*b[14] + a[15]*b[15];
}

}; // namespace android