本來想用這一篇部落格把cameraHAL的實現和流程都給寫完的.搞了半天,東西實在是太多了.這篇先寫cameraHAL的基本實現框架,下一篇在具體寫camerahal的流程吧.

cameraHAL的實現:

對於初學者來說,最大的疑問是系統是如何呼叫hardware的.
這裡就以camera來舉例說明.
呼叫hardware的程式是cameraservice,我們就去它裡面看看它是如何找到hardware的

先把原始碼貼上來:

/*
**
** Copyright (C) 2008, 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 "CameraService"
//#define LOG_NDEBUG 0

#include <stdio.h>
#include <sys/types.h>
#include <pthread.h>

#include <binder/IPCThreadState.h>
#include <binder/IServiceManager.h>
#include <binder/MemoryBase.h>
#include <binder/MemoryHeapBase.h>
#include <cutils/atomic.h>
#include <cutils/properties.h>
#include <gui/SurfaceTextureClient.h>
#include <hardware/hardware.h>
#include <media/AudioSystem.h>
#include <media/mediaplayer.h>
#include <surfaceflinger/ISurface.h>
#include <utils/Errors.h>
#include <utils/Log.h>
#include <utils/String16.h>

#include "CameraService.h
 
"
#include "CameraHardwareInterface.h"

namespace android {

// ----------------------------------------------------------------------------
// Logging support -- this is for debugging only
// Use "adb shell dumpsys media.camera -v 1" to change it.
static volatile int32_t gLogLevel = 0;

#define LOG1(...) LOGD_IF(gLogLevel >= 1, __VA_ARGS__);
#define LOG2(...) LOGD_IF(gLogLevel >= 2, __VA_ARGS__);

static
 
 void setLogLevel(int level) {
    android_atomic_write(level, &gLogLevel);
}

// ----------------------------------------------------------------------------

static int getCallingPid() {
    return IPCThreadState::self()->getCallingPid();
}

static int getCallingUid() {
    return IPCThreadState::self()->getCallingUid();
}

// ----------------------------------------------------------------------------

// This is ugly and only safe if we never re-create the CameraService, but
// should be ok for now.
static CameraService *gCameraService;

CameraService::CameraService()
:mSoundRef(0), mModule(0)
{
    LOGI("CameraService started (pid=%d)", getpid());
    gCameraService = this;
}

void CameraService::onFirstRef()
{
    BnCameraService::onFirstRef();

    if (hw_get_module(CAMERA_HARDWARE_MODULE_ID,
                (const hw_module_t **)&mModule) < 0) {
        LOGE("Could not load camera HAL module");
        mNumberOfCameras = 0;
    }
    else {
        mNumberOfCameras = mModule->get_number_of_cameras();
        if (mNumberOfCameras > MAX_CAMERAS) {
            LOGE("Number of cameras(%d) > MAX_CAMERAS(%d).",
                    mNumberOfCameras, MAX_CAMERAS);
            mNumberOfCameras = MAX_CAMERAS;
        }
        for (int i = 0; i < mNumberOfCameras; i++) {
            setCameraFree(i);
        }
    }

    // Read the system property to determine if we have to use the
    // AUDIO_STREAM_ENFORCED_AUDIBLE type.
    char value[PROPERTY_VALUE_MAX];
    property_get("ro.camera.sound.forced", value, "0");
    if (strcmp(value, "0") != 0) {
        mAudioStreamType = AUDIO_STREAM_ENFORCED_AUDIBLE;
    } else {
        mAudioStreamType = AUDIO_STREAM_MUSIC;
    }
}

CameraService::~CameraService() {
    for (int i = 0; i < mNumberOfCameras; i++) {
        if (mBusy[i]) {
            LOGE("camera %d is still in use in destructor!", i);
        }
    }

    gCameraService = NULL;
}

int32_t CameraService::getNumberOfCameras() {
    return mNumberOfCameras;
}

status_t CameraService::getCameraInfo(int cameraId,
                                      struct CameraInfo* cameraInfo) {
    if (!mModule) {
        return NO_INIT;
    }

    if (cameraId < 0 || cameraId >= mNumberOfCameras) {
        return BAD_VALUE;
    }

    struct camera_info info;
    status_t rc = mModule->get_camera_info(cameraId, &info);
    cameraInfo->facing = info.facing;
    cameraInfo->orientation = info.orientation;
    return rc;
}

sp<ICamera> CameraService::connect(
        const sp<ICameraClient>& cameraClient, int cameraId) {
    int callingPid = getCallingPid();
    sp<CameraHardwareInterface> hardware = NULL;

    LOG1("CameraService::connect E (pid %d, id %d)", callingPid, cameraId);

    if (!mModule) {
        LOGE("Camera HAL module not loaded");
        return NULL;
    }

    sp<Client> client;
    if (cameraId < 0 || cameraId >= mNumberOfCameras) {
        LOGE("CameraService::connect X (pid %d) rejected (invalid cameraId %d).",
            callingPid, cameraId);
        return NULL;
    }

    char value[PROPERTY_VALUE_MAX];
    property_get("sys.secpolicy.camera.disabled", value, "0");
    if (strcmp(value, "1") == 0) {
        // Camera is disabled by DevicePolicyManager.
        LOGI("Camera is disabled. connect X (pid %d) rejected", callingPid);
        return NULL;
    }

    Mutex::Autolock lock(mServiceLock);
    if (mClient[cameraId] != 0) {
        client = mClient[cameraId].promote();
        if (client != 0) {
            if (cameraClient->asBinder() == client->getCameraClient()->asBinder()) {
                LOG1("CameraService::connect X (pid %d) (the same client)",
                    callingPid);
                return client;
            } else {
                LOGW("CameraService::connect X (pid %d) rejected (existing client).",
                    callingPid);
                return NULL;
            }
        }
        mClient[cameraId].clear();
    }

    if (mBusy[cameraId]) {
        LOGW("CameraService::connect X (pid %d) rejected"
             " (camera %d is still busy).", callingPid, cameraId);
        return NULL;
    }

    struct camera_info info;
    if (mModule->get_camera_info(cameraId, &info) != OK) {
        LOGE("Invalid camera id %d", cameraId);
        return NULL;
    }

    char camera_device_name[10];
    snprintf(camera_device_name, sizeof(camera_device_name), "%d", cameraId);

    hardware = new CameraHardwareInterface(camera_device_name);
    if (hardware->initialize(&mModule->common) != OK) {
        hardware.clear();
        return NULL;
    }

    client = new Client(this, cameraClient, hardware, cameraId, info.facing, callingPid);
    mClient[cameraId] = client;
    LOG1("CameraService::connect X");
    return client;
}

void CameraService::removeClient(const sp<ICameraClient>& cameraClient) {
    int callingPid = getCallingPid();
    LOG1("CameraService::removeClient E (pid %d)", callingPid);

    for (int i = 0; i < mNumberOfCameras; i++) {
        // Declare this before the lock to make absolutely sure the
        // destructor won't be called with the lock held.
        sp<Client> client;

        Mutex::Autolock lock(mServiceLock);

        // This happens when we have already disconnected (or this is
        // just another unused camera).
        if (mClient[i] == 0) continue;

        // Promote mClient. It can fail if we are called from this path:
        // Client::~Client() -> disconnect() -> removeClient().
        client = mClient[i].promote();

        if (client == 0) {
            mClient[i].clear();
            continue;
        }

        if (cameraClient->asBinder() == client->getCameraClient()->asBinder()) {
            // Found our camera, clear and leave.
            LOG1("removeClient: clear camera %d", i);
            mClient[i].clear();
            break;
        }
    }

    LOG1("CameraService::removeClient X (pid %d)", callingPid);
}

sp<CameraService::Client> CameraService::getClientById(int cameraId) {
    if (cameraId < 0 || cameraId >= mNumberOfCameras) return NULL;
    return mClient[cameraId].promote();
}

status_t CameraService::onTransact(
    uint32_t code, const Parcel& data, Parcel* reply, uint32_t flags) {
    // Permission checks
    switch (code) {
        case BnCameraService::CONNECT:
            const int pid = getCallingPid();
            const int self_pid = getpid();
            if (pid != self_pid) {
                // we're called from a different process, do the real check
                if (!checkCallingPermission(
                        String16("android.permission.CAMERA"))) {
                    const int uid = getCallingUid();
                    LOGE("Permission Denial: "
                         "can't use the camera pid=%d, uid=%d", pid, uid);
                    return PERMISSION_DENIED;
                }
            }
            break;
    }

    return BnCameraService::onTransact(code, data, reply, flags);
}

// The reason we need this busy bit is a new CameraService::connect() request
// may come in while the previous Client's destructor has not been run or is
// still running. If the last strong reference of the previous Client is gone
// but the destructor has not been finished, we should not allow the new Client
// to be created because we need to wait for the previous Client to tear down
// the hardware first.
void CameraService::setCameraBusy(int cameraId) {
    android_atomic_write(1, &mBusy[cameraId]);
}

void CameraService::setCameraFree(int cameraId) {
    android_atomic_write(0, &mBusy[cameraId]);
}

// We share the media players for shutter and recording sound for all clients.
// A reference count is kept to determine when we will actually release the
// media players.

MediaPlayer* CameraService::newMediaPlayer(const char *file) {
    MediaPlayer* mp = new MediaPlayer();
    if (mp->setDataSource(file, NULL) == NO_ERROR) {
        mp->setAudioStreamType(mAudioStreamType);
        mp->prepare();
    } else {
        LOGE("Failed to load CameraService sounds: %s", file);
        return NULL;
    }
    return mp;
}

void CameraService::loadSound() {
    Mutex::Autolock lock(mSoundLock);
    LOG1("CameraService::loadSound ref=%d", mSoundRef);
    if (mSoundRef++) return;

    mSoundPlayer[SOUND_SHUTTER] = newMediaPlayer("/system/media/audio/ui/camera_click.ogg");
    mSoundPlayer[SOUND_RECORDING] = newMediaPlayer("/system/media/audio/ui/VideoRecord.ogg");
}

void CameraService::releaseSound() {
    Mutex::Autolock lock(mSoundLock);
    LOG1("CameraService::releaseSound ref=%d", mSoundRef);
    if (--mSoundRef) return;

    for (int i = 0; i < NUM_SOUNDS; i++) {
        if (mSoundPlayer[i] != 0) {
            mSoundPlayer[i]->disconnect();
            mSoundPlayer[i].clear();
        }
    }
}

void CameraService::playSound(sound_kind kind) {
    LOG1("playSound(%d)", kind);
    Mutex::Autolock lock(mSoundLock);
    sp<MediaPlayer> player = mSoundPlayer[kind];
    if (player != 0) {
        player->seekTo(0);
        player->start();
    }
}

// ----------------------------------------------------------------------------

CameraService::Client::Client(const sp<CameraService>& cameraService,
        const sp<ICameraClient>& cameraClient,
        const sp<CameraHardwareInterface>& hardware,
        int cameraId, int cameraFacing, int clientPid) {
    int callingPid = getCallingPid();
    LOG1("Client::Client E (pid %d)", callingPid);

    mCameraService = cameraService;
    mCameraClient = cameraClient;
    mHardware = hardware;
    mCameraId = cameraId;
    mCameraFacing = cameraFacing;
    mClientPid = clientPid;
    mMsgEnabled = 0;
    mSurface = 0;
    mPreviewWindow = 0;
    mHardware->setCallbacks(notifyCallback,
                            dataCallback,
                            dataCallbackTimestamp,
                            (void *)cameraId);

    // Enable zoom, error, focus, and metadata messages by default
    enableMsgType(CAMERA_MSG_ERROR | CAMERA_MSG_ZOOM | CAMERA_MSG_FOCUS |
                  CAMERA_MSG_PREVIEW_METADATA);

    // Callback is disabled by default
    mPreviewCallbackFlag = CAMERA_FRAME_CALLBACK_FLAG_NOOP;
    mOrientation = getOrientation(0, mCameraFacing == CAMERA_FACING_FRONT);
    mPlayShutterSound = true;
    cameraService->setCameraBusy(cameraId);
    cameraService->loadSound();
    LOG1("Client::Client X (pid %d)", callingPid);
}

// tear down the client
CameraService::Client::~Client() {
    int callingPid = getCallingPid();
    LOG1("Client::~Client E (pid %d, this %p)", callingPid, this);

    // set mClientPid to let disconnet() tear down the hardware
    mClientPid = callingPid;
    disconnect();
    mCameraService->releaseSound();
    LOG1("Client::~Client X (pid %d, this %p)", callingPid, this);
}

// ----------------------------------------------------------------------------

status_t CameraService::Client::checkPid() const {
    int callingPid = getCallingPid();
    if (callingPid == mClientPid) return NO_ERROR;

    LOGW("attempt to use a locked camera from a different process"
         " (old pid %d, new pid %d)", mClientPid, callingPid);
    return EBUSY;
}

status_t CameraService::Client::checkPidAndHardware() const {
    status_t result = checkPid();
    if (result != NO_ERROR) return result;
    if (mHardware == 0) {
        LOGE("attempt to use a camera after disconnect() (pid %d)", getCallingPid());
        return INVALID_OPERATION;
    }
    return NO_ERROR;
}

status_t CameraService::Client::lock() {
    int callingPid = getCallingPid();
    LOG1("lock (pid %d)", callingPid);
    Mutex::Autolock lock(mLock);

    // lock camera to this client if the the camera is unlocked
    if (mClientPid == 0) {
        mClientPid = callingPid;
        return NO_ERROR;
    }

    // returns NO_ERROR if the client already owns the camera, EBUSY otherwise
    return checkPid();
}

status_t CameraService::Client::unlock() {
    int callingPid = getCallingPid();
    LOG1("unlock (pid %d)", callingPid);
    Mutex::Autolock lock(mLock);

    // allow anyone to use camera (after they lock the camera)
    status_t result = checkPid();
    if (result == NO_ERROR) {
        if (mHardware->recordingEnabled()) {
            LOGE("Not allowed to unlock camera during recording.");
            return INVALID_OPERATION;
        }
        mClientPid = 0;
        LOG1("clear mCameraClient (pid %d)", callingPid);
        // we need to remove the reference to ICameraClient so that when the app
        // goes away, the reference count goes to 0.
        mCameraClient.clear();
    }
    return result;
}

// connect a new client to the camera
status_t CameraService::Client::connect(const sp<ICameraClient>& client) {
    int callingPid = getCallingPid();
    LOG1("connect E (pid %d)", callingPid);
    Mutex::Autolock lock(mLock);

    if (mClientPid != 0 && checkPid() != NO_ERROR) {
        LOGW("Tried to connect to a locked camera (old pid %d, new pid %d)",
                mClientPid, callingPid);
        return EBUSY;
    }

    if (mCameraClient != 0 && (client->asBinder() == mCameraClient->asBinder())) {
        LOG1("Connect to the same client");
        return NO_ERROR;
    }

    mPreviewCallbackFlag = CAMERA_FRAME_CALLBACK_FLAG_NOOP;
    mClientPid = callingPid;
    mCameraClient = client;

    LOG1("connect X (pid %d)", callingPid);
    return NO_ERROR;
}

static void disconnectWindow(const sp<ANativeWindow>& window) {
    if (window != 0) {
        status_t result = native_window_api_disconnect(window.get(),
                NATIVE_WINDOW_API_CAMERA);
        if (result != NO_ERROR) {
            LOGW("native_window_api_disconnect failed: %s (%d)", strerror(-result),
                    result);
        }
    }
}

void CameraService::Client::disconnect() {
    int callingPid = getCallingPid();
    LOG1("disconnect E (pid %d)", callingPid);
    Mutex::Autolock lock(mLock);

    if (checkPid() != NO_ERROR) {
        LOGW("different client - don't disconnect");
        return;
    }

    if (mClientPid <= 0) {
        LOG1("camera is unlocked (mClientPid = %d), don't tear down hardware", mClientPid);
        return;
    }

    // Make sure disconnect() is done once and once only, whether it is called
    // from the user directly, or called by the destructor.
    if (mHardware == 0) return;

    LOG1("hardware teardown");
    // Before destroying mHardware, we must make sure it's in the
    // idle state.
    // Turn off all messages.
    disableMsgType(CAMERA_MSG_ALL_MSGS);
    mHardware->stopPreview();
    mHardware->cancelPicture();
    // Release the hardware resources.
    mHardware->release();

    // Release the held ANativeWindow resources.
    if (mPreviewWindow != 0) {
        disconnectWindow(mPreviewWindow);
        mPreviewWindow = 0;
        mHardware->setPreviewWindow(mPreviewWindow);
    }
    mHardware.clear();

    mCameraService->removeClient(mCameraClient);
    mCameraService->setCameraFree(mCameraId);

    LOG1("disconnect X (pid %d)", callingPid);
}

// ----------------------------------------------------------------------------

status_t CameraService::Client::setPreviewWindow(const sp<IBinder>& binder,
        const sp<ANativeWindow>& window) {
    Mutex::Autolock lock(mLock);
    status_t result = checkPidAndHardware();
    if (result != NO_ERROR) return result;

    // return if no change in surface.
    if (binder == mSurface) {
        return NO_ERROR;
    }

    if (window != 0) {
        result = native_window_api_connect(window.get(), NATIVE_WINDOW_API_CAMERA);
        if (result != NO_ERROR) {
            LOGE("native_window_api_connect failed: %s (%d)", strerror(-result),
                    result);
            return result;
        }
    }

    // If preview has been already started, register preview buffers now.
    if (mHardware->previewEnabled()) {
        if (window != 0) {
            native_window_set_scaling_mode(window.get(),
                    NATIVE_WINDOW_SCALING_MODE_SCALE_TO_WINDOW);
            native_window_set_buffers_transform(window.get(), mOrientation);
            result = mHardware->setPreviewWindow(window);
        }
    }

    if (result == NO_ERROR) {
        // Everything has succeeded.  Disconnect the old window and remember the
        // new window.
        disconnectWindow(mPreviewWindow);
        mSurface = binder;
        mPreviewWindow = window;
    } else {
        // Something went wrong after we connected to the new window, so
        // disconnect here.
        disconnectWindow(window);
    }

    return result;
}

// set the Surface that the preview will use
status_t CameraService::Client::setPreviewDisplay(const sp<Surface>& surface) {
    LOG1("setPreviewDisplay(%p) (pid %d)", surface.get(), getCallingPid());

    sp<IBinder> binder(surface != 0 ? surface->asBinder() : 0);
    sp<ANativeWindow> window(surface);
    return setPreviewWindow(binder, window);
}

// set the SurfaceTexture that the preview will use
status_t CameraService::Client::setPreviewTexture(
        const sp<ISurfaceTexture>& surfaceTexture) {
    LOG1("setPreviewTexture(%p) (pid %d)", surfaceTexture.get(),
            getCallingPid());

    sp<IBinder> binder;
    sp<ANativeWindow> window;
    if (surfaceTexture != 0) {
        binder = surfaceTexture->asBinder();
        window = new SurfaceTextureClient(surfaceTexture);
    }
    return setPreviewWindow(binder, window);
}

// set the preview callback flag to affect how the received frames from
// preview are handled.
void CameraService::Client::setPreviewCallbackFlag(int callback_flag) {
    LOG1("setPreviewCallbackFlag(%d) (pid %d)", callback_flag, getCallingPid());
    Mutex::Autolock lock(mLock);
    if (checkPidAndHardware() != NO_ERROR) return;

    mPreviewCallbackFlag = callback_flag;
    if (mPreviewCallbackFlag & CAMERA_FRAME_CALLBACK_FLAG_ENABLE_MASK) {
        enableMsgType(CAMERA_MSG_PREVIEW_FRAME);
    } else {
        disableMsgType(CAMERA_MSG_PREVIEW_FRAME);
    }
}

// start preview mode
status_t CameraService::Client::startPreview() {
    LOG1("startPreview (pid %d)", getCallingPid());
    return startCameraMode(CAMERA_PREVIEW_MODE);
}

// start recording mode
status_t CameraService::Client::startRecording() {
    LOG1("startRecording (pid %d)", getCallingPid());
    return startCameraMode(CAMERA_RECORDING_MODE);
}

// start preview or recording
status_t CameraService::Client::startCameraMode(camera_mode mode) {
    LOG1("startCameraMode(%d)", mode);
    Mutex::Autolock lock(mLock);
    status_t result = checkPidAndHardware();
    if (result != NO_ERROR) return result;

    switch(mode) {
        case CAMERA_PREVIEW_MODE:
            if (mSurface == 0 && mPreviewWindow == 0) {
                LOG1("mSurface is not set yet.");
                // still able to start preview in this case.
            }
            return startPreviewMode();
        case CAMERA_RECORDING_MODE:
            if (mSurface == 0 && mPreviewWindow == 0) {
                LOGE("mSurface or mPreviewWindow must be set before startRecordingMode.");
                return INVALID_OPERATION;
            }
            return startRecordingMode();
        default:
            return UNKNOWN_ERROR;
    }
}

status_t CameraService::Client::startPreviewMode() {
    LOG1("startPreviewMode");
    status_t result = NO_ERROR;

    // if preview has been enabled, nothing needs to be done
    if (mHardware->previewEnabled()) {
        return NO_ERROR;
    }

    if (mPreviewWindow != 0) {
        native_window_set_scaling_mode(mPreviewWindow.get(),
                NATIVE_WINDOW_SCALING_MODE_SCALE_TO_WINDOW);
        native_window_set_buffers_transform(mPreviewWindow.get(),
                mOrientation);
    }
    mHardware->setPreviewWindow(mPreviewWindow);
    result = mHardware->startPreview();

    return result;
}

status_t CameraService::Client::startRecordingMode() {
    LOG1("startRecordingMode");
    status_t result = NO_ERROR;

    // if recording has been enabled, nothing needs to be done
    if (mHardware->recordingEnabled()) {
        return NO_ERROR;
    }

    // if preview has not been started, start preview first
    if (!mHardware->previewEnabled()) {
        result = startPreviewMode();
        if (result != NO_ERROR) {
            return result;
        }
    }

    // start recording mode
    enableMsgType(CAMERA_MSG_VIDEO_FRAME);
    mCameraService->playSound(SOUND_RECORDING);
    result = mHardware->startRecording();
    if (result != NO_ERROR) {
        LOGE("mHardware->startRecording() failed with status %d", result);
    }
    return result;
}

// stop preview mode
void CameraService::Client::stopPreview() {
    LOG1("stopPreview (pid %d)", getCallingPid());
    Mutex::Autolock lock(mLock);
    if (checkPidAndHardware() != NO_ERROR) return;


    disableMsgType(CAMERA_MSG_PREVIEW_FRAME);
    mHardware->stopPreview();

    mPreviewBuffer.clear();
}

// stop recording mode
void CameraService::Client::stopRecording() {
    LOG1("stopRecording (pid %d)", getCallingPid());
    Mutex::Autolock lock(mLock);
    if (checkPidAndHardware() != NO_ERROR) return;

    mCameraService->playSound(SOUND_RECORDING);
    disableMsgType(CAMERA_MSG_VIDEO_FRAME);
    mHardware->stopRecording();

    mPreviewBuffer.clear();
}

// release a recording frame
void CameraService::Client::releaseRecordingFrame(const sp<IMemory>& mem) {
    Mutex::Autolock lock(mLock);
    if (checkPidAndHardware() != NO_ERROR) return;
    mHardware->releaseRecordingFrame(mem);
}

status_t CameraService::Client::storeMetaDataInBuffers(bool enabled)
{
    LOG1("storeMetaDataInBuffers: %s", enabled? "true": "false");
    Mutex::Autolock lock(mLock);
    if (checkPidAndHardware() != NO_ERROR) {
        return UNKNOWN_ERROR;
    }
    return mHardware->storeMetaDataInBuffers(enabled);
}

bool CameraService::Client::previewEnabled() {
    LOG1("previewEnabled (pid %d)", getCallingPid());

    Mutex::Autolock lock(mLock);
    if (checkPidAndHardware() != NO_ERROR) return false;
    return mHardware->previewEnabled();
}

bool CameraService::Client::recordingEnabled() {
    LOG1("recordingEnabled (pid %d)", getCallingPid());

    Mutex::Autolock lock(mLock);
    if (checkPidAndHardware() != NO_ERROR) return false;
    return mHardware->recordingEnabled();
}

status_t CameraService::Client::autoFocus() {
    LOG1("autoFocus (pid %d)", getCallingPid());

    Mutex::Autolock lock(mLock);
    status_t result = checkPidAndHardware();
    if (result != NO_ERROR) return result;

    return mHardware->autoFocus();
}

status_t CameraService::Client::cancelAutoFocus() {
    LOG1("cancelAutoFocus (pid %d)", getCallingPid());

    Mutex::Autolock lock(mLock);
    status_t result = checkPidAndHardware();
    if (result != NO_ERROR) return result;

    return mHardware->cancelAutoFocus();
}

// take a picture - image is returned in callback
status_t CameraService::Client::takePicture(int msgType) {
    LOG1("takePicture (pid %d): 0x%x", getCallingPid(), msgType);

    Mutex::Autolock lock(mLock);
    status_t result = checkPidAndHardware();
    if (result != NO_ERROR) return result;

    if ((msgType & CAMERA_MSG_RAW_IMAGE) &&
        (msgType & CAMERA_MSG_RAW_IMAGE_NOTIFY)) {
        LOGE("CAMERA_MSG_RAW_IMAGE and CAMERA_MSG_RAW_IMAGE_NOTIFY"
                " cannot be both enabled");
        return BAD_VALUE;
    }

    // We only accept picture related message types
    // and ignore other types of messages for takePicture().
    int picMsgType = msgType
                        & (CAMERA_MSG_SHUTTER |
                           CAMERA_MSG_POSTVIEW_FRAME |
                           CAMERA_MSG_RAW_IMAGE |
                           CAMERA_MSG_RAW_IMAGE_NOTIFY |
                           CAMERA_MSG_COMPRESSED_IMAGE);

    enableMsgType(picMsgType);

    return mHardware->takePicture();
}

// set preview/capture parameters - key/value pairs
status_t CameraService::Client::setParameters(const String8& params) {
    LOG1("setParameters (pid %d) (%s)", getCallingPid(), params.string());

    Mutex::Autolock lock(mLock);
    status_t result = checkPidAndHardware();
    if (result != NO_ERROR) return result;

    CameraParameters p(params);
    return mHardware->setParameters(p);
}

// get preview/capture parameters - key/value pairs
String8 CameraService::Client::getParameters() const {
    Mutex::Autolock lock(mLock);
    if (checkPidAndHardware() != NO_ERROR) return String8();

    String8 params(mHardware->getParameters().flatten());
    LOG1("getParameters (pid %d) (%s)", getCallingPid(), params.string());
    return params;
}

// enable shutter sound
status_t CameraService::Client::enableShutterSound(bool enable) {
    LOG1("enableShutterSound (pid %d)", getCallingPid());

    status_t result = checkPidAndHardware();
    if (result != NO_ERROR) return result;

    if (enable) {
        mPlayShutterSound = true;
        return OK;
    }

    // Disabling shutter sound may not be allowed. In that case only
    // allow the mediaserver process to disable the sound.
    char value[PROPERTY_VALUE_MAX];
    property_get("ro.camera.sound.forced", value, "0");
    if (strcmp(value, "0") != 0) {
        // Disabling shutter sound is not allowed. Deny if the current
        // process is not mediaserver.
        if (getCallingPid() != getpid()) {
            LOGE("Failed to disable shutter sound. Permission denied (pid %d)", getCallingPid());
            return PERMISSION_DENIED;
        }
    }

    mPlayShutterSound = false;
    return OK;
}

status_t CameraService::Client::sendCommand(int32_t cmd, int32_t arg1, int32_t arg2) {
    LOG1("sendCommand (pid %d)", getCallingPid());
    int orientation;
    Mutex::Autolock lock(mLock);
    status_t result = checkPidAndHardware();
    if (result != NO_ERROR) return result;

    if (cmd == CAMERA_CMD_SET_DISPLAY_ORIENTATION) {
        // Mirror the preview if the camera is front-facing.
        orientation = getOrientation(arg1, mCameraFacing == CAMERA_FACING_FRONT);
        if (orientation == -1) return BAD_VALUE;

        if (mOrientation != orientation) {
            mOrientation = orientation;
            if (mPreviewWindow != 0) {
                native_window_set_buffers_transform(mPreviewWindow.get(),
                        mOrientation);
            }
        }
        return OK;
    } else if (cmd == CAMERA_CMD_ENABLE_SHUTTER_SOUND) {
        switch (arg1) {
            case 0:
                enableShutterSound(false);
                break;
            case 1:
                enableShutterSound(true);
                break;
            default:
                return BAD_VALUE;
        }
        return OK;
    } else if (cmd == CAMERA_CMD_PLAY_RECORDING_SOUND) {
        mCameraService->playSound(SOUND_RECORDING);
    }

    return mHardware->sendCommand(cmd, arg1, arg2);
}

// ----------------------------------------------------------------------------

void CameraService::Client::enableMsgType(int32_t msgType) {
    android_atomic_or(msgType, &mMsgEnabled);
    mHardware->enableMsgType(msgType);
}

void CameraService::Client::disableMsgType(int32_t msgType) {
    android_atomic_and(~msgType, &mMsgEnabled);
    mHardware->disableMsgType(msgType);
}

#define CHECK_MESSAGE_INTERVAL 10 // 10ms
bool CameraService::Client::lockIfMessageWanted(int32_t msgType) {
    int sleepCount = 0;
    while (mMsgEnabled & msgType) {
        if (mLock.tryLock() == NO_ERROR) {
            if (sleepCount > 0) {
                LOG1("lockIfMessageWanted(%d): waited for %d ms",
                    msgType, sleepCount * CHECK_MESSAGE_INTERVAL);
            }
            return true;
        }
        if (sleepCount++ == 0) {
            LOG1("lockIfMessageWanted(%d): enter sleep", msgType);
        }
        usleep(CHECK_MESSAGE_INTERVAL * 1000);
    }
    LOGW("lockIfMessageWanted(%d): dropped unwanted message", msgType);
    return false;
}

// ----------------------------------------------------------------------------

// Converts from a raw pointer to the client to a strong pointer during a
// hardware callback. This requires the callbacks only happen when the client
// is still alive.
sp<CameraService::Client> CameraService::Client::getClientFromCookie(void* user) {
    sp<Client> client = gCameraService->getClientById((int) user);

    // This could happen if the Client is in the process of shutting down (the
    // last strong reference is gone, but the destructor hasn't finished
    // stopping the hardware).
    if (client == 0) return NULL;

    // The checks below are not necessary and are for debugging only.
    if (client->mCameraService.get() != gCameraService) {
        LOGE("mismatch service!");
        return NULL;
    }

    if (client->mHardware == 0) {
        LOGE("mHardware == 0: callback after disconnect()?");
        return NULL;
    }

    return client;
}

// Callback messages can be dispatched to internal handlers or pass to our
// client's callback functions, depending on the message type.
//
// notifyCallback:
//      CAMERA_MSG_SHUTTER              handleShutter
//      (others)                        c->notifyCallback
// dataCallback:
//      CAMERA_MSG_PREVIEW_FRAME        handlePreviewData
//      CAMERA_MSG_POSTVIEW_FRAME       handlePostview
//      CAMERA_MSG_RAW_IMAGE            handleRawPicture
//      CAMERA_MSG_COMPRESSED_IMAGE     handleCompressedPicture
//      (others)                        c->dataCallback
// dataCallbackTimestamp
//      (others)                        c->dataCallbackTimestamp
//
// NOTE: the *Callback functions grab mLock of the client before passing
// control to handle* functions. So the handle* functions must release the
// lock before calling the ICameraClient's callbacks, so those callbacks can
// invoke methods in the Client class again (For example, the preview frame
// callback may want to releaseRecordingFrame). The handle* functions must
// release the lock after all accesses to member variables, so it must be
// handled very carefully.

void CameraService::Client::notifyCallback(int32_t msgType, int32_t ext1,
        int32_t ext2, void* user) {
    LOG2("notifyCallback(%d)", msgType);

    sp<Client> client = getClientFromCookie(user);
    if (client == 0) return;
    if (!client->lockIfMessageWanted(msgType)) return;

    switch (msgType) {
        case CAMERA_MSG_SHUTTER:
            // ext1 is the dimension of the yuv picture.
            client->handleShutter();
            break;
        default:
            client->handleGenericNotify(msgType, ext1, ext2);
            break;
    }
}

void CameraService::Client::dataCallback(int32_t msgType,
        const sp<IMemory>& dataPtr, camera_frame_metadata_t *metadata, void* user) {
    LOG2("dataCallback(%d)", msgType);

    sp<Client> client = getClientFromCookie(user);
    if (client == 0) return;
    if (!client->lockIfMessageWanted(msgType)) return;

    if (dataPtr == 0 && metadata == NULL) {
        LOGE("Null data returned in data callback");
        client->handleGenericNotify(CAMERA_MSG_ERROR, UNKNOWN_ERROR, 0);
        return;
    }

    switch (msgType & ~CAMERA_MSG_PREVIEW_METADATA) {
        case CAMERA_MSG_PREVIEW_FRAME:
            client->handlePreviewData(msgType, dataPtr, metadata);
            break;
        case CAMERA_MSG_POSTVIEW_FRAME:
            client->handlePostview(dataPtr);
            break;
        case CAMERA_MSG_RAW_IMAGE:
            client->handleRawPicture(dataPtr);
            break;
        case CAMERA_MSG_COMPRESSED_IMAGE:
            client->handleCompressedPicture(dataPtr);
            break;
        default:
            client->handleGenericData(msgType, dataPtr, metadata);
            break;
    }
}

void CameraService::Client::dataCallbackTimestamp(nsecs_t timestamp,
        int32_t msgType, const sp<IMemory>& dataPtr, void* user) {
    LOG2("dataCallbackTimestamp(%d)", msgType);

    sp<Client> client = getClientFromCookie(user);
    if (client == 0) return;
    if (!client->lockIfMessageWanted(msgType)) return;

    if (dataPtr == 0) {
        LOGE("Null data returned in data with timestamp callback");
        client->handleGenericNotify(CAMERA_MSG_ERROR, UNKNOWN_ERROR, 0);
        return;
    }

    client->handleGenericDataTimestamp(timestamp, msgType, dataPtr);
}

// snapshot taken callback
void CameraService::Client::handleShutter(void) {
    if (mPlayShutterSound) {
        mCameraService->playSound(SOUND_SHUTTER);
    }

    sp<ICameraClient> c = mCameraClient;
    if (c != 0) {
        mLock.unlock();
        c->notifyCallback(CAMERA_MSG_SHUTTER, 0, 0);
        if (!lockIfMessageWanted(CAMERA_MSG_SHUTTER)) return;
    }
    disableMsgType(CAMERA_MSG_SHUTTER);

    mLock.unlock();
}

// preview callback - frame buffer update
void CameraService::Client::handlePreviewData(int32_t msgType,
                                              const sp<IMemory>& mem,
                                              camera_frame_metadata_t *metadata) {
    ssize_t offset;
    size_t size;
    sp<IMemoryHeap> heap = mem->getMemory(&offset, &size);

    // local copy of the callback flags
    int flags = mPreviewCallbackFlag;

    // is callback enabled?
    if (!(flags & CAMERA_FRAME_CALLBACK_FLAG_ENABLE_MASK)) {
        // If the enable bit is off, the copy-out and one-shot bits are ignored
        LOG2("frame callback is disabled");
        mLock.unlock();
        return;
    }

    // hold a strong pointer to the client
    sp<ICameraClient> c = mCameraClient;

    // clear callback flags if no client or one-shot mode
    if (c == 0 || (mPreviewCallbackFlag & CAMERA_FRAME_CALLBACK_FLAG_ONE_SHOT_MASK)) {
        LOG2("Disable preview callback");
        mPreviewCallbackFlag &= ~(CAMERA_FRAME_CALLBACK_FLAG_ONE_SHOT_MASK |
                                  CAMERA_FRAME_CALLBACK_FLAG_COPY_OUT_MASK |
                                  CAMERA_FRAME_CALLBACK_FLAG_ENABLE_MASK);
        disableMsgType(CAMERA_MSG_PREVIEW_FRAME);
    }

    if (c != 0) {
        // Is the received frame copied out or not?
        if (flags & CAMERA_FRAME_CALLBACK_FLAG_COPY_OUT_MASK) {
            LOG2("frame is copied");
            copyFrameAndPostCopiedFrame(msgType, c, heap, offset, size, metadata);
        } else {
            LOG2("frame is forwarded");
            mLock.unlock();
            c->dataCallback(msgType, mem, metadata);
        }
    } else {
        mLock.unlock();
    }
}

// picture callback - postview image ready
void CameraService::Client::handlePostview(const sp<IMemory>& mem) {
    disableMsgType(CAMERA_MSG_POSTVIEW_FRAME);

    sp<ICameraClient> c = mCameraClient;
    mLock.unlock();
    if (c != 0) {
        c->dataCallback(CAMERA_MSG_POSTVIEW_FRAME, mem, NULL);
    }
}

// picture callback - raw image ready
void CameraService::Client::handleRawPicture(const sp<IMemory>& mem) {
    disableMsgType(CAMERA_MSG_RAW_IMAGE);

    ssize_t offset;
    size_t size;
    sp<IMemoryHeap> heap = mem->getMemory(&offset, &size);

    sp<ICameraClient> c = mCameraClient;
    mLock.unlock();
    if (c != 0) {
        c->dataCallback(CAMERA_MSG_RAW_IMAGE, mem, NULL);
    }
}

// picture callback - compressed picture ready
void CameraService::Client::handleCompressedPicture(const sp<IMemory>& mem) {
    disableMsgType(CAMERA_MSG_COMPRESSED_IMAGE);

    sp<ICameraClient> c = mCameraClient;
    mLock.unlock();
    if (c != 0) {
        c->dataCallback(CAMERA_MSG_COMPRESSED_IMAGE, mem, NULL);
    }
}


void CameraService::Client::handleGenericNotify(int32_t msgType,
    int32_t ext1, int32_t ext2) {
    sp<ICameraClient> c = mCameraClient;
    mLock.unlock();
    if (c != 0) {
        c->notifyCallback(msgType, ext1, ext2);
    }
}

void CameraService::Client::handleGenericData(int32_t msgType,
    const sp<IMemory>& dataPtr, camera_frame_metadata_t *metadata) {
    sp<ICameraClient> c = mCameraClient;
    mLock.unlock();
    if (c != 0) {
        c->dataCallback(msgType, dataPtr, metadata);
    }
}

void CameraService::Client::handleGenericDataTimestamp(nsecs_t timestamp,
    int32_t msgType, const sp<IMemory>& dataPtr) {
    sp<ICameraClient> c = mCameraClient;
    mLock.unlock();
    if (c != 0) {
        c->dataCallbackTimestamp(timestamp, msgType, dataPtr);
    }
}

void CameraService::Client::copyFrameAndPostCopiedFrame(
        int32_t msgType, const sp<ICameraClient>& client,
        const sp<IMemoryHeap>& heap, size_t offset, size_t size,
        camera_frame_metadata_t *metadata) {
    LOG2("copyFrameAndPostCopiedFrame");
    // It is necessary to copy out of pmem before sending this to
    // the callback. For efficiency, reuse the same MemoryHeapBase
    // provided it's big enough. Don't allocate the memory or
    // perform the copy if there's no callback.
    // hold the preview lock while we grab a reference to the preview buffer
    sp<MemoryHeapBase> previewBuffer;

    if (mPreviewBuffer == 0) {
        mPreviewBuffer = new MemoryHeapBase(size, 0, NULL);
    } else if (size > mPreviewBuffer->virtualSize()) {
        mPreviewBuffer.clear();
        mPreviewBuffer = new MemoryHeapBase(size, 0, NULL);
    }
    if (mPreviewBuffer == 0) {
        LOGE("failed to allocate space for preview buffer");
        mLock.unlock();
        return;
    }
    previewBuffer = mPreviewBuffer;

    memcpy(previewBuffer->base(), (uint8_t *)heap->base() +